HK1088487B - Access point and wireless transmitting/receiving unit for network management using periodic measurements of indicators - Google Patents

Description

Access point and wireless transmission/reception unit for managing network with periodic measurement of indices

Technical Field

The present invention relates to beacon (beacon) measurement request signals and network management used in wireless slotted communications. More particularly, the present invention relates to network management using periodic parameter measurements, 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 are typically effected via wireless LAN Access Points (APs), which are typically a single stand-alone unit, but may include networks with multiple APs providing 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 the access point association in which it is present. If the STA senses weak signals, the roaming STA may perform re-association services to associate with 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 incoming packets that may come 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 ID of the PS station with buffered unicast packets (unicasting packets) in the AP. The PS station should remain awake for the remaining beacon interval upon receiving its ID. Under the connected 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 transmits a delivery tim (dtim) in a beacon frame to indicate that there are buffered broadcast packets. The delivery TIMs are separated by a fixed number of beacon intervals. Just after the DTIM, the buffered broadcast packets are transmitted.

Because IEEE802.11 assumes that the mobile stations are 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 a time division duplex mode. To support higher layer functions for efficient network management in the IEEE802.11 standard, 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 quantitative and comparative measure of the received signal quality in all channels/rates and in 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 by 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 parameter measurement, 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.

According to one aspect of the present invention, there is provided an Access Point (AP) configured to transmit a beacon request, wherein the beacon request includes a measurement duration of two octets in length, is set equal to the duration of the requested measurement, and is expressed in Time Units (TUs).

In accordance with another aspect of the present invention, there is also provided a wireless transmit/receive unit (WTRU) configured to receive a beacon request, wherein the beacon request includes a measurement duration of two octets in length, set equal to the duration of the requested measurement, and represented by a TU.

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 an absolute threshold on data rate selection.

Fig. 4 is a graph showing relative threshold values of APs in service 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

Hereinafter, a wireless transmit/receive unit (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 network environment. When referring to the following, an access point includes, but is not limited to, a node B, a location 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 wireless connections 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, assuming the WLAN itself has connectivity to the network.

Network management by performing parameter measurements, such as RCPI and PSNI, is a way to perform measurements periodically rather than at once. The impact of performing periodic measurements on network performance and the attendant benefits are described in the preferred embodiment. In particular, the beneficial effects of performing periodic measurements over a beacon request extension to support roaming and dynamic data rates are described. Even though the present invention is described in the context of a particular standard IEEE802.11, the present invention is contemplated to have application in other scenarios as well.

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. The beacon request allows a scan mode, which 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 STA beacon report in this measurement includes one information element for each STA from which a beacon or probe response was detected, regardless of whether this probe response was 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 is performing 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 when 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 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 provide periodic measurements that reduce the amount of management traffic so that a single measurement request produces multiple reports. These multiple reports are only provided when considered relevant. Crossing of the absolute threshold of the sensed signal to noise indicator (PSIN) can be used as a condition for providing 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) can be considered as 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 APs that are not capable of periodic beacon measurements will ignore such periodic extensions. 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 a proximity detector suitable for determining position and proximity relative to an AP. The relative threshold with respect to the serving AP is used to detect the situation for handover (handoff).

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 specification indicates the channel number, frequency band, measurement duration, and number of 8-bit bytes (octets) for the scan mode. For comparison, table 1 also represents a periodically extended 8-bit byte 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 includes the measurement requirements and channel number used by the request. The response to the beacon request is a beacon report.

TABLE 1 Beacon request

Channel number

Frequency band

Duration of measurement

Scanning mode

8 bit 1121

BSSID

Measuring period

Reporting a situation

Threshold/offset

Hysteresis

8 bit 62111

If the AP is unable to perform periodic measurements and therefore cannot recognize these extensions, the AP ignores the extensions 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 back the detected beacon and probe response. In the beacon request, the channel number field indicates the channel number where the requesting STA instructs the receiving STA to report back the detected beacon and probe response. The band field indicates, from table 1, the band in which the receiving STA performs its measurements. The scan mode field is set to the type of scan, according to table 2 (below). 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 an information element for each STA on the specific channel, from which it detects a beacon or probe response. If the measurement channel is also the serving channel, the STA performs its normal data traffic operations at the same time.

In beacon table mode, the 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, denoted TU.

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

Table 2-channel band definition for radio measurement request:

name (R)	Frequency band
		2.4-GHz band	0
5-GHz band	1

Table 3-scan pattern definition for beacon request elements:

name (R)	Frequency band
		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 are detectable on a predetermined channel. When this measurement is performed on any AP on this channel, this BSSID is set to the broadcast BSSID. The broadcast BSSID is used when the AP BSSID 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 periodic measurement period; in this case, the measurements are performed on a best effort basis and are made as frequently as the case may be.

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

Table 4-report case definitions for beacon request elements

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
		When the RCPI level of the measured AP crosses the absolute threshold with hysteresis downwardsGive a report	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
Reports are issued when the RCPI level of the measured AP crosses upward above a threshold defined by an offset (with hysteresis) from the RCPI of the serving AP	5
		Reports are issued 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
Reports are issued when the PSNI level of the measured AP crosses above a threshold defined by an offset (with hysteresis) from the PSNI of the serving AP	7
		Reports are issued when the PSNI level of the measured AP crosses down a threshold defined by an offset (with hysteresis) from the PSNI of the serving AP	8
When the RCPI level of the measured AP comes within and remains within the range encompassed by an offset (with hysteresis) of the RCPI of the serving AP and the RCPI from the serving AP, periodic reporting (one report per measurement) begins	9
		When the PSNI level of the measured AP comes within and is maintained within a range surrounded by an offset (with hysteresis) of the PSNI of the serving AP and the PSNI from the serving AP, periodic reporting (one report per measurement) is started	10
Retention	11-255

The threshold/offset provides a threshold value or offset value to be used by the condition report. The threshold value is an 8-bit integer with an unsigned number equal to PSNI or RCPI units. 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 equal 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 the embodiment illustrated, the WLANs 12, 13 are capable of establishing network connections 22, either directly or via a Radio Network Controller (RNC) 23.

Fig. 2 shows measurement or report types, indicating 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 thresholds, serving AP thresholds, and serving AP periodic ranges. While indicating periodic reports for each trigger event for comparison. 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, an in-service AP threshold 35, or an in-service AP cycle range 36. The absolute boundary value 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 including the serving AP threshold PSNI 47 and the serving AP threshold RCPI 48. This serving AP period range is not used for a single report 31, but a serving AP period range 36 including a serving AP period range PSNI 57 and a serving AP period range RCPI58 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 case 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 periodic range PSNI 57, serving AP periodic range RCPI58, 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 low 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 STA3 have PSNI levels above the threshold level. As time passes, STA3 has received a PSNI level that exceeds the second threshold and then falls below the absolute threshold. STA3 can thus change to a 5.5Mbps rate, but must drop to a 2Mbps rate and eventually 1Mbps, with the PSNI level dropping. STA 2 remains at 2Mbps until later when STA 2 has sufficient PSNI level to change to a 5.5Mbps rate. These changes in PSNI levels may also be used to change the AP by selecting an AP with a higher rate or PSNI level if resources from that AP are available.

Fig. 4 is a graph of relative threshold values using an in-service AP for handover. This graph also illustrates the change in measured values versus time for AP1 and AP2 at a meeting at a location representing 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 reporting drift and showing the relative threshold triggering of APs 1, 2, and 3 presenting reporting range and when reporting terminates. The graph illustrates the ISCP threshold and reporting events for the timeslot ISCP versus time. The triggered event and the periodic reporting of the PSNI level each represent an example of a reduced PSNI level due to the offset. Reporting of the serving AP3 continues during a peak period of the PSNI reported from the third AP, AP3, but does not continue when the signal from AP3 falls below the PSNI offset report from the serving AP.

Fig. 6 is a graph showing RCPI levels of an AP in service. The triggering event here is an absolute threshold value being exceeded. This trigger event triggers a report.

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

The specific embodiment is as follows:

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 status, threshold, 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

the beacon extension includes a period subfield 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

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 used as an unsigned integer representative of a repetition 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 conditions, threshold values, 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 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

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. The method as in embodiment 9, wherein the beacon request extension includes a periodic subfield used as an unsigned integer representative of a repetition interval for periodic measurements.

16. A method as in embodiment 9, wherein the beacon request extension includes a period subfield that includes 14LSBs as an unsigned integer representative of a repetition time interval of a 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

whether the measurement response is obtained in the beacon signal.

18. The method as in embodiment 17, wherein the measurement response comprises one of measurements to support roaming, measurements to support dynamic data rate adjustment, and measurements to support related signal control functions.

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

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

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

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

Claims (73)

1. An access point, characterized by:

the access point is configured to transmit a beacon request, wherein the beacon request includes a measurement duration that is two octets long, is set equal to the duration of the requested measurement, and is expressed in units of time.

2. The access point of claim 1, wherein a measurement request field corresponds to said beacon request.

3. The access point of claim 1, wherein said beacon request includes a channel number of one octet length indicating the channel number to which said measurement request applies.

4. The access point of claim 1, wherein said beacon request includes an octet-long channel band indicating the frequency band to which said measurement request applies.

5. The access point of claim 4 wherein a channel band value of 0 indicates a 2.4GHz frequency band and a channel band value of 1 indicates a 5GHz frequency band.

6. The access point of claim 1 wherein said beacon request includes a scan pattern of one octet length indicating said scan pattern utilized for said measurements.

7. The access point of claim 6, wherein a scan mode value of 0 indicates a passive scan mode, a scan mode value of 1 indicates an active scan mode, and a scan mode value of 2 indicates a beacon table mode.

8. The access point of claim 6 wherein scan pattern values in the range of 3-255 are reserved.

9. The access point of claim 8 wherein the passive scanning mode directs the measuring stations to passively receive on a particular channel and to transmit back a beacon report containing an information element for each station from which a beacon or probe response is detected, wherein the stations are synchronized to perform their normal data traffic operations if the measuring channel is also the serving channel.

10. The access point of claim 7 wherein the active scan mode instructs the measuring stations to transmit a probe request with a broadcast service set identifier and to send back a beacon report containing an information element for each station from which a beacon or probe response is detected, regardless of whether the probe response is triggered by a probe request owned by the measuring station itself.

11. The access point of claim 7 wherein the beacon table mode indicates that the measurement station returns a beacon report including a current content of a beacon table without performing additional measurements.

12. The access point of claim 1, wherein the beacon request includes a basic service set identifier of six octets in length to indicate the basic service set identifier of the particular base station requested by a beacon report.

13. The access point of claim 12 wherein the basic service set identifier is set to a broadcast basic service set identifier when requesting beacon reports for all basic service sets on the channel.

14. The access point of claim 1, wherein the beacon request includes a measurement period of two octets in length to indicate whether the measurement is a single measurement event or a periodic measurement that is repeated every measurement period.

15. The access point of claim 14, wherein the measurement period is divided into a time unit subfield and a period subfield, and the time unit subfield defines a time unit of the period subfield.

16. The access point of claim 15, wherein the periodic subfield comprises a 14-bit unsigned integer representing a repeat interval of the periodic measurement.

17. The access point of claim 16, wherein a value of a periodic subfield value of 0 indicates that the measurement is not a periodic measurement but a single measurement.

18. The access point of claim 15 wherein said time unit subfield contains the 2 most significant bits of said measurement period.

19. The access point of claim 1, wherein the beacon request includes a reporting request of one octet length defining when the measured result is reported to the requesting measuring station.

20. The access point of claim 19, wherein a report case value of 0 indicates that a report is to be sent after each measurement.

21. The access point of claim 19 wherein a reporting condition value of 1 indicates that a report will be issued when the received channel power indicator level of the measured signal crosses an absolute threshold with hysteresis upward.

22. The access point of claim 19 wherein a report case value of 2 indicates that a report will be issued when the received channel power indicator level of the measured signal crosses below an absolute threshold with hysteresis.

23. The access point of claim 19 wherein a reporting condition value of 3 indicates that a report will be issued when the sensed signal-to-noise indicator level of the measured signal crosses an absolute threshold with hysteresis upward.

24. The access point of claim 19 wherein a reporting condition value of 4 indicates that a report will be issued when the sensed signal-to-noise level of the measured signal crosses an absolute threshold having hysteresis downward.

25. The access point of claim 19 wherein a report case value of 5 indicates that a report will be sent when the received channel power indicator level of the measured signal crosses upward above a threshold defined by a hysteresis offset from a serving access point.

26. The access point of claim 19 wherein a reporting condition value of 6 indicates that a report will be sent when the received channel power indicator level of the measured signal crosses downward past a threshold defined by a hysteresis offset from a serving access point.

27. The access point of claim 19 wherein a reporting condition value of 7 indicates that a report will be issued when the sensed signal-to-noise figure level of the measured signal crosses upward above a threshold defined by a hysteresis offset from a serving access point.

28. The access point of claim 19 wherein a reporting condition value of 8 indicates that a report will be issued when the sensed signal-to-noise figure level of the measured signal crosses downward past a threshold defined by a hysteresis offset from a serving access point.

29. The access point of claim 19 wherein a reporting condition value of 9 indicates that a periodic report will begin when the received channel power indicator level of the measured signal enters and remains within a range defined by a hysteresis-induced offset of the received channel power indicator of the serving access point from the received channel power indicator of the serving access point.

30. The access point of claim 19, wherein a reporting condition value of 10 indicates that periodic reporting will begin when a sensed signal-to-noise indicator level of the measured signal enters and remains within a range defined by a delayed version of the sensed signal-to-noise indicator of the serving access point and the sensed signal-to-noise indicator from the serving access point.

31. The access point of claim 19 wherein report case values between 11-255 are retained.

32. The access point of claim 1 wherein the beacon request includes a threshold or offset of one octet length that provides a threshold or offset value to be used by the condition report.

33. The access point of claim 32 wherein the threshold value is an unsigned 8 bit integer having the same units as the sensed signal-to-noise indicator or the received channel power indicator and the offset value is a signed 7 bit integer in the range of [ -127, +127 ].

34. The access point of claim 1, wherein the beacon request includes a hysteresis of one octet length to provide an unsigned 8 bit integer and having a hysteresis value in the same units as used for the threshold or offset field.

35. The access point of claim 1, wherein the access point is configured to receive at least one beacon report transmitted in response to a beacon request.

36. The access point of claim 1, wherein said beacon request is transmitted in a beacon of said access point.

37. A wireless transmit/receive unit, comprising:

the wtru is configured to receive a beacon request, wherein the beacon request includes a measurement duration of two octets in length, is set equal to the duration of the requested measurement, and is expressed in units of time.

38. The wtru of claim 37 wherein the beacon request directs the wtru to take and report measurements of at least one signal condition.

39. The wtru of claim 38, further configured to take and report guided measurements.

40. The wtru of claim 39, further configured to report the guided measurements in at least one beacon report.

41. The wtru of claim 39 wherein a measurement request field corresponds to said beacon request.

42. The WTRU of claim 40 wherein the beacon request includes an octet-long channel number indicating the channel number to which the measurement request applies.

43. The WTRU of claim 40, wherein the beacon request includes an octet-long channel band indicating the frequency band to which the measurement request applies.

44. The wtru of claim 43 wherein a channel band value of 0 indicates a 2.4GHz frequency band and a channel band value of 1 indicates a 5GHz frequency band.

45. The WTRU of claim 40 wherein the beacon request includes a scan pattern of one octet length indicating the scan pattern utilized for the measurement.

46. The WTRU of claim 45 wherein a scan mode value of 0 indicates passive scan mode, a scan mode value of 1 indicates active scan mode, and a scan mode value of 2 indicates beacon table mode.

47. The WTRU of claim 45 wherein scan pattern values in the range of 3-255 are reserved.

48. The wtru of claim 46 wherein the passive scanning mode indicates that the stations under measurement are passively receiving on a particular channel and returning a beacon report containing an information element for each station from which a beacon or probe response was detected, wherein if the channel under measurement is also the serving channel, the stations synchronously complete their normal data traffic operations.

49. The wtru of claim 46 wherein the active scanning mode instructs the measuring stations to transmit probe requests with broadcast service set identifiers and to transmit back a beacon report including an information element for each station from which a beacon or probe response is detected, regardless of whether the probe response is triggered by a probe request owned by the measuring station itself.

50. The wtru of claim 46 wherein the beacon table mode indicates that the measuring station returns a beacon report including a current content of a beacon table without performing additional measurements.

51. The WTRU of claim 40 wherein the beacon request includes a basic service set identifier of six octets in length to indicate the basic service set identifier of the particular base station requested by a beacon report.

52. The WTRU of claim 51 wherein the BSS identifier is set to a broadcasted BSS identifier when a beacon report of all BSSs is requested on the channel.

53. The WTRU of claim 40 wherein the beacon request includes a measurement period of two octets length to indicate whether the measurement is a single measurement event or a periodic measurement that is repeated every measurement period.

54. The wtru of claim 53 wherein the measurement period is divided into a time unit subfield and a period subfield, and the time unit subfield defines a time unit of the period subfield.

55. The wtru of claim 54 wherein the period subfield comprises a 14-bit unsigned integer representing a repetition time interval of the periodic measurement.

56. The wtru of claim 55 wherein a value of the period subfield value of 0 indicates that said measurement is not a periodic measurement but a single measurement.

57. The wtru of claim 54 wherein the time unit subfield contains the 2 most significant bits of the measurement period.

58. The WTRU of claim 40 wherein the beacon request includes a report of one octet length defining when the measured result is reported to the requesting measuring station.

59. The wtru of claim 58 wherein a report situation value of 0 indicates that a report is to be sent after each measurement.

60. The wtru of claim 58 wherein a reporting condition value of 1 indicates that a report will be sent when the received channel power indicator level of the measured signal crosses an absolute threshold with hysteresis upward.

61. The wtru of claim 58 wherein a reporting condition value of 2 indicates that a report will be issued when the received channel power indicator level of the measured signal crosses below an absolute threshold with hysteresis.

62. The wtru of claim 58 wherein a reporting condition value of 3 indicates that a report will be issued when the sensed signal-to-noise level of the measured signal crosses an absolute threshold having hysteresis upward.

63. The wtru of claim 58 wherein a reporting condition value of 4 indicates that a report will be issued when the sensed signal-to-noise level of the measured signal crosses an absolute threshold with hysteresis downward.

64. The WTRU of claim 58 wherein a report condition value of 5 indicates that a report will be sent when the received channel power indicator level of the measured signal crosses upward above a threshold defined by a hysteresis offset from a serving access point.

65. The wtru of claim 58 wherein a reporting condition value of 6 indicates that a report will be sent when the received channel power indicator level of the measured signal crosses downward past a threshold defined by a hysteresis offset from a serving access point.

66. The wtru of claim 58 wherein a reporting condition value of 7 indicates that a report will be issued when the sensed signal-to-noise level of the measured signal crosses upward above a threshold defined by a hysteresis offset from a serving access point.

67. The wtru of claim 58 wherein the report condition value of 8 indicates that a report will be issued when the sensed signal-to-noise level of the measured signal crosses downward past a threshold defined by a hysteresis offset from a serving access point.

68. The wtru of claim 58 wherein the report condition value of 9 indicates that the periodic reporting is to begin when the received channel power indicator level of the measured signal enters and remains within a range defined by the received channel power indicator of the serving access point and an offset from the serving access point with hysteresis.

69. The wtru of claim 58 wherein the reporting condition value of 10 indicates that periodic reporting will begin when the sensed signal to noise figure level of the measured signal enters and remains within a range defined by the sensed signal to noise figure level of the in-service access point and an offset from the in-service access point with hysteresis.

70. The wtru of claim 58 wherein report status values between 11-255 are reserved.

71. The WTRU of claim 40 wherein the beacon request includes an octet length threshold or offset that provides a threshold or offset value to be used for condition reporting.

72. The wtru of claim 71 wherein the threshold value is an unsigned 8 bit integer having the same units as the sensed signal-to-noise indicator or the received channel power indicator and the offset value is a signed 7 bit integer in the range of [ -127, +127 ].

73. The WTRU of claim 40 wherein the beacon request includes a hysteresis of one octet length to provide an unsigned 8 bit integer and has the same unit hysteresis value as used for the threshold or offset field.