HK1134390A - A wireless transmit/receive unit configured to request and receive measurements - Google Patents

Description

Wireless transmitting/receiving unit configured to request and receive measurements

The present application is a divisional application of the chinese patent application having an application number of 200480012891.7, an application date of 2004, 5/13/2004, and a title of "an access point and a wireless transmission/reception unit for managing a network by measuring an index period".

Technical Field

The present invention relates to a beacon (beacon) measurement request signal and network management used in wireless slotted communications (wireless slotted communications). More particularly, the present invention relates to network management using periodic measurements of parameters such as new beacon received power level or signal quality.

Background

The IEEE802.11 communication protocol allows a user to roam between multiple access points that may operate on the same or separate channels. IEEE802.11 communications typically come in effect via a wireless LAN Access Point (AP), which is typically a single stand-alone unit, but can include a network with multiple APs that provide roaming functionality. To support roaming functionality, each access point typically transmits a beacon signal every 100 ms. The roaming Station (STA) uses this beacon to measure the strength of its existing access point connection. If the STA senses a weak signal, the roaming STA may perform re-association services to connect to the access point transmitting a stronger signal.

IEEE802.11 supports two power modes; activation and Power Saving (PS). The protocols of the underlying network and the hoc network are different. In the infrastructure network, there is an AP that monitors the mode of each mobile station. Stations in active mode are fully powered and can therefore transmit and receive at any time. Conversely, a station in PS mode is only periodically woken up to check for possible incoming packets from the AP. A station always informs its AP when changing modes. The AP periodically transmits beacon frames (beacon frames) separated by a fixed beacon interval. The PS station should monitor these frames. A Traffic Indication Map (TIM) is transmitted within each beacon frame, containing the IDs of PS stations with buffered unicast packets in the AP. The PS station should stay awake for the remaining beacon interval upon receiving its ID. Under the connection period (i.e., DCF), the awakened PS station may send a PS-POLL to the AP to retrieve the buffered packet. While during a contention-free period (i.e., PCF), the PS station waits for the AP to poll it (poll). The AP sends a delivery tim (dtim) in the beacon frame to indicate that there are buffered broadcast packets. The delivery TIMs are separated by a fixed number of beacon intervals. Immediately after the DTIM, the buffered broadcast packet is transmitted.

Because IEEE802.11 assumes that the mobile station is fully connected, the transmission of a beacon frame can be used to synchronize the beacon intervals of all stations. In addition to use in IEEE802.11, beacon signals are generally useful in other WLAN communications as well as wireless communications. Periodic measurements are implemented in a system implementing a third generation partnership project (3GPP) wideband code division multiple access (W-CDMA) system. Such systems use time division duplex mode. To support higher layer functions in the IEEE802.11 standard for efficient network management, several physical parameters for different forms of network management are desirable.

One such parameter is the sensed signal-to-noise indicator (PSNI), the measurement of which provides a quantized, comparative measure of received signal quality between all channels/rates and all physical channels and between all stations. Another parameter is the Received Channel Power Indicator (RCPI) measured at the antenna connector, which is a measure of the received RF power in the selected channel. This RCPI parameter may be a measurement of the PHY sublayer via the received RF power in the channel measured over the PLCP header (preamble) and the entire received frame. RCPI is a monotonically increasing logarithmic function of received power level defined in dBm. An exemplary allowed value for the RCPI parameter may be an 8-bit value ranging from 0 to 220.

In the known method, the measurement of the parameters RCPI and PSNI is performed as a single measurement, which has certain drawbacks. It is desirable to provide improved methods of making measurements of parameters, such as RCPI and PSNI, to produce certain advantages in more efficient network measurements.

Disclosure of Invention

In accordance with the present invention, periodic measurements of new beacon requests are used in order to support roaming and dynamic data rate adjustment and related functions.

In accordance with one aspect of the present invention, there is provided a wireless transmit/receive unit (WTRU) configured to request and receive measurements, the WTRU comprising: a receiver configured to receive a beacon request comprising a mode field, a measurement duration field, a Basic Service Set Identifier (BSSID) field, a channel number field, and a beacon report information field, the beacon report information field comprising a report case element and a threshold element; and a transmitter configured to transmit the beacon report corresponding to the beacon request.

Drawings

Fig. 1 is a diagram of a network architecture in which a WLAN communicates with a wireless transmit/receive unit (WTRU) via one or more access points.

Fig. 2 is a diagram showing the type of measurement or report.

Fig. 3 is a graph of the effect of absolute threshold on data rate selection.

Fig. 4 is a graph showing relative threshold values using a serving AP for handover (handoff).

Fig. 5 is a graph showing the effect of report skew.

Fig. 6 is a graph showing a Received Channel Power Indicator (RCPI) of a serving AP.

Detailed Description

The following wireless transmit/receive units (WTRUs) include, but are not limited to, user equipment, mobile stations, fixed or mobile subscriber units, pagers, or any other type of device capable of operating in a wireless network environment. When referred to below, an access point includes, but is not limited to, a node B, a site controller, an access point, or any other type of interfacing device in a wireless environment.

An "access point" (AP) in a typical IEEE802.11 implementation is a station or device that provides wireless access for devices to establish a wireless connection with a LAN, as well as to establish a portion of a wireless LAN (wlan). If the AP is a fixed device on the WLAN, the AP is a station that transmits and receives data. The AP allows the WTRU to connect to a network as long as the WLAN itself has connectivity to the network.

Network management by performing measurements of parameters such as RCPI and PSNI is performed periodically rather than in a one-time measurement manner. The impact of performing periodic measurements on network performance and the attendant advantages are described in the preferred embodiments. In particular, the beneficial effects of performing periodic measurements on beacon request extensions to support roaming and dynamic data rates are described. Although the present invention is described in the particular context of the standard IEEE802.11, it is contemplated that the present invention may also be applied in other scenarios.

The periodic beacon request is made during a connection between the WTRU and the AP on the WLAN. The measurement request field corresponding to the beacon request contains a measurement duration value and the channel number to which the request applies. This beacon request allows a scan mode that includes an "active scan" mode, a "passive scan" mode, and a "beacon table" mode. In the active scanning mode, a measuring Station (STA) transmits a probe request with a broadcast Service Station Identifier (SSID). The beacon report of the STA in this measurement includes one information element for each STA from which a beacon or probe response is detected, regardless of whether this probe response is triggered by the probe request of the STA in the measurement itself. In passive scan mode, the measuring STA passively receives and replies to a beacon report containing an information element for each STA on a particular channel, from which a beacon or probe response is detected. If the channel under measurement is also the serving channel, the STA performs its normal data traffic operations at the same time. In beacon table mode, a measuring STA returns a beacon report containing the current contents of its beacon table without performing additional measurements. The measurement duration field is set equal to the duration of the requested measurement, expressed in Time Units (TU).

The following are some potential advantages of periodic measurements compared to single measurement methods:

periodic measurements reduce management traffic: a single measurement request generates multiple reports, but only if the reports are relevant.

Absolute threshold crossing (crossing) over PSNI measurements is ideal for triggering data rate changes.

Absolute threshold crossing on RCPI measurement is ideal for a proximity detector of position.

The condition for handover is detected relative to a relative threshold value of the serving AP.

This beacon request also contains a periodicity extension (information field) specifying periodic beacon measurements. The extension field is used to provide parameters for periodic measurements and status reports of the measurements. These fields provide periodic measurements that reduce management traffic so that a single measurement request produces multiple reports. The multiple reports are provided only when considered relevant. Crossing an absolute threshold of a sensed signal to noise indicator (PSIN) can be used as a condition to provide a measurement report. These measurements on PSNI are suitable for triggering data rate changes. Crossing of the absolute threshold of the Received Channel Power Indicator (RCPI) may be used as a condition for providing a measurement report.

This periodic extension is an extra field in the beacon request that is used for periodic beacon measurements. The function of making periodic measurements is a selective function of the APs and therefore an AP that is not capable of periodic beacon measurements will ignore the periodic extension. A beacon report is a request to perform a measurement. A beacon report is a response containing the requested beacon measurements.

Absolute threshold crossing is suitable for use by a proximity detector to determine location and approximate position relative to the AP. The relative threshold with respect to the serving AP is used for the handover detection case.

The measurement request field corresponding to the beacon request is shown in table 1 and contains the measurement duration and the channel number of the requesting application. Extensions (additional information fields) needed to specify periodic measurements and case reporting are also included in table 1. Table 1 generally shows a measurement request field format of a beacon request. The current measurement description indicates the channel number, frequency band, measurement duration, and the number of octets (octets) used for the scan pattern. For comparison, table 1 also shows a periodically extended eight-bit set with respect to Basic Service Set Identifier (BSSID), measurement period, reporting case, threshold/offset, and hysteresis (hysteresis) effects. In particular, the measurement request field corresponding to the beacon request is shown in fig. 1 and contains the measurement duration and channel number used by the request. The response to the beacon request is a beacon report.

TABLE 1 Beacon request

If the AP is unable to perform periodic measurements and therefore cannot recognize the extension, the AP ignores this extension and provides a single measurement and a single report.

In table 1, the channel number indicates the channel number where the requesting STA instructs the receiving STA to report the detected beacon and probe response. In the beacon request, the channel number field indicates the channel number at which the requesting STA instructs the receiving STA to report the detected beacon and probe response. The channel band field in table 1 indicates that the band is a band in which the receiving STA performs measurement. According to table 2 (below), the scan mode field is set to the type of scan. These scanning behaviors are as follows:

in active scanning mode, the measuring STA transmits a probe request with the broadcast SSID. The beacon report of this measurement STA contains one information element for each STA, from which the STA detects a beacon or probe response, regardless of whether this probe response is triggered by the probe request of the measuring STA itself.

In passive scanning mode, the measuring STA passively receives and returns a beacon report containing information elements for each STA on a specific channel, from which it detects a beacon or probe response. If the measurement channel is also the serving channel, the STA simultaneously performs its normal data traffic operations.

In beacon table mode, a measured STA returns a beacon report containing the current contents of its beacon table without performing additional measurements.

The measurement duration field is set equal to the duration of the requested measurement, denoted TU.

Tables 2 and 3 show the channel band definition of the wireless measurement request and the scan pattern definition for the beacon request element.

Table 2-channel band definition for radio measurement request:

name (R)	Channel frequency band
		2.4-GHz band	0
5-GHz band	1

Table 3-scan pattern definition for beacon request elements:

name (R)	Scanning mode
		Passive scanning	0
Active scanning	1
		Beacon meter	2
Retention	3-255

The BSSID indicates the BSSID of the particular AP requested for this measurement. The BSSID specifies which AP to measure when several APs can be detected on a given channel. When the measurements are performed on any AP on this channel, the BSSID is set to the broadcast BSSID. The broadcast BSSID is used when the APBSSID is unknown.

The measurement period indicates whether the measurement is a single measurement event or a periodic measurement that is repeated at each measurement period. This measurement period is divided into two subfields: unit and period. The unit subfield defines a time unit for the period subfield and is composed of 2 MSBs having the following values.

The period subfield consists of 14LSBs and is an unsigned integer representing the repetition time interval of this period measurement. The period subfield value 0 represents that the measurement is not periodic but a single measurement. The period sub-field value 16383(3FFF hex) represents that the measurement is periodic with an unsolicited period measurement period; in this case, the measurements are performed on a best effort basis and are made as frequently as the situation allows.

The reporting situation defines when the measurement results are reported to the requesting STA. This report case value is defined in table 4.

Table 4-report case definition for beacon request element

Description of the situation	Reporting a situation
		Reporting after each measurement	0
Reporting when the RCPI level of the measured AP crosses an absolute threshold with hysteresis upwards	1
		Reporting when the RCPI level of the measured AP crosses down an absolute threshold with hysteresis	2
Reporting when the PSNI level of the measured AP crosses an absolute threshold with hysteresis upwards	3
		Reporting when the PSNI level of the measured AP crosses down an absolute threshold with hysteresis	4
Reporting when the RCPI level of the measured AP crosses upward a threshold defined by an offset (with hysteresis) from the RCPI of the serving AP	5
		Reporting when the RCPI level of the measured AP crosses downward past a threshold defined by an offset (with hysteresis) from the RCPI of the serving AP	6
Reporting when the PSNI level of the measured AP crosses above a threshold defined by an offset (with hysteresis) relative to the PSNI of the serving AP	7
		Reporting when the PSNI level of the measured AP crosses downward past a threshold defined by an offset (with hysteresis) relative to the PSNI of the serving AP	8
When the RCPI level of the measured AP enters and maintains the RCPI level of the measured APWhen the RCPI of the service AP is within the range with the deviation (with hysteresis) of the RCPI relative to the service AP as a boundary, the periodic report (one report per measurement) is started	9
		When the PSNI level of the measured AP comes within and is maintained within a range bounded by the PSNI of the serving AP and the offset (with hysteresis) from the PSNI of the serving AP, periodic reporting (one report per measurement) is started	10
Retention	11-255

The threshold/offset provides a threshold or offset value for condition reporting. The threshold value is an unsigned 8-bit integer having units equivalent to PSNI or RCPI. The offset value is a signed 7-bit integer in the range (-127, + 127).

The hysteresis provides an unsigned 8-bit integer hysteresis value in a unit equivalent to the unit used in the threshold/offset field.

Fig. 1 is a schematic diagram of a network architecture 11 in which one or more WLANs 12, 13 communicate with a WTRU 15 via one or more APs 17-19. In this example it is described that the WLANs 12, 13 are able to establish a network connection 22 either directly or via a Radio Network Controller (RNC) 23.

Fig. 2 is a diagram showing measurement or report types, showing how event detection triggers a report, or triggers periodic reporting. In particular, for comparison, FIG. 2 shows a single reporting scheme for PSNI and RCPI when compared to similar periodic case reports for absolute threshold, serving AP periodic range. Periodic reporting of each trigger event for comparison is also shown. The broadest scenario is measurement 26. As used herein, "measurement" may be a measurement or a report. The measurement 26 may be a single 27 or periodic 28 measurement. The single measurement generates a single report 29 comprising a single report PSNI 30 and a single report RCPI 31. This periodic measurement 28 may generate a situation report 32 or a periodic report 33. The condition report 32 may provide an absolute threshold 34, a serving AP threshold 35, or a serving AP period range 36. The absolute threshold 34 includes an absolute threshold PSNI 37 and an absolute threshold RCPI 38. The serving AP threshold 35 includes a serving AP threshold PSNI 47 and a serving AP threshold RCPI 48. The serving AP cycle range 36 includes a serving AP cycle range PSNI 57 and a serving AP cycle range RCPI 58. The periodic report 33 includes a periodic report PSNI 67 and a periodic report RCPI 68.

Further, single report 31 may be conditionally reported based on absolute threshold 34, which includes absolute threshold PSNI 37 and absolute threshold RCPI 38. Also, the single report 31 may be conditionally reported based on the serving AP threshold 35, which includes the serving AP threshold PSNI 47 and the serving AP threshold RCPI 48. This serving AP period range is not used for the single report 31, but a serving AP period range 36 including a serving AP period range PSNI 57 and a serving AP period range RCPI 58 for periodic measurement reporting may be provided.

The single and periodic measurements 27, 28 are of the measurement type. The single report 31 and the condition report 32 periodically report the absolute threshold 34, the serving AP threshold 35, and the serving AP periodic range 36 triggering events. The results of the measurements are single report PSNI 27, single report RCPI 28, absolute threshold PSNI 37, absolute threshold RCPI38, serving AP threshold PSNI 47, serving AP threshold RCPI 48, serving AP cycle range PSNI 57, serving AP cycle range RCPI 58, periodic report PSNI 67, and periodic report RCPI 68. For case reporting, event detection triggers one or more of these single event reporting outputs or periodic reporting outputs.

Fig. 3 is a graph showing the effect of absolute thresholds on data rate selection and showing the variation in measured quality over time for three different channels having 5.5Mbps, 2.0Mbps, and 1.0Mbps, respectively. At the start of the graph, STA 1 receives a lower PSNI level from the AP, substantially below the absolute threshold, as measured at the STA. This rate is established at 1 Mbps. STA 2 and STA 3 have PSNI levels above the threshold level. As time passes, STA 3 has received a PSNI level that exceeds the second threshold and then drops below the absolute threshold. STA 3 can therefore change to a 5.5Mbps rate as PSNI levels fall, but must fall to a 2Mbps rate and eventually to 1 Mbps. Then when STA 2 has enough PSNI level to change to a 5.5Mbps rate, STA 2 is maintained at 2 Mbps. These changes in PSNI levels can also be used to change APs by selecting APs with higher rates or PSNI levels as long as resources from the AP are available.

Fig. 4 is a graph of relative threshold values using a serving AP for handover. This graph also illustrates the change in measured values versus time for AP 1 and AP 2 that meet at a location that represents a reporting event. The graph shows signals received by the STA from a first AP (serving AP) and a second AP (AP 2). The measurement of the serving AP is reduced by an offset value where PSNI is lower in favor of AP 2. Therefore, the PSNI measurement of the serving AP is artificially lowered by the offset value. This causes early triggering of the handover due to this offset.

Fig. 5 is a graph showing the effect of report bias and showing the relative threshold triggers of APs 1, 2, and 3 presenting report range and when the report terminates. This graph illustrates the ISCP threshold and reporting events for slot ISCP versus time. Both the triggered event and the periodic reporting of the PSNI level represent examples of reduced PSNI levels due to skew. The reporting of the serving AP 3 continues during a peak period of the PSNI reported from the third AP, AP 3, but does not continue when the signal from AP 3 falls below the PSNI offset report relative to the serving AP.

Fig. 6 is a graph showing RCPI levels of a serving AP. The triggering event here is the exceeding of an absolute threshold. This trigger event triggers a report.

Although the features and elements of the present invention are described in the particular embodiments, each feature can be used alone (without the other features and elements of the preferred embodiments) or in various combinations with or without other features and elements of the present invention.

Examples

1. A wireless communication system for transmitting a beacon signal in response to a beacon request by at least one access point, the beacon signal indicating channel, measurement and mode data, wherein the wireless communication system is extended to incorporate additional signal information, the wireless communication system comprising:

at least one extension of the beacon request, the extension providing a measure of signal conditions.

2. The wireless communication system of embodiment 1 wherein the extension includes one of BSSID, measurement period, reporting condition, threshold value, measurement offset and hysteresis.

3. The wireless communication system of embodiment 1 wherein the extension includes one of PSNI and RCPI measurements.

4. The wireless communication system according to embodiment 1, wherein the wireless communication system implements a wireless LAN connection and the beacon signal is provided in the implementation of the LAN connection.

5. The wireless communication system according to embodiment 1, wherein:

the response protocol includes a beacon extension; and is

The beacon extension includes a period subfield that is provided as an unsigned integer representative of a repetition time interval of the periodic measurement.

6. The wireless communication system according to embodiment 1, wherein:

the response protocol includes a beacon extension; and is

The beacon extension includes a period subfield that includes 14LSBs as an unsigned integer representative of a repetition time interval of the periodic measurement, where a period subfield value of 0 indicates a single aperiodic measurement.

7. The wireless communication system of embodiment 1, wherein the beacon request extension includes a period subfield provided as an unsigned integer representative of a repetition time interval of the periodic measurement.

8. The wireless communication system of embodiment 1 wherein the beacon request extension includes a period subfield that includes 14LSBs as unsigned integers representative of a repetition interval of a periodic measurement, wherein a period subfield value of 0 represents a single aperiodic measurement.

9. A method in a Wireless Local Area Network (WLAN) to operate an Access Point (AP) using a beacon signal, the method comprising:

periodic measurements are provided in the beacon signal in response to the beacon request to support one of roaming, dynamic data rate adjustment, and related signal control functions.

10. The method of embodiment 9 wherein the WLAN implements a WLAN connection and the beacon signal is provided in the implementation of the WLAN connection.

11. The method of embodiment 9 wherein the extension comprises one of BSSID, measurement period, reporting case, threshold, measurement offset, and hysteresis.

12. The method of embodiment 9 wherein the extension includes one of PSNI and RCPI measurements.

13. The method of embodiment 9, wherein:

the response protocol includes a beacon extension;

the beacon extension includes a period subfield that is provided as an unsigned integer representative of a repetition time interval of the periodic measurement.

14. The method of embodiment 9, wherein:

the response protocol includes a beacon extension; and is

The beacon extension includes a period subfield that includes 14LSBs as an unsigned integer representative of a repetition time interval of the periodic measurement, where a period subfield value of 0 indicates a single aperiodic measurement.

15. A method as in embodiment 9 wherein the beacon request extension comprises a periodic subfield provided as an unsigned integer representative of a repetition time interval for periodic measurements.

16. A method according to embodiment 9, characterized in that the beacon request extension comprises a period subfield comprising 14LSB as unsigned integer representative of a repetition time interval of the periodic measurement, wherein a period subfield value of 0 represents a single aperiodic measurement.

17. A method of operating a wireless transmit/receive unit (WTRU) in a Wireless Local Area Network (WLAN) including at least one Access Point (AP) and at least one WTRU, the method comprising:

providing a beacon request comprising at least one measurement response;

receiving a beacon signal in response to the request; and

the measurement response is obtained if provided in the beacon signal.

18. The method of embodiment 17 wherein the measurement response comprises one of a measurement supporting roaming, a measurement supporting dynamic data rate adjustment, and a measurement supporting a related signal control function.

19. The method of embodiment 17 wherein the wireless communication system implements a WLAN connection and the beacon signal is provided in the implementation of the WLAN connection.

20. The method of embodiment 17, wherein the beacon request extension comprises one of BSSID, measurement period, reporting case, threshold, measurement offset, and hysteresis.

21. The method of embodiment 17, wherein the beacon request extension comprises one of PSNI and RCPI measurements.

22. The method of embodiment 17, wherein:

the response protocol includes a beacon extension;

the beacon extension includes a period subfield that is provided as an unsigned integer representative of a repetition time interval of the periodic measurement.

23. The method of embodiment 17, wherein:

the response protocol includes a beacon extension; and

the beacon extension includes a period subfield that includes 14LSBs as an unsigned integer representative of a repetition time interval of the periodic measurement, where a period subfield value of 0 indicates a single aperiodic measurement.

24. The method of embodiment 17 wherein the beacon request extension includes a period subfield provided as an unsigned integer representative of a repetition interval of the periodic measurement.

25. According to the method of embodiment 17, the beacon request extension includes a period subfield including 14LSBs as an unsigned integer representative of a repetition time interval of the periodic measurement, where a period subfield value of 0 represents a single aperiodic measurement.

Claims (13)

1. A wireless transmit/receive unit (WTRU) configured to request and receive measurements, the WTRU comprising:

a receiver configured to receive a beacon request comprising a mode field, a measurement duration field, a Basic Service Set Identifier (BSSID) field, a channel number field, and a beacon report information field, the beacon report information field comprising a report case element and a threshold element; and

a transmitter configured to transmit the beacon report corresponding to the beacon request.

2. The WTRU of claim 1, wherein the report case element is an 8-bit integer representing a number used to transmit the beacon report.

3. The WTRU of claim 1, further comprising:

a measurement unit configured to perform measurement, wherein the report case element has a value of 0, and transmit the beacon report after each measurement.

4. The WTRU of claim 1, wherein the report case element has a value of 1 and the beacon report is transmitted in response to a measured Received Channel Power Indicator (RCPI) above a threshold indicated by the threshold element.

5. The WTRU of claim 1, wherein the report case element has a value of 2 and the beacon report is transmitted in response to a measured Received Channel Power Indicator (RCPI) that is below a threshold indicated by the threshold element.

6. The WTRU of claim 1, wherein the reporting situation element has a value of 3 and the beacon report is transmitted if a signal-to-noise indicator (SNI) is greater than a threshold indicated by the threshold element.

7. The WTRU of claim 1, wherein the reporting situation element has a value of 4 and the beacon report is transmitted in response to a signal-to-noise indicator (SNI) being below an absolute threshold with hysteresis.

8. The WTRU of claim 1, wherein the report case element has a value of 5 and the beacon report is transmitted in response to a measured Received Channel Power Indicator (RCPI) that is above a threshold defined by an offset from a RCPI of a serving Access Point (AP).

9. The WTRU of claim 1, wherein the report case element has a value of 6, and the beacon report is transmitted in response to a Received Channel Power Indicator (RCPI) below a threshold defined by an offset from a RCPI of a serving Access Point (AP).

10. The WTRU of claim 1, wherein the reporting situation element has a value of 7 and the beacon report is transmitted in response to a signal-to-noise indicator (SNI) above a threshold defined by an offset of the SNI relative to a signal of a serving Access Point (AP).

11. The WTRU of claim 1, wherein the reporting situation element has a value of 8 and the beacon report is transmitted in response to a signal-to-noise indicator (SNI) below a threshold defined by an offset of the SNI relative to a signal of a serving Access Point (AP).

12. The WTRU of claim 1, wherein the report case element has a value of 9, and the beacon report is transmitted periodically in response to a Received Channel Power Indicator (RCPI) within a range bounded by a serving Access Point (AP) and an offset reference value.

13. The WTRU of claim 1, wherein the reporting case element has a value of 10 and the beacon report is transmitted periodically in response to a signal-to-noise indicator (SNI) of a serving Access Point (AP) within a range bounded by an SNI and an offset reference value.