System and method for measurement report time stamping to ensure reference time

• US 20070002806A1
• Filed: 05/03/2004
• Published: 01/04/2007
• Est. Priority Date: 05/09/2003
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Soomro, Amjad
• Granted Patent: US 7,519,033 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 43/067 using time frame reporting
• CPC Class Codes: H04L 43/106 using time related information in packets, e.g. by adding timestamps
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A system and method is provided that resolves a possible ambiguity in WLAN measurement reports by having a measuring entity include timer values in returned measurement reports. The time a measurement was requested to be performed and the actual time it was done by a measuring entity can be compared by the receiver to ensure that no ambiguities occurred.

Claims

1. A method for creating a measurement report (400) among a plurality of stations (201) in a wireless local area network (WLAN), comprising the steps of:

receiving (301) by a measurement capable station (201) of said plurality of stations (201) a measurement request for at least one measurement report element (500) to be made at a given time;

recording by the measurement capable station (201) said at least one measurement report element (500);

creating by the measurement capable station (201) a measurement report (400) comprising said at least one measurement report element (500) as one of measurement report elements contained therein (405);

respectively time-stamping (404, 504) with an absolute time reference at least one of said at least one recorded measurement report element (500) and said measurement report (400); and

transmitting (308) by the measurement capable station said created measurement report.

2. The method of claim 1, wherein said time-stamping step further comprises the step of setting by the measurement capable station each said absolute time reference to a time synchronization function (TSF) timer value (306).

3. The method of claim 1, further comprising the steps of:

if at least one measurement element has been time-stamped with an absolute time reference (504),

determining by the measurement capable station (201) an earliest said absolute time reference (504) of a measurement report element, and

setting by the measurement capable station (201) said measurement report time-stamp (404) to said determined earliest absolute time reference of a measurement report element.

4. The method of claim 3, wherein said time-stamping step further comprises the step of setting by the measurement capable station (201) each said absolute time to a time synchronization function (TSF) timer value (306).

5. The method of claim 1, wherein said creating step further comprises the step of including in said measurement report a plurality of fields formatted as one of

Dialog Measurement Category Action Token reserved Report Elements 401 402 403 404 405 Octets:

6. The method of claim 5, wherein:

the WLAN is an IEEE 802.11 WLAN;

the Element Id (501) is set to a unique identifier specified by an IEEE 802.11 standard;

each Time Stamp field (404, 504) is a time synchronization function (TSF) timer value (306); and

the combined length of the measurement report elements (405) is less than or equal to the maximum allowed medium access control (MAC) management protocol data unit (MMPDU) size.

7. A method for creating an autonomous measurement report (400) having at least one measurement report element (500), among a plurality of stations (201) in a wireless local area network, comprising the steps of:

recording by a measurement capable station (201) of said plurality of stations (201) at least one pre-determined measurement report element (500);

optionally time-stamping with an absolute time reference by the measurement capable station (201) said at least one recorded measurement report element;

creating by the measurement capable station an autonomous measurement report (400) comprising said at least one measurement report element (500);

optionally time-stamping with an absolute time reference of the earliest time of a measurement report element contained therein said autonomous measurement report (400), and

transmitting (308) by the measurement capable station said autonomous measurement report (400),

wherein, at least one of said autonomous measurement report time-stamp (504) and said at least one measurement report element time-stamp (404) is included in said autonomous measurement report (400).

8. The method of claim 7, wherein each said time-stamping step further comprises the step of setting by the measurement capable station (201) each said absolute time-stamp (404, 504) to a time synchronization function (TSF) timer value.

9. A method for ensuring correctness of a time reference of a requested measurement among a plurality of stations (STAs) (201) in a wireless local area network (WLAN), comprising the steps of:

transmitting (308) by a first station (201) a request for at least one time-stamped measurement report element to be performed at a given time;

receiving (301) by a second station both the measurement request and a corresponding measurement report (400) comprising the requested at least one measurement report element (500) and at least one time-stamp (404, 504) comprising an absolute time reference of when the measurement (507) recorded therein was done;

comparing by the second station (201) the given time of the measurement request with the at least one time-stamp (404, 504) to determine correctness of the time-stamp.

10. The method of claim 9, wherein said receiving step further comprises the step of receiving in said measurement report (400) a plurality of fields formatted as one of

Dialog Measurement Category Action Token reserved Report Elements 401 402 403 404 405 Octets:

11. The method of claim 10, wherein:

the WLAN is an IEEE 802.11 WLAN;

the Element Id (501) is set to a unique identifier set by an IEEE 802.11 standard;

each said Time Stamp (504) is a time synchronization function (TSF) timer value (306); and

the combined length of the measurement report elements is less than or equal to the maximum allowed medium access control (MAC) management protocol data unit (MMPDU) size.

12. The method of claim 10, wherein said receiving (301) step further comprises the step of receiving a measurement report having each said Time Stamp (404, 405) set using a time synchronization function (TSF) timer value (306).

13. An apparatus configured for resource measurement among a plurality of stations in a wireless local area network (WLAN), comprising:

a receiver (301) for receiving an incoming signal;

a measurement acquisition circuit (303) that measures resources of said incoming signal received therein as at least one measurement report element (500);

a timer (306) that provides an absolute time reference;

a control processor (305), coupled to said measurement acquisition circuit (303) and said timer (306) and beginning at a predetermined absolute time, configured to acquire at least one measurement report element of said incoming signal and optionally associate one of (1) an absolute time reference (306) of the start of the first measurement reported (500) within a measurement report (400) as a time-stamp (404) and (2) an absolute time reference (306) of the start of each measurement report element reported therein (507) with a measurement report element time-stamp (504).

14. The apparatus of claim 13, further comprising:

a memory (304), coupled to said control processor (305) to store said obtained measurement report elements (500) and optionally said associated measurement report element time-stamps (504); and

wherein, said control processor (305) is further configured to compare the predetermined absolute time with at least one said absolute time-stamp (404, 504) to determine correctness of said at least one absolute time-stamp (404, 504).

15. The apparatus of claim 14, further comprising a transmitter that transmits a measurement report comprising a plurality of fields formatted as one of

Dialog Measurement Category Action Token reserved Report Elements 401 402 403 404 405 Octets:

16. The apparatus of claim 15, wherein:

the WLAN is an IEEE 802.11 WLAN;

the Element Id (501) is set to a unique identifier specified by an IEEE 802.11 standard;

each said Time-Stamp (404, 504) is a time synchronization function (TSF) timer value (306); and

the combined length of the measurement report elements is less than or equal to the maximum allowed medium access control (MAC) management protocol data unit (MMPDU) size.

17. The apparatus of claim 15, further comprising a receiver (301) for receiving a measurement request comprising at least one measurement request element to be measured and reported as a measurement report element (500) and the predetermined time to start measuring.

18. The apparatus of claim 17, wherein said measurement request is transmitted by a station (201) of said plurality of stations (201).

19. The apparatus of claim 17, wherein said measurement request is transmitted by an access point (200) of said plurality of stations (201).