Co-Sequence Interference Detection and Treatment

• US 20080274727A1
• Filed: 06/18/2004
• Published: 11/06/2008
• Est. Priority Date: 06/18/2004
• Status: Active Grant

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Olsson, Magnus, Hui, Dennis, Axnas, Johan
• Granted Patent: US 8,023,938 B2
• Time in Patent Office: Days
• US Class Current: 455/423
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 25/03178 Arrangements involving sequence estimation techniques
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry

Abstract

Signal properties of a signal section (106) comprising a training sequence are compared with corresponding signal properties of other signal sections (108, 110). At a too large discrepancy, co-sequence interference is concluded to be present. The used signal property can preferably be a signal-to-noise ratio measure or a signal statistics measure. If the existence of co-sequence interference (102) is concluded, measures can be taken to avoid such interference and to mitigate the effects of the interference. A method for mitigating effects of co-sequence interference in channel estimation comprises a joint detection and estimation procedure performed under constrictions assuming presence of co-sequence interference.

Claims

1. Method in communication system, comprising the steps of:

receiving a signal, comprising a first signal section involving a training sequence, and a second signal section;

evaluating at least a part of the first signal section for determining a first value of a signal property measure of the first signal section;

evaluating at least a part of the second signal section for determining a second value for the signal property measure of the second signal section; and

detecting an existence of co-sequence interference in the signal based on a comparison between the first and second values.

2. Method according to claim 1, wherein the signal property measure is a signal-to-noise ratio estimate.

3. Method according to claim 1, wherein the signal property measure is a measure of signal statistics.

4. Method according to claim 3, wherein the signal property measure is an autocorrelation function.

5. Method according to claim 1, wherein existence of co-sequence interference is detected if an absolute value of a difference between the first and second values is larger than a predetermined third value.

6. Method according to claim 1, wherein existence of co-sequence interference is detected if a ratio between an absolute value of a difference between the first and second values, and the first value, is larger than a predetermined third value.

7. Method according to claim 1, further comprising a step of initiating a change of training sequence and/or radio resource.

8. Method according to claim 1, further comprising a step of mitigating effects of co-sequence interference in the signal.

9. Method according to claim 8, wherein the step of mitigating comprises the step of excluding the signal from being used in procedures using time averaging of signals.

10. Method according to claim 9, wherein the procedures using time averaging of signals comprise beam selection procedures in fixed multibeam adaptive antennas.

11. Method according to claim 8, wherein the step of mitigating comprises the step of refraining to use the signal in procedures using signal power measures.

12. Method according to claim 8, further comprising a step of determining a signal power ratio between true signal and co-sequence interference for the signal in the first signal section, and compensating apparent signal power of the first signal section using the determined signal power ratio.

13. Method according to claim 11, wherein the procedures using signal power measures comprise link adaptation procedures.

14. Method according to claim 8, further comprising a step of:

performing a joint detection and channel estimation procedure assuming the presence of co-sequence interference.

15. Method according to claim 14, comprising the further step of:

identifying a channel response for the desired signal from two or more estimated channel responses.

16. Method according to claim 14, wherein a channel estimation and detection procedure is performed on both the first and second signal sections, whereby a difference in appearing channel responses between the signal sections is interpreted as the desired and interfering signals having different values.

17. Method according to claim 14, wherein the step of performing a joint detection and channel estimation procedure comprises per-survivor channel tracking, whereby additional constraints are imposed by assuming the presence of co-sequence interference.

18. Method according to claim 17, wherein the additional constraints are introduced as bias to branch metrics.

19. Method according to claim 1, further comprising a step of refraining from employing co-channel interference cancellation if co-sequence interference is determined to exist.

20. Method according to claim 1, wherein the signal is a radio signal.

21. Method according to claim 1, wherein the signal is a signal received over cable or fibre.

22. Method in communication system, comprising the steps of:

receiving a signal, comprising a first signal section involving a training sequence, and a second signal section;

determining if co-sequence interference is present in the signal;

performing a joint detection and channel estimation procedure assuming the presence of the co-sequence interference.

23. Method according to claim 22, comprising the further step of:

identifying a channel response for the desired signal from two or more estimated channel responses.

24. Method according to claim 22, wherein the step of performing a joint detection and channel estimation procedure comprises per-survivor channel tracking, whereby additional constraints are imposed by assuming the presence of co-sequence interference.

25. Method according to claim 24, wherein the additional constraints are introduced as bias to branch metrics.

26. Receiver device, comprising:

receiver means for a signal comprising a first signal section involving a training sequence, and a second signal section;

means for evaluating at least a part of the first signal section for determining a first value of a signal property measure of the first signal section;

means for evaluating at least a part of the second signal section for determining a second value for the signal property measure of the second signal section; and

means for detecting an existence of co-sequence interference in the signal based on a comparison between the first and second values.

27. Receiver device according to claim 26, further comprising means for initiating a change of training sequence and/or radio resource.

28. Receiver device according to claim 26, further comprising means for mitigating effects of co-sequence interference in the signal.

29. Mobile terminal comprising a receiver device, said receiver device in turn comprising:

receiver means for a signal comprising a first signal section involving a training sequence, and a second signal section;

means for evaluating at least a part of the first signal section for determining a first value of a signal property measure of the first signal section;

means for evaluating at least a part of the second signal section for determining a second value for the signal property measure of the second signal section; and

means for detecting an existence of co-sequence interference in the signal based on a comparison between the first and second values.

30. Base station in a mobile communications system comprising a receiver device, said receiver device in turn comprising:

receiver means for a signal comprising a first signal section involving a training sequence, and a second signal section;

means for evaluating at least a part of the first signal section for determining a first value of a signal property measure of the first signal section;

means for evaluating at least a part of the second signal section for determining a second value for the signal property measure of the second signal section; and

means for detecting an existence of co-sequence interference in the signal based on a comparison between the first and second values.