Title of Invention

APPARATUS AND METHOD FOR CONTROLLING OPERATIONAL STATES OF MEDIUM ACCESS CONTROL LAYER IN A BROADBAND WIRELESS ACCESS COMMUNICATION SYSTEM

Abstract Disclosed is a method for controlling an operational state of a medium access control layer, by an access terminal, in a broadband wireless access communication system. The method comprises the steps of performing an uplink access of a contention-based scheme to an access point (100) using resources required to perform the uplink access according to the contention-based scheme when data to be transmitted in an access state is detected, and being allocated resources required to perform an uplink access of a contention-free scheme from the access point in a case of failing in the uplink access of the contention-based scheme; and performing a state transition from the access state into the traffic state (219) in a case of having been allocated the resource required for the contention-free scheme, and performing the uplink access of the contention-free scheme to the access point (100) using the allocated resource in the traffic state (219).
Full Text APPARATUS AND METHOD FOR CONTROLLING OPERATIONAL
STATES OF MEDIUM ACCESS CONTROL LAYER IN A
BROADBAND WIRELESS ACCESS COMMUNICATION SYSTEM
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a broadband wireless access
communication system, and more particularly to an apparatus and a method for
controlling the operational states of a medium access control layer.
2. Description of the Related Art
A 4th generation ('4G') communication system, which is a next
generation communication system, is being actively designed and studied in
order to provide users with services having various Qualities of Service ('QoS')
at a high transmission rate. Meanwhile, a wireless local area network ('LAN')
system and a wireless metropolitan area network ('MAN') system generally
provide transmission speeds of about 20 Mbps to 50 Mbps. Therefore, the
current 4G communication system is developing into a system that assures
mobility and a QoS in the wireless LAN and MAN systems which inturn assure a
relatively-high transmission speed.
In the following description, the broadband wireless access
communication system will be explained with reference to FIG. 1.
FIG. 1 is a view showing a construction of a general broadband wireless
access communication system.
Prior to the explanation of FIG. 1, it is noted that a wireless MAN system
is a type of broadband wireless access communication system capable of
providing a wider service coverage area and a higher transmission speed than that
of a wireless LAN system. An IEEE(Institute of Electrical and Electronics
Engineers) 802.16a communication system applies an orthogonal frequency
division multiplexing (OFDM) scheme and an orthogonal frequency division
multiplexing access (OFDMA) scheme to a physical channel of the wireless
MAN system in order to support a broadband transmission network. Since the
IEEE 802.16a communication system applies the OFDM/OFDMA scheme to the
wireless MAM system, the IEEE 802.16a communication system transmits a
physical channel signal by using a plurality of sub-carriers, so that it is possible
to transmit high-speed data. Meanwhile, an IEEE 802.16e communication
system is achieved by supplementing the above-described IEEE 802.16a
communication system to enable the mobility of an access terminal (AT).
However, currently, the IEEE 802.16e communication system has not been
standardized in detail.
Both IEEE 802.16a and IEEE 802.16e communication systems are
broadband wireless access communication systems using the OFDM/OFDMA
scheme. For the convenience of explanation, only the IEEE 802.16a
communication system will be described below as an example. The IEEE
802.16a and IEEE 802.16e communication systems can use either the
OFDM/OFDMA scheme or a single carrier(SC) scheme, but the following
description will be given in consideration of only the OFDM/OFDMA scheme.
Referring to FIG. 1, the IEEE 802.16a communication system has a
single cell structure and includes an access point (AP) 100 and a plurality of
access terminals 110, 120, and 130 which are managed by the access point 100.
The access point conducts signal communications with the access terminals 110,
120, and 130 by using the OFDM/OFDMA scheme.
The wireless MAN system is suitable for high-speed communication
services because it has a wide service coverage area and provides a high
transmission speed. However, since the wireless MAN system does not take
into consideration the user's mobility, that is the mobility of an access terminal,
handoff according to high-speed mobility of the access terminal is also not taken
into consideration in the wireless MAN system. It is therefore necessary to
develop a definite operation scheme of a medium access control ('MAC') layer
which minimize power consumption of an access terminal moving at a high
speed and" supports an operation for a high-speed packet data transmission
between the access terminal and an access point.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made to solve at least the
above-mentioned problems occurring in the prior art, and an object of the present
invention is to provide an apparatus and a method for controlling the operational
states of a medium access control (MAC) layer in a broadband wireless access
communication system.
Another object of the present invention is to provide an apparatus and a
method for controlling the operational states of a medium access control the
MAC layer so as to minimize the power consumption of an access terminal in a
broadband wireless access communication system.
Still another object of the present invention is to provide an apparatus
and a method for controlling the operational states of a medium access control
(MAC) layer so as to support an uplink access according to the grade of service
in a broadband wireless access communication system.
Still another object of the present invention is to provide an apparatus
and a method for controlling the operational states of a medium access control
(MAC) layer so as to support a fast access in a broadband wireless access
communication system.
In accordance with one aspect of the present invention, there is provided
an apparatus for transmitting a wake-up channel in a broadband wireless access
communication system. The apparatus comprises a symbol repeater for receiving
wake-up indicators, a number of frames constructing a super frame of a wake-up
channel, and a frame period, the wake-up indicators representing whether or not
access terminals in a sleeping mode of a sleeping state wake up, the wake-up
channel including the wake-up indicators, the frame period representing a period
in which the wake-up indicators are transmitted in the super frame, and for
repeating a symbol of the wake-up indicators according to a transmission format
of the wake-up channel; a wake-up channel information mapper for receiving slot
index information according to a predetermined control and on/off setting
information of the wake-up indicator, and for setting the wake-up indicators,
which exists in slots corresponding to the slot index information, from among
signals output from the symbol repeater, according to the on/off setting
information; and a controller for determining access terminals to which data or
updated system information is transmitted when there is data to be transmitted or
when the system information is updated, and for outputting slot index
information and first setting information to the wake-up channel information
mapper, the slot index information monitored by the determined access terminals,
the first information representing that wake-up indicators corresponding to the
slot index information have to be set to 'on'.
In accordance with another aspect of the present invention, there is
provided a method for controlling an operational state of a medium access control
layer in a broadband wireless access communication system. The method
comprising the steps of performing an uplink access of a contention-based
scheme to an access point using resources required to perform the uplink access
according to the contention-based scheme when data to be transmitted is detected
in an access state; receiving resources required to perform an uplink access of a
contention-free scheme from the access point in a case of failing in the uplink
access of the contention-based scheme; and performing a state transition from the
access state into a traffic state in a case of receiving the resources required to
perform the uplink access of the contention-free scheme, and performing the
uplink access of the contention-free scheme to the access point using the received
resources in the traffic state.
In accordance with still another aspect of the present invention, there is
provided a method for controlling an operational state of a medium access control
layer in a broadband wireless access communication system, the medium access
control layer having a null state for performing an initial operation following a
reset, an initialization state for acquiring synchronization with an access point
and performing a network entry operation to the access point, a sleeping state for
performing a wake-up operation by a control of the access point or when there is
data to be transmitted to the access point, an access state for performing an uplink
access of a contention-free scheme to the access point, and a traffic state for
transmitting data to the access point or receiving data from the access point. The
method comprises the steps of allocating codes by the access point for uplink
access of a contention-based scheme and allocating codes by the access point for
the uplink access of the contention-free scheme according to QoS (Quality of
Service) classes; selecting a first code by an access terminal, according to the
QoS classes of data to be transmitted from among the allocated codes for the
uplink access of the contention-based scheme, when the data to be transmitted
through an uplink in the access state is generated, and performing an uplink
access of the contention-based scheme to the access point using the first code;
allocating by the access point a second code, from among the codes for uplink
access of the contention-free scheme, to the access terminal so that the access
terminal can perform an uplink access of the contention-free scheme, when it
fails to allocate the access terminal a resource for data transmission of the access
terminal in response to the uplink access performed by the access terminal; and
performing by the access terminal a state transition from the access state into the
traffic state when allocated the second code, and performing an uplink access of
the contention-free scheme to the access point using the second code in the traffic
state.
In accordance with still another aspect of the present invention, there is
provided a method for controlling an operational state of a medium access control
layer in a broadband wireless access communication system. The method
comprising of the steps of acquiring synchronization with an access point to
which an access terminal belongs in a system detecting mode of an initialization
state, performing a mode change from the system detecting mode into a network
entry mode, and performing a network entry operation to the access point in the
network entry mode; entering a sleeping mode of a sleeping state from the
network entry mode when there is no data to be transmitted to the access point or
received from the access point, entering an access state from the network entry
mode when there is data to be transmitted to the access point, and entering a
traffic state from the network entry mode when there is data to be received from
the access point, after performing the network entry operation; entering an awake
mode of the sleeping state when there is data to be transmitted to the access point
or when a wake-up is requested from the access point in the sleeping state, and
entering the access state from the awake mode when there is data to be
transmitted to the access point; and receiving predetermined information from the
access point in the awake mode, and entering either the sleeping mode or the
traffic state from the awake mode according to the predetermined information.
In accordance with still another aspect of the present invention, there is
provided a method for controlling an operational state of a medium access control
layer in a broadband wireless access communication system. The method
comprising the steps of transmitting by an access point a pilot channel signal and
a broadcast channel signal, the pilot cannel signal being used for synchronization
acquisition with an access terminal, the broadcast channel signal including
system information of the broadband wireless access communication system;
acquiring by the access terminal synchronization with the access point, to which
the access terminal itself belongs, using the pilot channel signal in a system
detecting mode of an initialization state, and entering a network entry mode;
receiving by the access terminal the broadcast channel signal and transmitting a
network entry request message to the access point in the network entry mode;
transmitting by the access point a network entry response message to the access
terminal in response to the network entry request message, the network entry
response message including slot index information of a wake-up channel which
the access terminal monitors in the sleeping mode of the sleeping state; and
receiving by the access terminal the network entry response message, and
entering the sleeping mode when there is no data to be transmitted to the access
point or received from the access point, thereby monitoring a wake-up indicator
of the wake-up channel corresponding to the slot index information.
In accordance with still another aspect of the present invention, there is
provided a method for transmitting a wake-up channel in a broadband wireless
access communication system. The method comprising the steps of: receiving
wake-up indicators, a number of frames constructing a super frame of a wake-up
channel, and a frame period, the wake-up indicators representing whether or not
access terminals in a sleeping mode of a sleeping state wake up, the wake-up
channel including the wake-up indicators, the frame period representing a period
in which the wake-up indicators are transmitted in the super frame, and repeating
a symbol of the wake-up indicators according to a transmission format of the
wake-up channel; determining access terminals to which data or updated system
information is transmitted when there is the data to be transmitted or when the
system information is updated, and determining slot index information which the
determined access terminals monitor; and setting wake-up indicators
corresponding to the determined slot index information to 'on', and transmitting
the wake-up channel signal.
In accordance with still another aspect of the present invention, there is
provided a method for controlling an operational state of a medium access control
layer in a broadband wireless access communication system. The method
comprising the steps of entering an active mode of a traffic state, when there is
data to be received from an access point in one of an initialization state and in a
sleeping state, or when an uplink bandwidth is allocated according to uplink
access performance of a contention-based scheme in an access state; entering a
hold mode when data transmission to the access point or data reception from the
access point is interrupted for a predetermined period of time during data
transmission to the access point or data reception from the access point while in
an active mode; receiving a predetermined channel signal in the hold mode so as
to monitor whether or not a wake-up request is generated from the access point,
entering the active mode when a wake-up request is generated from the access
point, and entering the fast access mode when data to be transmitted to the access
point is generated in the hold mode; and performing an uplink access of a
contention-free scheme to the access point in the fast access mode using
resources for the uplink access of the contention-free scheme, and entering the
active mode when being allocated the uplink bandwidth as a result of the uplink
access performance of the contention-free scheme.
In accordance with still another aspect of the present invention, there is
provided a method for controlling an operational state of a traffic state in a
broadband wireless access communication system. The method comprising the
steps of: 1) transmitting data to an access point or receiving data from an access
point by an access terminal in an active mode; 2) requesting the access terminal
to perform a mode change from the active mode into a hold mode by the access
point, when the data transmission to the access terminal or data reception from
the access terminal, which is in the active mode, is interrupted during a
predetermined period of time; 3) entering the hold mode by the access terminal
after transmitting a response to the access point in response to the mode change
request of step 2), receiving a set channel signal, which is monitored to determine
if a wake-up request is generated from the access point, entering the active mode
when a wake-up request is generated from the access point, and entering a fast
access mode when data to be transmitted to the access point are generated in the
hold mode; 4) requesting by the access terminal in the fast access mode that a
mode of the access terminal is changed from the fast access mode into active
mode using a resource for uplink access of a contention-free scheme; and 5)
transmitting a response to the access terminal by the access point in response to a
mode change request of step 4), thereby causing the access terminal to perform a
mode change from the fast access mode into the active mode and to transmit the
data to the access point.
In accordance with still another aspect of the present invention, there is
provided a method for controlling an operational state of a traffic state in a
broadband wireless access communication system. The method comprises the
steps of: 1) requesting by an access terminal an access point that a mode of the
access terminal itself is changed from an active mode into a hold mode when data
transmission or data reception is interrupted for a predetermined period of time
during the data transmission/reception to/from the access point while in the active
mode; 2) transmitting by the access point a response to a mode change request of
step 1) to the access terminal, thereby causing the access terminal to enter the
hold mode; 3) requesting by the access point the access terminal to change a
mode of the access terminal from the hold mode into the active mode when
detecting that data to be transmitted to the access terminal being in the hold mode
are generated; and 4) performing by the access terminal a mode change from the
hold mode into the active mode according to a mode change request of step 3),
thereby receiving the data from access point.
ACCOMPNYING
BRIEF DESCRIPTION OF THE/DRAWINGS
The above and other objects, features and advantages of the present
invention will be more apparent from the following detailed description taken in
conjunction with the accompanying drawings, in which:
FIG. 1 is a structure diagram schematically illustrating a construction of a
general broadband wireless access communication system;
FIG. 2 is a state diagram schematically illustrating operational states
supported by a MAC layer in a broadband wireless access communication system
according to an embodiment of the present invention;
FIG. 3 is a diagram schematically illustrating operation modes of a
initialization state a sown in FIG. 2;
FIG. 4 is a diagram schematically illustrating operation modes of a
sleeping state shown in FIG. 2;
FIG. 5 is a flowchart illustrating a signal transmitting/receiving process
performed between an access point and an access terminal in a initialization state
shown in FIG. 2;
FIG. 6 is a flowchart illustrating a signal transmitting/receiving process
performed between an access point and an access terminal in a sleeping state
shown in FIG. 2;
FIG. 7 is a flowchart illustrating an operation process of the access point
in a sleeping state shown in FIG. 2;
FIG. 8 is a flowchart illustrating an operation process of the access
terminal in a sleeping state shown in FIG. 2;
FIG. 9 is a block diagram illustrating a construction of a DL-WUCH
transmitter according to an embodiment of the present invention;
FIG. 10 is a flowchart illustrating an operation process of an access
terminal in an access state shown in FIG. 2;
FIG. 11 is a flowchart illustrating a signal transmitting/receiving process
performed between an access point and an access terminal in an access state
shown in FIG. 2;
FIG 12 is a flowchart illustrating an operation process of an access point
in a access state shown in FIG. 2;
FIG. 13 is a view showing operation modes of a traffic state shown in FIG.
2;
FIG. 14 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change from an active mode 1300 into a hold mode, which is
performed upon request from an access point and is shown in FIG. 13;
FIG. 15 is a signal flowchart illustrating a mode change process from a
hold mode into an active mode, which is performed upon request from an access
terminal and is shown in FIG. 13;
FIG. 16 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change from an active mode 1300 into a hold mode, which is
performed upon request from an access terminal and is shown in FIG. 13;
FIG. 17 is a signal flowchart illustrating a mode change process from a
hold mode into an active mode , which is performed upon request from an access
point and is shown in FIG. 13;
FIG. 18 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change process from a hold mode into an active mode, which
is performed upon request from an access point and is shown in FIG. 13; and
FIG. 19 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change process from a hold mode into an active mode, which
is performed upon request from an access terminal and is shown in FIG. 13.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereinafter, preferred embodiments of an apparatus and a method for
controlling operational states of a medium access control (MAC) layer in a
broadband wireless access communication system according to the present
invention will be described with reference to the accompanying drawings. In
the following description of the present invention, a detailed description of
known functions and configurations incorporated herein will be omitted when it
may obscure the subject matter of the present invention.
The present invention proposes a scheme for controlling the operational
states of the MAC layer in the broadband wireless access communication system.
Particularly, the control scheme for the operational states of the MAC layer,
which is proposed in the present invention, supports the mobility of an access
terminal (AT), and enables a fast access while minimizing the power
consumption of the access terminal.
First, in order to support the operational states of the MAC layer the
present invention proposes new downlink channels and new uplink channels
and the newly proposed downlink channels and uplink channels will be described
with reference to Table 1.

A description will be given for each of downlink channels shown in Table
1.
(1) Pilot Channel ('DL-PICH')
The DL-PICH is a channel for cell identification and for the
synchronization acquisition between an access point (AP) and an access terminal.
The access point may manage either a plurality of cells or only one cell, but, in
the following description, it is assumed for the convenience of explanation that
one access point manages only one cell. Therefore, it should be noted that the
term "cell" will be used as having the same meaning as that of the term "access
point". The access terminal receives the DL-PICH signals transmitted from a
plurality of access points after being powered on, and determines which access
point transmits a DL-PICH signal of the greatest power level, for example a DL-
PICH signal having the greatest carrier-to-interference-and-noise ratio ('CINR'),
from among the received DL-PICH signals as the access point to which the
access terminal belongs. In the following description about downlink channels,
it should be noted that the acronym 'DL' is commonly used to represent
'downlink channel'.
(2) Broadcast Channel ('DL-BCCH')
The DL-BCCH is a channel for transmitting the system configuration
information related to the broadband wireless access communication system,
neighbor cell information, the downlink and uplink channel configuration
information, the downlink and uplink access information, the paging information
representing that there is a call to a specific access terminal, the slot index
information of a wake-up channel ('DL-WUCH'). An access terminal has to
monitor the DL-WUCH so as to perform a mode shifting operation from a
sleeping mode of a sleeping state to an awake mode, etc.
The sleeping mode is a mode for minimizing the power consumption in
such a manner that the access terminal monitors only the DL-WUCH and then
monitors the DL-BCCH only when the wake-up indicator of the DL-WUCH
allocated into the access terminal itself is turned on. The awake mode is a mode
in which the access terminal monitors a DL-BCCH, which is transmitted from the
access point, to determine whether or not the system information is updated or
paging information is received. The detailed operations of the sleeping mode
and the awake mode have no direct connection with the present invention, and
the detailed description of them will be omitted herein. When the system
configuration information, the downlink and uplink channel configuration
information, the downlink and uplink access information, and the like are
changed, the access point updates the changed information and periodically
transmits the updated information to an access terminal through the DL-BCCH.
In addition, a response to the uplink access is also transmitted through the DL-
BCCH. The DL-BCCH is established as a super frame unit, and the information
is periodically and repeatedly transmitted in a super frame unit. Herein the
super frame includes a predetermined number of frames.
When the access point determines that a slot index of a DL-WUCH,
which an access terminal monitors to perform a mode shifting operation from a
sleeping mode of a sleeping state to an awake mode, the access point allocates a
particular slot index of the DL-WUCH to each of the access terminals managed
by the access point, and maintains the allocated slot index of the DL-WUCH
until the access terminal is handed off to a new access point. The number of
slot indexes of the DL-WUCH to be allocated by the access point may change
depending on the configuration of the DL-WUCH, and the present invention does
not involve the configuration of the DL-WUCH, so the detailed description of
that will be omitted herein.
(3) Downlink-Uplink Scheduling Channel ('DL-USCCH')
The DL-USCCH is a channel which transmits the scheduling information
for the transmission of an uplink traffic channel ('UL-TCH') and control
information related to an uplink, such as an adaptive-modulation-and-coding
( 'AMC') scheme. Particularly, through the DL-USCCH, a bandwidth
allocation response message is transmitted in response to a bandwidth allocation
request message. When it is necessary for the access terminal to transmit traffic
through an uplink, the access terminal transmits a bandwidth allocation request
message for the uplink traffic transmission to the access point through an uplink
access channel ('UL-ACH'), and monitors whether or not a bandwidth allocation
response message, which is a response message to the bandwidth allocation
request message, is received from the access point through the DL-USCCH.
When receiving a bandwidth allocation response message through the DL-
USCCH, the access terminal transmits the traffic through an uplink according to
the control information included in the bandwidth allocation response message.
When the access terminal performs a connection establishment operation
for traffic transmission to an access point, if there is a predetermined convention,
the access point may continuously allocate a predetermined bandwidth to the
access terminal although the access terminal does not transmit an additional
bandwidth allocation request message through an uplink. The access terminal
may transmit traffic data through the allocated bandwidth, and may transmit a
bandwidth allocation request message for data to be transmitted through the UL-
TCH in a contention-free scheme method. Then, the access terminal determine
the allocation information of an uplink by monitoring the DL-USCCH. In order
to transmit traffic data to the access point through the UL-TCH, the access
terminal must also continuously monitor the DL-USCCH to monitor for
information about bandwidth allocation performed by the access point.
(4) Traffic Channel ('DL-TCH')
The DL-TCH is a channel for transmitting the actual packet data.
According to the characteristics of packet data to be transmitted, three logical
channels may be mapped in the DL-TCH as described below.
a. Burst Traffic Channel
The burst traffic channel is a logical channel for transmitting burst traffic,
in which the burst traffic is transmitted in a time-shared scheme that provides a
burst-based dynamic allocation scheme based on a dynamic scheduling scheme.
A description will be given for service classes, that is the Qualities of Service
('QoS'), of the broadband wireless access communication system with reference
to Table 2.

Through the burst traffic channel, the real-time service data are
scheduled to be transmitted, the non-real-time service data are transmitted, or the
best effect service data are transmitted.
b. Dedicated Traffic Channel
The dedicated traffic channel is a channel for allocating a fixed minimum
bandwidth. Data, such the (UGS data, to which a minimum bandwidth is
continuously allocated are transmitted through the dedicated traffic channel.
c. Signaling Channel
The signaling channel is a channel for transmitting a signaling message
which is control information.
(5) Traffic Control Channel ('DL-TCCH')
The DL-TCCH is a channel for transmitting the control information for
an access terminal to efficiently process the data transmitted through the DL-
TCH, that is the control information related to the DL-TCH. The DL-TCCH is
always transmitted in connection with the DL-TCH. The control information
transmitted through the DL-TCH includes AMC scheme information applied to
the data transmitted through the DL-TCH, information used in the data decoding
such as encoded packet size ('EP') information, an MAC control message, etc.
Also, the access point may feedback AMC scheme information related to the
packet data, which is transmitted through an uplink, to the access terminal
through the DL-TCCH.
(6) Wake Up Channel ('DL-WUCH')
The DL-WUCH, which is a channel for minimizing the power
consumption of an access terminal, is monitored by the access terminal in a
sleeping mode of a sleeping state. A wake-up indicator exists in a specific part
of the DL-WUCH, the access terminal performs a mode shifting operation from
the sleeping mode to an awake mode according to whether the wake-up indicator
is turned on or off. That the wake-up indicator is turned on represents that the
value of the wake-up indicator is set to a first value, for example, 'one', and in
contrast, that the wake-up indicator is turned off represents that the value of
wake-up indicator is set to a second value, for example, 'zero'. Also, the DL-
WUCH is transmitted as a super frame unit like the DL-BCCH.
The above description with reference to Table 2 has defined the downlink
channels proposed in the present invention. The uplink channels proposed in
the present invention will be described with reference to Table 3.

Each uplink channel shown in Table 3 will now be described.
(1) Access Channel ('UL-ACH')
The UL-ACH is a channel used by an access terminal when the access
terminal transmits a bandwidth allocation request signal to request a bandwidth
allocation, for the purpose of data transmission through an uplink, that is, for the
purpose of uplink access. According to the grade of the access terminal or the
characteristics of data to be transmitted through the uplink, two logical channels
as described below may be mapped to the UL-ACH.
a. Access Channel
The access channel is a channel for uplink access of a contention-based
scheme, and is used when the access terminal enters a network or when the
access terminal requests a bandwidth allocation. Through the access channel, a
very small amount of data, such as a TCP (Transmission Control Protocol)
ACK/NACK signal, may be transmitted together with an uplink access request
signal (access preamble + packet data).
b. Fast Access Channel
The fast access channel is a channel for the uplink access of a contention-
free scheme. An orthogonal code, such as a pseudorandom noise (PN) code, or
a time slot position, which is used for the uplink access, is allocated to an access
terminal from an access point. Then, the access terminal performs the uplink
access through the fast access channel using the orthogonal code or the time slot
position allocated from the access point. In the following description, a PN
code which is used for the uplink access through the UL-FACCH, that is, for fast
access, is called a 'fast access PN code', and a time slot used for the fast access is
called a 'fast access time slot'. The fast access PN code and the fast access time
slot will be described later in detail.
(2) Traffic Channel ('UL-TCH')
The UL-TCH is a channel used when an access terminal transmits data to
an access point. According to the characteristics of the data transmitted through
the UL-TCH, three logical channels may be mapped in the UL-TCH as described
above. Herein, the traffic channel is also included to the downlink channels as
described above. For convenience of description, the traffic channel of an
uplink is called an 'UL-TCH'.
a. Burst Traffic Channel
The burst traffic channel has the same function as that of the burst traffic
channel mapped to the DL-TCH, and has only one difference in that the burst
traffic channel is mapped not to the DL-TCH but to the UL-TCH, and so, a
detailed description thereof will be omitted.
b. Dedicated Traffic Channel
The dedicated traffic channel has the same function as that of the
dedicated traffic channel mapped to the DL-TCH, and has only one difference in
that the dedicated traffic channel is mapped not to the DL-TCH but in the UL-
TCH, and so, a detailed description thereof will be omitted.
c. Signaling Channel
The signaling channel has the same function as that of the signaling
channel mapped to the DL-TCH, and has only one difference in that the signaling
channel is mapped not to the DL-TCH but to the UL-TCH, and so, a detailed
description thereof will be omitted.
Hereinafter, a description will be given for the MAC operational states
for performing the actual operations, with reference to FIG. 2, using the newly
proposed downlink and uplink channels in the present invention as described in
Tables 1 and 3.
FIG. 2 is a state diagram showing the operational states supported by a
MAC layer in a broadband wireless access communication system according to
an embodiment of the present invention.
Referring to FIG. 2, the MAC layer of the broadband wireless access
communication system proposed in the present invention supports five types of
operational states, that is, a null state 211, an initialization state 213, a sleeping
state 215, an access state 217, and a traffic state 219. The operational states of
the MAC layer proposed in the present invention supports the mobility of an
access terminal (AT), and enables the fast access while minimizing the power
consumption of the access terminal.
Each of the operational states of the MAC layer will now be described.
First, a description will be given for the null state 211. The null state
211 is a state to perform an initial operation, when an access terminal is powered
on, or when the access terminal is reset by an abnormal operation. It is possible
that the state transition can be performed from each of the initialization state 213,
the sleeping state 215, the access state 217, and the traffic state 219, into the null
state 211. As described above, when the access terminal normally performs an
initial operation following a reset or power-on of the access terminal, the access
terminal performs a state transition from the null state 211 into the initialization
state 213.
Secondly, a description will be given for the initialization state 213. In
the initialization state 213, when having normally completed an initial operation
following a reset or power-on, the access terminal performs a synchronization
acquisition operation with an access point. In order to perform a
synchronization acquisition operation with the access point, the access terminal
monitors all frequency bands, which are predetermined in the access terminal,
and detects a DL-PICH signal having the greatest intensity, that is, having the
greatest CINR. When the access terminal is handed off from a cell in which the
access terminal itself exists, that is, from a prior access point, to a new cell, that is,
to a target access point, the access terminal also performs a synchronization
acquisition operation with the target access point in the initialization state 213.
In an IEEE (Institute of Electrical and Electronics Engineers) 802.16a
communication system, which is a typical broadband wireless access
communication system, since the mobility of the access terminal is not
considered, it is enough to consider only the case in which the access terminal is
powered on or is reset. In contrast, in a broadband wireless access
communication system that considers the mobility of the access terminal, such as
an IEEE 802.16e communication system, since the mobility of the access
terminal is considered, not only the case in which the access terminal is powered
on or is reset but also the case in which the access terminal is handed off has to
be considered. Therefore, an apparatus and a method of the present invention is
constructed taking into consideration not only the case in which the access
terminal is powered on or is reset, but also the case in which the access terminal
is handed off. That is, the access terminal has to continuously monitor whether
or not there is a second access point which transmits a DL-PICH signal having a
greater CINR than that of a DL-PICH signal transmitted from a first access point
to which the access terminal currently belongs, by considering a hand-off state.
Under a continuous monitoring operation, when there is a second access point
which transmits a DL-PICH signal having a greater CINR than that of a DL-
PICH signal transmitted from a first access point to which the access terminal
currently belongs, the access terminal performs a cell reselection operation.
The access terminal, which has acquired synchronization with the access
point, receives a DL-BCCH signal transmitted from the access point to receive
the system information (SI). Next, the access terminal performs a network entry
operation for the registration and the authentication to the access point to perform
an operation for transmitting/receiving normal packet data to/from the access
point, and then performs a state transition into the sleeping state 215, the access
state 217, or the traffic state 219. The system information includes system
configuration information, neighbor access point information, downlink and
uplink channel configuration information, and downlink and uplink access
information.
In the initialization state 213, when the access terminal loses its
synchronization with the access point due to a problem, such as a system error,
the access terminal performs a state transition from the initialization state 213
into the null state 211, thereby performing an initial operation again. That is,
when the access terminal is reset due to a problem, such as a system error, it is
necessary that the access terminal starts its operation in the null state 211. The
access terminal also performs a state transition from the initialization state 213
into the traffic state 219 when the access terminal receives paging information to
represent that there is data transmitted from the access terminal to the access
point after performing a network entry operation for the registration and the
authentication to the access point.
The operation of an access terminal in the initialization state 213 will be
simplified as follows.
(1) DL-PICH monitoring and synchronization acquisition with the access
point
(2) DL-BCCH monitoring operation
Receiving system configuration information, neighbor access point
information, downlink and uplink channel configuration information, and
downlink and uplink access information, paging information representing that
there is a call to an access terminal, and slot index information of a DL-WUCH
which an access terminal has to monitor to perform a mode shifting operation
from a sleeping mode to an awake mode.
(3) Network entry operation for the registration and the authentication to
the access point
In the network entry operation, the access terminal uses the UL-ACH
when performing an uplink access to an access point. A response signal to the
uplink access, which relates to a network entry operation and is performed
through the UL-ACH, is received through the DL-BCCH.
Thirdly, a description will be given for the sleeping state 215. The case
in which the access terminal performs a state transition from the initialization
state 213 into the sleeping state 215 occurs when the access terminal has no data
to be transmitted/received to/from an access point after performing a network
entry operation in the initialization state 213. That is, after the access terminal
performs a network entry operation in the initialization state 213, if there is no
data transmitted/received between the access terminal and the access point, the
access terminal performs a state transition into the sleeping state 215 so as to
minimize power consumption.
In the sleeping state 215, the access terminal wakes up according to the
control of the access point, and the access point notifies the access terminal to
wake-up as instructed through the wake-up indicator of the DL-WUCH. That is,
when the wake-up indicator of the DL-WUCH is turned on, the access terminal
wakes up. The access terminal can recognizes a slot index of a position into
which an indicator of the DL-WUCH is inserted, through the DL-BCCH in the
initialization state 213. One access point allocates a particular slot index of a
position, into which an indicator of the DL-WUCH is inserted, as described
above, into each of the access terminals, and the allocated slot index of the DL-
WUCH is maintained until the access terminal is handed off to a new access
point. In the sleeping state 215, the access terminal does not continuously
monitor the DL-BCCH so as to minimize the power consumption but monitors
only the DL-WUCH. Then, the access terminal wakes up to monitor the DL-
BCCH only when the wake-up indicator of the DL-WUCH is turned on, thereby
minimizing the power consumption. Also, while the access terminal is
monitoring the DL-BCCH, the access terminal does not monitor the DL-WUCH.
Also, while monitoring the DL-BCCH in the sleeping state 215, if the
access terminal receives information representing that there is a paging to be
received by the access terminal, the access terminal performs a state transition
from the sleeping state 215 into the traffic state 219, to receive the data from the
access point. In the sleeping state 215, when the access terminal loses its
synchronization with the access point due to a problem, such as a system error,
the access terminal performs a state transition from the sleeping state 215 into the
null state 211, thereby performing an initial operation again. That is, when the
access terminal is reset due to a problem, such as a system error, it is necessary
that the access terminal restart its operation in the null state 211.
Fourthly, a description will be given for the access state 217. The case in
which the access terminal performs a state transition from the initialization state
213 into the access state 217 occurs when the access terminal has data to be
transmitted/received to/from an access point after performing a network entry
operation in the initialization state 213. After the access terminal performs a
network entry operation in the initialization state 213, if there is data to be
transmitted/received between the access terminal and the access point, the access
terminal performs a state transition into the access state 217 so as to access the
access point.
In the access state 217, the access terminal performs an access operation
to the access point. The access to the access point, which is performed in the
access state 217, is basically carried out in a contention-based scheme. The
access terminal requests bandwidth allocation to the access point so as to transmit
data, that is, traffic, to the access point. The access to an access point, that is,
uplink access, of a contention-based scheme is performed using the UL-ACH.
In an embodiment of the present invention, the access point allocates
different numbers of PN codes to the uplink access depending on the QoS of the
traffic in response to a bandwidth allocation request. Each of the PN codes has
an orthogonal feature. In the broadband wireless access communication system,
a PN code is created by segmenting a PN sequence having a predetermined
length, for example, '2 -1' bits, in predetermined units. When it is assumed
that P PN codes are generated by the above-mentioned scheme, from among the P
PN codes, K PN codes are allocated to be used to a bandwidth allocation request
for the UGS data transmission, L PN codes are allocated to be used to a
bandwidth allocation request for the real time service data transmission, M PN
codes are allocated to be used to a bandwidth allocation request for the non-real
time service data transmission, N PN codes are allocated to be used to a
bandwidth allocation request for the best effort data transmission, and S PN
codes are allocated to be used for the fast access. Herein, the PN code allocated
for the fast access is called a 'fast access PN code', and the relationship of P, K, L,
M, N, and S may be defined as Equation 1.
P = K + L + M + N+S(wherein,K>L>M>N) ........(1)
For example, it is assumed that the number of PN codes capable of being
used for the bandwidth allocation request is 48 in the broadband wireless access
communication system. Then, the access point allocates 17 PN codes from
among the 48 PN codes to be used to a bandwidth allocation request for the UGS
data transmission, allocates 13 PN codes from among the remaining PN codes to
be used to a bandwidth allocation request for the real time service data
transmission, allocates 7 PN codes from among the remaining PN codes to be
used to a bandwidth allocation request for the non-real time service data
transmission, allocates 4 PN codes from among the remaining PN codes to be
used to a bandwidth allocation request for the best effort data transmission, and
allocates the remaining PN codes to be used as the fast access PN codes.
The access point allocates more PN codes to a bandwidth allocation
request for uplink data having a high priority QoS class, as compared with a low
priority QoS class, thereby enabling the data having the high priority QoS classto
be processed prior to the data having a lower priority QoS class. The fast access
can then be achieved, so that it is also possible to minimize the power
consumption of an access terminal when the access terminal performs uplink
access. While a description is given above for the case in which the access
point allocates fast access PN codes for fast access, the access point may allocate
separate fast access time slots for fast access. The fast access, the fast access
PN code, and the fast access time slot will be described in detail later.
The access terminal attempts an uplink access by transmitting the
bandwidth allocation request message through the UL-ACH. When
transmitting the bandwidth allocation request message, the access terminal uses
only PN codes which are allocated according to the QoS of the data to be
transmitted, thereby enabling an access priority to be provided according to the
QoS. In this case, the access point can determine which of the QoS classes
corresponds to a PN code employed for the bandwidth allocation request message.
The access point allocates the fast access PN code only to a higher priority QoS
class from among the QoS classes, for example, only to a UGS and a real time
service. That is, when there is no uplink bandwidth to be allocated, data
corresponding to a lower priority QoS class are denied the uplink access, and are
required to undergo a normal uplink resumption process, that is, to undergo an
uplink access resumption process of a contention-based scheme. In contrast,
data corresponding to a higher priority QoS class , when there is no uplink
bandwidth to be allocated, are processed to accomplish the uplink access by
including the fast access PN code information, provided that the access terminal
performs a state transition into the traffic state 219 and the actual data is
transmitted later when there is an uplink bandwidth to be allocated. In this case,
as described above, the fast access time slots may be used instead of the fast
access PN codes.
According to a bandwidth allocation request of the access terminal, the
access point allocates a bandwidth to be used by the access terminal into the
access terminal when there is a currently available bandwidth, and notifies the
access terminal of the allocated bandwidth information. Of course, as described
above, in a case in which the bandwidth allocation for the data corresponding to a
higher priority QoS class is requested in a state in which there is no bandwidth to
be allocated, the access point must notify the access terminal of fast access PN
code information. The access point transmits the allocated bandwidth
information or fast access PN code information to the access terminal through the
DL-USCCH.
The access terminal, which has determined that the bandwidth is
allocated, performs a state transition from the access state 217 into the traffic
state 219. In contrast, when the access terminal does not receive a bandwidth
allocation from the access point in spite of the request of bandwidth, that is, when
the access terminal fails to access the access point, the access terminal performs a
state transition from the access state 217 to the sleeping state 215. When the
allocation of bandwidth fails, the access terminal may again request a bandwidth
allocation, and the access terminal performs a state transition from the access
state 217 into the sleeping state 215 only when the bandwidth allocation is not
accomplished during a predetermined period of time. Of course, when access
terminal cancels the data transmission, as well as when the access terminal fails
to access the access point, the access terminal performs a state transition from the
access state 217 to the sleeping state 215.
When the access terminal performs a state transition from the access state
217 to the sleeping state 215, the access terminal monitors a DL-WUCH
indicator in the same slot index as that of a DL-WUCH monitored before in the
sleeping state 215. However, when the access terminal performs a state
transition from the access state 217 to the sleeping state 215, it is possible that the
access terminal does not monitor the DL-WUCH but monitors only the DL-
BCCH.
Meanwhile, while the access terminal is performing the uplink access in
the access state 217, if the access terminal loses synchronization with the access
point due to a problem, such as a system error, the access terminal performs a
state transition from the access state 217 into the null state 211, thereby
performing an initial operation again. That is, when the access terminal is
reset due to a problem, such as a system error, it is necessary that the access
terminal restart its operation in the null state 211.
Fifthly, a description will be given for the traffic state 219. In the traffic
state 219, the access terminal transmits/receives data to/from the access point.
Also, in the traffic state 219, although the access terminal does not directly
transmit/receive actual data to/from the access point, the access terminal is
allocated resources for a later transmission/reception of data. That is, in the
traffic state 219. since resources have been allocated for the
transmission/reception of the data although there in no actual data to be
transmitted/received between the access terminal and the access point, the access
terminal can rapidly access the access point when data to be transmitted/received
is generated, and the data can be normally transmitted/received. Uplink access
using the fast access PN code or fast access time slot is performed in the traffic
state 219.
In the traffic state 219, when there is no data to be transmitted/received
between the access terminal and the access point, or when it is needed to reduce
the power consumption of the access terminal itself, the access terminal performs
a state transition from the traffic state 219 to the sleeping state 215. Also, in the
traffic state 219, when the access terminal loses synchronization with the access
point due to a problem, such as a system error, the access terminal performs a
state transition from the traffic state 219 into the null state 211, thereby
performing an initial operation again. When the access terminal is reset due to a
problem, such as a system error, it is necessary for the access terminal restart its
operation in the null state 211.
The above description with reference to FIG. 2 has shown MAC
operational states proposed in the present invention. Hereinafter, the
initialization state 213 will be described with reference to FIG. 3.
FIG. 3 is a diagram schematically illustrating operation modes of the
initialization state 213 shown in FIG. 2.
Referring FIG. 3, the initialization state 213 includes two operation
modes, that is, a system detecting mode 300 and a network entry mode 350. As
described with reference to FIG. 2, when the access terminal normally performs
an initial operation following a reset or power-on, the access terminal performs a
state transition from the null state 211 into the initialization state 213 (step 311).
Also, if the access terminal loses synchronization with the access point due to a
problem, such as a system error, in the initialization state 213, the access terminal
performs a state transition from the initialization state 213 into the null state 211,
thereby again performing an initial operation (step 313). Meanwhile, when the
access terminal performs a state transition from the null state 211 into the
initialization state 213, the access terminal enters the system detecting mode 300
of the initialization state 213. The system detecting mode 300 will be described
hereinafter.
In the system detecting mode 300, the access terminal receives DL-PICH
signals transmitted from a plurality of access points, and detects a DL-PICH
signal having the greatest intensity, that is, having the highest CINR. In this
state, when the access terminal is handed off from a prior access point, to which
the access terminal had belonged, to a target access point, the access terminal
also performs a synchronization acquisition operation with the target access point.
Because the access terminal has to consider a hand-off state, the access terminal
has to continuously monitor whether or not there is a second access point which
transmits a DL-PICH signal having a higher CINR than that of a DL-PICH signal
transmitted from a first access point, to which the access terminal currently
belongs. Under such a continuous monitoring operation, when there is a second
access point which transmits a DL-PICH signal having a higher CINR than that
of a DL-PICH signal transmitted from a first access point to which the access
terminal currently belongs, the access terminal performs a cell reselection
operation.
When detecting a DL-PICH signal having the highest CINR as described
above, the access terminal determines that an access point transmitting the
detected DL-PICH signal is to be an access point to which the access terminal
belongs, that is, to be a serving access point, and receives a DL-BCCH signal
transmitted from the serving access point. The access terminal receives the DL-
BCCH signal to detect the system configuration information, the neighbor access
point information, the downlink and uplink channel configuration information,
the downlink and uplink access information, etc. When the access terminal
normally performs the operation required in the system detecting mode 300, that
is the synchronization acquisition operation with the access point, the access
terminal performs a mode change from the system detecting mode 300 into the
network entry mode 350 so as to perform a network entry operation tor
transmitting/receiving data to/from the access point (step 315).
In the network entry mode 350, the access terminal performs an initial
uplink access operation for network entry using the uplink access information
received in the system detecting mode 300. Herein, the initial uplink access
operation for the network entry is performed in a contention-based scheme, the
access terminal performs the initial uplink access operation through an UL-ACH,
and the access point transmits a response to the initial uplink access to the access
terminal. The initial uplink access and the response thereto are
transmitted/received through an MAC message. In the MAC message in which
a response to the initial uplink access is included, also included is the slot index
information of a DL-WUCH which the access terminal monitors in the sleeping
state 215.
After the access terminal performs a network entry operation in the
network entry mode 350, the access terminal performs a state transition into the
access state 217 if there is data to be transmitted to the access point (step 319).
Also, after the access terminal performs a network entry operation in the network
entry mode 350, the access terminal performs a state transition into the traffic
state 219 if the access terminal receives paging information which represents that
there is data to be transmitted to the access terminal through a DL-BCCH (step
321). Also, when the access terminal has no data to be transmitted/received
to/from the access point in the network entry mode 350, the access terminal
performs a state transition into the sleeping state 215 (step 323). Finally, in the
network entry mode 350, when the access terminal does not perform a normal
operation due to a system error and the like, the access terminal performs a mode
change into the system detecting mode 300 and again performs an initial
operation following a reset.
The above description with reference to FIG. 3 has shown the operation
modes of the initialization state 213. Hereinafter, the sleeping state 215 will be
described with reference to FIG. 4.
FIG. 4 is a diagram schematically illustrating operation modes of the
sleeping state 215 shown in FIG. 2. Referring to FIG. 4, the sleeping state 215
includes two operation modes, that is, a sleeping mode 400 and an awake mode
450. As described with reference to FIG. 2, when the access terminal normally
performs an network entry operation, the access terminal performs a state
transition from the initialization state 213 into the sleeping state 215 (step 411).
Also, if the access terminal loses synchronization with the access point due to a
problem, such as a system error, in the sleeping state 215, the access terminal
performs a state transition from the sleeping state 215 into the null state 211,
thereby again performing an initial operation (step 413). Meanwhile, when the
access terminal performs a state transition from the initialization state 213 into
the sleeping state 215, the access terminal enters the sleeping mode 400 or the
awake mode 450 in the sleeping state 215.
First, the sleeping mode 400 will be described hereinafter.
In the sleeping mode 400, the access terminal does not continuously
monitor a DL-BCCH transmitted from the access point, but monitors only a DL-
WUCH. Therefore, only the case in which the wake-up indicator of the DL-
WUCH is turned on, the access terminal performs a mode change from the
sleeping mode 400 into the awake mode 450 so as to monitor an DL-BCCH.
The case in which the access point sets the wake-up indicator of the DL-WUCH
to 'on' occurs when the system information is updated or when the access point
contains paging information to notify the access terminal of data to be
transmitted to the access terminal. The access terminal monitors only a DL-
WUCH while in the sleeping mode 400. The access terminal monitors the DL-
BCCH only when the wake-up indicator of the DL-WUCH allocated into the
access terminal itself is turned on, thereby minimizing the power consumption.
During the monitoring of only the DL-WUCH, when the wake-up indicator of the
DL-WUCH is turned on, the access terminal performs a mode change from the
sleeping mode 400 into the awake mode 450 (step 415).
Secondly, the awake mode 450 will be described hereinafter. In the
awake mode 450, the access terminal monitors a DL-BCCH transmitted from the
access point. As described above, since the access point wakes up the access
terminal to update the system information or to transmit paging information for
notifying the access terminal of data to be transmitted to the access terminal, the
access terminal monitors the DL-BCCH and may check whether or not the
system information is undated and whether or not the paging information is
received from the access point. As a result of the monitoring of the DL-BCCH,
when the system information is updated, the access terminal confirms the updated
system information and performs a mode change from the awake mode 450 into
the sleeping mode 400 (step 417). Also, as a result of the monitoring of the DL-
BCCH, when there is paging information that is targeted to access terminal, the
access terminal performs a state transition from the awake mode 450 into the
traffic state 219 (step 425).
Meanwhile, when the access terminal has data to transmit to the access
point, the access terminal performs a state transition from the awake mode 450
into the access state 217, thereby performing an uplink access of a contention-
based scheme (step 419). Also, when the access terminal fails in the uplink
access in spite of performing the uplink access of a contention-based scheme
during a predetermined period of time in the access state 217, the access terminal
performs a state transition from the access state 217 into the sleeping state 215
(step 421).
In addition, also when the access terminal cancels the data transmission
as well as when the access terminal fails in the uplink access, the access terminal
performs a state transition from the access state 217 into the sleeping state 215.
Also, in the traffic state 219, when the access terminal has no data to be
transmitted to the access point, or when it is needed to reduce the power
consumption of the access terminal itself, the access terminal performs a state
transition from the traffic state 219 into the sleeping state 215 (step 423).
The above description with reference to FIG. 4 has illustrated the
operating modes of the sleeping state 215. Hereinafter, the signal
transmitting/receiving process performed between an access point and an access
terminal in the initialization state 213 will be described with reference to FIG. 5.
FIG. 5 is a flowchart illustrating a signal transmitting/receiving process
performed between an access point and an access terminal in the initialization
state 213 shown in FIG. 2. Referring to FIG. 5, first, when the access terminal is
powered on (step 511), the access terminal performs an initial operation in the
null state 211. When normally completing the initial operation, the access
terminal performs a state transition into the system detecting mode 300 of the
initialization state 213. In the system detecting mode 300, the access point
transmits a pilot signal through a DL-PICH (step 513), and transmits the system
configuration information, the neighbor access point information, the downlink
and uplink channel configuration information, the downlink and uplink access
information, etc. through a DL-BCCH (step 515). The access terminal acquires
synchronization with the access point using a pilot signal received through the
DL-PICH in the system detecting mode 300, and then performs a mode change
into the network entry mode 350. Then, the access terminal transmits a network
entry request message to the access point through a UL-ACH which corresponds
to uplink access information received through the DL-BCCH in the network
entry mode 350 (step 517). When sensing a network entry request of the access
terminal, the access point transmits a network entry response message through a
DL-BCCH in response to the network entry request message of the access
terminal (step 519). Herein, the network entry response message, as described
above, includes slot index information of a DL- WUCH which the access terminal
monitors in the sleeping mode.
The above description with reference to FIG. 5 has shown the signal
transmitting/receiving process performed between an access point and an access
terminal in the initialization state 213. Hereinafter, a signal
transmitting/receiving process performed between an access point and an access
terminal in the sleeping state 215 will be described with reference to FIG. 6.
FIG. 6 is a flowchart illustrating a signal transmitting/receiving process
performed between an access point and an access terminal in the sleeping state
215 shown in FIG. 2.
Referring to FIG. 6, first, when the access terminal accomplishes a
network entry in the initialization state 213 (step 611), the access terminal
performs a state transition into the sleeping state 215. Herein, the case in which
the access terminal performs a state transition from the initialization state 213
into the sleeping state 215 occurs when there is no data to be transmitted/received
between the access terminal and the access point. As described above, After
accomplishing the network entry in the initialization state 213, if the access
terminal has data to be transmitted to the access point, the access terminal
performs a state transition into the access state 217, and if the access terminal has
data to be received from the access point, the access terminal performs a state
transition into the traffic state 219. The access point transmits a wake-up
indicator to the access terminal through a DL-WUCH since the access terminal is
in the sleeping mode 400 of the sleeping state 215 (step 613).
When the wake-up indicator is in an 'on' state, the access terminal
performs a mode change from the sleeping mode 400 into the awake mode 450,
but when the wake-up indicator is in an 'off' state, the access terminal is
maintained in the sleeping mode 400. In FIG. 6, it is assumed that the wake-up
indicator of a DL-WUCH transmitted from the access point in step 613 is in an
'off state. When the wake-up indicator of a DL-WUCH transmitted from the
access point in step 613 is in an 'on' state, the following step 615 may be omitted.
When the wake-up indicator of the DL-WUCH is in an 'off state, the access
terminal is maintained in the sleeping mode 400 and receives a DL-WUCH signal
transmitted from the access point (step 615).
Meanwhile, in step 615, when the wake-up indicator of a DL-WUCH
transmitted from the access point is in an 'on' state, the access terminal performs
a mode change from the sleeping mode 400 into the awake mode 450. When
the access terminal is in the awake mode 450, the access point transmits the
updated system information or paging information through the DL-BCCH (step
617). As described above, when the access point has updated system
information to be transmitted through the DL-BCCH, or when the access point
desires to transmit paging information to the access terminal, the access terminal
first transmits the wake-up indicator of the DL-WUCH which is in an 'on' state,
and then transmits the updated system information or paging information through
the DL-BCCH.
When there are performed in connection with the sleeping state 215,
although the steps are not performed actually in the sleeping state 215.
The above description with reference to FIG. 6 has shown the signal
transmitting/receiving process performed between an access point and an access
terminal in the sleeping state 215. Hereinafter, an operation process of the
access point in the sleeping state 215 will be described with reference to FIG. 7.
FIG. 7 is a flowchart illustrating an operation of the access point in the
sleeping state 215 shown in FIG. 2.
Referring to FIG. 7, first, the access point determines whether or not data
to be transmitted to the access terminal is generated in step 711. As a result,
when data to be transmitted to the access terminal is not generated, the access
point proceeds to step 713. In step 713, since no data is to be transmitted to the
access terminal, the access point sets the wake-up indicator of a DL-WUCH to
'off, transmits the wake-up indicator of the DL-WUCH, and returns to step 711.
As a result, when there is data to be transmitted to the access terminal, the access
point proceeds to step 715. In step 715, the access point determines an access
terminal which the access point targets for the data to be transmitted, and then
proceeds to step 717.
In step 717, since there is data to be transmitted to the access terminal,
the access point sets the wake-up indicator of a DL-WUCH to 'on', transmits the
wake-up indicator of the DL-WUCH, and then proceeds to step 719. In this time,
the access terminal monitors only the DL-WUCH because it is in the sleeping
mode 400 of the sleeping state 215, and the access terminal performs a mode
change from the sleeping mode 400 into the awake mode 450 only when it
receives the wake-up indicator of the DL-WUCH that is set to 'on'. In step 719,
the access point transmits the paging information, which represents that there is
data to be transmitted to the access terminal, to the access terminal through a DL-
BCCH, and then proceeds to step 721. Then, the access terminal receives the
paging information through the DL-BCCH, and performs a state transition from
the awake mode 450 into the traffic state 219.
In step 721, the access point transmits the control information for
transmitting a DL-TCH, which is used to transmit data, to the access terminal
through a DL-TCCH, transmits data to the access terminal through the DL-TCH,
and then proceeds to step 723. Herein, the control information to be transmitted
through the DL-TCCH includes the AMC scheme information, the information
used in a data decoding, such as EP, the MAC control information, etc.
In step 723, the access terminal determines whether or not the data
transmission is complete. Whether or not the data transmission is completed
may be determined according to whether or not there is any remaining data in a
transmission buffer to be sent to the access point. That is, when there is data
stored in the transmission buffer, the access point determines that the data is
being transmitted, but when there is no data stored in the transmission buffer, the
access point determines that the data transmission is complete. As a result of
step 723, when the data transmission is not complete, the access point returns to
step 721. As a result of step 723, when the data transmission is complete, the
access point returns to step 711.
In the description with reference to FIG. 7, an operation of the access
point is explained with respect to the case in which the access point transmits
data to the access terminal which is in the sleeping state 215. Although a
separate description is not given in FIG. 7, that the access point transmits the
updated system information can also be achieved in a similar operation to that
described in FIG. 7. That is, when the access point determines that there is
updated system information, the access point sets the wake-up indicator of a DL-
WUCH to 'on', transmits the wake-up indicator of the DL-WUCH, and then
transmits the updated system information through the DL-BCCH. The access
terminal receives the wake-up indicator of the DL-WUCH which is set to 'on',
and performs a mode change from the sleeping mode 400 into the awake mode
450, thereby receiving the updated system information through the DL-BCCH.
After this, the access terminal performs a mode change from the awake mode 450
into the sleeping mode 400.
The above description with reference to FIG. 7 has shown the operation
process of the access point in the sleeping state 215. Hereinafter, an operation
process of the access terminal in the sleeping state 215 will be described with
reference to FIG. 8.
FIG. 8 is a flowchart illustrating an operation process of the access
terminal in the sleeping state 215 shown in FIG. 2. Referring to FIG. 8, first, the
access terminal monitors only a DL-WUCH in the sleeping mode 400 of the
sleeping state 215 in step 811, and then proceeds to step 813. In step 813, the
access terminal determines whether or not the wake-up indicator of the DL-
WUCH is set to 'on'. As a result, when the wake-up indicator of the DL-
WUCH is not set to 'on', that is, when the wake-up indicator of the DL-WUCH
is set to 'off, the access terminal returns to step 811. As a result of step 813,
when the wake-up indicator of the DL-WUCH is set to 'on', the access terminal
proceeds to step 815. In step 815, the access terminal performs a mode change
from the sleeping mode 400 into the awake mode 450, monitors a DL-BCCH in
the awake mode 450, and proceeds to step 817. Through the DL-BCCH,
updated system information and paging information is transmitted. Herein, a
description will be given with reference to FIG. 8 for the case in which paging
information is transmitted through the DL-BCCH as an example, corresponding
to the operation of the access point shown in FIG. 7. When the access terminal
receives the paging information through the DL-BCCH, the access terminal
performs a state transition from the awake mode 450 into the traffic state 219.
In step 817, the access terminal receives a DL-TCH signal and a DL-
TCCH signal transmitted from the access point, and then proceeds to step 819.
In step 819, the access terminal determines whether or not the data reception is
complete. As a result, when the data reception is complete, the access terminal
returns to step 811. In contrast, as a result, when the data reception is not
complete, the access terminal returns to step 817.
In the description with reference to FIG. 8, an operation of the access
terminal is explained with respect to the case in which the access point transmits
data to the access terminal which is in the sleeping state 215. Although a
separate description is not given in FIG. 8, the transmission of the updated system
information by the access point can also be achieved in a similar operation to that
shown in FIG. 8. That is, when the access point senses that there is updated
system information, the access point sets the wake-up indicator of a DL-WUCH
to 'on', transmits the wake-up indicator of the DL-WUCH, and then transmits the
updated system information through the DL-BCCH. In this time, the access
terminal receives the wake-up indicator of the DL-WUCH which is set to 'on',
and performs a mode change from the sleeping mode 400 into the awake mode
450, thereby receiving the updated system information through the DL-BCCH.
After this, the access terminal performs a mode change from the awake mode 450
into the sleeping mode 400.
The above description with reference to FIG. 8 has shown the operation
process of the access terminal in the sleeping state 215. Hereinafter, a
construction of a DL-WUCH transmitter will be described with reference to FIG.
9.
FIG. 9 is a block diagram illustrating a construction of a DL-WUCH
transmitter according to an embodiment of the present invention. Referring to
FIG. 9, first, when a wake-up indicator to be transmitted through a DL-WUCH is
input into the transmitter, the wake-up indicator is transferred to a symbol
repeater 911. Not only the wake-up indicator but also a wake-up indicator rate
and a marked rate are simultaneously input to the symbol repeater 911. The
wake-up indicator rate represents the number of frames included in a super frame,
and the marked rate represents a transmission period of a wake-up indicator to be
transmitted to an access terminal. For example, in a case in which four frames
make one super frame and the wake-up indicator is transmitted in one frame unit,
the wake-up indicator rate is 'four' and the marked rate is 'one'. The symbol
repeater 911 repeats a symbol of the input wake-up indicator, and then outputs
the wake-up indicator to a DL-WUCH information mapper 913. According to
the symbol repetition operation of the symbol repeater 911, the transmission rate
of the DL-WUCH is determined.
Meanwhile, when data has been generated, a controller 917 determines
an access terminal targeted by the generated data, and transmits DL-WUCH slot
index information of the access terminal to which the data is to be transmitted
and the information representing that the wake-up indicator has to be set to 'on',
to the DL-WUCH information mapper 913. The DL-WUCH information
mapper 913 sets the wake-up indicator to 'on' in a slot, which corresponds to a
DL-WUCH slot index information of the access terminal to which the data is to
be transmitted, and then outputs the wake-up indicator to a channel gain
multiplier 915. When there is no data, the controller 917 transmits DL-WUCH
slot index information of a relevant access terminal and information representing
that the wake-up indicator has to be set to 'off, to the DL-WUCH information
mapper 913. The DL-WUCH information mapper 913 sets the wake-up
indicator to 'off in a slot, which corresponds to a DL-WUCH slot index
information of the relevant access terminal, and then outputs the wake-up
indicator to the channel gain multiplier 915. The channel gain multiplier 915
multiplies a signal output from the DL-WUCH information mapper 913 by a
predetermined channel gain value, and then outputs the resultant. Accordingly,
a signal output from the channel gain multiplier 915 is transmitted, to an access
terminal.
The above description with reference to FIG. 9 has shown the
construction of a DL-WUCH transmitter according to an embodiment of the
present invention. Hereinafter, an operation of an access terminal in the access
state 217, which is shown in FIG. 2, will be described with reference to FIG. 10.
FIG. 10 is a flowchart illustrating an operation process of an access
terminal in the access state 217 shown in FIG. 2. Prior to the description of FIG.
10, it should be noted that the access state 217 proposed in the present invention
is a state for transmitting a bandwidth allocation request message from an access
terminal to an access point when the access terminal desires to transmit traffic,
and a state for receiving a bandwidth allocation response message which is a
response message to the bandwidth allocation request message, thereby
performing uplink access. Also, as described above, it should be noted that the
access point has already allocated the PN codes, which are used when an access
terminal transmits a bandwidth allocation request message, according to the QoS
of the traffic, and the access terminal uses the PN codes differentially applied
according to the QoS of the transmitted traffic when transmitting a bandwidth
allocation request message.
Referring to FIG. 10, first, when traffic to be transmitted from the access
terminal is generated, the access terminal detects the QoS of the traffic to be
transmitted in step 1011, and then proceeds to step 1013. Herein, to detect the
QoS of the traffic, as described above, means to detect a QoS class of the traffic.
That is, to detect whether the traffic is UGS traffic, or real time service traffic, or
non-real time service traffic, or best effort traffic. In step 1013, the access
terminal selects a PN code, which is applied to a bandwidth allocation request
message, according to the detected QoS and then proceeds to step 1015.
Herein, to select a PN code corresponding to the detected QoS, as
described above, means to select a certain PN code from among the PN codes
allocated to be applied to UGS traffic in a case in which the QoS is UGS, to
select a certain PN code from among PN codes allocated to be applied to real
time service traffic in a case in which the QoS is real time service, to select a
certain PN code from among PN codes allocated to be applied to non-real time
service traffic in a case in which the QoS is non-real time service, and to select a
certain PN code from among PN codes allocated to be applied to best effort
traffic in a case in which the QoS is best effort. Accordingly, the PN code is
used as a scrambling code. Meanwhile, the access terminal can receive
information about the PN codes allocated according to the QoS of the traffic,
through the DL-BCCH, in the initialization state 213 or the sleeping state 215,
that is, in a state before a state transition is performed into the access state 217.
In step 1015, the access terminal tries the uplink access, that is, the
access terminal scrambles the bandwidth allocation request message using the
selected PN code and transmits the scrambled bandwidth allocation request
message to the access point through the UL-ACH, and then proceeds to step 1017.
In step 1017, the access terminal determines whether or not the uplink access is
accomplished, that is, whether or not the access terminal receives a bandwidth
allocation response message in response to the bandwidth allocation request
message by monitoring a DL-USCCH transmitted from the access point. Here,
the access terminal may update the PN code information using the bandwidth
allocation response message transmitted through the DL-USCCH. That is, the
access terminal acquires PN code information transmitted from the access point
through a DL-BCCH when performing the uplink access, since the access point
notifies the access terminal of a PN code through the DL-USCCH so that the
access terminal may perform the fast access when the access terminal is not
allocated an uplink bandwidth as a result of the uplink access performance.
As a result of step 1017, the access terminal does not receive a bandwidth
allocation response message through the DL-USCCH, the access terminal
proceeds to step 1025. In step 1025, the access terminal determines whether or
not an Access_Try_Time, which is a waiting time for receiving the bandwidth
allocation response message, lapses. As a result, when the Access_Try_Time
does not lapse, the access terminal returns to step 1017 and continuously
monitors whether or not the access terminal receives a bandwidth allocation
response message through the DL-USCCH. In contrast, as a result of step 1025,
when the Access_Try_Time lapses, the access terminal proceeds to step 1027.
In step 1027, since the access terminal fails in the uplink access, the access
terminal performs a state transition from the access state 217 into the sleeping
state 215 and ends the uplink access process.
As a result of step 1017, the access terminal receives a bandwidth
allocation response message through the DL-USCCH, the access terminal
proceeds to step 1019. In step 1019, since the access terminal receives the
bandwidth allocation response message, the access terminal performs a state
transition from the access state 217 into the traffic state 219 and ends the uplink
access process. A state transition procedure from the access state 217 into the
traffic state 219 will be described in detail hereinafter.
The bandwidth allocation response message includes either the uplink
bandwidth information which the access point allocates into the access terminal
for uplink traffic transmission of the access terminal, or the PN code information,
that is, the fast access PN code information, which the access point allocates to
the access terminal to first allocate an uplink bandwidth into the access terminal
when the access point has no currently available uplink bandwidth, that is, so as
to permit a fast access of the access terminal. In the access state 217, although
the access terminal is allocated only the fast access PN code through the
bandwidth allocation response message, the access terminal determines that the
uplink access has already been accomplished, thereby performing a state
transition from the access state 217 into the traffic state 219. When performing
a state transition from the access state 217 into the traffic state 219, the transition
is performed into the different modes of the traffic state 219 depending on
whether the access terminal is allocated the uplink bandwidth or the access
terminal is allocated the fast access PN code, which will be described in detail
later.
Also, as described with reference to FIG. 2, although not shown in FIG. 3,
when the access terminal cancels the traffic transmission as well as when the
access terminal fails in the uplink access in the access state 217, the access
terminal also performs a state transition from the access state 217 into the
sleeping state 215. Meanwhile, while the access terminal is performing the
uplink access in the access state 217, if the access terminal loses its
synchronization with the access point due to a problem, such as a system error,
the access terminal performs a state transition from the access state 217 into the
null state 211, thereby performing an initial operation again. That is, when the
access terminal is reset due to a problem, such as a system error, it is necessary
that the access terminal newly starts its operation in the null state 211.
The above description with reference to FIG. 10 has shown the operation
process of an access terminal in the access state 217. Hereinafter, a signal
transmitting/receiving process performed between an access point and an access
terminal in the access state 217, which is shown in FIG. 2, will be described with
reference to FIG. 11.
FIG. 11 is a flowchart illustrating a signal transmitting/receiving process
performed between an access point and an access terminal in the access state 217
shown in FIG. 2. Referring to FIG. 11, first, while the access terminal is in the
initialization state 213 or in the sleeping state 215 (step 1111), the access terminal
receives the system configuration information, overhead information, etc., which
are transmitted from the access point through a DL-BCCH (step 1113). Then,
either in the sleeping state 215 or after the access terminal accomplishes the
network entry in the initialization state 213, when the access terminal has traffic
to be transmitted to the access point, the access terminal performs a state
transition from the initialization state 213 or from the sleeping state 215 into the
access state 217.
In the access state 217, since the access terminal has traffic to be
transmitted through an uplink, the access terminal detects the QoS of the traffic to
be transmitted, and selects a PN code allocated according to the detected QoS.
The access terminal scrambles a bandwidth allocation request message using the
selected PN code and transmits the scrambled bandwidth allocation request
message to the access point through a UL-ACH (step 1115). After transmitting
the bandwidth allocation request message, the access terminal monitors a DL-
USCCH and receives a bandwidth allocation response message which is a
response message to the bandwidth allocation request message (step 1117).
When receiving the bandwidth allocation response message, the access terminal
performs a state transition from the access state 217 into the traffic state 219.
Then, in the traffic state 219, the access terminal transmits traffic to the access
point through a UL-TCH which corresponds to the uplink bandwidth allocation
information included in the bandwidth allocation response message (step 1119).
Of course, as described above, when the bandwidth allocation response message
includes only fast access PN code information, the access terminal does not
directly transmit the traffic in the traffic state 219, but can transmit the traffic
when an available uplink bandwidth exists in the access point.
The above description with reference to FIG. 11 has shown the signal
transmitting/receiving process performed between an access point and an access
terminal in the access state 217 shown in FIG. 2. Hereinafter, an operation
process of an access point in the access state 217, which is shown in FIG. 2, will
be described with reference to FIG. 12.
FIG. 12 is a flowchart illustrating an operation process of an access point
in the access state 217 shown in FIG. 2. Referring to FIG. 12, first, the access
point monitors a UL-ACH in step 1211, and then proceeds to step 1213. In step
1213, the access point determines whether or not the access point receives a
bandwidth allocation request message from the access terminal, as a result of the
monitoring of the UL-ACH. As a result, when the access point does not receive
a bandwidth allocation request message from the access terminal, the access point
proceeds to step 1211 to continuously monitor the UL-ACH.
In contrast, as a result of step 1213, the access point receives a bandwidth
allocation request message from the access terminal, the access point proceeds to
step 1215. In step 1215, the access point determines the QoS of the traffic,
which the access terminal desires to transmit through an uplink, according to a
PN code by which the bandwidth allocation request message is scrambled, and
then allocates a resource for the traffic to the access terminal. After this, the
access point proceeds to step 1217, Here, 'resource' means either an uplink
bandwidth or a fast access PN code. When the access point can allocate an
uplink bandwidth to an access terminal, the uplink bandwidth becomes the
'resource'. In contrast, in the case where the access point cannot allocate an
uplink bandwidth to an access terminal because there is no available uplink
bandwidth, when the QoS of traffic to be transmitted from the access terminal
through an uplink is high, the access terminal allocates a fast access PN code to
the access terminal so that the access terminal may perform the fast access later
and receive an uplink bandwidth. In this case, the fast access PN code becomes
the 'resource'. In step 1217, the access point causes the information about the
allocated resource to be included in a bandwidth allocation response message,
and transmits the bandwidth allocation response message to the access terminal
through a DL-USCCH.
In FIG. 12, for the convenience of description, while a description is
given for a case in which the access point allocates a resource to the uplink
access of one access terminal, it will be understood that the access point may
allocate the resource of the uplink access to a plurality of access terminals to
which the access point provides service.
The above description with reference to FIG. 12 has shown the operation
process of an access point in the access state 217 shown in FIG. 2. Hereinafter,
operation modes of the traffic state 219 will be described with reference to FIG.
13.
FIG. 13 is a view showing operation modes of the traffic state 219 shown
in FIG. 2. Referring to FIG. 13, first, the traffic state 219 includes three
operation modes, that is, an active mode 1300, a fast access mode 1330, and a
hold mode 1360. As described with reference to FIG. 2, after the access
terminal normally performs a network entry operation, the access terminal
monitors a DL-USCCH transmitted from the access point. During the
monitoring of the DL-USCCH, when the access terminal senses that there is data
to be transmitted from the access point to the access terminal, the access terminal
performs a state transition from the initialization state 213 into the traffic state
219 (step 1311). Also, if the access terminal loses its synchronization with the
access point due to a problem, such as a system error, in the traffic state 219, the
access terminal performs a state transition from the traffic state 219 into the null
state 211, thereby performing an initial operation (step 1321). Meanwhile,
when the access terminal performs a state transition from the initialization state
213 into the traffic state 219, the access terminal enters the active mode 1300 of
the traffic state 219.
Also, during monitoring of the channels, such as the DL-BCCH, DL-
WUCH, DL-USCCH, etc., in the sleeping state 215, when the access terminal
senses that there is data to be transmitted from the access point to the access
terminal itself, the access terminal enters the active mode 1300 of the traffic state
219 (step 1313). Unlike this, when data transmission/reception between the
access point and the access terminal has been completed in the traffic state 219,
the access terminal performs a state transition into the sleeping state 215 (step
1315). Here, the access terminal, which has performed the state transition into
the sleeping state 215, monitors the wake-up indicator of a DL-WUCH allocated
from the access point, as described with reference to FIG. 2, thereby minimizing
power consumption.
Also, when the access terminal accomplishes the uplink access in the
access state 217, the access terminal enters either the active mode 1300 or the fast
access mode 1330 of the traffic state 219 (step 1317). Now, a detailed
description will be given for cases in which the access terminal enters the active
mode 1300 or the fast access mode 1330 of the traffic state 219 from the access
state 217.
First, a case in which the access terminal enters the active mode 1300 of
the traffic state 219 from the access state 217 occurs when the access terminal is
allocated an uplink bandwidth from the access point according to the uplink
access in the access state 217. Secondly, a case in which the access terminal
enters the fast access mode 1330 of the traffic state 219 from the access state 217
occurs when the access terminal is not allocated an uplink bandwidth but is
allocated either a fast access PN code or a fast access time slot as a result of
uplink access performance in the access state 217.
The active mode 1300 will now be described. First, the active mode
1300 is a mode in which data of all QoS classes can be transmitted. During
transmitting/receiving of the data between the access terminal and the access
point in the active mode 1300, when the transmission/reception of the data is
temporarily interrupted, the access terminal enters the hold mode 1360 (step
1329). However, with respect to the UGS data and the real time service data,
the hold mode 1360 is not supported. That is, the UGS data and the real time
service data has a rigid limitation to a delay time due to inherent characteristics of
the data when the data is transmitted/received. Therefore, although the
transmission/reception of data is temporarily interrupted while the access
terminal is transmitting/receiving the UGS data or the real time service data
to/from the access point in the active mode 1300, the access terminal does not
enter the hold mode 1360 but is maintained in the active mode 1300, thereby
rapidly supporting the transmission/reception of data to be re-generated later. A
mode change from the active mode 1300 into the hold mode 1360 is achieved
when the access point or the access terminal transmits a mode change request
message, which will be described in detail later.
Next, a description will be given for the fast access mode 1330. The
fast access mode 1330, as described above, is a mode in which the access
terminal performs the fast access to the access point, when the access terminal is
not allocated an actual uplink bandwidth in its uplink access attempt but is
allocated a fast access PN code or a fast access time slot. When the access
terminal performs the uplink access using the allocated fast access PN code, the
probability of contention is minimized in performing the uplink access of a
contention-based scheme, so that the access terminal can perform fast access.
Also, the access terminal performs the uplink access using the allocated fast
access time slot, the access terminal performs the fast access in a contention-free
scheme. As a result, when the access point accomplishes the uplink access in
the fast access mode 1330, the access terminal enters the active mode 1300 so as
to transmit data to the access point (step 1323).
Next, a description will be given for the hold mode 1360. The hold
mode 1360, as described above, is a mode in which the transmission/reception
between the access terminal and the access point is temporarily interrupted.
When data to be transmitted to the access point is generated in the hold mode
1360, the access terminal performs the uplink access to the access point. Also,
since the hold mode 1360 is not a state in which the connection itself for
transmission/reception of data is ended, a case in which the access terminal has to
transmit a response message to the data transmitted from the access point, or a
different message corresponding to the response message, may occur. In this
case, since the access terminal has to perform faster uplink access than normal
uplink access performed in the access state 217, the access terminal performs a
mode change from the hold mode 1360 into the fast access mode 1330 (step
1325).
Meanwhile, in the hold mode 1360, the access terminal does not
continuously monitor a DL-BCCH, but monitors a DL-WUCH, thereby
minimizing the power consumption. During the monitoring of the DL-WUCH
in the hold mode 1360 as described above, when a wake-up indicator is turned on,
the access terminal enters the active mode 1300, thereby receiving data from the
access point (step 1327).
The above description with reference to FIG. 13 has shown the operation
modes of the traffic state 219. Hereinafter, a mode change process from the
active mode 1300 into the hold mode 1360 in the traffic state 219, which is
performed upon request from the access point, will be described with reference to
FIG. 14.
FIG. 14 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change from the active mode 1300 into the hold mode 1360,
which is performed upon request from the access point and is shown in FIG. 13.
Referring to FIG. 14, first, when the access point determines that the access
terminal has to perform a mode change from the active mode 1300 into the hold
mode 1360, the access point transmits a mode change request message to the
access terminal through a DL-TCH (step 1411). In this case, the access point
may transmit the fast access PN code information or the fast access time slot
information, which the access terminal uses in the fast access mode 1330,
through the mode change request message. That is, when the access terminal
being in the hold mode 1360 has to transmit data to the access point, it is
reasonable that the access terminal does not perform the uplink access of a
contention-based scheme but performs the uplink access of a contention-free
scheme, so that the access point causes the fast access PN code information or the
fast access time slot information, which the access terminal uses in the fast access
mode 1330, to be included in the mode change request message. Here, the
reason why the access point transmits the fast access PN code information or the
fast access time slot information is that the access terminal does not monitor the
DL-BCCH in the hold mode 1360.
When the access terminal receives the mode change request message
through the DL-TCH in the active mode 1300, the access terminal transmits a
mode change response message, which is a response message to the mode change
request message, to the access point through an UL-TCH. Also, after
transmitting the mode change response message, the access terminal performs a
mode change from the active mode 1300 into the hold mode 1360 (step 1413).
In the hold mode 1360, the access terminal monitors a DL-WUCH, and
periodically checks whether a wake-up indicator is turned on or off (step 1415).
The above description with reference to FIG. 14 has shown the mode
change process from the active mode 1300 into the hold mode 1360 in the traffic
state 219, which is performed upon the request from the access point.
Hereinafter, a mode change process from the hold mode 1360 into the active
mode 1300 in the traffic state 219, which is performed upon request from the
access terminal, will be described with reference to FIG. 15.
FIG. 15 is a signal flowchart illustrating a mode change process from the
hold mode 1360 into the active mode 1300, which is performed upon request
from the access terminal and is shown in FIG. 13. First, as described with
reference to FIG. 14, the access terminal performs a mode change from the active
mode 1300 into the hold mode 1360 according to a request generated from the
access point (steps 1511 and 1513). Next, when the access terminal, which is in
the hold mode 1360, senses that data to be transmitted to the access point is
generated, the access terminal performs a mode change from the hold mode 1360
into the fast access mode 1330. After this, in the fast access mode 1330, the
access terminal transmits a mode change request message to the access point
through a UL-FACCH, using a fast access PN code allocated from the access
point in the active mode 1300 (step 1515). When the access point receives the
mode change request message from the access terminal through the UL-FACCH,
the access point allocates a resource to the access terminal, and transmits a mode
change response message, which includes the allocated resource information, to
the access terminal through a DL-USCCH (step 1517).
Here, 'resource' means either an uplink bandwidth or a fast access PN
code or a fast access time slot. When the access point can allocate an uplink
bandwidth to an access terminal, the uplink bandwidth becomes the 'resource'.
In contrast, as described above, when the access point cannot allocate an uplink
bandwidth to an access terminal because having no currently available uplink
bandwidth, the fast access PN code or the fast access time slot becomes the
'resource'. Meanwhile, while the above description is given for the case in
which the access terminal receives a mode change response message in response
to a mode change request message, the access terminal may judges that the access
terminal receives the mode change response message also in a case in which the
access terminal receives not the mode change response message itself but only
the DL-USCCH. When it is assumed that resource information included in the
mode change response message is uplink bandwidth information in FIG. 15, the
access terminal performs a mode change from the fast access mode 1330 into the
active mode 1300, and transmits the data through a UL-TCH using the allocated
uplink bandwidth (step 1519).
The above description with reference to FIG. 15 has shown the mode
change process from the hold mode 1360 into the active mode 1300 in the traffic
state 219, which is performed upon request from the access terminal.
Hereinafter, a mode change process from the active mode 1300 into the hold
mode 1360 in the traffic state 219, which is performed upon request from the
access terminal, will be described with reference to FIG. 16.
FIG. 16 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change from the active mode 1300 into the hold mode 1360,
which is performed upon the request from the access terminal and is shown in
FIG. 13. Referring to FIG. 16, first, when the access terminal determines to
perform a mode change from the active mode 1300 into the hold mode 1360, the
access terminal transmits a mode change request message to the access point
through a UL-TCH (step 1611). When the access point receives the mode
change request message through the UL-TCH from the access terminal, the
access point causes the fast access PN code information or the fast access time
slot information, which the access terminal uses in the fast access mode 1330, to
be included in a mode change response message which is a response message to
the mode change request message, thereby transmitting the fast access PN code
information or the fast access time slot information to the access terminal through
an DL-TCH (step 1613). The reason why the access point transmits the fast
access PN code information or the fast access time slot information to the access
terminal is that the access terminal does not perform normal uplink access of a
contention-based scheme, but performs fast uplink access of a contention-free
scheme when the access terminal in the hold mode 1360 has to transmit data to
the access point. Therefore, the access point transmits the fast access PN code
information or the fast access time slot information through the mode change
response message. Also, the reason the access point transmits the fast access
PN code information or the fast access time slot information is that the access
terminal does not monitor the DL-BCCH in the hold mode 1360.
When the access terminal receives the mode change response message
through the DL-TCH in the active mode 1300, the access terminal performs a
mode change from the active mode 1300 into the hold mode 1360. After this, in
the hold mode 1360, the access terminal monitors a DL-WUCH, and periodically
determines whether a wake-up indicator is turned on or off (step 1615).
The above description with reference to FIG. 16 has shown the mode
change process from the active mode 1300 into the hold mode 1360 in the traffic
state 219, which is performed upon request from the access terminal
Hereinafter, a mode change process from the hold mode 1360 into the active
mode 1300 m the traffic state 219, which is performed upon request from the
access point, will be described with reference to FIG. 17
FIG.17 is a signal flochart illustrating a mode change process from the hold
mode 1360 into the active mode 1300, which is performed upon the request
from the access point and is shown in FIG. 13. First, as described with reference
to FIG.16 the access performs a mode change from the active mode

1300 into the hold mode 1360 according to a request generated from the active mode
terminal (steps 1711 and 1713).Next,when the access point senses that data to
be transmitted to the access terminal which is in the hold mode 1360 is
generated,the access point sets a wake-up indicator corresponding to the access

terminal to 'on', and transmits a DL-WUCH to the access terminal (step 1715).

The access terminal receives the DL-WUCH including the croresponding wake-

up indicator which is which is set to 'on' , and performs a mode change from the hold
mode 1360 into the fast access mode 1330. After this, in the fast access mode
1330, the access terminal transmits a mode change response message to the
access point through a UL-FACCH, using a fast access PN code or a fast access
time slot which is allocated from the access point in the active mode 1300 (step
1717). When the access point receives the mode change response message
from the access terminal through the UL-FACCH, the access point transmits the
data to the access terminal through a DL-TCH (step 1719). While the above
description is given for the case in which the access terminal performs a mode
change from the hold mode 1360 into the fast access mode 1330 when receiving
a DL-WUCH in which a corresponding wake-up indicator is set to 'on', and
transmits a mode change response message, it will be understood that the access
terminal may perform a mode change from the hold mode 1360 into the active
mode 1300 when receiving a DL-WUCH in which a corresponding wake-up
indicator is set to 'on', and transmit the data directly to the access point.
The above description with reference to FIG. 17 has shown the mode
change process from the hold mode 1360 into the active mode 1300, which is
performed upon request from the access point and is shown in FIG. 13.
Hereinafter, a message transmitting/receiving process for a mode change process
from the hold mode 1360 into the active mode 1300, which is performed upon
request from the access point, will be described with reference to FIG. 18.
FIG. 18 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change process from the hold mode 1360 into the active mode
1300, which is performed upon request from the access point and is shown in FIG.
13. Referring to FIG. 18, first, as described with reference to FIG. 17, when the
access point senses that data to be transmitted to the access terminal which is in
the hold mode 1360 is generated, the access point sets a wake-up indicator
corresponding to the access terminal to 'on', and transmits a DL-WUCH to the
access terminal (step 1811). The access terminal receives the DL-WUCH
including the corresponding wake-up indicator which is set to 'on', and performs
a mode change from the hold mode 1360 into the fast access mode 1330. After
this, in the fast access mode 1330, the access terminal transmits a mode change
response message to the access point through a UL-FACCH, using a fast access
PN code or a fast access time slot which is allocated from the access point in the
active mode 1300. Next, the access terminal performs a mode change from the
fast access mode 1330 into the active mode 1300 (step 1813). Then, the access
point receives the mode change response message from the access terminal
through the UL-FACCH, and transmits the data to the access terminal through a
DL-TCH (step 1815). While the above description is given for the case in
which the access terminal performs.a mode change from the hold mode 1360 into
the fast access mode 1330 when receiving a DL-WUCH in which a
corresponding wake-up indicator is set to 'on', and transmits a mode change
response message, it will be understood that the access terminal may perform a
mode change from the hold mode 1360 into the active mode 1300 when receiving
a DL-WUCH in which a corresponding wake-up indicator is set to 'on', and
transmit data directly to the access point.
The above description with reference to FIG. 18 has shown the message
transmitting/receiving process for a mode change process from the hold mode
1360 into the active mode 1300, which is performed upon request from the access
point and is shown in FIG. 13. Hereinafter, a message transmitting/receiving
process for a mode change process from the hold mode 1360 into the active mode
1300, which is performed upon request from the access terminal, will be
described with reference to FIG. 19.
FIG. 19 is a signal flowchart illustrating a message transmitting/receiving
process for a mode change process from the hold mode 1360 into the active mode
1300, which is performed upon request from the access terminal and is shown in
FIG. 13. Referring to FIG. 19, as described with reference to FIG. 13, when the
access terminal, which is in the hold mode 1360, senses that data to be
transmitted to the access point are generated, the access terminal performs a
mode change from the hold mode 1360 into the fast access mode 1330. After
this, in the fast access mode 1330, the access terminal transmits a mode change
request message to the access point through a UL-FACCH, using a fast access PN
code or a fast access time slot allocated from the access point in the active mode
1300 (step 1911). When the access point receives the mode change request
message from the access terminal through the UL-FACCH, the access point
allocates a resource to the access terminal, and transmits a mode change response
message, which includes the allocated resource information, to the access
terminal through a DL-USCCH (step 1913).
Here, 'resource' means either an uplink bandwidth or a fast access PN
code or a fast access time slot. When the access point can allocate an uplink
bandwidth to an access terminal, the uplink bandwidth becomes the 'resource'.
In contrast, as described above, when the access point cannot allocate an uplink
bandwidth to an access terminal because there is no currently available uplink
bandwidth, the fast access PN code or the fast access time slot becomes the
'resource'. Meanwhile, while the above description is given for the case in
which the access terminal receives a mode change response message in response
to a mode change request message, the access terminal may determines that the
access terminal receives the mode change response message also in a case in
which the access terminal receives not the mode change response message itself
but only the DL-USCCH. When it is assumed that resource information
included in the mode change response message is uplink bandwidth information
in FIG. 19, the access terminal performs a mode change from the fast access
mode 1330 into the active mode 1300, and transmits the data through a UL-TCH
using the allocated uplink bandwidth (step 1915).
As described above, an apparatus and a method according to the present
invention provides new operational states of a MAC layer suitable to a broadband
wireless access communication system, thereby having an advantage in that it is
possible to support the fast data transmission and the mobility of an access
terminal. In addition, an apparatus and a method according to the present
invention, that provide new operational states of a MAC layer suitable to a
broadband wireless access communication system, has an advantage in that an
access terminal can achieve the fast access while minimizing the power
consumption. In addition, an apparatus and a method according to the present
invention, that provide new operational states of a MAC layer suitable to a
broadband wireless access communication system, has an advantage in that it is
possible to minimize the power consumption of an access terminal when the data
transmission/reception is temporarily interrupted while it is possible maximize
the data transmission efficiency by performing the fast access when the data
transmission/reception is resumed.
While the present invention has been shown and described with reference
to certain preferred embodiments thereof, it will be understood by those skilled in
the art that various changes in form and details may be made therein without
departing from the spirit and scope of the invention as defined by the appended
claims.
We Claim:
1. A method for controlling an operational state of a medium access control
layer in a broadband wireless access communication system, the medium
access control layer having a null state (211) for performing an initial
operation following a reset, an initialization state (213) for acquiring
synchronization with an access point (100) and performing a network
entry operation to the access point, a sleeping state (215) with sleeping
mode (400) and awake mode (450) for performing a wake-up operation
by a control of the access point or when there is data to be transmitted to
the access point, an access state for performing an uplink access of a
contention-free scheme to the access point, and a traffic state (219) for
transmitting data to the access point or receiving data from the access
point, the method comprising the steps of:
performing an uplink access and allocating codes by the access point
for uplink access of a contention-based scheme and allocating codes by
the access point for the uplink access of the contention-free scheme
according to Quality of Service (QoS) classes;
selecting a first code by an access terminal, according to the QoS
classes of data to be transmitted from among the allocated codes for the
uplink access of the contention-based scheme, when the data to be
transmitted through an uplink in the access state is generated, and
performing an uplink access of the contention-based scheme to the access
point using the first code;
allocating by the access point a second code, from among the codes
for uplink access of the contention-free scheme, to the access terminal so
that the access terminal can perform an uplink access of the contention-
free scheme, when it fails to allocate the access terminal a resource for
data transmission of the access terminal in response to the uplink access
performed by the access terminal; and
performing by the access terminal a state transition from the access
state or the awake mode of the sleeping state into the traffic state when
allocated the second code, and performing an uplink access of the
contention-free scheme to the access point using the second code in the
traffic state.
2. The method as claimed in claim 1, wherein the data is transmitted by the
access point when the uplink access of the contention-free scheme is
succeeded after performing the uplink access of the contention-free
scheme.
3.The method as claimed in claim 1, wherein the second code is allocted
when the data has a QoS class is equal to or greater than a reference
priority.
4.The method as claimed in claim 1, wherein the higher the priority of the
Qos class, the more the Codes are Classified to the Qos Class are.
5. An apparatus for controlling an operational state of a medium access
control layer in a broadband wireless access communication system in a
method as claimed in claim 1.

Disclosed is a method for controlling an operational state of a medium access
control layer, by an access terminal, in a broadband wireless access
communication system. The method comprises the steps of performing an uplink
access of a contention-based scheme to an access point (100) using resources
required to perform the uplink access according to the contention-based scheme
when data to be transmitted in an access state is detected, and being allocated
resources required to perform an uplink access of a contention-free scheme from
the access point in a case of failing in the uplink access of the contention-based
scheme; and performing a state transition from the access state into the traffic
state (219) in a case of having been allocated the resource required for the
contention-free scheme, and performing the uplink access of the contention-free
scheme to the access point (100) using the allocated resource in the traffic state
(219).

Documents:

00055-kolnp-2006-abstract.pdf

00055-kolnp-2006-claims.pdf

00055-kolnp-2006-description complete.pdf

00055-kolnp-2006-drawings.pdf

00055-kolnp-2006-form 1.pdf

00055-kolnp-2006-form 2.pdf

00055-kolnp-2006-form 3.pdf

00055-kolnp-2006-form 5.pdf

00055-kolnp-2006-gpa.pdf

00055-kolnp-2006-international publication.pdf

00055-kolnp-2006-international search authority.pdf

00055-kolnp-2006-pct forms.pdf

55-kolnp-2006-granted-abstract.pdf

55-kolnp-2006-granted-claims.pdf

55-kolnp-2006-granted-correspondence.pdf

55-kolnp-2006-granted-description (complete).pdf

55-kolnp-2006-granted-drawings.pdf

55-kolnp-2006-granted-examination report.pdf

55-kolnp-2006-granted-form 1.pdf

55-kolnp-2006-granted-form 13.pdf

55-kolnp-2006-granted-form 18.pdf

55-kolnp-2006-granted-form 2.pdf

55-kolnp-2006-granted-form 3.pdf

55-kolnp-2006-granted-form 5.pdf

55-kolnp-2006-granted-gpa.pdf

55-kolnp-2006-granted-reply to examination report.pdf

55-kolnp-2006-granted-specification.pdf

55-kolnp-2006-granted-translated copy of priority document.pdf

abstract-00055-kolnp-2006.jpg


Patent Number 233676
Indian Patent Application Number 55/KOLNP/2006
PG Journal Number 14/2009
Publication Date 03-Apr-2009
Grant Date 01-Apr-2009
Date of Filing 05-Jan-2006
Name of Patentee SAMSUNG ELECTRONICS CO., LTD.
Applicant Address 416, MAETAN-DONG, YEONGTON-GU, SUWON-SI, GYEONGGI-DO
Inventors:
# Inventor's Name Inventor's Address
1 HYUN-JEONG KANG #203, DOGOK VILLA, 954-6, DOGOK 1-DONG, GANGNAM-GU, SEOUL
2 CHANG-HOI KOO 2ND FLOOR, 241-8, JOENGJA-DONG BUNDANG-GU SEONGNAM-SI GYEONGGI-DO
3 SO-HYUN KIM #530-1402, SHINAN APT YEONGTONG-DONG, PALDAL-GU, SUWON-SI GYEONGGI-DO
4 SUNG-JIN LEE #133-1701, HWANGGOLMAEUL APT YEONGTONG-DONG, PALDAL-GU, SUWON-SI GYEONGGI-DO
5 YEONG-MOON SON #102, JEONGWOOVILLA 897-1, ANYANG 3-DONG, MANAN-GU, ANYANG-SI, GYEONGGI-DO
6 JUNG-JE SON #401-905, 181, SANGNOKMAEUL BOSEONG APT JEONGJA-DONG BUNDANG-GU, SEONGNAM-SI, GYEONGGI-DO
PCT International Classification Number H04B 7/00
PCT International Application Number PCT/KR2004/002176
PCT International Filing date 2004-08-30
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10-2003-0065394 2003-09-20 Republic of Korea
2 10-2003-0065398 2003-09-20 Republic of Korea
3 10-2003-0060289 2003-08-29 Republic of Korea
4 10-2003-0065396 2003-09-20 Republic of Korea