Title of Invention

A METHOD FOR AUTOMATIC CONFIGURATION OF BASE STATIONS IN WIRELESS MULTIMEDIA NETWORKS

Abstract

The invention provides a method for automatic configuration of access points in wireless multimedia networks based on the effect of installation of a new access point (AP) on the quality of service of the existing flows. It proposes the mechanisms to estimate the interference on other access points and the probability of the interference crossing a desired threshold due to configuration of the new AP. These values of the probability are used to estimate the rate violation, mean delay violation, delay bound violation, jitter violation and corresponding configuration parameters for the new AP. It is also an object of the invention to confer a method for the self-configuration in wireless networks when an access point goes down.

Full Text

FIELD OF THE INVENTION This invention in general relates to the field of wireless multimedia networks. Further, this invention relates to communication and configuration of base stations in wireless multimedia networks. This invention relates to a method and system for the self-configuration of base stations in wireless multimedia networks taking into account of quality of service of existing flows. More particularly, this invention relates to a method for automatic configuration of access points in wireless multimedia networks. DESCRIPTION OF RELATED ART A wireless network system comprises a plurality of base stations and many numbers of wireless terminals (mobile terminals), which are used by the users to run applications over the wireless medium within its range. Schematic diagram of a typical wireless network is shown in Figure 1. In the figure, MT represents the mobile terminal and AP represents the access point, also called as the base station (BS). As is apparent from the figure, access point is a node to which the MT communicates to access the wireless medium. It can be seen that the access points are connected to the backbone network through access router (AR), also known as access point controller (APC). Access router/Access point controller is a node that monitors the events at the AP's. The memory at the AP is usually much smaller than that at the AR and the communication between Access Point (AP) and Access Router (AR) is usually through a wire-line link. Access Point Controller (APC)/ Access Router (AR) gets IP (Internet Protocol) layer packets, fragments those to MAC (Medium access control) packets and sends to the corresponding Access Points (AP). Then the Access point (AP) serves packets over the air-link for the Mobile Terminals (MT). The physical layer (PHY) and medium access control (MAC) standard for this type of networks are according to IEEE standard 802.16-2001, part 16: Air interface for fixed broadband wireless access systems. In a wireless network, when a new AP is installed by an operator, the parameters, capabilities and the other necessary information about the AP has to be broadcast to the other AP's in the network. It is necessary for the other AP's in the system to know about the presence of the new AP for the following reasons: 1. The existing APs have to update their neighbor list, which, in turn, can be used for mobility management. Updating the neighbor list also helps the existing AP's and the AR's to enable efficient packet routing 2. It is important for the existing AP's to update the information about the new AP so that the interference caused by the new AP to the MT's associated with the existing AP's can be computed. 3. The information about the new AP is also used for efficient radio resource management (RRM) at the other AP's. The configuration of a new AP results in interference experienced by the Mobile Terminals (MT) in other cells. Consequently it leads to the degradation of the quality of service (QoS) of the flows in the existing cells and results in the reconfiguration of existing AP's. The reconfigurations must take into account, the effect on the QoS obtained by existing flows in the system. Presently there are no efficient automatic configuration mechanisms that take into account Quality of Service (QoS) of existing flows. Also, when a new AP is configured, it could result in multiple re-configurations at the existing AP's in the system and there are no efficient methods to prevent multiple re-configurations of existing AP's due to the configuration of a new AP. As a solution to the above mentioned deficiencies in the prior art the present invention proposes an effective method for configuration, which take into account the effect of the new AP on the Quality of service (QoS) of the existing flows. This invention makes use of the position of the new AP to estimate the Carrier to Interference Noise Ratio (CINR) at all the MT's in the system and hence estimate the degradation of the QoS based on the CINR estimates. SUMMARY OF THE INVENTION It is therefore the primary object of the invention to provide a method for automatic configuration of access points in wireless multimedia networks based on the effect of installation of a new access point (AP) on the quality of service of the existing flows. It is another object of the invention to estimate the degradation of the quality of sen/ice based on the CINR estimates and to take the corrective measures accordingly. It is yet another object of the invention to provide a method to limit the re-configuration of the existing access points due to the arrival of the new access points on the basis of a threshold on the number of re-configurations, the quality of service violation statistics and vendor specific parameters. It is a further object of the invention to confer a method for the self-configuration in wireless networks when an access point goes down. Accordingly, the present invention comprises a method for automatic configuration of access points in a wireless networks by a management server which takes into account the quality of service of existing flows while installing the new access point, the method comprising the steps of: a) receiving the maximum transmit power, cell coverage, number and set of channels used, location and vendor specific information conveyed by the new access point; b) broadcasting the above set of information to other access points in the system; c) obtaining the information about the number of mobile terminals in the cell, their locations, the types of services supported, the quality of service parameters and the disturbance experienced at each mobile terminal in the cell, access point due to the effect of the said new access point; d) estimating the interference and the probability of the interference crossing a desired threshold due to configuration of the new AP; e) approximating the rate violation and corresponding configuration parameters for the new access point from the probability values; and f) determining whether to disallow the said new access point to use the present channel or to allow using the channel with lesser transmit power to serve best effort flows alone in order to avoid the re configuration of other access points in the system Accordingly, the present invention further comprises a method for self configuration in wireless networks when an access point goes down, the method comprising the steps of: (a) setting a timer at each of the existing access points; (b) updating the carrier-to-interference noise ratio (CINR) If there are no flows from the cell that need to be directed to the said existing access points when the timer expires; and a) observing the flows if incident on the access point, suitably re-allocating and re-associating it with other existing access points Other advantages and features of the invention will become more clearly apparent from the following description of the embodiments of the invention given as non-restrictive examples only and represented in the accompanying drawings. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Figure 1 depicts a wireless Network. Figure 2 illustrates a cellular system with 37 circular cells. Figure 3 shows a flow chart showing the configuration mechanisms during the installation of a new access point. Figure 4 shows a flow chart showing the re-configuration mechanisms when an access point goes down. Figure 5 shows the signal exchanges between the access router and the existing access points as well as the new access point when a new access point is installed. Figure 6 shows the signal exchanges between the access router and the other existing access points when an access point goes down. DETAILED DESCRIPTION OF THE INVENTION The preferred embodiments of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art on how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. As mentioned earlier in this description in a wireless network, IP packets are segmented to MAC packets before they are transmitted over the air by the Base Station (BS) towards MT. Each flow in the network is identified by a unique connection identifier (CID). For the purpose of QoS negotiation these flows are classified as follows: Class C1: This type of flows include flows such as voice over IP (VOIP) and streaming video that have very stringent requirements over delay bound and jitter. These flows may also specify their required rate. Class C2: This includes flows such as web browsing which specify an average delay requirement and their required rate. Class C3: It includes the flows such as file transfer protocol (FTP), which specify their required rate alone. Class C4: This class of flows has no QoS requirements and are called best effort flows According to a preferred embodiment of the invention the shape of each cell is modelled as a circle as shown in Figure 2. A hexagonal model for each cell can also be used. It is to be noted that the mechanisms described in this invention are applicable to any shape for a cell. When a new AP is to be configured, it conveys the following information to the management server. 1. The maximum transmit power and cell coverage. 2. The number and set of channels that is used (In case the system is a single carrier system, then this information is not required) 3. The location of the new AP (i.e., the geographical co-ordinates, which can be obtained by using a global positioning system (GPS)) 4. The vendor and vendor specific information The management server can be a separate server or part of the Access Router (AR). The management server will then broadcast the above set of information in the system to other AP's. Then the existing AP's shall provide the information about the number of MT's in the cell, their locations, the types of services supported, the QoS parameters and the disturbance experienced at each MT in the cell and the AP. Using this information the management server can estimate the interference measured at the existing MT's due to the new AP. Consequently configuration of the access point and the channel allocation can be performed. The invention proposes the mechanisms to estimate the interference and the probability of the interference crossing a desired threshold due to configuration of the new AP. These values of the probability are used to estimate the rate violation and corresponding configuration parameters for the new AP. The mechanisms employed according to the invention are described below with Mechanism I: For Class C3 flows It is essential to provide the specified required rate to flows belonging to this class and therefore each class C3 flow in a cell specifies the minimum rate that is required to receive or transmit data. The mechanism makes use of the rate requirements and the rate violation statistics of the existing FTP type flows, which have requirements on the rate of data transmission and reception. When a service that has similar requirements. As explained in mechanism I, the location delay greater than the value specified by the delay bound. In general for class Ck, it is desired that the fraction of flows violating the delay bound requirement flows at low power. Mechanism IV: For Class C1 flows Mechanism III provides an approach for configuration of a new AP based on Mechanism V: Stopping criterion Mechanisms l-IV presented methods to reduce the reconfiguration probability of existing AP's when a new AP arrives into the system. However, since the measurements are statistical, they could still result in reconfiguration of existing AP's and sometimes multiple re-configurations. For example, if a particular channel n1 was used for serving class C1 flows the ith cell and if configuration of a new AP resulted in re-configuration of the class C1 flow on channel n1 to channeln2, which, in turn, could result in re-configuration of class C1 flows on channel 2 in some other cell. To avoid such multiple re-configurations, we propose this mechanism. From the statistics obtained using Mechanisms l-IV, and based on the vendor information of the new AP and the existing AP's, each vendor specifies a required threshold on the number of flows in each class that need to meet their QoS requirements. For example, a particular vendor can specify that at least 90% of class C1 flows must suffer a delay of less than a specified limit in cells provided by that vendor. This limit is different from thresholds are specified for other classes of traffic also. When the specified threshold is reached due to re-configurations of the AP's provided by the vendor, the management server prevents further re-configurations of the existing AP and disallows configuration of the new AP on the specified channels. WHEN A BASE STATION IS REMOVED FROM THE SYSTEM When a base station leaves the system because it fails, the flows served by the base station need to be served by the other base station so as to satisfy the QoS requirements. When an AP goes down, the interference experienced by the MT's in the neighbouring cells reduces. However, the channels in the neighbouring cells cannot be reconfigured as the flows that were in progress in the current cell need to be served. These flows have to be distributed between the existing AP's. These flows can be treated as handoff flows and suitable mechanisms as proposed in Mukesh Taneja, S. Anand and G. Viswanath, "Methods and system for recommended and active set selection for handoff in wireless multimedia networks," Patent Filed, Application number 190/CHE/2004 can be used for QoS based handoff. However, some of the information required for the handoff may not be available due to failure of the AP. Therefore the following mechanisms are proposed. ith cell that need to be directed to the existing AP's when the timer expires, the CINR on the set of channels, 5,, is updated. However, if there exists at least one flow from the ith cell that needs to be served, then the following procedures are followed. It is noted that before the following procedures are applied, the neighbouring AP's need to have sufficient buffer space to accommodate the flows from the ith cell. Appropriate Methods and system explained in Mukesh Taneja, "System and methods for dynamic flow control, buffer management and admission control in wireless multimedia networks," Patent Filed, Application number 439/CHE/2004 are applied for buffer management and admission control of these flows before re-allocating them. Mechanism VI: AR and MT driven When the AP of the ith cell goes down, we first consider the case when the class C1 flows are re-allocated to the other cells first and then flows of the other classes are re-allocated. The AR broadcasts the context of all the existing flows to all the other AP's and also the corresponding channels used by the flows. The existing AP's make use of the information broadcast by the AR. For class C1 flows, the MT checks with the neighbouring AP if the set of channels, siC1 is available for use at the AP for class C1 flows. The set of channels siC is available for use at the neighbouring AP if (i) the set of channels was not being used at the neighbouring AP and the CINR on those channels are above the threshold for class C1 flows or (ii) The set of channels ith were used for serving flows of classes C2, C3 or C4. If the class C1 flows of the ith ceW can continue in the set stC1 then they are allowed to continue in Sic1'. Otherwise, consider the set of flows that used the subset of channels among Sic1 and that cannot be used in the neighbouring cell. For these flows, the MT measures CINR and computes for each channel n, a parameter, DRC(n), which is the maximum rate at which the MT can receive without violating CINR requirements. Then, the MT chooses the Mechanism VII: AR and MT driven with parallel channel allocation Mechanism VI assumes that when an AP goes down, the channel re-allocation is first made for class C1 flows and then to flows of other classes. However, it is possible that the flows could try to find an alternative AP in parallel. In such a system, the flows belonging to all the classes could make measurements of DRC{n) on all the channels. The neighbouring AP's are then required to schedule the flows to allocate resources (in this case, channels), efficiently. Scheduling mechanisms to meet the QoS requirements of flows was for 3G systems as proposed in Mukesh Taneja, "Methods and system for efficient per-flow resource allocation in wireless multimedia networks," Patent filed, Application number 887/CHE/2003 can be used here. The AP first performs the channel allocation for all the class C1 flows and then all the class C2 flows and then for all the class C3 flows and then the best effort flows. Mechanism VIM: AR and MT driven with parallel channel allocation Again, consider the system in which channel allocation is made in parallel for all the flows. As mentioned earlier, it is desired that the violation of QoS for each class of flow below a specified threshold. The scheduling for the flows can also The flowcharts for the above mechanisms are explained in Figures 3 and 4. In the figures, TOT_NBR is the number of neighbours, TOT_FLO is the number of flows in each neighbour and FLO# and NBR# are the flow and the neighbour indices, respectively. The signal flow for the new AP installation is given in Figure 5. In the figure, the signals are as follows. AP-CFG_REQ is the AP configuration request message and AP-CFG_RSP is the AP configuration response message. AP-ATT are the AP attributes, AP-CFG_PRM is the configuration parameters message as given by the AR after following mechanisms l-IV. AP-RCG_REQ and AP-RCG_RSP are the AP re-configuration request and response messages, respectively. These messages are exchanged between the existing AP's and the AR after following mechanism V. The signal flow when an AP goes down and the system with AR and MT driven re-allocation is given in Figure 6. In the figure, AP-DWN_TRG is the AP down trigger message. When the AP of the f cell goes down, this message is sent to all other AP's. Upon receiving this message the existing AP's wait for a timeTimer_FlowReconfig and updates the CINR only if there are no now flows from the ith cell re-allocated to this AP till the timer expires. FLO-ATT are the flow attributes of the flows in the ith cell, using which mechanisms VI-VIII are applied, after which, the existing AP's re-configure using the AP-RCG_REQ and AP-RCG_RSP messages. The signals remain the same for the MT driven system also, except that the AP-DWN_TRG message changes. The message formats for the messages shown in Figures 5 and 6 are given below in Tables 1 - 5. The descriptions of these messages are also provided in the tables. All these messages are allocated the basic connection identifier (CID) in the generic MAC header. The reasons for rejection include reasons like including reasons like AP address already exists, authentication failed, authorization failed, vendor unidentified and APC-CFG_REQ in error. The AP-RCG_REQ shall be of the same format as the AP_CFG_REQ except that the message type varies. The AP-RCG_RSP shall be of the same format as the AP-CFG_RSP except that reasons for rejection shall not have the failure due to authentication, unidentified vendor, existing AP address. Table 5: AP-DWN_TRG Explanation of commands AP-CFG_REQ: AP configuration request message, it is given by a new AP to the AR to register itself and negotiate its parameters AP-CFG_RSP: AP configuration response message, it is given by the AR to a new AP in response to the AP-CFG_REQ message just acknowledging the receipt of the message AP-RCG_REQ: AP re-configuration request message, it is given by an existing AP to the AR to re-configure its parameters AP-RCG_RSP: AP re-configuration response message, it is given by the AR to an AP in response to the AP-RCG_REQ message just acknowledging the receipt of the message NEW-APJND: New AP indicator, it is a message given by the AR to the existing AP's informing the AP's of the arrival of a new AP and the location of the new AP. AP-CFG_PRM: AP configuration parameter message, it is given by the AR to the new AP specifying its parameters AP-ATT: Attributes of the AP, it is given by an AP to the AR. This shall include the flows incident on the AP and the description of the flows and the channels used by the AP for the corresponding flows. AP-DWN_TRG: AP down trigger message, this is given by the AR to the other AP's when an AP goes down, it contains the AP that went down and the details of the context of the flows incident on that AP and whether the re-allocation is AR and MT driven or only MT driven. If AR and MT driven, then it also contains the channels used by the flows. FLO-ATT: Attributes of the flows, it is given by an AP to the AR. This shall include the flows incident on the AP and the description of the flows and the channels used by the AP for the flow. TLV: Type, length value, a format for encoding information in the messages 2 It will also be obvious to those skilled in the art that other control methods and apparatuses can be derived from the combinations of the various methods and apparatuses of the present invention as taught by the description and the accompanying drawings and these shall also be considered within the scope of the present invention. Further, description of such combinations and variations is therefore omitted below. It should also be noted that the host for storing the applications include but not limited to a computer, printer or a multi function device. Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are possible and are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom. WE CLAIM 1. A method for automatic configuration of access points in a wireless networks by a management server which takes into account the quality of service of existing flows while installing the new access point, the method comprising the steps of: (b) receiving the maximum transmit power, cell coverage, number and set of channels used, location and vendor specific information conveyed by the new access point; (c) broadcasting the above set of information to other access points in the system; (d) obtaining the information about the number of mobile terminals in the cell, their locations, the types of services supported, the quality of service parameters and the disturbance experienced at each mobile terminal in the cell & access point due to the effect of the said new access point; (e) estimating the interference and the probability of the interference crossing a desired threshold due to configuration of the new access point; (f) approximating the rate violation and corresponding configuration parameters for the new access point from the probability values; and (g) determining whether to disallow the said new access point to use the present channel or to allow using the channel with lesser transmit power to serve best effort flows alone in order to avoid the re-configuration of other access points in the system. 2. The method as claimed in claim 1 wherein the said management server is part of the access router. 3. The method as claimed in claim 1 wherein the configuration mechanism make use of the rate requirements and the rate violation statistics of the existing type flows which have requirements on the rate of data transmission and reception in order to calculate the said threshold values to configure the new access point. 4. The method according to claim 3 wherein the flow pertains to file transfer protocol (FTP). 5. The method as claimed in claim 1 wherein the management server (access router) takes into account the mean delay violation statistics and the average rate violation statistics flows, which specify a mean delay requirement as well as rate requirement in order to calculate the said threshold values to configure the new access point. 6. The method according to claim 5 wherein the flow pertains to hypertext transfer protocol (HTTP). 7. The method as claimed in claim 1 wherein the management server (Access Router) takes into account the delay bound and jitter violation statistics of the real time flows in order to calculate the said threshold values to configure the new access point. 8. The method according to claim 7 wherein the real time flow pertains to MPEG-n streaming video or VoIP. 9. The method according to claim 7 wherein the management server (Access Router) takes into account of the violation of delay and jitter constraints for the flows after configuration of the new access points. 10. The method according to any of the preceding claims wherein the management server (access router) limits the re-configuration of the existing access points due to the arrival of the new access points based on a threshold on the number of re-configurations, the quality of service violation statistics and vendor specific parameters. 11. A method for self configuration in wireless networks when an access point goes down, the method comprising the steps of: (a) setting a timer at each of the existing access points; (b) updating the carrier-to-interference noise ratio (CINR) If there are no flows from the cell that need to be directed to the said existing access points when the timer expires; and (c) observing the flows if incident on the access point, suitably re-allocating and re-associating it with other existing access points.. 12. The method according to claim 11 wherein the method is driven by access router and mobile terminal. 13. The method as claimed in claim 12 wherein the first priority for re-allocation is given to real time flows. 14. The method as claimed in claim 13 wherein the access router informs the existing access points not only the context of the flows but also the corresponding channels used by the flows. 15. The method as claimed in claim 12 wherein all the existing flows try to find new access points and the quality of service statistics are used in prioritizing the flows. 16. The method as claimed in claim 11 wherein the re-allocation is driven only by the mobile terminal. 17. The method according to claim 16 wherein access router informs the existing access pointers of the context of the flows and not the channels used by the flows. 18. The method according to any of the claims 11 to 17 wherein the configuration is achieved by the corresponding signals between the access points and access router. 19. A method for automatic configuration of access points in a wireless networks by a management server which takes into account of the quality of service of existing flows while installing the new access point, substantially as herein above described and illustrated with reference to the accompanying drawings. 20. A method for self-configuration in wireless networks when an access point goes down, substantially as herein above described and illustrated with reference to the accompanying drawings.

Documents:

1233-che-2004-abstract.pdf

1233-che-2004-claims.pdf

1233-che-2004-correspondnece-others.pdf

1233-che-2004-correspondnece-po.pdf

1233-che-2004-description(complete).pdf

1233-che-2004-drawings.pdf

1233-che-2004-form 1.pdf

1233-che-2004-form 13.pdf

1233-che-2004-form 26.pdf