Title of Invention	A METHOD OF ALLOCATING RESOURCE-AREA IN WIRELESS ACCESS SYSTEM
Abstract	A method of allocating a radio resource in a wireless access system is disclosed. The method includes receiving a control message associated with radio resource allocation for transmitting uplink data to the base station, wherein the control message comprises a first persistent uplink allocation information element comprising first resource allocation information associated with a first resource allocation region for transmitting the uplink data of a mobile station and transmitting an acknowledgment (ACK) message from the mobile station to the base station in response to successfully receiving the first persistent uplink allocation information element.

Title of Invention

A METHOD OF ALLOCATING RESOURCE-AREA IN WIRELESS ACCESS SYSTEM

Abstract

A method of allocating a radio resource in a wireless access system is disclosed. The method includes receiving a control message associated with radio resource allocation for transmitting uplink data to the base station, wherein the control message comprises a first persistent uplink allocation information element comprising first resource allocation information associated with a first resource allocation region for transmitting the uplink data of a mobile station and transmitting an acknowledgment (ACK) message from the mobile station to the base station in response to successfully receiving the first persistent uplink allocation information element.

Full Text	[DESCRIPTION] [Invention Title] A METHOD OF ALLOCATING RESOURCE-AREA IN WIRELESS ACCESS SYSTEM [Technical Field] The present invention relates to a wireless access system, and more particularly to a packet transmission method for frequent packet transmission and a method of allocating radio resources in the wireless communication system. [Background Art] A broadband wireless access system to transmit a packet to user equipment (UE) based on an IP-based Voice over Internet Protocol (VoIP) service is described below. VoIP traffic is created with a fixed size having a fixed period within a VoIP codec. VoIP communication may be classified into a talk-spurt period and a silence period. During the talk-spurt period, a speech mode is maintained between users. During the silence period, the user listens to the other party without talking to the other party. The silence period may occupy 50% or more of a general call session. Therefore, in order to allocate different amounts of bandwidths to the talk-spurt period and the silence period, a variety of voice codecs may be used. A representative example of the voice codec is an adaptive multi-rate (AMR) for use in a Global System for Mobile communication (GSM) and a Universal Mobile Telecommunications System (UMTS). Voice data is not generated during the silence period. If the bandwidth is allocated to the silence period, radio resources may be wasted. In order to prevent this problem, VoIP supports a silence suppression scheme. According to the silence suppression scheme, a vocoder for generating the VoIP traffic does not generate traffic data. However, the vocoder periodically generates comfort noise to inform the other user that the call is still ongoing. For example, the vocoder based on the above-mentioned AMR codec generates a fixed-sized packet at intervals of 20 ms in the talk-spurt period, and generates the comfort noise at intervals of 160 ms in the silence period. In order to perform resource allocation of traffic data, which has a fixed-sized constant period such as a VoIP, a Node-B or base station (BS) may fixedly assign a predetermined region to a specific UE. For example, the BS assigns the region as large as the initially-defined size to the UE capable of supporting the VoIP service. The BS may also inform the UE of the assigned resource region information using a control channel or a control message such as a UL-MAP or a DL-MAP. Accordingly, the control channel or the control message, which is initially transmitted, may also include period information of the next allocation region. From the next period, the BS may successively assign a corresponding region without any specified notification associated with the above region which has been notified to the mobile station (MS), using the initially-transmitted control channel or the initially-transmitted control message. Therefore, the MS transmits the VoIP packet to the assigned region using region information which has been initially assigned on the map and transmits the VoIP packet from the next period to the same region using period information. For example, when the frame length is set to 5 ms in consideration of the VoIP service and a frame period assigned to the MS for VoIP packet transmission is set to 4 frames, the frame period assigned to the MS for the VoIP packet transmission may be changed to another according to service characteristics. Specifically, if the same VoIP service is used, the frame period assigned for VoIP packet transmission may be defined in different ways according to individual elements such as system characteristic and VoIP service status. For example, the system characteristic may be changed according to the frame length and the VoIP service status may be either the talk-spurt period or the silence period. The BS located at an initial frame informs the MS of the allocation region information to transmit the VoIP packet via the UL-MAP. If the BS is located at a fourth or eighth frame corresponding to each period, it does not inform the region information via the UL-MAP and assigns only the region for VoIP packet transmission. In this case, the period assigned for the VoIP packet transmission may be 4 frames or 20 ms. The MS stores region allocation information contained in the UL-MAP message received from the initial frame. Therefore, the MS can transmit the VoIP packet via a corresponding region although the UL-MAP message is not additionally received from the fourth and eighth frames corresponding to the resource allocation period. Accordingly, the BS is fixed to a single VoIP connection due to the VoIP traffic characteristic and can persistently assign resources to this VoIP connection. If a control message for assigning a new transmission region is lost in a wired or wireless downlink, the conventional system has a disadvantage in that individual transmission region information recognized by the MS and the BS is unavoidably different from each other. Therefore, in case of the downlink, the MS is unable to receive the VoIP packet from the BS. In case of the uplink, although the MS transmits the VoIP packet via the second transmission region, the BS may assign the second transmission region to another MS, resulting in unexpected problems. In other words, if the MS transmits the VoIP packet via the second transmission region, a packet transmission by another MS may fail. If the system uses an incremental redundancy (HARQ-IR) scheme, the number of retransmission will be increased, resulting in unexpected problems. [Disclosure] [Technical Problem] Accordingly, the present invention is directed to a packet transmission method for resource allocation in a broadband wireless access system that substantially obviates one or more problems due to limitations and disadvantages of the related art. An object of the present invention is to provide a method for assigning a resource area and a control channel to provide the mobile station (MS) with the persistent service. Another object of the present invention is to provide a method for solving the problems encountered when the mobile station (MS) does not receive the control message for assigning the radio resources. Another object of the present invention is to provide a method for reassigning the transmission area when the mobile station (MS) does not receive the control message for assigning the VoIP packet transmission area during the UL/DL VoIP packet transmission. Another object of the present invention is to provide a method for solving the problems encountered when the radio resources for VoIP packet transmission/reception are assigned, modified, and deleted. [Technical Solution] The present invention has been devised to solve the above-mentioned objects. According to an embodiment of the present invention, a method of allocating a radio resource in a wireless access system is provided. The method includes receiving a control message associated with radio resource allocation for transmitting uplink data to the BS, wherein the control message comprises a first persistent uplink allocation information element comprising first resource allocation information associated with a first resource allocation region for transmitting the uplink data of the MS and transmitting an acknowledgment (ACK) message from the MS to the BS in response to successfully receiving the first persistent uplink allocation information element. In an aspect of the present invention, the method further includes transmitting the uplink data to the BS by the MS via the assigned first resource allocation region. If the ACK message is not received from the MS, the first persistent allocation information element is retransmitted. Preferably, the retransmission of the first persistent allocation information element occurs after a predetermined number of frames after not receiving the ACK message. Preferably, a payload size of the uplink data is fixed and the uplink data includes an IP-based Voice over Internet Protocol (VoIP) data. In another aspect of the present invention, the first resource allocation information comprises at least one of orthogonal frequency division mulitiplxing access (OFDMA) symbol offset, subchannel offset, and information of OFDMA slot. Besides, the first persistent uplink allocation information element further comprises first ACK information associated with ACK transmission region, and the ACK message is transmitted via an ACK transmission region which is indicated by the first ACK information. In another aspect of the present invention, the first persistent uplink allocation information element futher comprises a field for indicating whether the first resource allocation region is allocated or de-allocated. In another aspect of the present invention, the method also includes storing the first persistent uplink allocation information element in the MS. The method may further include receiving a second persistent uplink allocation information element comprising second resource allocation information associated with a second resource allocation region for transmitting the uplink data. Furthermore, the method may include storing the second persistent uplink allocation information element and transmitting an acknowledgment (ACK) signal from the MS to the BS in response to successfully receiving the second persistent uplink allocation information element. The method may include transmitting the uplink data to the BS via the assigned second resource allocation region. The MS continues transmitting the uplink data to the BS via the first resource allocation region until a second persistent uplink allocation information element associated with using a second resource allocation region is received. In the other aspect of present invention, the second persistent uplink allocation information element further comprises second ACK information associated with ACK transmission region, and the ACK message is transmitted via an ACK transmission region which is indicated by the second ACK information. According to an embodiment of the present invention, the method of allocating a radio resource in a wireless access system includes receiving a control message associated with radio resource allocation for receiving downlink data from the BS, wherein the control message comprises a first persistent downlink allocation information element comprising first resource allocation information associated with a first resource allocation region for receiving the downlink data from the BS and transmitting an acknowledgment (ACK) message from the MS to the BS in response to successfully receiving the first persistent downlink allocation information element. In an aspect of the present invention, the method further includes receiving the downlink data from the BS via the assigned first resource allocation region. Preferably, a payload size of the downlink data is fixed. In another aspect of the present invention, the method further includes receiving a second persistent downlink allocation information element including second resource allocation information associated with a second resource allocation region for receiving downlink data. The method may further include storing the second persistent downlink allocation information element and transmitting an acknowledgment (ACK) signal from the MS to the BS in response to successfully receiving the second persistent downlink allocation information element. The method may also include receiving the downlink data from the BS via the assigned second resource allocation region. The MS continues receiving the downlink data from the BS via the first resource allocation region until a second persistent downlink allocation information element associated with using a second resource allocation region is received. The first resource persistent downlink allocation information may comprise at least one of OFDMA symbol offset, subchannel offset, and information of OFDMA slot. According to an embodiment of the present invention, the method of allocating a radio resource in a wireless access system includes transmitting a control message associated with radio resource allocation for communicating data to the MS, wherein the control message comprises a first persistent allocation information element comprising first resource allocation information associated with a first resource allocation region for communicating the data and receiving an acknowledgment (ACK.) message from the MS in response to successfully receiving the first persistent allocation information element. The method may further include communicating the data via the assigned first resource allocation region. Preferably, a payload size of the data is fixed. In an aspect of the present invention, the method further includes transmitting a second persistent allocation information element including second resource allocation information associated with a second resource allocation region for communicating the data. The method may further include storing the second persistent allocation information element and receiving an acknowledgment (ACK) signal from the MS in response to successfully receiving the second persistent allocation information element. In another aspect of the present invention, the method may also include transmitting the data to the MS via the assigned second resource allocation region. The BS continues receiving the data from the MS via the first resource allocation region until a second persistent allocation information element associated with using a second resource allocation region is received by the MS. In the other aspect of the present invention, the first persistent allocation information element further comprises ACK transmission region allocation information, and the ACK message is received via an ACK transmission region which is indicated by the ACK transmission region allocation information. At this time, the first persistent uplink allocation information futher comprises a field for indicating whether the first resource allocation region is allocated or de-allocated. Moreover, the first resource persistent downlink allocation information comprises at least one of OFDMA symbol offset, subchannel offset, and information of OFDMA slot. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. [Advantageous Effects] The present invention has the following effects. Firstly, although a control message for assigning the transmission area to provide the VoIP service is lost or has faulty or erroneous operations, the present invention can quickly retransmit the control message, such that it can solve the lost or damaged packet generated between the mobile station (MS) and the base station (BS). Secondly, the present invention can solve the problem encountered when a transmission area recognized by each mobile station (MS) is different from that of the base station (BS) in the uplink. That is, the present invention prevents the lost VoIP packet encountered when the mobile station (MS) and the base station (BS) have recognized different transmission areas. Also, the mobile station (MS) has information of another area instead of an area assigned to the mobile station (MS) itself, such that the collision problem encountered when another mobile station (MS) transmits the packet can be solved. Thirdly, although the control message for assigning the transmission area is damaged or lost, the present invention can immediately re-assign the transmission area. Therefore, the present invention can solve the problem that the mobile station (MS) is unable to recognize the downlink transmission area assigned from the base station (BS). Fourthly, the present invention can reduce an amount of overhead of the MAP message to implement a periodic traffic pattern and a connection of fixed-sized payload (e.g., data information). [Description of Drawings] The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. FIG. 1 is a flow chart illustrating a BS assigning fixed radio resources to a MS using a MAP message in an uplink. FIG. 2 is a flow chart illustrating the BS assigning fixed radio resources to the MS using the MAP message in a downlink. FIG. 3 is a flow chart illustrating assignment of a radio-resource region to provide the VoIP service according to an embodiment of the present invention. FIG. 4 is a flow chart illustrating transmission of a VoIP-associated MAP message in an uplink according to an embodiment of the present invention. FIG. 5 is a flow chart illustrating transmission of a VoIP-associated MAP message in a downlink according to an embodiment of the present invention. FIG. 6 is a flow chart illustrating retransmission of a VoIP-associated MAP message in an uplink according to an embodiment of the present invention. FIG. 7 is a flow chart illustrating retransmission of a VoIP-associated MAP message in a downlink according to an embodiment of the present invention. FIG. 8 is a flow chart illustrating retransmission of a VoIP-associated MAP message in an uplink according to an embodiment of the present invention. FIG. 9 is a flow chart illustrating retransmission of a VoIP-associated MAP message in a downlink according to an embodiment of the present invention. FIG. 10 is a flow chart illustrating retransmission of a VoIP-associated control message in an uplink according to an embodiment of the present invention. FIG. 11 is a flow chart illustrating retransmission of a VoIP-associated control message in a downlink according to an embodiment of the present invention. [Mode for Invention] In the following detailed description, reference is made to the accompanying drawing figures which form a part hereof, and which show by way of illustration specific embodiments of the invention. It is to be understood by those of ordinary skill in this technological field that other embodiments may be utilized, and structural, electrical, as well as procedural changes may be made without departing from the scope of the present invention. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. Prior to describing the present invention, it should be noted that most terms disclosed in the present invention correspond to general terms well known in the art, but some terms have been selected by the applicant as necessary and will hereinafter be disclosed in the following description of the present invention. Therefore, it is preferable that the terms defined by the applicant be understood on the basis of their meanings in the present invention. The present invention relates to a wireless access system. In more detail, the present invention provides the packet transmission method when the packet is frequently transmitted and a method of assigning radio resources in the wireless access system. The order of operations disclosed in the embodiments of the present invention may be changed. Some components or characteristics of any embodiment may also be included in other embodiments, or may be replaced with those of other embodiments as necessary. The following embodiments of the present invention will be disclosed on the basis of a data communication relationship between the BS and the MS. The BS is used as a terminal node of a network via which the BS can directly communicate with the MS. Specific operations to be conducted by the MS in the present invention may also be conducted by an upper node of the BS as necessary. Various operations for enabling the BS to communicate with the MS in a network composed of several network nodes including the BS may be conducted by the BS or other network nodes other than the BS. The base station (BS) may also be called as a fixed station, Node-B, eNode-B (eNB), or an access point as necessary. The mobile station (MS) may also be called as a user equipment (UE) or a mobile subscriber station (MSS) as necessary. The following embodiments of the present invention will disclose the VoIP service as an exemplary service which requires frequent packet transmission. However, it should be noted that the present invention is not limited to the VoIP service and can also be applied to other services requesting frequent packet transmission/reception. A packet transmission method for VoIP and the resource allocation method for the same VoIP under the condition that the packet transmission is frequently required will be described hereinafter. FIG. 1 shows an uplink case in which the MS transmits the VoIP packet to the BS. Referring to FIG. 1, the MS and the BS determine whether the resource allocation method is made available while the VoIP service is generated in S11. If it is determined that the resource allocation is made available in S101, the BS includes "VoIP_UL_IE" in the UL-MAP message and assigns the radio transmission region for providing the VoIP service in S102. The UL-MAP message is used as a control message and includes a radio transmission region which enables the MS to transmit the VoIP packet to the BS. The BS assigns a first transmission region to the MS via the UL-MAP message. When the MS receives the UL-MAP message from the BS, the MS stores allocation information for the first transmission region included in the UL-MAP message in S103. Subsequently, the MS transmits the VoIP packet to the BS via the first transmission region which has been assigned from the BS in S104. In order to assign the traffic resources having a fixed-sized constant period, such as the VoIP packet, the BS fixedly assigns a first transmission region to the MS in S102. Therefore, the BS can continuously assign the first transmission region to the MS without notifying other messages via an initial transmission control channel or an initial transmission control message. The VoIP packet is transmitted at intervals of a predetermined time, such that the MS goes to the next period, for example, a lapse of 20 ms, and transmits the next VoIP packet to the BS via the first transmission region in S105. While the MS transmits/receives the VoIP service to/from the BS, channel environments or data transmission environments may be unexpectedly deteriorated and it may be difficult to implement packet transmission/reception via the first transmission region. Therefore, the BS includes "VoIP_UL_IE" in the control message "UL-MAP" and assigns a second transmission region to the MS. In this case, the second transmission region is assigned to a specific location different from that of the first transmission region in S106. When the MS receives the above mentioned UL-MAP message in S106, the first transmission region for the VoIP service is updated with the second transmission region included in the UL-MAP message in S107. Subsequently, the MS transmits the VoIP packet to the BS via the second transmission region in S108. The BS receiving the VoIP packet via the second transmission region may need to change a current transmission region to another transmission region, if necessary. Therefore, in order to assign a third transmission region that is different from the second transmission region to the MS, the BS transmits the UL-MAP message including "VoIP_UL_IE" to the MS in S109. However, the UL-MAP message may be lost during wired or wireless transmission in S109 such that the MS does not receive the UL-MAP message. Alternatively, although the MS receives the UL-MAP message, it may be unable to detect the UL-MAP message due to the faulty or erroneous operation of the UL-MAP message. In this case, the MS is unable to recognize the information of the third transmission region in S109 and transmits the VoIP packet to the BS using the previous information, for example, information of the second transmission region for the next period in S110. Therefore, if the BS assigns the second transmission region for the VoIP service of another MS in SI 10, at least two MSs transmit the VoIP packet to the same second transmission region. As a result, packets may collide with each other and the BS may not receive such packets. Further, the BS does not receive the packet via the third transmission region assigned to the MS and is unable to receive the packet normally from the MS. Referring to FIG. 2, it is noted that S201-S203 of FIG. 2 are similar to S101-S103 of FIG. 1. In other words, in a downlink, the BS transmits the first transmission region to the MS using the DL-MAP message acting as the control message in S202. The MS stores allocation information of the first transmission region in S 203 and is ready to receive the VoIP packet from the BS. The BS transmits the VoIP packet to the MS via the first transmission region in S204. In this case, in order to assign radio resources for traffic, such as VoIP packet, having a fixed-sized period, the BS fixedly assigns the first transmission region to the MS in S202. Therefore, the BS can continuously assign the transmission region to the MS without notifying other messages via an initial transmission control channel or an initial transmission control message. The VoIP packet is transmitted at intervals of a predetermined time such that the BS goes to the next period, for example, a lapse of 20 ms, and transmits the next VoIP packet to the MS via the first transmission region in S205. While the MS transmits/receives the VoIP service to/from the BS, channel environments or data transmission environments may be unexpectedly deteriorated and it may be difficult to perform packet transmission/reception via the first transmission region. In this case, the BS includes "VoIP_DL_IE" in the control message "DL-MAP" and may assign a second transmission region that is different from the first transmission region to the MS in S206. When the MS receives the above mentioned DL-MAP message in S206, the second transmission region contained in the DL-MAP message is updated in S207. The BS transmits the VoIP packet to the MS via the second transmission region assigned to the MS in S208. The BS providing the VoIP service via the second transmission region may need to change a current VoIP packet transmission region to another transmission region. Therefore, in order to assign a third transmission region that is different from the second transmission region, the BS transmits the DL-MAP message including "VoIP_DL_IE" to the MS in S209. However, the DL-MAP message may be lost during wired or wireless transmission in S209 and the MS may not receive the DL-MAP message. Alternatively, although the MS receives the DL-MAP message, it may be unable to detect the DL-MAP message due to the faulty or erroneous operation of the DL-MAP message. In this case, the MS is unable to receive the DL-MAP message normally in S209 and unable to recognize information of the third transmission region. Therefore, the BS continues to transmit the VoIP packet periodically to the MS via the second transmission region and the MS is unable to receive the VoIP packet via the third transmission region. FIGS. 1 and 2 show that the BS assigns the resource region to the MS using the control message "MAP IE". However, when the MS receives the MAP IE message abnormally and the BS changes a transmission region for the VoIP service to another region, an unexpected problem may arise during packet transmission because the MS and the BS have information of different transmission regions. Referring to FIG. 3, a VoIP service is generated between the MS and the BS in S301. The BS and the MS negotiate with each other about the persistent resource allocation method used when the VoIP service is generated in S301. According to an embodiment of the present invention, the persistent resource allocation is available or the persistent allocation is enabled. The BS assigns the first transmission region to transmit/receive the VoIP packet to/from the MS using the control message such as the MAP message in S302. The BS transmits/receives the VoIP packet to/from the MS via the first transmission region. In other words, in the uplink, the MS transmits the VoIP packet to the BS via the first transmission region and in the downlink, the BS transmits the VoIP packet to the MS via the first transmission region. While the BS transmits the VoIP service to the MS, user environment may be changed or communication quality may be deteriorated. In this case, the BS determines to change a packet transmission region for the VoIP service in S303. The BS assigns the changed second transmission region to the MS. The BS transmits or receives the VoIP service to/from the MS via the second transmission region in S304. The BS may use the control message in order to assign the second transmission region to the MS in S304. A message characterized by its solidity is used as the control message which includes a MAP message. The MAP message (DL-MAP/UL-MAP) is used to assign unique resource for each user. This MAP message is a MAC management message which dynamically informs the MS of the resource allocation result at intervals of each frame. In the downlink, the UL-MAP message designates the location of sub-channel dynamically assigned to each MS and the number of the sub-channel. In the uplink, the DL-MAP message designates the location of sub-channel dynamically assigned to each MS and the number of the sub-channel. In particular, the DL-MAP message is a broadcast message which indicates the set of information associated with total connection managed by a single BS. For example, the DL-MAP message may include the principal information, band allocation information, frame construction information, and ACK/NACK information. The following table 1 shows an example of the VoIP UL-MAP information element (VoIP_UL IE) which may be used to perform resource allocation, modify the resource allocation, and delete the same. Referring back to FIG. 3, in order to assign the second transmission region, the BS transmits the control message to the MS in S304. In this case, the MS receives the control message and can recognize the second transmission region in S305. If the MS receives the control message and recognizes the second transmission region ('Yes' in S305), it transmits or receives the VoIP packet to/from the BS via the second transmission region in S306. The MS may not receive the control message in S305 ('No') due to a loss of the control message during wired or wireless transmission. Or, even if the control message is received by the MS, it may not be recognized due to errors in the control message. In this case, the BS reallocates the second transmission region to the MS using a specific algorithm in S307. This step may be repeated until the second transmission region equal to a new transmission region is recognized. The number of repetition may be determined according to the communication environment and a system requirement. In order to reallocate the second transmission region, a variety of algorithms may be used in S307. According to one of various algorithms, if a control message for allocating the second transmission region is received normally, an acknowledgment (ACK) signal for the control message is transmitted to the BS such that the MS indicates that the second transmission region has been normally recognized. If the MS does not receive the control message normally, it is unable to transmit the ACK signal. Provided that the BS transmits the control message for assigning the transmission region and does not receive the ACK signal from the MS, it may retransmit the above-mentioned control message after a lapse of a predetermined number of frames, for example, N frames, in the next frame or system. According to another algorithm, the BS determines the presence or absence of a signal of the second transmission region in S307 such that it may reallocate the second transmission region. In this case, the BS does not use the ACK signal and determines whether the signal is transmitted from the MS to the second transmission region. Further, other types of algorithms may also be used to assign the second transmission region. According to an embodiment of the present invention, a method for using the ACK signal to reply to the control message, which can assign, modify, or delete radio resources for the VoIP service, is described below. If the MS receives the VoIP-associated MAP IE message from the BS when the MAP IE message, such as VoIP_DL_IE VoIP_UL_IE, is used as a control message, the MS may transmit the ACK signal to the BS in response to the MAP IE message. In this case, the BS allocates the control channel to a designated frame such that the MS can transmit the ACK signal. The ACK signal transmitted from the MS to the BS in response to the control message may be an ACK/NACK or ACK message of a Hybid Automatic Repeat Request (HARQ), or an ACK header. If the BS does not receive the ACK signal at a corresponding frame, the BS may retransmit the control message, which has been transmitted to the MS, to the designated frame, or may allocate radio resources to the MS using the radio-resource information pre-notified to the MS. Referring to FIG. 4, in an uplink, the process for generating the VoIP service between the MS and the BS and allocating the first transmission region is equivalent to S101~S104 of FIG. 1. Therefore, these steps are omitted and the next steps are described in FIG. 4. The MS transmits the VoIP packet to the BS via the first transmission region assigned from the BS in S401. While the VoIP packet is transmitted or received, the transmission region may need to be changed to another region due to poor communication environments or some other reasons. In this case, the BS may allocate the second transmission region to the MS using the UL-MAP message (VoIP_UL_IE) acting as a control message in S402. Also, the BS may allocate a specific region capable of transmitting the ACK signal via the control message. When the MS receives the control message from the BS, the MS updates the second transmission region contained in the control message to a new transmission region in S403. When the MS has received the control message normally in S402, the MS transmits the ACK signal, such as HARQ, ARK, ACK message or ACK header, to the BS in order to reply to the normally-received control message in S404. Then, the MS transmits the VoIP packet to the BS via the second transmission region, which was assigned as the new transmission region from the BS, in S405. Referring to FIG. 5, in a downlink, the process for generating the VoIP service between the MS and the BS and allocating the first transmission region is equivalent to S201-S204 of FIG. 2. Therefore, the same steps are omitted and the next steps are described in FIG. 5. The BS transmits the VoIP packet to the MS via the first transmission region assigned to the MS in S501. While the VoIP packet is transmitted or received, the transmission region may need be changed to another region due to poor communication environments or some other reasons. In this case, the BS may allocate the second transmission region to the MS using the DL-MAP message (VoIP_DL_IE) acting as a control message in S502. Also, the BS may allocate a specific region capable of transmitting the ACK signal via the control message. If the MS receives the control message from the BS, the MS updates the second transmission region contained in the control message to a new transmission region in S503. When the MS has received the control message normally in S502, the MS can transmit the ACK signal, such as HARQ, ARK, ACK message or ACK header, to the BS in order to reply to the normally-received control message in S504. Then, the BS transmits the VoIP packet via the second transmission region, which was assigned to the MS as the new transmission region, in S505. Referring to FIG. 6, in an uplink, the BS and the MS generate the VoIP service and the BS allocates the transmission region for providing the MS with the VoIP service. The above-mentioned operations are similar to S101-S104 of FIG. 1, and therefore, the same steps are omitted and the next steps are described in FIG. 6. The MS transmits the VoIP packet via the first transmission region assigned from the BS in S601. While the BS transmits the VoIP service to the MS, it may need to change the radio resources assigned to the MS to other radio resources. In this case, the BS allocates the second transmission region to the MS using the UL-MAP message (VoIP_UL_IE) used as a control message in S602. However, it should be noted that the control message transmitted from the BS to the MS may be lost or damaged during wired or wireless transmission, or the MS may not recognize the control message due to faulty or erroneous operations. When the control message is lost, the MS is unable to transmit the ACK signal associated with the above-mentioned control message of S602 to the BS in S603. The BS transmits the control message in S602 and waits for the ACK signal to determine whether the MS has recognized the second transmission region. However, since the MS is unable to transmit the ACK signal in S603 because the control message has been lost, the BS determines that the second transmission region has not been recognized by the MS. Therefore, the BS retransmits the UL-MAP message and reallocates the second transmission region in S604. The BS retransmits the UL-MAP message for reallocating the second transmission region to the MS after a lapse of a predetermined value, for example, N frames, as determined by the next fame or system in S604. The UL-MAP message is immediately retransmitted at the next frame after S603. The MS recognizes the second transmission region contained in the UL-MAP message retransmitted from the BS and updates the first transmission region for VoIP-packet transmission with the second transmission region in S605. Then, the MS transmits the ACK signal to the BS in response to the received UL-MAP message in S606 and transmits the VoIP packet via the second transmission region assigned from the BS. Even if the MS does not receive a new transmission region by the above described steps, the MS according to the present invention can quickly receive the transmission region from the BS such that it can effectively provide the VoIP service. Referring to FIG. 7, in a downlink, the BS and the MS generate the VoIP service and the BS allocates the transmission region for providing the MS with the VoIP service. The above-mentioned operations are similar to S201 to S204 of FIG. 2, and therefore, the same steps are omitted and the next steps are described in FIG. 7. The BS transmits the VoIP packet via the first transmission region assigned to the MS in S701. While the BS transmits the VoIP service to the MS, the radio resources assigned to the MS may need to be changed to other radio resources. In this case, the BS allocates the second transmission region to the MS using the DL-MAP message (VoIP_DL_IE) used as a control message in S702. However, it should be noted that the control message transmitted from the BS to the MS may be lost or damaged during wired or wireless transmission in S702, or the MS may not recognize the control message due to faulty or erroneous operations in S702. As a result, the MS is unable to transmit the ACK signal associated with the above-mentioned control message from S702 to the BS in S703. The BS transmits the control message in S702 and waits for the ACK signal to determine whether the MS has recognized the second transmission region. However, since the DL-MAP message transmitted from the BS has been lost in S702, the MS is unable to transmit the ACK signal. Therefore, the BS determines that the second transmission region has not been recognized by the MS and retransmits the DL-MAP message to reallocate the second transmission region in S704. The BS retransmits the DL-MAP message to reallocate the second transmission region to the MS after a lapse of a predetermined value, for example, N frames, determined by the next fame or system in S704. The DL-MAP message is retransmitted immediately at the next frame after S703. The MS recognizes the second transmission region contained in the DL-MAP message retransmitted from the BS and updates the first transmission region for VoIP-packet transmission with the second transmission region in S705. Then, the MS transmits the ACK signal to the BS in response to the received DL-MAP message in S706 and the BS transmits the VoIP packet to the MS via the assigned second transmission region in S 707. Accordingly, even if me MS has not received a new transmission region by the above described steps, the BS according to an embodiment of the present invention can quickly reallocate the transmission region to provide the VoIP service effectively. Referring to FIG. 8, in an uplink, the BS and the MS generate the VoIP service and the BS allocates the transmission region for providing the MS with the VoIP service. The above-mentioned operations are similar to steps S101~S104 of FIG. 1, and therefore, the same steps are omitted and only different steps are described with reference to FIG. 8. The MS transmits the VoIP packet via the first transmission region assigned from the BS in S801. The resource-allocation region may need to be changed to another region during the VoIP packet communication between the BS and the MS. In this case, the BS may allocate the new second transmission region to the MS using the UL-MAP message (VoIP_UL_IE) used as a control message in S802. However, it should be noted that the control message transmitted from the BS to the MS may be lost or damaged during wired or wireless transmission or the MS may not recognize the control message due to faulty or erroneous operations. , When the UL-MAP message is lost in S802, the MS is unable to transmit the ACK signal via the above mentioned region, which has been allocated to the MS for ACK signal transmission, in S803. Since the BS has not received the ACK signal from the MS in S803, it does not allocate the first transmission region, which has been pre-assigned to the MS, to either another MS or another service. Also, the BS may allocate resources to the corresponding MS using the previous information. Since the MS has not received the UL-MAP message, it is unable to transmit the VoIP packet via the second transmission region. Therefore, the MS continues to transmit the VoIP packet to the BS via the pre-assigned first transmission region in S804. When the BS receives the VoIP packet from the MS via the first transmission region, it determines that the control message in S802 has not been received normally by the MS. Specifically, even after the BS assigns the second transmission region to the MS, when the MS retransmits the VoIP packet via the first transmission region, the BS determines that the MS has not received the control message normally in S802. Therefore, after a lapse of the next frame or N frames of S803, the BS retransmits the UL-MAP message (VoIP_UL_IE) to the MS to allocate the second transmission region in S805. When the MS has received the UL-MAP message normally from the BS in S805, the MS transmits the ACK signal to the BS via a predetermined region for transmitting the ACK signal contained in the above-mentioned UL-MAP message in S806. Referring to FIG. 9, in a downlink, the BS and the MS generate the VoIP service and the BS allocates the first transmission region for providing the MS with the VoIP service. The above-mentioned operations are similar to S201-S204 of FIG. 2, and therefore, the same steps are omitted and only different steps are described with reference to FIG. 9. The BS transmits the VoIP packet via the first transmission region assigned to the MS in S901. The resource-allocation region may need to be changed to another region during the VoIP packet communication between the BS and the MS. In this case, the BS may allocate the new second transmission region to the MS using the DL-MAP message (VoIP_DL_IE) used as a control message in S902. However, it should be noted that the control message transmitted from the BS to the MS may be lost or damaged during wired or wireless transmission in S902, or the control message may be received by the MS abnormally due to faulty or erroneous operations. In S902, the DL-MAP message has been lost, and therefore, the MS does not transmit the ACK signal via the above described region, which has been allocated from the BS to transmit the ACK signal, in S903. Since the BS has not received the ACK signal from the MS in S903, it does not allocate the first transmission region, which has been pre-allocated to the MS, to either another MS or another service. Also, the BS allocates resources to the corresponding MS using the previous information. As shown in S903, the BS has not received the ACK signal in response to the DL-MAP message of S902. Therefore, the BS determines that the MS has not recognized the second transmission region yet and transmits the VoIP packet via the first transmission region in S904. When the BS has not received ACK signal from the MS, it determines that the MS has received the control message of S902 abnormally. Therefore, after a lapse of the next frame or the predetermined N frames of the S803, the BS retransmits the DL-MAP message (VoIP_DL_IE) to the MS to allocate the second transmission region in S905. When the MS has received the DL-MAP message normally from the BS in S905, the MS transmits the ACK signal to the BS via a predetermined region to transmit the ACK signal contained in the above-mentioned DL-MAP message in S906. As described above, if the radio resources for the VoIP service are allocated according to the present invention, FIGS. 4-9 show not only a method for allocating radio resources between the BS and the MS using the ACK signal, but also a method for recovering a synchronization failure. According to another embodiment of the present invention, a method is provided for determining whether there is a signal associated with a radio resource region assigned to the MS by the BS and retransmitting the control message according to the determined result. According to yet another embodiment, the present invention can solve the inconsistency in radio-resource-region allocation between the BS and the MS. For example, if no signal associated with the uplink traffic is detected as a signal of the radio-resource region which has been allocated to the MS, the BS determines that it has recognized another radio-resource region instead of the above radio-resource region having been assigned to the MS. Therefore, the BS retransmits the control message to reallocate the radio-resource region. In case of a downlink, the BS transmits the packet to a specific region pre-assigned to the MS in association with downlink traffic. However, if no signal is detected in the radio-resource region assigned to the MS, the BS determines that the MS has information different from that of the radio-resource region allocated by the BS in association with the downlink. Therefore, the MS retransmits the control message to reallocate the radio-resource region. Referring to FIG. 10, in an uplink, the VoIP service is generated between the MS and the BS and the BS allocates the first transmission region for providing the MS with the VoIP service. The above-mentioned operations are similar to S101 ~S 104 of FIG. 1, and therefore, the same steps are omitted and only different steps are described with reference to FIG. 10. The MS transmits the VoIP packet via the first transmission region assigned from the BS to implement VoIP packet transmission in S1001. While the VoIP packet is transmitted or received, the transmission region may need to be changed to another region due to poor communication environments or some other reasons. In this case, the BS may allocate the second transmission region different from the first transmission region to the MS using the UL-MAP message (VoIP_UL_IE) acting as a control message in S1002. However, it should be noted that the above-mentioned UL-MAP message may be lost or damaged during wired or wireless transmission in S1002, or the MS may receive the UL-MAP message abnormally in S1002. According to another embodiment of the present invention, the UL-MAP message has been lost and the MS does not receive the UL-MAP message. Even if the MS has not received the UL-MAP message, the BS can allocate the second transmission region to the MS nonetheless in S1003. However, in S1003, the BS does not actually allocate the radio resource region to the MS using the control message. The UL-MAP message used as the control message is transmitted only when the transmission region needs to be changed to another region. Since the MS has not received the UL-MAP message in S1002, it is unable to transmit the VoIP packet in S1004. If the BS detects no signal in the second transmission region which has been assigned to the MS, it retransmits the UL-MAP message to the MS in order to reallocate the second transmission region to the MS in S1005. Referring to FIG. 11, in a downlink, the VoIP service is generated between the MS and the BS and the BS allocates the first transmission region for providing the MS with the VoIP service. The above-mentioned operations are similar to S201-S204 of FIG. 1, and therefore, the same steps are omitted and only different steps are described with reference to FIG. 11. The BS assigns the first transmission region to the MS to transmit the VoIP packet and transmits the VoIP packet to the MS via the first transmission region in S1101. While the VoIP packet is communicated between the MS and the BS, a first transmission region for providing a current VoIP service may need to be changed to a new second transmission region. In this case, the BS may allocate the second transmission region different from the first transmission region to the MS using the DL-MAP message (VoIP_DL_IE) acting as a control message in S1102. However, it should be noted that the above-mentioned DL-MAP message may be lost or damaged during wired or wireless transmission in S1102, or the MS may receive the DL-MAP message abnormally in S1102. According to another embodiment of the present invention, the DL-MAP message is lost and the MS receives no DL-MAP message. Even if the MS receives no DL-MAP message and does not recognize the second transmission region as a new transmission region, the BS can allocate the second transmission region to the MS nonetheless in S1103. However, in S1103, the BS does not actually allocate the radio-resource region to the MS using the control message. The DL-MAP message used as the control message is transmitted only when the transmission region needs to be changed to another region. The BS transmits the VoIP packet to the MS via the allocated second transmission region in S1104. However, although the BS transmits the VoIP packet to the MS via the second transmission region in S1104, the MS has recognized the first transmission region as the VoIP-service region. As a result, the MS is unable to receive the VoIP packet which has been transmitted to the second transmission region by the BS. Therefore, the MS is unable to transmit the ACK signal for the VoIP packet to the BS in S1105. The ACK signal of S1105 plays a unique role which is different from those of FIGS. 4~9. In other words, the ACK signal in S1105 is equivalent to the ACK signal for the VoIP packet. The ACK signals of FIGS. 4-9 are related to the ACK signals for the control message. When the BS detects no signal in the second transmission region which has been assigned to the MS, it retransmits the DL-MAP message to the MS in order to reallocate the second transmission region to the MS in S1106. As described above, FIGS. 4 to 11 have depicted various embodiments of the present invention. The above-mentioned methods proposed by the above embodiments can be applied not only to the above described embodiments in which the radio resources are allocated, but also to the other cases in which the allocated resources are modified or deleted or new resources are continuously allocated. The present invention has the following effects. First, although a control message for assigning the transmission region to provide the VoIP service is lost or has faulty or erroneous operations, the present invention can quickly retransmit the control message such that it can solve the lost or damaged packet generated between the MS and the BS. Second, the present invention can solve the problem encountered when a transmission region recognized by each MS is different from that of the BS in the uplink. That is, the present invention prevents the lost VoIP packet encountered when the MS and the BS have recognized different transmission regions. Also, the MS has information of another region instead of a region assigned to the MS itself such that the collision problem encountered when another MS transmits the packet can be solved. Third, although the control message for assigning the transmission region is damaged or lost, the present invention can immediately re-assign the transmission region. Therefore, the present invention can solve the problem when the MS is unable to recognize the downlink transmission region assigned from the BS. Fourth, the present invention can reduce an amount of overhead of the MAP message to implement a periodic traffic pattern and a connection of fixed-sized payload, for example, data information. The above-mentioned messages and parameters are disclosed for only illustrative purposes of the present invention. If required, other messages or other parameters may also be used to implement the same purpose as that of the present invention. It should be noted that most terminology disclosed in the present invention is defined in consideration of functions of the present invention, and can be differently determined according to intention of those skilled in the art or usual practices. Therefore, it is preferable that the above-mentioned terminology be understood on the basis of all contents disclosed in the present invention. Although the preferred embodiments of the present invention were disclosed for illustrative purposes, those skilled in the art will appreciate that various variations and modifications are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. [Industrial Applicability] As apparent from the above description, the present invention provides a method for allocating radio resources to implement frequent packet transmission in a wireless access system, and a packet transmission method. The present invention can also be applied to a variety of wireless access systems. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. [CLAIMS] [Claim 1] A method of allocating a radio resource in a wireless access system, the method comprising: receiving a control message associated with radio resource allocation for transmitting uplink data to the base station, wherein the control message comprises a first persistent uplink allocation information element comprising first resource allocation information associated with a first resource allocation region for transmitting the uplink data of a mobile station; and transmitting an acknowledgment (ACK) message from the mobile station to the base station in response to successfully receiving the first persistent uplink allocation information element. [Claim 2] The method of claim 1, further comprising: transmitting the uplink data to the base station by the mobile station via the assigned first resource allocation region. [Claim 3] The method of claim 1, wherein the base station retransmits the first persistent uplink allocation information element if the ACK message is not received from the mobile station. [Claim 4] The method of claim 3, wherein the first persistent uplink allocation information is retransmitted after a predetermined number of frames after not receiving the ACK message. [Claim 5] The method of claim 1, wherein a payload size of the uplink data is fixed. [Claim 6] The method of claim 1, wherein the uplink data comprises an IP-based Voice over Internet Protocol (VoIP) data. [Claim 7] The method of claim 1, wherein the first resource allocation information comprises at least one of orthogonal frequency division mulitiplxing access (OFDMA) symbol offset, subchannel offset, and information of OFDMA slot. [Claim 8] The method of claim 1, wherein the first persistent uplink allocation information element further comprises first ACK information associated with ACK transmission region; and the ACK message is transmitted via an ACK transmission region which is indicated by the first ACK information. [Claim 9] The method of claim 1, wherein the first persistent uplink allocation information element further comprises a field for indicating whether the first resource allocation region is allocated or de-allocated. [Claim 101 The method of claim 1, further comprising: receiving a second persistent uplink allocation information element comprising second resource allocation information associated with a second resource allocation region for transmitting the uplink data. [Claim 11] The method of claim 10, further comprising: storing the second persistent uplink allocation information element; and transmitting an acknowledgment (ACK) message from the mobile station to the base station in response to successfully receiving the second persistent uplink allocation information element. [Claim 12] The method of claim 11, further comprising: transmitting the uplink data to the base station via the assigned second resource allocation region. [Claim 13] The method of claim 10, wherein the second persistent uplink allocation information element further comprises second ACK information associated with ACK transmission region; and the ACK message is transmitted via an ACK transmission region which is indicated by the second ACK information. [Claim 14] The method of claim 1, wherein the mobile station continues transmitting the uplink data to the base station via the first resource allocation region until a second persistent uplink allocation information element associated with using a second resource allocation region is received. [Claim 15] A method of allocating a radio resource in a wireless access system, the method comprising: receiving a control message associated with radio resource allocation for receiving downlink data from the base station, wherein the control message comprises a first persistent downlink allocation information element comprising first resource allocation information associated with a first resource allocation region for receiving the downlink data from the base station; and transmitting an acknowledgment (ACK) message from the mobile station to the base station in response to successfully receiving the first persistent downlink allocation information element. [Claim 16] The method of claim 16, further comprising: receiving the downlink data from the base station via the assigned first resource allocation region. [Claim 17] The method of claim 15, wherein a payload size of the downlink data is fixed. [Claim 18] The method of claim 15, further comprising: receiving a second persistent downlink allocation information element comprising second resource allocation information associated with a second resource allocation region for receiving downlink data. [Claim 19] The method of claim 18, further comprising: storing the second persistent downlink allocation information element; and transmitting an acknowledgment (ACK) signal from the mobile station to the base station in response to successfully receiving the second persistent downlink allocation information element. [Claim 20] The method of claim 19, further comprising: receiving the downlink data from the base station via the assigned second resource allocation region. [Claim 21] The method of claim 15, wherein the first persistent downlink allocation information element further comprises ACK transmission region allocation information; and the ACK message is transmitted via an ACK transmission region which is indicated by the ACK transmission region allocation information. [Claim 22] The method of claim 21, wherein the first persistent downlink allocation information element futher comprises a field for indicating whether the first resource allocation region is allocated or de-allocated. [Claim 23] The method of claim 15, wherein the mobile station continues receiving the downlink data from the base station via the first resource allocation region until a second persistent downlink allocation information element associated with using a second resource allocation region is received. [Claim 24] The method of claim 15, wherein the first resource persistent downlink allocation information comprises at least one of OFDMA symbol offset, subchannel offset, and information of OFDMA slot. , [Claim 25] A method of allocating a radio resource in a wireless access system, the method comprising: transmitting a control message associated with radio resource allocation for communicating data to a mobile station, wherein the control message comprises a first persistent allocation information element comprising first resource allocation information associated with a first resource allocation region for communicating the data; and receiving an acknowledgment (ACK.) message from the mobile station in response to successfully receiving the first persistent allocation information element. [Claim 261 The method of claim 25, further comprising: communicating the data via the assigned first resource allocation region. [Claim 27] The method of claim 25, wherein a payload size of the data is fixed. [Claim 28] The method of claim 25, further comprising: transmitting a second persistent allocation information element comprising second resource allocation information associated with a second resource allocation region for communicating the data. [Claim 29] The method of claim 28, further comprising: storing the second persistent allocation information element; and receiving an acknowledgment (ACK) signal from the mobile station in response to successfully receiving the second persistent allocation information element. [Claim 30] The method of claim 29, further comprising: transmitting the data to the mobile station via the assigned second resource allocation region. [Claim 31] The method of claim 30, wherein the first -persistent allocation information element further comprises ACK transmission region allocation information; and the ACK message is received via an ACK transmission region which is indicated by the ACK transmission region allocation information. [Claim 32] The method of claim 31, wherein the first persistent uplink allocation information futher comprises a field for indicating whether the first resource allocation region is allocated or de-allocated. [Claim 33] The method of claim 25, wherein the base station continues communicating the data with the mobile station via the first resource allocation region until a second persistent allocation information element associated with using a second resource allocation region is transmitted to the mobile station. [Claim 34] The method of claim 25, wherein the first resource persistent downlink allocation information comprises at least one of OFDMA symbol offset, subchannel offset, and information of OFDMA slot. A method of allocating a radio resource in a wireless access system is disclosed. The method includes receiving a control message associated with radio resource allocation for transmitting uplink data to the base station, wherein the control message comprises a first persistent uplink allocation information element comprising first resource allocation information associated with a first resource allocation region for transmitting the uplink data of a mobile station and transmitting an acknowledgment (ACK) message from the mobile station to the base station in response to successfully receiving the first persistent uplink allocation information element.

Full Text

[DESCRIPTION]
[Invention Title]
A METHOD OF ALLOCATING RESOURCE-AREA IN WIRELESS ACCESS
SYSTEM
[Technical Field]
The present invention relates to a wireless access system, and more particularly to a
packet transmission method for frequent packet transmission and a method of allocating radio
resources in the wireless communication system.
[Background Art]
A broadband wireless access system to transmit a packet to user equipment (UE) based
on an IP-based Voice over Internet Protocol (VoIP) service is described below. VoIP traffic is
created with a fixed size having a fixed period within a VoIP codec. VoIP communication may
be classified into a talk-spurt period and a silence period. During the talk-spurt period, a speech
mode is maintained between users. During the silence period, the user listens to the other party
without talking to the other party. The silence period may occupy 50% or more of a general
call session.
Therefore, in order to allocate different amounts of bandwidths to the talk-spurt period
and the silence period, a variety of voice codecs may be used. A representative example of the
voice codec is an adaptive multi-rate (AMR) for use in a Global System for Mobile
communication (GSM) and a Universal Mobile Telecommunications System (UMTS).
Voice data is not generated during the silence period. If the bandwidth is allocated to
the silence period, radio resources may be wasted. In order to prevent this problem, VoIP
supports a silence suppression scheme. According to the silence suppression scheme, a vocoder
for generating the VoIP traffic does not generate traffic data. However, the vocoder periodically

generates comfort noise to inform the other user that the call is still ongoing. For example, the
vocoder based on the above-mentioned AMR codec generates a fixed-sized packet at intervals of
20 ms in the talk-spurt period, and generates the comfort noise at intervals of 160 ms in the
silence period.
In order to perform resource allocation of traffic data, which has a fixed-sized constant
period such as a VoIP, a Node-B or base station (BS) may fixedly assign a predetermined region
to a specific UE. For example, the BS assigns the region as large as the initially-defined size to
the UE capable of supporting the VoIP service. The BS may also inform the UE of the
assigned resource region information using a control channel or a control message such as a
UL-MAP or a DL-MAP. Accordingly, the control channel or the control message, which is
initially transmitted, may also include period information of the next allocation region.
From the next period, the BS may successively assign a corresponding region without
any specified notification associated with the above region which has been notified to the mobile
station (MS), using the initially-transmitted control channel or the initially-transmitted control
message. Therefore, the MS transmits the VoIP packet to the assigned region using region
information which has been initially assigned on the map and transmits the VoIP packet from the
next period to the same region using period information.
For example, when the frame length is set to 5 ms in consideration of the VoIP service
and a frame period assigned to the MS for VoIP packet transmission is set to 4 frames, the frame
period assigned to the MS for the VoIP packet transmission may be changed to another
according to service characteristics. Specifically, if the same VoIP service is used, the frame
period assigned for VoIP packet transmission may be defined in different ways according to
individual elements such as system characteristic and VoIP service status. For example, the
system characteristic may be changed according to the frame length and the VoIP service status

may be either the talk-spurt period or the silence period.
The BS located at an initial frame informs the MS of the allocation region information to
transmit the VoIP packet via the UL-MAP. If the BS is located at a fourth or eighth frame
corresponding to each period, it does not inform the region information via the UL-MAP and
assigns only the region for VoIP packet transmission.
In this case, the period assigned for the VoIP packet transmission may be 4 frames or 20
ms.
The MS stores region allocation information contained in the UL-MAP message received
from the initial frame. Therefore, the MS can transmit the VoIP packet via a corresponding
region although the UL-MAP message is not additionally received from the fourth and eighth
frames corresponding to the resource allocation period. Accordingly, the BS is fixed to a single
VoIP connection due to the VoIP traffic characteristic and can persistently assign resources to
this VoIP connection.
If a control message for assigning a new transmission region is lost in a wired or wireless
downlink, the conventional system has a disadvantage in that individual transmission region
information recognized by the MS and the BS is unavoidably different from each other.
Therefore, in case of the downlink, the MS is unable to receive the VoIP packet from the BS.
In case of the uplink, although the MS transmits the VoIP packet via the second
transmission region, the BS may assign the second transmission region to another MS, resulting
in unexpected problems. In other words, if the MS transmits the VoIP packet via the second
transmission region, a packet transmission by another MS may fail. If the system uses an
incremental redundancy (HARQ-IR) scheme, the number of retransmission will be increased,
resulting in unexpected problems.
[Disclosure]

[Technical Problem]
Accordingly, the present invention is directed to a packet transmission method for
resource allocation in a broadband wireless access system that substantially obviates one or more
problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method for assigning a resource area
and a control channel to provide the mobile station (MS) with the persistent service.
Another object of the present invention is to provide a method for solving the problems
encountered when the mobile station (MS) does not receive the control message for assigning the
radio resources.
Another object of the present invention is to provide a method for reassigning the
transmission area when the mobile station (MS) does not receive the control message for
assigning the VoIP packet transmission area during the UL/DL VoIP packet transmission.
Another object of the present invention is to provide a method for solving the problems
encountered when the radio resources for VoIP packet transmission/reception are assigned,
modified, and deleted.
[Technical Solution]
The present invention has been devised to solve the above-mentioned objects.
According to an embodiment of the present invention, a method of allocating a radio resource in
a wireless access system is provided. The method includes receiving a control message
associated with radio resource allocation for transmitting uplink data to the BS, wherein the
control message comprises a first persistent uplink allocation information element comprising
first resource allocation information associated with a first resource allocation region for
transmitting the uplink data of the MS and transmitting an acknowledgment (ACK) message
from the MS to the BS in response to successfully receiving the first persistent uplink allocation

information element.
In an aspect of the present invention, the method further includes transmitting the uplink
data to the BS by the MS via the assigned first resource allocation region. If the ACK message is
not received from the MS, the first persistent allocation information element is retransmitted.
Preferably, the retransmission of the first persistent allocation information element occurs after a
predetermined number of frames after not receiving the ACK message. Preferably, a payload
size of the uplink data is fixed and the uplink data includes an IP-based Voice over Internet
Protocol (VoIP) data.
In another aspect of the present invention, the first resource allocation information
comprises at least one of orthogonal frequency division mulitiplxing access (OFDMA) symbol
offset, subchannel offset, and information of OFDMA slot. Besides, the first persistent uplink
allocation information element further comprises first ACK information associated with ACK
transmission region, and the ACK message is transmitted via an ACK transmission region which
is indicated by the first ACK information.
In another aspect of the present invention, the first persistent uplink allocation
information element futher comprises a field for indicating whether the first resource allocation
region is allocated or de-allocated.
In another aspect of the present invention, the method also includes storing the first
persistent uplink allocation information element in the MS. The method may further include
receiving a second persistent uplink allocation information element comprising second resource
allocation information associated with a second resource allocation region for transmitting the
uplink data. Furthermore, the method may include storing the second persistent uplink allocation
information element and transmitting an acknowledgment (ACK) signal from the MS to the BS
in response to successfully receiving the second persistent uplink allocation information element.

The method may include transmitting the uplink data to the BS via the assigned second
resource allocation region. The MS continues transmitting the uplink data to the BS via the first
resource allocation region until a second persistent uplink allocation information element
associated with using a second resource allocation region is received.
In the other aspect of present invention, the second persistent uplink allocation
information element further comprises second ACK information associated with ACK
transmission region, and the ACK message is transmitted via an ACK transmission region which
is indicated by the second ACK information.
According to an embodiment of the present invention, the method of allocating a radio
resource in a wireless access system includes receiving a control message associated with radio
resource allocation for receiving downlink data from the BS, wherein the control message
comprises a first persistent downlink allocation information element comprising first resource
allocation information associated with a first resource allocation region for receiving the
downlink data from the BS and transmitting an acknowledgment (ACK) message from the MS to
the BS in response to successfully receiving the first persistent downlink allocation information
element.
In an aspect of the present invention, the method further includes receiving the downlink
data from the BS via the assigned first resource allocation region. Preferably, a payload size of
the downlink data is fixed.
In another aspect of the present invention, the method further includes receiving a second
persistent downlink allocation information element including second resource allocation
information associated with a second resource allocation region for receiving downlink data. The
method may further include storing the second persistent downlink allocation information
element and transmitting an acknowledgment (ACK) signal from the MS to the BS in response

to successfully receiving the second persistent downlink allocation information element.
The method may also include receiving the downlink data from the BS via the assigned
second resource allocation region. The MS continues receiving the downlink data from the BS
via the first resource allocation region until a second persistent downlink allocation information
element associated with using a second resource allocation region is received. The first resource
persistent downlink allocation information may comprise at least one of OFDMA symbol offset,
subchannel offset, and information of OFDMA slot.
According to an embodiment of the present invention, the method of allocating a radio
resource in a wireless access system includes transmitting a control message associated with
radio resource allocation for communicating data to the MS, wherein the control message
comprises a first persistent allocation information element comprising first resource allocation
information associated with a first resource allocation region for communicating the data and
receiving an acknowledgment (ACK.) message from the MS in response to successfully receiving
the first persistent allocation information element. The method may further include
communicating the data via the assigned first resource allocation region. Preferably, a payload
size of the data is fixed.
In an aspect of the present invention, the method further includes transmitting a second
persistent allocation information element including second resource allocation information
associated with a second resource allocation region for communicating the data. The method
may further include storing the second persistent allocation information element and receiving an
acknowledgment (ACK) signal from the MS in response to successfully receiving the second
persistent allocation information element.
In another aspect of the present invention, the method may also include transmitting the
data to the MS via the assigned second resource allocation region. The BS continues receiving

the data from the MS via the first resource allocation region until a second persistent allocation
information element associated with using a second resource allocation region is received by the
MS.
In the other aspect of the present invention, the first persistent allocation information
element further comprises ACK transmission region allocation information, and the ACK
message is received via an ACK transmission region which is indicated by the ACK
transmission region allocation information. At this time, the first persistent uplink allocation
information futher comprises a field for indicating whether the first resource allocation region is
allocated or de-allocated. Moreover, the first resource persistent downlink allocation information
comprises at least one of OFDMA symbol offset, subchannel offset, and information of OFDMA
slot.
It is to be understood that both the foregoing general description and the following
detailed description of the present invention are exemplary and explanatory and are intended to
provide further explanation of the invention as claimed.

[Advantageous Effects]
The present invention has the following effects.
Firstly, although a control message for assigning the transmission area to provide the
VoIP service is lost or has faulty or erroneous operations, the present invention can quickly
retransmit the control message, such that it can solve the lost or damaged packet generated
between the mobile station (MS) and the base station (BS).
Secondly, the present invention can solve the problem encountered when a transmission
area recognized by each mobile station (MS) is different from that of the base station (BS) in the
uplink. That is, the present invention prevents the lost VoIP packet encountered when the
mobile station (MS) and the base station (BS) have recognized different transmission areas.
Also, the mobile station (MS) has information of another area instead of an area assigned to the
mobile station (MS) itself, such that the collision problem encountered when another mobile
station (MS) transmits the packet can be solved.
Thirdly, although the control message for assigning the transmission area is damaged or
lost, the present invention can immediately re-assign the transmission area. Therefore, the
present invention can solve the problem that the mobile station (MS) is unable to recognize the
downlink transmission area assigned from the base station (BS).
Fourthly, the present invention can reduce an amount of overhead of the MAP message to
implement a periodic traffic pattern and a connection of fixed-sized payload (e.g., data
information).
[Description of Drawings]
The accompanying drawings, which are included to provide a further understanding of
the invention, illustrate embodiments of the invention and together with the description serve to
explain the principle of the invention.

FIG. 1 is a flow chart illustrating a BS assigning fixed radio resources to a MS using a
MAP message in an uplink.
FIG. 2 is a flow chart illustrating the BS assigning fixed radio resources to the MS using
the MAP message in a downlink.
FIG. 3 is a flow chart illustrating assignment of a radio-resource region to provide the
VoIP service according to an embodiment of the present invention.
FIG. 4 is a flow chart illustrating transmission of a VoIP-associated MAP message in an
uplink according to an embodiment of the present invention.
FIG. 5 is a flow chart illustrating transmission of a VoIP-associated MAP message in a
downlink according to an embodiment of the present invention.
FIG. 6 is a flow chart illustrating retransmission of a VoIP-associated MAP message in
an uplink according to an embodiment of the present invention.
FIG. 7 is a flow chart illustrating retransmission of a VoIP-associated MAP message in a
downlink according to an embodiment of the present invention.
FIG. 8 is a flow chart illustrating retransmission of a VoIP-associated MAP message in
an uplink according to an embodiment of the present invention.
FIG. 9 is a flow chart illustrating retransmission of a VoIP-associated MAP message in a
downlink according to an embodiment of the present invention.
FIG. 10 is a flow chart illustrating retransmission of a VoIP-associated control message
in an uplink according to an embodiment of the present invention.
FIG. 11 is a flow chart illustrating retransmission of a VoIP-associated control message
in a downlink according to an embodiment of the present invention.
[Mode for Invention]
In the following detailed description, reference is made to the accompanying drawing

figures which form a part hereof, and which show by way of illustration specific embodiments of
the invention. It is to be understood by those of ordinary skill in this technological field that
other embodiments may be utilized, and structural, electrical, as well as procedural changes may
be made without departing from the scope of the present invention. Wherever possible, the
same reference numbers will be used throughout the drawings to refer to the same or similar
parts.
Prior to describing the present invention, it should be noted that most terms disclosed in
the present invention correspond to general terms well known in the art, but some terms have
been selected by the applicant as necessary and will hereinafter be disclosed in the following
description of the present invention. Therefore, it is preferable that the terms defined by the
applicant be understood on the basis of their meanings in the present invention.
The present invention relates to a wireless access system. In more detail, the present
invention provides the packet transmission method when the packet is frequently transmitted and
a method of assigning radio resources in the wireless access system.
The order of operations disclosed in the embodiments of the present invention may be
changed. Some components or characteristics of any embodiment may also be included in
other embodiments, or may be replaced with those of other embodiments as necessary.
The following embodiments of the present invention will be disclosed on the basis of a
data communication relationship between the BS and the MS. The BS is used as a terminal
node of a network via which the BS can directly communicate with the MS. Specific operations
to be conducted by the MS in the present invention may also be conducted by an upper node of
the BS as necessary. Various operations for enabling the BS to communicate with the MS in a
network composed of several network nodes including the BS may be conducted by the BS or
other network nodes other than the BS.

The base station (BS) may also be called as a fixed station, Node-B, eNode-B (eNB), or
an access point as necessary. The mobile station (MS) may also be called as a user equipment
(UE) or a mobile subscriber station (MSS) as necessary.
The following embodiments of the present invention will disclose the VoIP service as an
exemplary service which requires frequent packet transmission. However, it should be noted
that the present invention is not limited to the VoIP service and can also be applied to other
services requesting frequent packet transmission/reception. A packet transmission method for
VoIP and the resource allocation method for the same VoIP under the condition that the packet
transmission is frequently required will be described hereinafter.
FIG. 1 shows an uplink case in which the MS transmits the VoIP packet to the BS.
Referring to FIG. 1, the MS and the BS determine whether the resource allocation method is
made available while the VoIP service is generated in S11.
If it is determined that the resource allocation is made available in S101, the BS includes
"VoIP_UL_IE" in the UL-MAP message and assigns the radio transmission region for providing
the VoIP service in S102. The UL-MAP message is used as a control message and includes a
radio transmission region which enables the MS to transmit the VoIP packet to the BS. The BS
assigns a first transmission region to the MS via the UL-MAP message.
When the MS receives the UL-MAP message from the BS, the MS stores allocation
information for the first transmission region included in the UL-MAP message in S103.
Subsequently, the MS transmits the VoIP packet to the BS via the first transmission region
which has been assigned from the BS in S104.
In order to assign the traffic resources having a fixed-sized constant period, such as the
VoIP packet, the BS fixedly assigns a first transmission region to the MS in S102. Therefore,
the BS can continuously assign the first transmission region to the MS without notifying other

messages via an initial transmission control channel or an initial transmission control message.
The VoIP packet is transmitted at intervals of a predetermined time, such that the MS
goes to the next period, for example, a lapse of 20 ms, and transmits the next VoIP packet to the
BS via the first transmission region in S105. While the MS transmits/receives the VoIP service
to/from the BS, channel environments or data transmission environments may be unexpectedly
deteriorated and it may be difficult to implement packet transmission/reception via the first
transmission region. Therefore, the BS includes "VoIP_UL_IE" in the control message
"UL-MAP" and assigns a second transmission region to the MS. In this case, the second
transmission region is assigned to a specific location different from that of the first transmission
region in S106.
When the MS receives the above mentioned UL-MAP message in S106, the first
transmission region for the VoIP service is updated with the second transmission region included
in the UL-MAP message in S107. Subsequently, the MS transmits the VoIP packet to the BS via
the second transmission region in S108.
The BS receiving the VoIP packet via the second transmission region may need to
change a current transmission region to another transmission region, if necessary. Therefore, in
order to assign a third transmission region that is different from the second transmission region
to the MS, the BS transmits the UL-MAP message including "VoIP_UL_IE" to the MS in S109.
However, the UL-MAP message may be lost during wired or wireless transmission in
S109 such that the MS does not receive the UL-MAP message. Alternatively, although the MS
receives the UL-MAP message, it may be unable to detect the UL-MAP message due to the
faulty or erroneous operation of the UL-MAP message.
In this case, the MS is unable to recognize the information of the third transmission
region in S109 and transmits the VoIP packet to the BS using the previous information, for

example, information of the second transmission region for the next period in S110. Therefore,
if the BS assigns the second transmission region for the VoIP service of another MS in SI 10, at
least two MSs transmit the VoIP packet to the same second transmission region. As a result,
packets may collide with each other and the BS may not receive such packets. Further, the BS
does not receive the packet via the third transmission region assigned to the MS and is unable to
receive the packet normally from the MS.
Referring to FIG. 2, it is noted that S201-S203 of FIG. 2 are similar to S101-S103 of
FIG. 1. In other words, in a downlink, the BS transmits the first transmission region to the MS
using the DL-MAP message acting as the control message in S202. The MS stores allocation
information of the first transmission region in S 203 and is ready to receive the VoIP packet from
the BS.
The BS transmits the VoIP packet to the MS via the first transmission region in S204. In
this case, in order to assign radio resources for traffic, such as VoIP packet, having a fixed-sized
period, the BS fixedly assigns the first transmission region to the MS in S202. Therefore, the
BS can continuously assign the transmission region to the MS without notifying other messages
via an initial transmission control channel or an initial transmission control message.
The VoIP packet is transmitted at intervals of a predetermined time such that the BS goes
to the next period, for example, a lapse of 20 ms, and transmits the next VoIP packet to the MS
via the first transmission region in S205. While the MS transmits/receives the VoIP service
to/from the BS, channel environments or data transmission environments may be unexpectedly
deteriorated and it may be difficult to perform packet transmission/reception via the first
transmission region. In this case, the BS includes "VoIP_DL_IE" in the control message
"DL-MAP" and may assign a second transmission region that is different from the first
transmission region to the MS in S206.

When the MS receives the above mentioned DL-MAP message in S206, the second
transmission region contained in the DL-MAP message is updated in S207. The BS transmits the
VoIP packet to the MS via the second transmission region assigned to the MS in S208.
The BS providing the VoIP service via the second transmission region may need to
change a current VoIP packet transmission region to another transmission region. Therefore, in
order to assign a third transmission region that is different from the second transmission region,
the BS transmits the DL-MAP message including "VoIP_DL_IE" to the MS in S209.
However, the DL-MAP message may be lost during wired or wireless transmission in
S209 and the MS may not receive the DL-MAP message. Alternatively, although the MS
receives the DL-MAP message, it may be unable to detect the DL-MAP message due to the
faulty or erroneous operation of the DL-MAP message.
In this case, the MS is unable to receive the DL-MAP message normally in S209 and
unable to recognize information of the third transmission region. Therefore, the BS continues
to transmit the VoIP packet periodically to the MS via the second transmission region and the
MS is unable to receive the VoIP packet via the third transmission region.
FIGS. 1 and 2 show that the BS assigns the resource region to the MS using the control
message "MAP IE". However, when the MS receives the MAP IE message abnormally and the
BS changes a transmission region for the VoIP service to another region, an unexpected problem
may arise during packet transmission because the MS and the BS have information of different
transmission regions.
Referring to FIG. 3, a VoIP service is generated between the MS and the BS in S301. The
BS and the MS negotiate with each other about the persistent resource allocation method used
when the VoIP service is generated in S301. According to an embodiment of the present
invention, the persistent resource allocation is available or the persistent allocation is enabled.

The BS assigns the first transmission region to transmit/receive the VoIP packet to/from
the MS using the control message such as the MAP message in S302.
The BS transmits/receives the VoIP packet to/from the MS via the first transmission
region. In other words, in the uplink, the MS transmits the VoIP packet to the BS via the first
transmission region and in the downlink, the BS transmits the VoIP packet to the MS via the first
transmission region.
While the BS transmits the VoIP service to the MS, user environment may be changed or
communication quality may be deteriorated. In this case, the BS determines to change a packet
transmission region for the VoIP service in S303.
The BS assigns the changed second transmission region to the MS. The BS transmits or
receives the VoIP service to/from the MS via the second transmission region in S304.
The BS may use the control message in order to assign the second transmission region to
the MS in S304. A message characterized by its solidity is used as the control message which
includes a MAP message. The MAP message (DL-MAP/UL-MAP) is used to assign unique
resource for each user. This MAP message is a MAC management message which dynamically
informs the MS of the resource allocation result at intervals of each frame.
In the downlink, the UL-MAP message designates the location of sub-channel
dynamically assigned to each MS and the number of the sub-channel. In the uplink, the
DL-MAP message designates the location of sub-channel dynamically assigned to each MS and
the number of the sub-channel. In particular, the DL-MAP message is a broadcast message
which indicates the set of information associated with total connection managed by a single BS.
For example, the DL-MAP message may include the principal information, band allocation
information, frame construction information, and ACK/NACK information.
The following table 1 shows an example of the VoIP UL-MAP information element

(VoIP_UL IE) which may be used to perform resource allocation, modify the resource
allocation, and delete the same.

Referring back to FIG. 3, in order to assign the second transmission region, the BS
transmits the control message to the MS in S304. In this case, the MS receives the control
message and can recognize the second transmission region in S305. If the MS receives the
control message and recognizes the second transmission region ('Yes' in S305), it transmits or
receives the VoIP packet to/from the BS via the second transmission region in S306.
The MS may not receive the control message in S305 ('No') due to a loss of the control
message during wired or wireless transmission. Or, even if the control message is received by
the MS, it may not be recognized due to errors in the control message. In this case, the BS

reallocates the second transmission region to the MS using a specific algorithm in S307. This
step may be repeated until the second transmission region equal to a new transmission region is
recognized. The number of repetition may be determined according to the communication
environment and a system requirement.
In order to reallocate the second transmission region, a variety of algorithms may be used
in S307. According to one of various algorithms, if a control message for allocating the second
transmission region is received normally, an acknowledgment (ACK) signal for the control
message is transmitted to the BS such that the MS indicates that the second transmission region
has been normally recognized.
If the MS does not receive the control message normally, it is unable to transmit the ACK
signal. Provided that the BS transmits the control message for assigning the transmission
region and does not receive the ACK signal from the MS, it may retransmit the above-mentioned
control message after a lapse of a predetermined number of frames, for example, N frames, in the
next frame or system.
According to another algorithm, the BS determines the presence or absence of a signal of
the second transmission region in S307 such that it may reallocate the second transmission
region. In this case, the BS does not use the ACK signal and determines whether the signal is
transmitted from the MS to the second transmission region. Further, other types of algorithms
may also be used to assign the second transmission region.
According to an embodiment of the present invention, a method for using the ACK signal
to reply to the control message, which can assign, modify, or delete radio resources for the VoIP
service, is described below. If the MS receives the VoIP-associated MAP IE message from the
BS when the MAP IE message, such as VoIP_DL_IE VoIP_UL_IE, is used as a control message,
the MS may transmit the ACK signal to the BS in response to the MAP IE message. In this

case, the BS allocates the control channel to a designated frame such that the MS can transmit
the ACK signal.
The ACK signal transmitted from the MS to the BS in response to the control message
may be an ACK/NACK or ACK message of a Hybid Automatic Repeat Request (HARQ), or an
ACK header. If the BS does not receive the ACK signal at a corresponding frame, the BS may
retransmit the control message, which has been transmitted to the MS, to the designated frame,
or may allocate radio resources to the MS using the radio-resource information pre-notified to
the MS.
Referring to FIG. 4, in an uplink, the process for generating the VoIP service between the
MS and the BS and allocating the first transmission region is equivalent to S101~S104 of FIG. 1.
Therefore, these steps are omitted and the next steps are described in FIG. 4.
The MS transmits the VoIP packet to the BS via the first transmission region assigned
from the BS in S401. While the VoIP packet is transmitted or received, the transmission region
may need to be changed to another region due to poor communication environments or some
other reasons. In this case, the BS may allocate the second transmission region to the MS using
the UL-MAP message (VoIP_UL_IE) acting as a control message in S402. Also, the BS may
allocate a specific region capable of transmitting the ACK signal via the control message.
When the MS receives the control message from the BS, the MS updates the second
transmission region contained in the control message to a new transmission region in S403.
When the MS has received the control message normally in S402, the MS transmits the ACK
signal, such as HARQ, ARK, ACK message or ACK header, to the BS in order to reply to the
normally-received control message in S404. Then, the MS transmits the VoIP packet to the BS
via the second transmission region, which was assigned as the new transmission region from the
BS, in S405.

Referring to FIG. 5, in a downlink, the process for generating the VoIP service between
the MS and the BS and allocating the first transmission region is equivalent to S201-S204 of
FIG. 2. Therefore, the same steps are omitted and the next steps are described in FIG. 5.
The BS transmits the VoIP packet to the MS via the first transmission region assigned to
the MS in S501. While the VoIP packet is transmitted or received, the transmission region may
need be changed to another region due to poor communication environments or some other
reasons. In this case, the BS may allocate the second transmission region to the MS using the
DL-MAP message (VoIP_DL_IE) acting as a control message in S502. Also, the BS may
allocate a specific region capable of transmitting the ACK signal via the control message.
If the MS receives the control message from the BS, the MS updates the second
transmission region contained in the control message to a new transmission region in S503.
When the MS has received the control message normally in S502, the MS can transmit the ACK
signal, such as HARQ, ARK, ACK message or ACK header, to the BS in order to reply to the
normally-received control message in S504.
Then, the BS transmits the VoIP packet via the second transmission region, which was
assigned to the MS as the new transmission region, in S505.
Referring to FIG. 6, in an uplink, the BS and the MS generate the VoIP service and the
BS allocates the transmission region for providing the MS with the VoIP service. The
above-mentioned operations are similar to S101-S104 of FIG. 1, and therefore, the same steps
are omitted and the next steps are described in FIG. 6.
The MS transmits the VoIP packet via the first transmission region assigned from the BS
in S601. While the BS transmits the VoIP service to the MS, it may need to change the radio
resources assigned to the MS to other radio resources. In this case, the BS allocates the second
transmission region to the MS using the UL-MAP message (VoIP_UL_IE) used as a control

message in S602.
However, it should be noted that the control message transmitted from the BS to the MS
may be lost or damaged during wired or wireless transmission, or the MS may not recognize the
control message due to faulty or erroneous operations. When the control message is lost, the
MS is unable to transmit the ACK signal associated with the above-mentioned control message
of S602 to the BS in S603.
The BS transmits the control message in S602 and waits for the ACK signal to determine
whether the MS has recognized the second transmission region. However, since the MS is
unable to transmit the ACK signal in S603 because the control message has been lost, the BS
determines that the second transmission region has not been recognized by the MS. Therefore,
the BS retransmits the UL-MAP message and reallocates the second transmission region in
S604.
The BS retransmits the UL-MAP message for reallocating the second transmission region
to the MS after a lapse of a predetermined value, for example, N frames, as determined by the
next fame or system in S604. The UL-MAP message is immediately retransmitted at the next
frame after S603.
The MS recognizes the second transmission region contained in the UL-MAP message
retransmitted from the BS and updates the first transmission region for VoIP-packet transmission
with the second transmission region in S605. Then, the MS transmits the ACK signal to the BS
in response to the received UL-MAP message in S606 and transmits the VoIP packet via the
second transmission region assigned from the BS. Even if the MS does not receive a new
transmission region by the above described steps, the MS according to the present invention can
quickly receive the transmission region from the BS such that it can effectively provide the VoIP
service.

Referring to FIG. 7, in a downlink, the BS and the MS generate the VoIP service and the
BS allocates the transmission region for providing the MS with the VoIP service. The
above-mentioned operations are similar to S201 to S204 of FIG. 2, and therefore, the same steps
are omitted and the next steps are described in FIG. 7.
The BS transmits the VoIP packet via the first transmission region assigned to the MS in
S701. While the BS transmits the VoIP service to the MS, the radio resources assigned to the MS
may need to be changed to other radio resources. In this case, the BS allocates the second
transmission region to the MS using the DL-MAP message (VoIP_DL_IE) used as a control
message in S702.
However, it should be noted that the control message transmitted from the BS to the MS
may be lost or damaged during wired or wireless transmission in S702, or the MS may not
recognize the control message due to faulty or erroneous operations in S702. As a result, the
MS is unable to transmit the ACK signal associated with the above-mentioned control message
from S702 to the BS in S703.
The BS transmits the control message in S702 and waits for the ACK signal to determine
whether the MS has recognized the second transmission region. However, since the DL-MAP
message transmitted from the BS has been lost in S702, the MS is unable to transmit the ACK
signal. Therefore, the BS determines that the second transmission region has not been
recognized by the MS and retransmits the DL-MAP message to reallocate the second
transmission region in S704.
The BS retransmits the DL-MAP message to reallocate the second transmission region to
the MS after a lapse of a predetermined value, for example, N frames, determined by the next
fame or system in S704. The DL-MAP message is retransmitted immediately at the next frame
after S703.

The MS recognizes the second transmission region contained in the DL-MAP message
retransmitted from the BS and updates the first transmission region for VoIP-packet transmission
with the second transmission region in S705. Then, the MS transmits the ACK signal to the BS
in response to the received DL-MAP message in S706 and the BS transmits the VoIP packet to
the MS via the assigned second transmission region in S 707. Accordingly, even if me MS has
not received a new transmission region by the above described steps, the BS according to an
embodiment of the present invention can quickly reallocate the transmission region to provide
the VoIP service effectively.
Referring to FIG. 8, in an uplink, the BS and the MS generate the VoIP service and the
BS allocates the transmission region for providing the MS with the VoIP service. The
above-mentioned operations are similar to steps S101~S104 of FIG. 1, and therefore, the same
steps are omitted and only different steps are described with reference to FIG. 8.
The MS transmits the VoIP packet via the first transmission region assigned from the BS
in S801. The resource-allocation region may need to be changed to another region during the
VoIP packet communication between the BS and the MS. In this case, the BS may allocate the
new second transmission region to the MS using the UL-MAP message (VoIP_UL_IE) used as a
control message in S802.
However, it should be noted that the control message transmitted from the BS to the MS
may be lost or damaged during wired or wireless transmission or the MS may not recognize the
control message due to faulty or erroneous operations. , When the UL-MAP message is lost in
S802, the MS is unable to transmit the ACK signal via the above mentioned region, which has
been allocated to the MS for ACK signal transmission, in S803.
Since the BS has not received the ACK signal from the MS in S803, it does not allocate
the first transmission region, which has been pre-assigned to the MS, to either another MS or

another service. Also, the BS may allocate resources to the corresponding MS using the
previous information.
Since the MS has not received the UL-MAP message, it is unable to transmit the VoIP
packet via the second transmission region. Therefore, the MS continues to transmit the VoIP
packet to the BS via the pre-assigned first transmission region in S804.
When the BS receives the VoIP packet from the MS via the first transmission region, it
determines that the control message in S802 has not been received normally by the MS.
Specifically, even after the BS assigns the second transmission region to the MS, when the MS
retransmits the VoIP packet via the first transmission region, the BS determines that the MS has
not received the control message normally in S802.
Therefore, after a lapse of the next frame or N frames of S803, the BS retransmits the
UL-MAP message (VoIP_UL_IE) to the MS to allocate the second transmission region in S805.
When the MS has received the UL-MAP message normally from the BS in S805, the MS
transmits the ACK signal to the BS via a predetermined region for transmitting the ACK signal
contained in the above-mentioned UL-MAP message in S806.
Referring to FIG. 9, in a downlink, the BS and the MS generate the VoIP service and the
BS allocates the first transmission region for providing the MS with the VoIP service. The
above-mentioned operations are similar to S201-S204 of FIG. 2, and therefore, the same steps
are omitted and only different steps are described with reference to FIG. 9.
The BS transmits the VoIP packet via the first transmission region assigned to the MS in
S901. The resource-allocation region may need to be changed to another region during the VoIP
packet communication between the BS and the MS. In this case, the BS may allocate the new
second transmission region to the MS using the DL-MAP message (VoIP_DL_IE) used as a
control message in S902.

However, it should be noted that the control message transmitted from the BS to the MS
may be lost or damaged during wired or wireless transmission in S902, or the control message
may be received by the MS abnormally due to faulty or erroneous operations. In S902, the
DL-MAP message has been lost, and therefore, the MS does not transmit the ACK signal via the
above described region, which has been allocated from the BS to transmit the ACK signal, in
S903.
Since the BS has not received the ACK signal from the MS in S903, it does not allocate
the first transmission region, which has been pre-allocated to the MS, to either another MS or
another service. Also, the BS allocates resources to the corresponding MS using the previous
information.
As shown in S903, the BS has not received the ACK signal in response to the DL-MAP
message of S902. Therefore, the BS determines that the MS has not recognized the second
transmission region yet and transmits the VoIP packet via the first transmission region in S904.
When the BS has not received ACK signal from the MS, it determines that the MS has
received the control message of S902 abnormally. Therefore, after a lapse of the next frame or
the predetermined N frames of the S803, the BS retransmits the DL-MAP message
(VoIP_DL_IE) to the MS to allocate the second transmission region in S905. When the MS has
received the DL-MAP message normally from the BS in S905, the MS transmits the ACK signal
to the BS via a predetermined region to transmit the ACK signal contained in the
above-mentioned DL-MAP message in S906.
As described above, if the radio resources for the VoIP service are allocated according to
the present invention, FIGS. 4-9 show not only a method for allocating radio resources between
the BS and the MS using the ACK signal, but also a method for recovering a synchronization
failure. According to another embodiment of the present invention, a method is provided for

determining whether there is a signal associated with a radio resource region assigned to the MS
by the BS and retransmitting the control message according to the determined result.
According to yet another embodiment, the present invention can solve the inconsistency in
radio-resource-region allocation between the BS and the MS.
For example, if no signal associated with the uplink traffic is detected as a signal of the
radio-resource region which has been allocated to the MS, the BS determines that it has
recognized another radio-resource region instead of the above radio-resource region having been
assigned to the MS. Therefore, the BS retransmits the control message to reallocate the
radio-resource region.
In case of a downlink, the BS transmits the packet to a specific region pre-assigned to the
MS in association with downlink traffic. However, if no signal is detected in the radio-resource
region assigned to the MS, the BS determines that the MS has information different from that of
the radio-resource region allocated by the BS in association with the downlink. Therefore, the
MS retransmits the control message to reallocate the radio-resource region.
Referring to FIG. 10, in an uplink, the VoIP service is generated between the MS and the
BS and the BS allocates the first transmission region for providing the MS with the VoIP service.
The above-mentioned operations are similar to S101 ~S 104 of FIG. 1, and therefore, the same
steps are omitted and only different steps are described with reference to FIG. 10.
The MS transmits the VoIP packet via the first transmission region assigned from the BS
to implement VoIP packet transmission in S1001. While the VoIP packet is transmitted or
received, the transmission region may need to be changed to another region due to poor
communication environments or some other reasons. In this case, the BS may allocate the
second transmission region different from the first transmission region to the MS using the
UL-MAP message (VoIP_UL_IE) acting as a control message in S1002.

However, it should be noted that the above-mentioned UL-MAP message may be lost or
damaged during wired or wireless transmission in S1002, or the MS may receive the UL-MAP
message abnormally in S1002. According to another embodiment of the present invention, the
UL-MAP message has been lost and the MS does not receive the UL-MAP message.
Even if the MS has not received the UL-MAP message, the BS can allocate the second
transmission region to the MS nonetheless in S1003. However, in S1003, the BS does not
actually allocate the radio resource region to the MS using the control message. The UL-MAP
message used as the control message is transmitted only when the transmission region needs to
be changed to another region.
Since the MS has not received the UL-MAP message in S1002, it is unable to transmit
the VoIP packet in S1004. If the BS detects no signal in the second transmission region which
has been assigned to the MS, it retransmits the UL-MAP message to the MS in order to
reallocate the second transmission region to the MS in S1005.
Referring to FIG. 11, in a downlink, the VoIP service is generated between the MS and
the BS and the BS allocates the first transmission region for providing the MS with the VoIP
service. The above-mentioned operations are similar to S201-S204 of FIG. 1, and therefore,
the same steps are omitted and only different steps are described with reference to FIG. 11.
The BS assigns the first transmission region to the MS to transmit the VoIP packet and
transmits the VoIP packet to the MS via the first transmission region in S1101. While the VoIP
packet is communicated between the MS and the BS, a first transmission region for providing a
current VoIP service may need to be changed to a new second transmission region. In this case,
the BS may allocate the second transmission region different from the first transmission region
to the MS using the DL-MAP message (VoIP_DL_IE) acting as a control message in S1102.
However, it should be noted that the above-mentioned DL-MAP message may be lost or

damaged during wired or wireless transmission in S1102, or the MS may receive the DL-MAP
message abnormally in S1102. According to another embodiment of the present invention, the
DL-MAP message is lost and the MS receives no DL-MAP message.
Even if the MS receives no DL-MAP message and does not recognize the second
transmission region as a new transmission region, the BS can allocate the second transmission
region to the MS nonetheless in S1103. However, in S1103, the BS does not actually allocate
the radio-resource region to the MS using the control message. The DL-MAP message used as
the control message is transmitted only when the transmission region needs to be changed to
another region.
The BS transmits the VoIP packet to the MS via the allocated second transmission region
in S1104. However, although the BS transmits the VoIP packet to the MS via the second
transmission region in S1104, the MS has recognized the first transmission region as the
VoIP-service region. As a result, the MS is unable to receive the VoIP packet which has been
transmitted to the second transmission region by the BS.
Therefore, the MS is unable to transmit the ACK signal for the VoIP packet to the BS in
S1105. The ACK signal of S1105 plays a unique role which is different from those of FIGS.
4~9. In other words, the ACK signal in S1105 is equivalent to the ACK signal for the VoIP
packet. The ACK signals of FIGS. 4-9 are related to the ACK signals for the control message.
When the BS detects no signal in the second transmission region which has been assigned to the
MS, it retransmits the DL-MAP message to the MS in order to reallocate the second transmission
region to the MS in S1106.
As described above, FIGS. 4 to 11 have depicted various embodiments of the present
invention. The above-mentioned methods proposed by the above embodiments can be applied
not only to the above described embodiments in which the radio resources are allocated, but also

to the other cases in which the allocated resources are modified or deleted or new resources are
continuously allocated.
The present invention has the following effects. First, although a control message for
assigning the transmission region to provide the VoIP service is lost or has faulty or erroneous
operations, the present invention can quickly retransmit the control message such that it can
solve the lost or damaged packet generated between the MS and the BS.
Second, the present invention can solve the problem encountered when a transmission
region recognized by each MS is different from that of the BS in the uplink. That is, the present
invention prevents the lost VoIP packet encountered when the MS and the BS have recognized
different transmission regions. Also, the MS has information of another region instead of a
region assigned to the MS itself such that the collision problem encountered when another MS
transmits the packet can be solved.
Third, although the control message for assigning the transmission region is damaged or
lost, the present invention can immediately re-assign the transmission region. Therefore, the
present invention can solve the problem when the MS is unable to recognize the downlink
transmission region assigned from the BS.
Fourth, the present invention can reduce an amount of overhead of the MAP message to
implement a periodic traffic pattern and a connection of fixed-sized payload, for example, data
information.
The above-mentioned messages and parameters are disclosed for only illustrative
purposes of the present invention. If required, other messages or other parameters may also be
used to implement the same purpose as that of the present invention. It should be noted that
most terminology disclosed in the present invention is defined in consideration of functions of
the present invention, and can be differently determined according to intention of those skilled in

the art or usual practices. Therefore, it is preferable that the above-mentioned terminology be
understood on the basis of all contents disclosed in the present invention.
Although the preferred embodiments of the present invention were disclosed for
illustrative purposes, those skilled in the art will appreciate that various variations and
modifications are possible, without departing from the scope and spirit of the invention as
disclosed in the accompanying claims. Thus, it is intended that the present invention cover the
modifications and variations of this invention provided they come within the scope of the
appended claims and their equivalents.
[Industrial Applicability]
As apparent from the above description, the present invention provides a method for
allocating radio resources to implement frequent packet transmission in a wireless access system,
and a packet transmission method. The present invention can also be applied to a variety of
wireless access systems.
Although the preferred embodiments of the present invention have been disclosed for
illustrative purposes, those skilled in the art will appreciate that various modifications, additions
and substitutions are possible, without departing from the scope and spirit of the invention as
disclosed in the accompanying claims.

[CLAIMS]
[Claim 1]
A method of allocating a radio resource in a wireless access system, the method
comprising:
receiving a control message associated with radio resource allocation for transmitting
uplink data to the base station, wherein the control message comprises a first persistent uplink
allocation information element comprising first resource allocation information associated with a
first resource allocation region for transmitting the uplink data of a mobile station; and
transmitting an acknowledgment (ACK) message from the mobile station to the base
station in response to successfully receiving the first persistent uplink allocation information
element.
[Claim 2]
The method of claim 1, further comprising:
transmitting the uplink data to the base station by the mobile station via the assigned first
resource allocation region.
[Claim 3]
The method of claim 1, wherein the base station retransmits the first persistent uplink
allocation information element if the ACK message is not received from the mobile station.
[Claim 4]
The method of claim 3, wherein the first persistent uplink allocation information is
retransmitted after a predetermined number of frames after not receiving the ACK message.
[Claim 5]
The method of claim 1, wherein a payload size of the uplink data is fixed.

[Claim 6]
The method of claim 1, wherein the uplink data comprises an IP-based Voice over
Internet Protocol (VoIP) data.
[Claim 7]
The method of claim 1, wherein the first resource allocation information comprises at
least one of orthogonal frequency division mulitiplxing access (OFDMA) symbol offset,
subchannel offset, and information of OFDMA slot.
[Claim 8]
The method of claim 1, wherein the first persistent uplink allocation information element
further comprises first ACK information associated with ACK transmission region; and
the ACK message is transmitted via an ACK transmission region which is indicated by
the first ACK information.
[Claim 9]
The method of claim 1, wherein the first persistent uplink allocation information element
further comprises a field for indicating whether the first resource allocation region is allocated or
de-allocated.
[Claim 101
The method of claim 1, further comprising:
receiving a second persistent uplink allocation information element comprising second
resource allocation information associated with a second resource allocation region for
transmitting the uplink data.
[Claim 11]
The method of claim 10, further comprising:
storing the second persistent uplink allocation information element; and

transmitting an acknowledgment (ACK) message from the mobile station to the base
station in response to successfully receiving the second persistent uplink allocation information
element.
[Claim 12]
The method of claim 11, further comprising:
transmitting the uplink data to the base station via the assigned second resource allocation
region.
[Claim 13]
The method of claim 10, wherein the second persistent uplink allocation information
element further comprises second ACK information associated with ACK transmission region;
and
the ACK message is transmitted via an ACK transmission region which is indicated by the
second ACK information.
[Claim 14]
The method of claim 1, wherein the mobile station continues transmitting the uplink data
to the base station via the first resource allocation region until a second persistent uplink
allocation information element associated with using a second resource allocation region is
received.
[Claim 15]
A method of allocating a radio resource in a wireless access system, the method
comprising:
receiving a control message associated with radio resource allocation for receiving
downlink data from the base station, wherein the control message comprises a first persistent

downlink allocation information element comprising first resource allocation information
associated with a first resource allocation region for receiving the downlink data from the base
station; and
transmitting an acknowledgment (ACK) message from the mobile station to the base
station in response to successfully receiving the first persistent downlink allocation information
element.
[Claim 16]
The method of claim 16, further comprising:
receiving the downlink data from the base station via the assigned first resource
allocation region.
[Claim 17]
The method of claim 15, wherein a payload size of the downlink data is fixed.
[Claim 18]
The method of claim 15, further comprising:
receiving a second persistent downlink allocation information element comprising second
resource allocation information associated with a second resource allocation region for receiving
downlink data.
[Claim 19]
The method of claim 18, further comprising:
storing the second persistent downlink allocation information element; and
transmitting an acknowledgment (ACK) signal from the mobile station to the base station in
response to successfully receiving the second persistent downlink allocation information
element.

[Claim 20]
The method of claim 19, further comprising:
receiving the downlink data from the base station via the assigned second resource
allocation region.
[Claim 21]
The method of claim 15, wherein the first persistent downlink allocation information
element further comprises ACK transmission region allocation information; and
the ACK message is transmitted via an ACK transmission region which is indicated by
the ACK transmission region allocation information.
[Claim 22]
The method of claim 21, wherein the first persistent downlink allocation information
element futher comprises a field for indicating whether the first resource allocation region is
allocated or de-allocated.
[Claim 23]
The method of claim 15, wherein the mobile station continues receiving the downlink
data from the base station via the first resource allocation region until a second persistent
downlink allocation information element associated with using a second resource allocation
region is received.
[Claim 24]
The method of claim 15, wherein the first resource persistent downlink allocation
information comprises at least one of OFDMA symbol offset, subchannel offset, and information
of OFDMA slot. ,
[Claim 25] A method of allocating a radio resource in a wireless access system, the method
comprising:

transmitting a control message associated with radio resource allocation for
communicating data to a mobile station, wherein the control message comprises a first persistent
allocation information element comprising first resource allocation information associated with a
first resource allocation region for communicating the data; and
receiving an acknowledgment (ACK.) message from the mobile station in response to
successfully receiving the first persistent allocation information element.
[Claim 261
The method of claim 25, further comprising:
communicating the data via the assigned first resource allocation region.
[Claim 27]
The method of claim 25, wherein a payload size of the data is fixed.
[Claim 28]
The method of claim 25, further comprising:
transmitting a second persistent allocation information element comprising second
resource allocation information associated with a second resource allocation region for
communicating the data.
[Claim 29]
The method of claim 28, further comprising:
storing the second persistent allocation information element; and
receiving an acknowledgment (ACK) signal from the mobile station in response to
successfully receiving the second persistent allocation information element.
[Claim 30]
The method of claim 29, further comprising:
transmitting the data to the mobile station via the assigned second resource allocation

region.
[Claim 31]
The method of claim 30, wherein the first -persistent allocation information element
further comprises ACK transmission region allocation information; and
the ACK message is received via an ACK transmission region which is indicated by the ACK
transmission region allocation information.
[Claim 32]
The method of claim 31, wherein the first persistent uplink allocation information futher
comprises a field for indicating whether the first resource allocation region is allocated or
de-allocated.
[Claim 33]
The method of claim 25, wherein the base station continues communicating the data with
the mobile station via the first resource allocation region until a second persistent allocation
information element associated with using a second resource allocation region is transmitted to
the mobile station.
[Claim 34]
The method of claim 25, wherein the first resource persistent downlink allocation
information comprises at least one of OFDMA symbol offset, subchannel offset, and information
of OFDMA slot.

A method of allocating a radio resource in a wireless access system is disclosed. The method includes receiving a
control message associated with radio resource allocation for transmitting uplink data to the base station, wherein the control message
comprises a first persistent uplink allocation information element comprising first resource allocation information associated with a
first resource allocation region for transmitting the uplink data of a mobile station and transmitting an acknowledgment (ACK) message
from the mobile station to the base station in response to successfully receiving the first persistent uplink allocation information
element.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=QC0VoOU/ugtxo2OvBkcUOg==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

269679

Indian Patent Application Number

1129/KOLNP/2010

PG Journal Number

45/2015

Publication Date

06-Nov-2015

Grant Date

30-Oct-2015

Date of Filing

29-Mar-2010

Name of Patentee

LG ELECTRONICS INC.

Applicant Address

20, YEOUIDO-DONG, YEONGDEUNGPO-GU, SEOUL 150-721 REPUBLIC OF KOREA

Inventors:

#	Inventor's Name	Inventor's Address
1	KIM, JEONG KI	LG INSTITUTE, HOGYE 1(IL)-DONG, DONGAN-GU, ANYANG-SI, GYEONGGI-DO 431-080 REPUBLIC OF KOREA
2	RYU, KI SEON	LG INSTITUTE, HOGYE 1(IL)-DONG, DONGAN-GU, ANYANG-SI, GYEONGGI-DO 431-080 REPUBLIC OF KOREA
3	CHO, HEE JEONG	LG INSTITUTE, HOGYE 1(IL)-DONG, DONGAN-GU, ANYANG-SI, GYEONGGI-DO 431-080 REPUBLIC OF KOREA
4	LIM, JAE WON	LG INSTITUTE, HOGYE 1(IL)-DONG, DONGAN-GU, ANYANG-SI, GYEONGGI-DO 431-080 REPUBLIC OF KOREA

PCT International Classification Number

H04B 7/26

PCT International Application Number

PCT/KR2008/005246

PCT International Filing date

2008-09-05

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10-2007-0095946	2007-09-20	Republic of Korea