AU2008200105B2 - Method and system for transferring transmit power control information between network management entities in a wireless communication system - Google Patents

Description

09-Jan-2008 03:52 PM WATERMARK 61398196010 6/32 P001 Section 29 Regulaion 3.2(2)

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number Lodged: Invention Title: Method and system for transferring transmit power control information between network management entities in a wireless communication system The following statement is a full description of this invention, including the best method of performing it known to us: P111AAIfI11 COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:52 PM WATERMARK 61398196010 7/32 00 O [00011 MI ETOD AND SYSTEM FOR TRANSFERRING TRANSMIT 0 POWER CONTROL INFORMATION BETWEEN NETWORK Cl MANAGEMENT ENTITIES IN A WIRELESS COMMVINICATION

SYSTEM

[0002] FIELD OF INVENTION S[0003] The preset inventionis relatedto wieess communicatio systems.

More particularly, the present invention is related to a method and system for in transferring transmit power control (TPC) information between a wireless transmitreceive unit (WTRU) and an access point (AP).

0 [(0004] BACKGROUND S[0005] Wireless local area networks (WLANs) have become more popular NC because of their convenience and flexibility. As new applications for such networks are being developed, their popularity is expected to significantly increase.

[0006] Institute of Electrical and Electronics Engineers (IEEE) working groups have defined an IEEE 802.11basoline standard having extensions which are intended to provide higher data rates and other network capabilities. Under the IEEE 802.11 standards, network entities include a 1nageet information base (MIB). The MIB may be either a media access control layer (MAC) layer MIE or a physical (PY) layer MIB. Data entries in a MEB table use IEEE 802.11 standards.

10007] Network management entities (NMEs), connected to a WLAN, communicate with each other by sending frames, There are three typos of MAC frames defined bytho 802.11 standards: 1) data frames; 2) control frames; and 3) management frames. Thera are also sub-types for each of these frames. For example, an action frame is a sub-type of a management frame. Action frames are further defined by categories. Currently, action frame categories are defined as follows: 0- spectrum management; 1- quality ofservice management; 2- direct link protocol; and 3- radio measurement.

(0008) A service primitive is an internal signaling message used for interlayer or inter-protocol entity exchanges, such as between a station management entity (SME) and a MAC layer management entity (MLME), with standardized -1- COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:53 PM WATERMARK 61398196010 8/32 00 0 message contents. Although a particularformat ofmessage is not specifiedbythe N standards, the standards do specify the content. Service primitives are typically used to initiate, confirm or report a particular action, such as by sending a C' particular frame for management purposes from one WTRU to another WTRU.

[00091 In accordance with IEEE 802.11 standards, an SME is incorporated into the WTRU in order to provide correct MAO operation. The SME is a layerindependent entity that may be viewed as residing in a separate management plane or as residing "offto the side." Thus, the SME may be viewed as being Sresponsible for such fumntions as the gathering of layerdependent status from q the various layer management entities, and similarly setting the value of layer- Sspecific parameters, The SIME typically performs such functions on behalf of Ci general system management enities and implements standard management protocols.

[0010] Furthermore, according to IEEE 802.11 standards, a WTRU contains configuration settings in the MIB that control its behavior. It is important fbr an AP to be able to understand the configuration of each WTRU in order to interpret the WTRU's behavior and to improve'performance in the context of WLAN radio resource management (RUM). For example, a WTRU keeps track, in its MIB, of sucoessfully received but not decodable data frames.

this is impartant infonration for an AP to provide a minimum level of quality of service to the WTRU.

[0011] RRM is one of the most important aspects in WLAN anagement.

A WLAN can achieve significant performance enhancement by peforming RM, including in-band interference mitigation and frequency re-use. For efficient RRM, it is necessary for an NME to retrieve WTRU specific TPO related information. A problem with the MIB data structure used in conventional wireless systems is that TPO information of a WTRU ia not stored in the MIB of anAP.

[0012] Interference mitigation is a classic technique used in wirless communication systems to avoid interfering with other users in the vicinity by minimizing the amount of transmission power. The IEEE 802.11h standard defines messaging of a maximum allowablo transmit power by means of -2- COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:53 PM WATERMARK 61398196010 9/32 00 0 BEACON and PROBE RESPONSE frames, and messaging by means of TPO N REQUEST and TPO REPORT frames to get the instantaneous transmit power and link margin. An AP broadcasts a BEACON frame, or replies with a PROBE SRESPONSE frame. A BEACON frame contains a country field, a power 0 constraint field, a transmit power field, and a link margin field. The country field contains the maximum regulatory power level, The power constraint field contains an offbet value compared to the maximum regulatory power level. The 2- transmit power field indicates the transmit power uned to transmit the TPC 0 0 REPORT frame. The link margin field is set to zero in the BEACON and PROBE 00 RESPONSE frames.

[00131 The request/report messaging and retrieving of a WTRU's physical C measurement data or MAC performance statistics, such as transmit/ receive power levels and link margins in a basic service set (BSS), are keyparameters for supporting interference mitigation and RRM. However, these physical measurements or MAC performance statistics are not passed from an LI PHY or L2 MAC protocol entity to the SME, which serves as an interface to an external WLAN RRM entity. The SME typically contains interface software to read/write into the MIBs. For example, upon receiving a command from a simple network management protocol (SNMP), a read ofa particular MIB entry is reported back to the SNMP.

[00141 Currently, WLANs usually transmit at a much higher power level than needed. With TPC, the tranmit power can be adjusted to the minimum level to still guarantee satisfactory signal reception while not creating more interference than needed interference to other WTRUs. It is also possible to perform effective load control and BSS range adjustments. Range adjustments, load balancing, and a maximum cell radius are determined by the transmit power of the AP and the receiver sensitivity ofthe WTRU. If transmit power is not properly controlled, WTRUs at the edge of the cell lose connection to the AP and will be forced to re-associate to neighboring APs. Therefore, proper power control enables effective load control and range adjustments.

-3- COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 00 8 SUMMARY OF THE INVENTION The present invention is a method and wireless communication system for transferring TPC information between a WTRU and an AP. The AP includes a first management entity and a second management entity. The WTRU including a t'q third management entity. The first management entity in the AP determines whether or not to adapt the transmit power level of the WTRU. The first management entity transmits a first message requesting TPC information to the 0second management entity in the AP if the first management entity determines to c adapt the transmit power level of the WTRU. The second management entity may 00oo transmit a message to the first management entity confirming receipt of the first message.

The second management entity in the AP transmits a second message to the WTRU requesting that the WTRU provide TPC information to the AP. In response to the WTRU receiving the second message, the third management entity in the WTRU performs one or more physical measurements to determine one or more TPC parameters. The third management entity then transmits a third message including the requested TPC information associated with results of the physical measurements to the AP.

The measurements performed by the third management entity may include a WTRU transmit power level measurement, a link margin measurement, a clear channel assessment (CCA), a perceived signal-to-noise indication (PSNI) measurement, a received signal strength indication (RSSI) measurement, and a received channel power indication (RCPI) measurement. The first management entity may be an SME and the second and third management entities may be MLMEs. The wireless communication system may be a WLAN.

In accordance with a first aspect, the present invention provides a method of exchanging measurements in wireless communications, the method including: communicating a first message from a first management entity to a second management entity; transmitting, in response to the first message, a measurement request from the second management entity, the measurement request including a request for a measurement of a parameter; 00 receiving a measurement report at the second management entity, wherein the measurement report includes the requested measurement of the parameter; and storing the requested measurement of the parameter in a management information base (MIB).

In accordance with a further aspect, the present invention provides a Owireless transmit receive unit (WTRU) including: Oa first management entity configured to communicate a first message; Sa second management entity configured to: 00 receive the communicated first message; transmit a measurement request including a request for a measurement of a parameter, in response to the first message, receive a measurement report containing the requested measurement of the parameter, and a management information base configured to store the requested measurement of the parameter.

BRIEF DESCRIPTION OF THE DRAWINGS A more detailed understanding of the invention may be had from the following description of a preferred example, given by way of example and to be understood in conjunction with the accompanying drawing wherein: Figure 1A is a block diagram of a wireless communication system 09-Jan-2008 03:55 PM WATERMARK 61398196010 12/32 00 0 operating in accordance with the present invention; CN- [0022] Figure 1B is a detailed block diagram illustrating the configuration of an AP and WTRU used in the wireless communication system of Pigure 1AL [0023] Figure 2 is a ignal flow diagram showing communication between a o WTRU and an AP for obtaining TPC information in accordance with the present invention; 1 0024 Figure 3 is a signal flow diagram showing communication between a WTRU and an AP for requesting and receiving a measurement report in Saccordance with the present invention; 00 [0025] Figure 4 is a signal flow diagram illustrating an exemplary process for transferring TPC information using service primitives between network C management entities in accordance with the present invention; and 10026] Figure 5 is a flowchart of an exemplary process including method steps for transferring TPO infonnation between network entities in accordance with the present invention.

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) [00283 Hereafter,. a WTRU includes but is not limited to a user equipment, a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, an AP includes but is not limited to a base station, a Node-B, a site controller, or any other type of interfacing device in a wireless environment.

[0029] The present invention will be described with reference to the drawing figures wherein like numerals represent like elements throughout. The present invention applies as add-on to the WLAN IEEE 802,11 standards (802.11 baseline, 802.1la, 802.11b, and 802.11g), and also applies to IEEE 8 0 2 .11e, 802.11h and 802.16.

[00301 The present invention may be further applicable to Time Division Duplex (TDD), Frequency Division Duplex (FDD), and Time Division Synchronous ODMA (TDSODMA), as applied to a Universal Mobile Telecommunications System (UC TS), ODMA 2000 and CDMA in general, but is envisaged to be applicable to other wireless systems as well.

COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:55 PM WATERMARK 61398196010 13/32 00 o [0081] The features of the present invention may be incorporated into an N integrated circuit (IC) or be confgured in a circuit comprising a multitude of Sinterconnecting components.

[0032] Figure 1A is a block diagram of a wireless communication system 0 100 including a plurality of WTRUs 105, a plurality of APs 110, a distribution system (DS) 115, anTNME 120 and a network 125. TheWTRUs 105 and APs 110 form respective base service sets (BSSs) 180. The BSSs 130 and the DS 115form an extended service set (ESS). The APs 110 are connected to the NME 120 Sthrough the network 125, The wireless communication system 100 may be a 00 10033] Figure 1B is a detailed block diagram illustrating the configuration C of the APs 110 and WTRUs 105 used in the wireless communication system 100.

The AP 110 includes a first management entity 150, a second management entity 155 and a first IB 160. The WTRU 105 includes a third management entity 165, a fourth management entity 170 and a second MIB 175. The MIBs 160 and 175 consist of one or more storage devices a counter, a register or other memory device) used to store configuration parameters, performance metrics and fault indicators.

[0034] The first management entity 150 may be an SME. The second management entity 155 may be an MLME. The third management entity 165 may he an MLME. The fourth management entity 170 may be an SME.

[0085] Referring to Figure 1A, an RRM controller (not shown) residing in the NME 120 comnuicates with the APs 110 via the network 125 and DS 115.

The APs 110 wirelessly communicate with the WTRUs 105. The NME 120 sends a message to the APs 110 to change admissible power levels in the AP's BSS by means of higher layer (layer 2 or higher) management protocols, such as SNMP or Extensible Markup Language (XML). The NM 120 writes allowable maximum and minimum values into the MIB 160 of the AP 110.

[0036] A process is implemented in the AP 110 that regularly reads the entries in the MIB 160 of the AP 110 and uses service primitives to send and receive MAC signalingframes. The MAC signaling frames, such as BEACON or TPC REQUEST, IMEASUREMENT REQUJEST or the like, commnicate to allof -6- COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:56 PM WATERMARK 61398196010 14/32 00 O the WTRUs 105 in the celli 0 CN [00371 When the AP 110 receives MAC signaling frames from the WTRUs S105 TPO REPORTS, MEASUREMENT REPORTS, or the lke), the AP 110 takes the reported meatremonts and uses service primitives to write the 0performance measurements in the MIB 160 of the AP 110. The NME 120 then reads these MIB entries in the APs 110 via the management protocols to learn ^f the etrent syatem performance. The NME 120 controls the transmitpower level of the WTRUs 105.

0 S[00381 The MIB may be either MAO MIB or PHY MM. MAC MIB is 00 generally preferred because most RRM units operate at the MAO level, which has Sa very fast response. Entries in the MIB table shall be included either in a per- C WTRU table, which is preferred, or in a global statistics table. By making these physical measurement data available to external entities by storing them in the MIB of the AP 110, it is possible to keep interference levels low, resulting in higher system capacity.

[0039] Figure 2 illustrates a process which supports communication between aWTRU 105 and an AP 110 in order to obtain TPO data in accordance with the present invention. Once an AP 110 transmits decides to obtain TPC data from a target WTRU 105, the AP 110 transmits a TPC request frame 205 to the target WTRU 105. In response to the TPO request frame 205, the WTRU 105 perlbrms one or more requested physical measurements and transmits a TPC report frame 210 to the AP 110. The AP 110 then stores the TPC data in the MIB 160 of the AP 110 which is made available to external entities, such as an NME120..

(0040] Referring to Figures 1A and 1B, the process to obtain TPC data can also be initiated by the NME 120, which in turn triggers the first management entity 150 in the AP 110 to send a primitive to the second management entity 155 to send a MAC signaling frame to the WTRU 105 and so on.

[0041] Figure 3 illustrates a process which supports communication between a WTRU 105 and an AP 110 in order for the AP 110 to request a WTRU 105 to perform one or more measurements and report specific physical parameters of the WTRU 105 to the AP 110. Once an AP 110 decides to request -7- COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:56 PM WATERMARK 61398196010 15/32 00 g physical measurement data from a WTRU 105, the AP 110 transmits a N measurement request frame 305 to a target WTRU 105 for measuring and reporting certain physical parametrs of the target WTRU 105. The measurements may include transmit power, link margin, a OOA report received o power indicator (RPI) bistogram report, or any other physical related measurements. These may be absolutevalues, statistical averages orhistogram values, or values that are calculated utilizing any type of algorithm or Soptimization routine. After perfarming the requested measurement, the target 0 WTRU 105 compiles measurement data and transmits a measurement report 00 frame 310 to the AP 110. The measurement data is stored in the MI 160 ofthe SAP 110 and, optionally, at the MIB 175 of the WTRU 105.

C [0042] The MIB 175 in the WTRU 105 stores two different categories of information. The first category inludes a variety of physicameasurements such as signal power, interference levels, noise histograms, or the like. The second categoryis a variety of MAC parformance statistics suchas OOA busy fractions, average back-off times, erroneous frame counters, or the like, 10043] When the received physical measurement and MAC performance statistics are stored in the MI 160 of the AP 110, it is made available to an entity which is responsible for RRM. The MIB 160 may be either a MAC MIB or a PHY MIB. A MAC MIB is preferred because RRM messaging is also performed in MAC layer, and it is much faster than PHY layer. These physical measurement data are made available to external entities by storing themin the MIB 160 of the AP 110. Thus, effective load control and BSS range adjustments become possible.

[0044] Figre 4 is a signal flow diagram illustrating an exemplary process 400 for obtaining TPO information using service primitives between an AP 110 and a WTRU 105. Internal messaging is performed with service primitives newly introduced by the present invention. Using process 400, an AP 110 may obtain TPC data from the WTRU 105 and store the TPO data in the MIB 160 of the AP 110.

[00451 TheAP 110 includes an SME 450 and an MLME 455. The WTRU 105 includes a MLME 465 and an SME 470. Referring to Figure 4, te SM 450 -8- COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:57 PM WATERMARK 61398196010 16/32 00 0 of the AP 110 determines whether or not to adapt transmit power level of the CNq WTRU 105 (step 402). In step 404, the SMhE 450 transmits a first message S(MLM-TPCADAPT.req) to the MLME 455 of the AP 110 requesting TPO Sinformation if the 1ME 450 determines in step 402 to adapt the transmit power O level of the WTRU 105. In step 406, the MMIE 455 transmits a second message (MLME-TPCADAPTcfm) to the SME 450 confirming receipt ofthe firstmessage n C(MLME-TPCADAPTreq). In step 408, the MILME 455 transmits a third message (TPO request frame) to the target WTRU 105 requesting TPC information, and 0 the MLME 465 of the target WTRU 105 receives the third message (TPC request Ci 00 frame). In step 410, the MILME 466 performs one or more physical monasurements to determine TPC parameters such as WTRU transmit power C level, WTU receive power level, link margin transmit power minus receive power), PSNI, RSSI, ROPI, or the like. The results of the measurements to determine TPC parameters may be forwarded to the SME 470 and stored in the MIB 175 of theWTRU 105, In step 412, the MLIME 465 ofthe target WTRU 105 transmits a forth signal (TFO report frame) including the requested TPO infbrmation to the AP 110. In step 414, the MLME 465 transmits a fifth message (MLME-TPOREPORT.ind) including the requested TPC information to the SME 450. The SME 450 may store the requested TPO informationin the MIB 160 of theAP 110, such that the TPO information is available to external RRM entitles.

The TPO request is completed in step 416.

[0046] Figure 5 is a flowchart of an exemplary process 500 including method steps for transferring TPO information between network entities in accordance with the present invention.

[0047] As shown in Figure 1A, process 500 is implemented in a wireless communication system 100 including at least one AP 110 and at least WTRU 105. As show n Figure 1B, theAP 110 includes a first management entity 150 and a second management entity 155. Furthennore, as shown in Figure 1B, the WTRU 105 includes a third management entity 165 and a fourth management entity 170.

[0048] Referring to Figure 5, the firstmanagement entity 150 in anAP 110 determines whether or not to adapt the transmit power level of the WTRU 105 -9- COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09 09-Jan-2008 03:58 PM WATERMARK 61398196010 17/32 O (step 505). In step 510, the first management entity 150 transmits a first Ci message to the second management entity 155 in the AP 110 requesting TPC Sinformation if the first management entity 150 determines to adapt the transmit power levelof the WTU 105 in step 505, In step 515, the second management o entity 155 transmits a second message to the first management entity 150 confirming receipt of the first message. In step 520, the second management Vt entity 155 transmits a third message including a request for TPC information to the WTRU105. In step 525, the third management entity 165 in the TRU 105 0 0 receives the third message. In step 680, the third management entity 165 OO performs one or more physical measurements to determine TPO parameters. The third management entity 165 may transfer the results of the physical Smeasurements to th.fourth management entity 170, which in turn may store the results of the physical measurements in the MIB 175. In step 535, the third management entity 165 transmits a forthmessage including the requested TPO information to the AP 110. In step 540, the second management entity 155 in the AP 110 receives the fourth message. In step 545, the secondmanagementntntity 155 transmits a fifth message including the requested TPO information to the first manageiment entity. The requested TPC information may then be stored in the MIB 160 of the AP 110.

[0049] While this invention has been particularly shown and described with reference to preferred embodiments, it willhe understood by those sklled in the art that various changes in form and details may be made therein without departing from the scope of the invention described hereinabove.

COMS ID No: ARCS-174599 Received by IP Australia: Time 16:04 Date 2008-01-09

Claims (17)

1. 2. The method of claim 1 further including: communicating a second message confirming receipt of the first message from the second management entity to the first management entity.
2. 3. The method of claim 1, wherein the measurement report includes an absolute value of the requested measurement.
3. 4. The method of claim 1, wherein the measurement report includes a statistical average of the requested measurement. The method of claim 1, wherein the measurement report includes a histogram of values of the parameter over time.
4. 6. The method of claim 1, wherein the parameter includes a signal-to-noise indicator.
5. 7. The method of claim 1, wherein the parameter includes a received channel power indicator (RCPI).
6. 8. The method of claim 1, wherein the parameter includes a link O measurement.
7. 9. The method of claim 1, wherein the parameter includes a clear channel 0assessment (CCA) busy fraction. S 5 10. The method of claim 1 wherein the request for the measurement is a Srequest for a stored measurement of the parameter. (co S11. The method of claim 1 wherein the request for the measurement is a 0 c request to perform a new measurement of the parameter.
8. 12. A wireless transmit receive unit (WTRU) including: a first management entity configured to communicate a first message; a second management entity configured to: receive the communicated first message; transmit a measurement request including a request for a measurement of a parameter, in response to the first message, receive a measurement report containing the requested measurement of the parameter, and a management information base configured to store the requested measurement of the parameter.
9. 13. The WTRU of claim 12 wherein the second management entity is further configured to: communicate a second message confirming receipt of the first message from the second management entity to the first management entity.
10. 14. The WTRU of claim 12, wherein the measurement report includes an absolute value of the requested measurement.
11. 15. The WTRU of claim 12, wherein the measurement report includes a statistical average of the requested measurement. 13 O 16. The WTRU of claim 12, wherein the measurement report includes a histogram of values of the parameter over time.
12. 17. The WTRU of claim 12, wherein the parameter includes a signal-to-noise 0indicator. C 5 18. The WTRU of claim 12, wherein the parameter includes a received Schannel power indicator (RCPI). oO
13. 19. The WTRU of claim 12, wherein the parameter includes a link cmeasurement. The WTRU of claim 12, wherein the parameter includes a clear channel assessment (CCA) busy fraction.
14. 21. The WTRU of claim 12 wherein the request for a measurement is a request for a stored measurement of a parameter.
15. 22. The WTRU of claim 12 wherein the request for a measurement is a request to perform a new measurement of a parameter.
16. 23. The method of claim 1 substantially as hereinbefore described with reference to the accompanying figures.
17. 24. The WTRU of claim 12 substantially as hereinbefore described with reference to the accompanying figures. INTERDIGITAL TECHNOLOGY CORPORATION WATERMARK PATENT TRADE MARK ATTORNEYS P26578AU01