Method and apparatus for measuring co-channel interference

• US 6,256,486 B1
• Filed: 03/02/2000
• Issued: 07/03/2001
• Est. Priority Date: 09/09/1999
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Barany, Peter A., Bontu, Chandra Sekhar, Rahman, Shamim Akbar
• Primary Examiner(s): Chang, Vivian
• Assistant Examiner(s): Lee, John J
• Application Number:
  US09/517,381
• Time in Patent Office: 488 Days
• Field of Search: 455/450, 455/452, 455/423, 455/424, 455/62, 455/63, 455/67.3, 455/296, 370/347, 370/18, 370/350, 370/503, 379/60, 375/346, 375/362
• US Class Current: 455/296
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

A mobile communication system includes cell segments each associated with a base station. The base station includes transceivers capable of communicating over two sets of carriers. A first set of carriers carry circuit-switched traffic, while the second set of carriers carry packet-switched data. Co-channel interference measurements are made by mobile units or by a serving base station in each cell segment during communications of active bursts of traffic or control signaling. Such bursts may include a training sequence that is used by the measuring device to recreate a burst without interference contributions. Co-channel interference is then determined based on the recreated bursts and the received bursts. Multiple interference values may be derived and applied to an averaging filter to calculate the final interference contribution value.

Claims

1. A method of measuring co-channel interference in a cell segment of a mobile communications system in which a desired signal of the cell segment is synchronized in time with a plurality of interfering signals of other cells, comprising:

waiting during a time period in which the desired signal and the plurality of interfering signals are all inactive;

receiving a burst on a carrier transmitted by a device in the cell segment during a time period in which the desired signal and the plurality of interfering signals are active, wherein the desired signal includes a transmitted copy of a training sequence;

constructing a representation of the desired signal based upon a stored copy of a training sequence code; and

measuring co-channel interference in the cell segment based upon the representation of the desired signal, the transmitted copy of the training sequence of the burst and other components of the burst.

2. The method of claim 1, wherein measuring the co-channel interference includes subtracting the representation of the desired signal from the burst.

3. The method of claim 1, wherein receiving the burst includes a mobile unit receiving the burst from a serving base station.

4. The method of claim 1, wherein receiving the burst includes a serving base station receiving the burst from a mobile unit in the cell segment.

5. The method of claim 1, wherein receiving the burst includes receiving a burst containing both the training sequence and data.

6. The method of claim 5, wherein receiving the burst includes receiving a traffic burst.

7. The method of claim 5, wherein receiving the burst includes receiving a packet associated control channel burst.

8. The method of claim 1, further comprising locally storing the training sequence code, wherein measuring the co-channel interference is based on the local copy of the training sequence code.

9. The method of claim 8, wherein constructing a representation of the desired signal further comprises recreating a version of a transmitted burst using the local copy of the training sequence code.

10. The method of claim 9, wherein measuring the co-channel interference includes comparing the received burst and the recreated version of the transmitted burst.

11. A method of determining co-channel interference in a mobile communications system in which a desired signal of a cell is time synchronized with a plurality of interfering signals of other cells, comprising:

waiting during a time period in which the desired signal and the plurality of interfering signals are all inactive;

receiving a burst containing a training sequence during a time period in which the desired signal and the plurality of interfering signals are active, wherein the burst includes interference caused by the plurality of interfering signals of other cells;

recreating a copy of the burst without interference contribution using a local copy of a training sequence code; and

deriving an interference contribution based on the received burst and the recreated copy of the burst.

12. The method of claim 11, wherein deriving the interference contribution is performed at least in part during the training sequence of the received burst.

13. The method of claim 11, wherein receiving the burst includes receiving the burst from a serving base station.

14. The method of claim 13, wherein recreating the copy of the burst includes using the local copy of the training sequence code of the serving base station.

15. The method of claim 11, further comprising using the first N symbols of the training sequence to estimate an equivalent channel response, wherein recreating the copy of the burst is further based on the equivalent channel response.

16. The method of claim 15, wherein deriving the interference contribution is performed for the last M symbols of the training sequence.

17. The method of claim 16, wherein deriving the interference contribution is performed by scanning the training sequence both from left to right and right to left to obtain interference contributions for the first N symbols and the last M symbols.

18. An apparatus for use in a mobile communications system having plural cell segments in which a desired signal of a cell segment and a plurality of interfering signals of other cell segments are time synchronized, the apparatus comprising:

a receiver that waits during a time period in which the desired signal and the plurality of interfering signals are all inactive and that receives a burst containing a training sequence during a time period in which the desired signal and the plurality of interfering signals are active;

a storage device containing a copy of a training sequence code of a serving base station; and

a controller adapted to estimate co-channel interference based on the copy of the training sequence code contained in the storage device and the burst.

19. The apparatus of claim 18, further comprising a mobile unit containing the receiver, storage device, and controller.

20. The apparatus of claim 18, further comprising a base station containing the receiver, storage device, and controller.

21. The apparatus of claim 18, wherein the burst includes a packet data traffic channel burst.

22. The apparatus of claim 18, wherein the burst includes a packet associated control channel burst.

23. The apparatus of claim 18, wherein the burst is according to an Enhanced GPRS Compact protocol.

24. An article including one or more machine-readable storage media containing instructions for determining co-channel interference in a mobile communications system having a plurality of cell segments in which a desired signal of a cell segment and a plurality of interfering signals of other cells are time synchronized, the instructions when executed causing a system to:

wait during a time period in which the desired signal and the plurality of interfering signals are all inactive;

receive a burst on a carrier transmitted by a device in the cell segment during a time period in which the desired signal and the plurality of interfering signals are active, wherein the desired signal includes a transmitted copy of the training sequence;

derive a first signal strength value based on a stored training sequence code of a first cell segment;

measure from the burst a second signal strength value contributed by a group of cell segments including the first cell segment; and

determine the co-channel interference based on the first signal strength value and the second signal strength value.

25. The article of claim 24, wherein the instructions causing the system to measure the second signal strength value includes causing the system to measure the signal strength value contributed by a group of cell segments having predetermined training sequence codes.

26. The method of claim 24, wherein the instructions causing the system to measure the second signal strength value includes causing the system to measure the signal strength value contributed by a group of synchronized cell segments.

27. An apparatus for determining co-channel interference in a mobile communications system having a plurality of cell segments in which a desired signal of a cell segment and a plurality of interfering signals of other cells are time synchronized, comprising:

means for waiting during a time period in which the desired signal and the plurality of interfering signals are all inactive;

means for receiving a burst on a carrier transmitted by a device in the cell segment during a time period in which the desired signal and the plurality of interfering signals are active, wherein the desired signal includes a transmitted copy of the training sequence;

means for constructing a representation of the desired signal based upon a stored copy of the training sequence; and

means for measuring co-channel interference in the cell segment by extracting the representation of the desired signal from the burst and considering a remaining portion of the burst.

28. The apparatus of claim 27, wherein measuring the co-channel interference includes subtracting the representation of the desired signal from the burst.

29. A mobile unit for use in a mobile communications system having time synchronized base stations in which a desired signal of a serving base station is and a plurality of interfering signals transmitted by other base stations are time synchronized, comprising:

an interface that waits during a time period in which the desired signal and the plurality of interfering signals are all inactive and that receives a burst from the serving base station containing a training sequence during a time period in which the desired signal and the plurality of interfering signals are active;

a storage device containing a copy of a training sequence code of a serving base station; and

a controller adapted to determine co-channel interference based on the received burst and the copy of the training sequence code.