HK1174470A - A method for use by wtru to exchange measurements in a wireless communication and wtru - Google Patents

Description

Method for exchanging measurements in wireless communication used by WTRU and WTRU

The present application is a divisional application of the chinese patent application having an application number of 200480019512.7, filed on 2004 as 7/15, entitled "method and apparatus for storing mobile station physical measurements and mac performance statistics in an ap management information base".

Technical Field

The present invention relates to wireless communication systems. More particularly, the present invention relates to a method and system for communicating Transmit Power Control (TPC) information between a wireless transmit/receive unit (WTRU) and an Access Point (AP).

Background

Wireless Local Area Networks (WLANs) have become more popular due to their convenience and flexibility. As new applications for such networks are developing, their popularity is expected to increase even more.

The Institute of Electronic and Electronics Engineers (IEEE) working group has defined an IEEE802.11 baseline (baseline) standard with extensions intended to provide higher data rates and other network capacities. In the IEEE802.11 standard, a network entity includes a Management Information Base (MIB). The MIB may be a medium access control layer (MAC) layer MIB or a Physical (PHY) layer MIB. The data entities in the MIB table use the IEEE802.11 standard.

Network Management Entities (NMEs) connected to the WLAN communicate with each other by sending frames. The 802.11 standard defines three types of MAC frames: 1) a data frame; 2) a control frame; and 3) management frames. Each of these frames also has a subtype. For example, action frames are a subtype of management frames. Action frames are further defined by categories. Currently, the definition of action frame categories is as follows: 0-spectrum management; 1-quality of service management; 2-direct link protocol; and 3-radio management.

A service primitive (service private) is an internal signaling message used by entities between layers or protocols to exchange standardized message content, for example between a station management entity (SEM) and a MAC Layer Management Entity (MLME). Although this standard does not specify a particular format for the message, this standard specifies the content. Service primitives are typically used to initiate, confirm, or report a specific action, such as by sending a specific frame from one WTRU to another for management purposes.

According to the IEEE802.11 standard, SMEs are incorporated into WTRUs in order to provide correct MAC operation. This SME is a layer-independent entity that can be considered to be located in a separate management plane or "close to the side". Thus, the SME can be considered to be responsible for this function when collecting layer-specific states from different layer management entities, and likewise set the values of layer-specific parameters. Such SMEs typically perform this function and implement standard management protocols instead of a general system management entity.

In addition, in accordance with the IEEE802.11 standard, the WTRU includes configuration settings in the MIB that control its behavior. It is important for the AP to be able to know the configuration of each WTRU in order to interrupt the behavior of this WTRU and improve performance in the context of WLAN Radio Resource Management (RRM). For example, the WTRU keeps track of data frames in its MIB that were successfully received but could not be decoded. This is important information for the AP to provide the WTRU with a minimum quality of service level.

RRM is one of the most important forms of WLAN management. WLANs can achieve considerable performance enhancement by performing RRM, including in-band (in-band) interference mitigation and frequency reuse. For efficient RRM, the NME needs to retrieve WTRU-specific TPC related information. A problem with the MIB data structures used in common wireless systems is that the WTRU's TPC information is not stored in the MIB of the AP.

Interference mitigation is a typical technique used in wireless communication systems to avoid interference with other users in nearby areas by minimizing the amount of transmit power. The IEEE802.11 h standard uses BEACON (BEACON) and PROBE RESPONSE (PROBE RESPONSE) frames to define maximum allowed transmit power messaging, and TPC REQUEST (TPC REQUEST) and TPC report (TPCREPORT) frames to define messaging to obtain immediate transmit power and link margin (linkmargin). The AP broadcasts a BEACON (BEACON) frame or responds with a PROBE RESPONSE (PROBE RESPONSE) frame. The beacon frame includes a country field (country field), a power limit field, a transmission power field, and a link margin field. The country field contains the maximum regulated power level. The power limit field contains an offset value compared to the maximum adjusted power level. The transmit power field indicates a transmit power used to transmit a TPC REQUEST (TPC REQUEST) frame. The link margin field is set to 0 in the BEACON (BEACON) and PROBE RESPONSE (PROBE RESPONSE) frames.

The WTRU's physical measurement data or request/report messaging and re-retrieval of MAC performance statistics (e.g., transmit/receive power level and link margin in basic service set (BBS)) are key parameters to support interference mitigation and RRM. However, these entity measurements or MAC performance statistics are not transferred from the L1 PHY or L2 MAC protocol entities to the SME used as an interface to the external WLAN RRM entity. This SME typically contains interfacing software to read/write into the MIBS. For example, upon receiving an instruction from a Simple Network Management Protocol (SNMP), a read of a particular MIB entity is reported back to the SNMP.

Currently, WLANs typically transmit at a much higher power level than is needed. Using TPC, the transmit power may be adjusted to a minimum level while still ensuring desired signal reception, but without creating more interference than is desired to other WTRUs. It is also possible to perform efficient load control and BSS range adjustment. Range adjustment, load balancing, and a maximum cell radius are determined by the transmit power of the AP and the receiver sensitivity of the WTRU. If the transmit power is not properly controlled, the WTRU at the cell edge loses connection to the AP and will be forced to re-associate with a neighboring AP. Thus, proper power control enables efficient load control and range adjustment.

Disclosure of Invention

The present invention is a wireless communication system and method for communicating TPC information between a WTRU and an AP. The AP comprises a first management entity and a second management entity. The WTRU includes a third management entity. A first management entity in the AP determines whether to use the transmit power level of the WTRU. The first management entity transmits a first message requesting TPC information to a second management entity in the AP if the first management entity determines to use the transmit power level of the WTRU. The second management entity may send a message to the first management entity confirming receipt of the first message.

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

The measurements performed by the third management entity may include WTRU transmit power level measurements, link margin measurements, Clear Channel Assessment (CCA), perceived signal-to-noise indication (PSNI) measurements, Received Signal Strength Indication (RSSI) measurements, and Received Channel Power Indication (RCPI) measurements. 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.

The present invention provides a method for use by a wireless transmit/receive unit (WTRU) for exchanging measurements in wireless communications, the method comprising: receiving a measurement request from an Access Point (AP), wherein the measurement request comprises a request for measurement of a parameter; and transmitting a measurement report to be stored in a Management Information Base (MIB) of the AP, wherein the measurement report includes the requested measurement of the parameter.

The present invention also provides a wireless transmit/receive unit (WTRU) comprising: a management entity configured to: receiving a measurement request from an Access Point (AP), wherein the measurement request comprises a request for measurement of a parameter; and transmitting a measurement report for storage in a Management Information Base (MIB) of the AP, wherein the measurement report includes the requested measurement of the parameter.

Drawings

A more detailed description of the invention will be obtained from the following description of preferred examples, which are illustrated in the accompanying drawings.

Fig. 1A is a block diagram of a wireless communication system operating in accordance with the present invention;

figure 1B is a detailed block diagram of an AP and WTRU configuration used in the wireless communication system of figure 1A;

figure 2 shows a flow diagram of a communication between a WTRU and an AP for obtaining TPC information in accordance with the present invention;

figure 3 shows a flow diagram for requesting and receiving measurement reports for communication between a WTRU and an AP in accordance with the present invention;

fig. 4 is a signal flow diagram illustrating an exemplary flow for communicating TPC information using service primitives between network management entities in accordance with the present invention, an

Fig. 5 is a flow chart of an exemplary flow of method steps for communicating TPC information between network entities in accordance with the present invention.

Detailed Description

Hereinafter, 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 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 (site controller), or any interfacing device in a wireless environment.

The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements. The present invention uses the WLAN 802.11 standards (802.11 baseline, 802.11a, 802.11b, and 802.11g) and is also applicable to IEEE802.11 e, 802.11h, and 802.16.

The invention is further applicable to Time Division Duplex (TDD), Frequency Division Duplex (FDD), and time division synchronous CDMA (tdscdma), when applied to Universal Mobile Telecommunications System (UMTS), CDMA2000, and CDMA, but may also be applied to other wireless systems.

Features of the present invention may be incorporated into an Integrated Circuit (IC) or be configured in a circuit comprising a plurality of interconnected components.

Fig. 1A is a block diagram of a wireless communication system 100 including a plurality of WTRUs 105, a plurality of APs 110, a Distribution System (DS) 115, an NME 120, and a network 125. The WTRU105 and the AP110 form a respective Basic Service Set (BSS) 130. The BBS 130 and the DS 115 form an Extended Service Set (ESS). The AP110 is connected to the NME 125 via a network 125. The wireless communication system 100 may be a WLAN.

Fig. 1B is a detailed block diagram illustrating the configuration of the AP110 and the WTRU105 used in the wireless communication system 100. The AP110 includes a first management entity 150, a second management entity 155, and a first MIB 160. The WTRU105 includes a third management entity 165, a fourth management entity 170, and a second MIB 175. MIBs 160 and 175 are comprised of one or more storage devices (e.g., counters, registers, or other memory devices) to store configuration parameters, performance metrics, and error indicators.

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

Referring to fig. 1A, an RRM controller (not shown) located in the NME 120 communicates with the AP110 via the network 125 and the DS 115. The AP110 and the WTRU105 communicate wirelessly. The NME 120 sends a message to the AP110 to change the allowed power level in the AP's BSS via a higher layer (second layer or higher) management protocol, such as SNMP or extensible markup language (XML). The NME 120 writes the allowable maximum and minimum values into the MIB160 of the AP 110.

A procedure is implemented in the AP 100 to constantly read the entities in the MIB160 of the AP110 and to use service primitives to send and receive MAC signaling frames. The MAC signaling frames, such as BEACONs (BEACONs) or TPC REQUESTs (TPC REQUESTs), measurement REQUESTs (measurement REQUESTs), etc., communicate with all WTRUs 105 in the cell.

When the AP110 receives signaling frames (e.g., TPC REPORTS (TPCREPORTS), MEASUREMENT REPORTS (MEASUREMENT REPORTS), etc.) from the WTRU105, the AP110 takes the reported MEASUREMENTs and uses service primitives to write the performance MEASUREMENTs into the MIB160 of the AP 110. The NME 120 then reads these MIB entities via the management protocol to learn about the current system performance. The NME 120 controls the transmit power level of the WTRU 105.

This MIB may be a MAC MIB or a PHY MIB. MAC MIB is generally preferred because most RRM units operate on MAC level, which has extremely fast response. The entities in the MIB table should be included in each WTRU table, which is preferred, or in the overall statistics table. By storing these entity data in the MIB of the AP110 so that they are available to external entities, interference levels can be maintained low, resulting in higher system capacity.

Figure 2 illustrates a flow of supporting communication between the WTRU105 and the AP110 to obtain TPC data in accordance with the present invention. Once the AP110 transmits a decision to obtain TPC data from the target WTRU105, the AP110 transmits a TPC request frame 205 to the target WTRU 105. In response to the TPC request frame 205, the WTRU105 performs one or more requested physical measurements and transmits a TPC report frame 210 to the AP 110. The AP110 then stores the TPC data in the MIB160 of the AP110, which is made available to external entities, such as the NME 120.

Referring to fig. 1A and 1B, the process of obtaining TPC data may also be initiated by the NME 120, which in turn triggers the first entity 150 in the AP110 to send a primitive to the second management entity 155, to send a MAC signaling frame to the WTRU105, and so on.

Figure 3 illustrates a process for supporting communications between a WTRU105 and an AP110 for the AP110 to request that the WTRU105 perform one or more measurements and report physical parameters of the particular WTRU105 to the AP 110. Once the AP110 decides to request physical measurement data from the WTRU105, the AP110 sends a measurement request frame 305 to the target WTRU105 to measure and report the specific physical parameters of the target WTRU 105. These measurements may include transmit power, link margin, CCA reports, Received Power Indicator (RPI) histogram (histogram) reports, or any other entity-related measurements. These may be absolute values, statistical mean or histogram values, or values calculated using any type of algorithm or optimization process (optimization routine). After performing the requested measurements, the target WTRU105 compiles measurement data and transmits a measurement report frame 310 to the AP 110. This measurement data is stored in the MIB160 of the AP110, and optionally, in the MIB 175 of the WTRU 105.

The MIB 175 in the WTRU105 stores two different information categories. The first category includes various physical measurements such as signal power, interference level, noise histogram, and the like. The second category is a variety of MAC performance statistics such as CCA busy fraction (busy fraction), average back-off number, error frame counter, etc.

When received entity measurements and MAC performance statistics are stored in the MIB160 of the AP110, they may be used by the entity responsible for RRM. This MIB160 may be a MAC MIB or a PHY MIB. MAC MIB is preferred because RRM messaging is also performed in the MAC layer and is faster than the PHY layer. These entity measurement data may be used externally by storing them within the MIB160 of the AP 110. Thus, efficient load control and BSS range adjustment becomes possible.

Fig. 4 is a signal flow diagram illustrating an exemplary procedure 400 for obtaining TPC information between an AP110 and a WTRU105 using service primitives. Internal messaging is performed with the newly introduced service primitives of the present invention. Using the process 400, the AP110 may obtain TPC data from the WTRU105 and store this TPC data in the MIB160 of the AP 110.

AP110 includes SME450 and MLME 455. The WTRU105 includes MLME465 and SME 470. Referring to fig. 4, the SME450 of the AP110 determines whether to use the transmit power level of the WTRU105 (step 402). In step 404, if the SME450 determines in step 402 to use the transmit power level of the WTRU105, the SME450 transmits a first message (MLME-TPC use. req (MLME-tpcadarp. req)) to the MLME 455 of the AP110 to request TPC information. At step 406, MLME 455 transmits a second message (MLME-TPC use.cfm (MLME-tpcadarp. cfm)) to SME450 to acknowledge receipt of the first message (MLME-TPC use.req). In step 408, the MLME 455 transmits a third message (TPC request frame) to the target WTRU105 to request TPC information, and the MLME465 of the target WTRU105 receives the third message (TPC request frame). At step 410, the MLME465 performs one or more physical measurements to determine TPC parameters, such as WTRU transmit power level, WTRU receive power level, link margin (i.e., transmit power minus receive power), PSNI, RSSI, RCPI, and the like. The measurements that determine the TPC parameters may be forwarded to the SME 470 and stored in the MIB 175 of the WTRU 105. At step 412, the MLME465 of the target WTRU105 transmits a fourth signal (TPC report frame) including the requested TPC information to the AP 110. In step 414, the MLME465 transmits a fifth message ((MLME-TPC report. ind) MLME-tpcreport. ind) including the requested TPC information to the SME 450. The SME450 can store the requested TPC information in the MIB160 of the AP110 so that the TPC information is available to external RRM entities. This TPC request is completed in step 416.

Fig. 5 is a flow diagram of an exemplary process 500 of method steps for communicating TPC information between network entities in accordance with the present invention.

As shown in fig. 1A, the process 500 is implemented in the wireless communication system 100 and includes at least one AP110 and at least one WTRU 105. As shown in fig. 1B, the AP110 includes a first management entity 150 and a second management entity 155. In addition, as shown in fig. 1B, the WTRU105 includes a third management entity 165 and a fourth management entity 170.

Referring to fig. 5, the first management entity 150 in the AP110 determines whether to use the transmit power level of the WTRU105 (step 505). In step 510, if the first management entity 150 determines in step 505 to use the transmit power level of the WTRU105, the first management entity 150 transmits a first message to a second management entity 155 in the AP110 requesting TPC information. In step 515, the second management entity 155 transmits a second message to the first management entity 150 to acknowledge receipt of the first message. The second management entity 155 transmits a third message including a request for TPC information to the WTRU105 at step 520. The third management entity 165 in the WTRU105 receives the third message at step 525. In step 530, the third management entity 165 performs one or more entity measurements to determine TPC parameters. The third management entity 165 may communicate the results of the physical measurements to the fourth management entity 170, which may then store the results of the physical measurements in the MIB 175. The third management entity 165 transmits a fourth message including the requested TPC information to the AP110 at step 535. The second management entity 155 in the AP110 receives the fourth message at step 540. The second management entity 155 transmits a fifth message including the requested TPC information to the first management entity in step 545. The requested TPC information is then stored in the MIB160 of the AP 110.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention described above.

Claims (20)

1. A method for use by a wireless transmit/receive unit (WTRU) for exchanging measurements in wireless communications, the method comprising:

receiving a measurement request from an Access Point (AP), wherein the measurement request comprises a request for measurement of a parameter; and

transmitting a measurement report to be stored in a Management Information Base (MIB) of the AP, wherein the measurement report includes the requested measurement of the parameter.

2. The method of claim 1, wherein the measurement report comprises an absolute value of the requested measurement.

3. The method of claim 1, wherein the measurement report comprises a statistical average of the requested measurements.

4. The method of claim 1, wherein the measurement report comprises a histogram of values of the parameter over time.

5. The method of claim 1, wherein the parameter comprises a signal-to-noise indicator.

6. The method of claim 1, wherein the parameter comprises a Received Channel Power Indicator (RCPI).

7. The method of claim 1, wherein the parameter comprises a link measurement.

8. The method of claim 1, wherein the parameter comprises a Clear Channel Assessment (CCA) busy segment.

9. The method of claim 1, wherein the request for the measurement is a request for a stored measurement of the parameter.

10. The method of claim 1, wherein the request for the measurement is a request to perform a new measurement of the parameter.

11. A wireless transmit/receive unit (WTRU), comprising:

a management entity configured to:

receiving a measurement request from an Access Point (AP), wherein the measurement request comprises a request for measurement of a parameter; and

transmitting a measurement report for storage in a Management Information Base (MIB) of the AP, wherein the measurement report includes the requested measurement of the parameter.

12. The WTRU of claim 11, wherein the measurement report includes an absolute value of the requested measurement.

13. The WTRU of claim 11, wherein the measurement report includes a statistical average of the requested measurements.

14. The WTRU of claim 11, wherein the measurement report includes a histogram of values of the parameter over time.

15. The WTRU of claim 11, wherein the parameter comprises a signal-to-noise indicator.

16. The WTRU of claim 11 wherein the parameter comprises a Received Channel Power Indicator (RCPI).

17. The WTRU of claim 11, wherein the parameter comprises a link measurement.

18. The WTRU of claim 11, wherein the parameter comprises a Clear Channel Assessment (CCA) busy segment.

19. The WTRU of claim 11, wherein the request for measurements is a request for stored measurements of parameters.

20. The WTRU of claim 11, wherein the request for measurements is a request to perform new measurements of parameters.