FLEXIBLE MIMO RESOURCE ALLOCATION THROUGH CROSS-CORRELATION NULLING AND FREQUENCY DOMAIN SEGMENTED RECEIVER PROCESSING

• US 20150280888A1
• Filed: 05/11/2015
• Published: 10/01/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Wi-LAN Labs, Inc. (Wi-LAN Inc.)
• Inventors: Karsi, Murat, Stanwood, Kenneth L., Gell, David
• Granted Patent: US 9,325,483 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0897 using beamforming per multi-path, e.g. to cope with different directions of arrival [DOA] at different multi-paths
• CPC Class Codes: H04J 11/0056 Inter-base station aspects
• CPC Class Codes: H04J 11/0059 Out-of-cell user aspects
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0058 Allocation criteria
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

An access node in a wireless communication network receives a transmission that includes first and second signals. The first and second signals may be layers of a multiple-input multiple-output transmission and may also be from first and second terminal nodes. The access node derives first and second local reference signals from the transmission received using first and second antennas and estimates channel transfer functions associated with the channel through with the transmission is received. Estimating the channel transfer function can include correlating at least a portion of an expected reference signal associated with the first signal with a corresponding portion of the first local reference signal and correlating at least a portion of an expected reference signal associated with the second signal with a corresponding portion of the second local reference signal. The expected reference signal portions used to estimate the channel transfer functions may be non-orthogonal.

Claims

1. An access node, comprising:

a first radio module configured to receive, using a first antenna, a transmission including a first signal and a second signal;

a second radio module configured to receive, using a second antenna, the transmission;

a memory module; and

a processor module coupled to the first and second radio modules and the memory module and configured to;

derive a first local reference signal from the received transmission of the first radio module;

derive a second local reference signal from the received transmission of the second radio module; and

estimate one or more channel transfer functions associated with the received transmission, the estimation of the one or more channel transfer functions including

correlating at least a portion of an expected reference signal associated with the first signal and at least a portion of an expected reference signal associated with the second signal with corresponding portions of the first and second local reference signals,

wherein the at least a portion of the expected reference signal associated with the first signal and the at least a portion of the expected reference signal associated with the second signal are non-orthogonal.

2. The access node of claim 1, wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are partially overlapping in frequency.

3. The access node of claim 1, wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are different sizes.

4. The access node of claim 1, wherein the first signal and the second signal are associated with different layers of a multiple-input multiple-output transmission.

5. The access node of claim 1, wherein the processor is further configured to determine decoded data conveyed in the received transmission using the one or more estimated channel transfer functions.

6. The access node of claim 1, wherein the estimation of the one or more channel transfer functions further includes applying a correction to the channel transfer function, the correction including correlating the at least a portion of the expected reference signal associated with the first signal with a corresponding portion of the second local reference signal, or correlating the at least a portion of the expected reference signal associated with the second signal with a corresponding portion of the first local reference signal.

7. The access node of claim 1, wherein the reference signals are demodulation reference signals.

8. The access node of claim 1, wherein the estimation of the one or more channel transfer functions further includes:

partitioning an aggregate frequency range into frequency range segments, the aggregate frequency range containing frequencies occupied by the first signal or the second signal; and

estimating a channel transfer function for each of the frequency range segments.

9. The access node of claim 8, wherein the frequency range segments are selected based at least in part on frequency selectivity of a channel associated with the received transmission.

10. The access node of claim 8, wherein the frequency range segments are selected based at least in part on frequencies occupied by the first signal and frequencies occupied by the second signal.

11. The access node of claim 8, wherein partitioning the aggregate frequency range includes:

dividing the aggregate frequency range into one or more frequency range sub-bands; and

segmenting the frequency range sub-bands into one or more frequency range segments.

12. The access node of claim 11, wherein dividing the aggregate frequency range into one or more frequency range sub-bands uses predetermined sub-band sizes.

13. The access node of claim 11, wherein dividing the aggregate frequency range into one or more frequency range sub-bands includes:

analyzing a channel associated with the received transmission for frequency selectivity; and

dividing the aggregate frequency range into the one or more frequency range sub-bands based on analyzed frequency selectivity.

14. The access node of claim 11, wherein the frequency range segments include segments of the frequency range sub-bands having unique combinations of first and second signals.

15. A method for receiving communications in a wireless communication system, the method comprising:

receiving, using a first antenna, a transmission that includes a first signal and a second signal;

receiving the transmission using a second antenna;

deriving a first local reference signal from the transmission received using the first antenna; and

deriving a second local reference signal from the transmission received using the second antenna; and

estimating one or more channel transfer functions associated with the received transmission, the estimating including

correlating at least a portion of an expected reference signal associated with the first signal and at least a portion of an expected reference signal associated with the second signal with corresponding portions of the first and second local reference signals,

wherein the at least a portion of the expected reference signal associated with the first signal and the at least a portion of the expected reference signal associated with the second signal are non-orthogonal.

16. The method of claim 15, wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are partially overlapping in frequency.

17. The method of claim 15, wherein the expected reference signal associated with the first signal and the expected reference signal associated with the second signal are different sizes.

18. The method of claim 15, wherein the first signal are the second signal are associated with different layers of a multiple-input multiple-output transmission.

19. The method of claim 15, further comprising determining decoded data conveyed in the received transmission using the one or more estimated channel transfer functions.

20. The method of claim 15, wherein the estimating further includes applying a correction to the channel transfer function, the correction including correlating the at least a portion of the expected reference signal associated with the first signal with a corresponding portion of the second local reference signal, or correlating the at least a portion of the expected reference signal associated with the second signal with a corresponding portion of the first local reference signal.

21. The method of claim 15, wherein the reference signals are demodulation reference signals.

22. The method of claim 15, wherein estimating the one or more channel transfer functions further includes:

partitioning an aggregate frequency range into frequency range segments, the aggregate frequency range containing frequencies occupied by the first signal or the second signal; and

estimating a channel transfer function for each of the frequency range segments.

23. The method of claim 22, wherein the frequency range segments are selected based at least in part on frequency selectivity of a channel associated with the first signal.

24. The method of claim 22, wherein the frequency range segments are selected based at least in part on frequencies occupied by the first signal and frequencies occupied by the second signal.

25. The method of claim 22, wherein partitioning the aggregate frequency range includes:

dividing the aggregate frequency range into one or more frequency range sub-bands; and

segmenting the frequency range sub-bands into one or more frequency range segments.

26. The method of claim 25, wherein dividing the aggregate frequency range into one or more frequency range sub-bands uses predetermined sub-band sizes.

27. The method of claim 25, wherein dividing the aggregate frequency range into one or more frequency range sub-bands includes:

analyzing a channel associated with the first signal for frequency selectivity; and

dividing the aggregate frequency range into the one or more frequency range sub-bands based on analyzed frequency selectivity.

28. The method of claim 25, wherein the frequency range segments include segments of the frequency range sub-bands having unique combinations of first and second signals.

29. A method for partitioning a channel, the method comprising:

dividing an aggregate frequency range into frequency range sub-bands, the aggregate frequency range being a range of frequencies occupied by one or more of a plurality of signals; and

segmenting the frequency range sub-bands into one or more frequency range segments based at least in part on identifying frequencies that are occupied by unique combinations of the plurality of signals.

30. The method of claim 29, wherein dividing the aggregate frequency range into one or more frequency range sub-bands uses predetermined sub-band sizes.

31. The method of claim 29, wherein dividing the aggregate frequency range into one or more frequency range sub-bands includes analyzing a channel associated with the plurality of signals for frequency selectivity.

32. The method of claim 31, wherein analyzing the channel associated with the plurality of signals for frequency selectivity includes generating metrics at frequencies in the aggregate frequency range from transmission data derived from reception of the plurality of signals.

33. The method of claim 32, wherein generating the metrics includes applying one or more envelope detection functions to the transmission data derived from the reception of the plurality of signals.

34. The method of claim 32, wherein analyzing the channel for frequency selectivity further includes:

dividing the aggregate frequency range into frequency range portions having unique combinations of the plurality of signals; and

analyzing portions of the metrics corresponding to the frequency range portions to determine frequency selectivity.

35. The method of claim 34, wherein analyzing the channel for frequency selectivity further includes:

dividing the frequency range portions determined to be frequency selective into frequency range sub-portions; and

analyzing portions of the metrics corresponding to the frequency range sub-portions to determine frequency selectivity.

36. A communication system, comprising:

a first terminal node including a first transmitter configured to transmit a first signal that includes a first expected reference signal;

a second terminal node including a second transmitter configured to transmit a second signal that includes a second expected reference signal, wherein the second expected reference signal is transmitted using frequencies that partially overlap with frequencies used by the first terminal node to transmit the first expected reference signal, or wherein the second expected reference signal and the first expected reference signal are non-orthogonal;

an access node comprising;

a first radio module configured to receive, using a first antenna, a transmission including the first signal and the second signal;

a second radio module configured to receive, using a second antenna, the transmission;

a memory module; and

a processor module coupled to the first and second radio modules and the memory module and configured to;

derive a first local reference signal from the received transmission of the first radio module;

derive a second local reference signal from the received transmission of the second radio module; and

estimate one or more channel transfer functions associated with the received transmission, the estimation of the one or more channel transfer functions including

correlating at least a portion of the first expected reference signal and at least a portion of the second expected reference signal with corresponding portions of the first and second local reference signals,

wherein the at least a portion of the first expected reference signal and the at least a portion of the second expected reference signal are non-orthogonal.