Reverse link interference cancellation

• US 9,071,344 B2
• Filed: 01/18/2006
• Issued: 06/30/2015
• Est. Priority Date: 08/22/2005
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Smee, John Edward, Hou, Jilei, Padovani, Roberto, Black, Peter John, Easton, Kenneth D.
• Primary Examiner(s): Iqbal, Khawar
• Application Number:
  US11/334,977
• Publication Number:
  US 20070040704A1
• Time in Patent Office: 3,450 Days
• Field of Search: 455/63.1, 455/422, 455/114.2, 455/296, 455/522, 455/631, 455/561, 455/67.13, 370/331, 370/335
• US Class Current: 1/1
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation
• CPC Class Codes: H04W 52/12 Outer and inner loops

Abstract

A method and system for reverse link interference cancellation. One method comprises demodulating and decoding at least one signal sent from at least one access terminal and received by a first base station, sending demodulated, decoded information of the signal to a second base station, reconstructing the signal at the second base station, and subtracting the reconstructed signal from a buffer at the second base station.

Claims

1. A method to reduce interference, the method comprising:

at a first base station, demodulating and decoding a signal sent from at least one access terminal and received by the first base station, wherein the signal comprises an interlace of time-separated subpackets corresponding to a packet;

during a time interval associated with receiving data that is interlaced between the time-separated subpackets, sending, by the first base station, demodulated, decoded information of the signal to a second base station;

reconstructing the signal at the second base station; and

subtracting the reconstructed signal at a buffer of the second base station,

wherein sending the demodulated, decoded information of the signal to the second base station occurs between receiving two subpackets of the interlace,

wherein decoding the signal comprises at least one of sending an acknowledgement signal for a successfully decoded packet and sending a negative acknowledgement signal for a non-successfully decoded packet, and

wherein demodulating and decoding the signal comprises demodulating the time-separated subpackets and decoding packets from subpackets sent from a plurality of access terminals and received by the first base station in a same time frame.

2. The method of claim 1, further comprising receiving at least a portion of the signal from the at least one access terminal at the second base station.

3. The method of claim 1, wherein the second base station is within a communication range of the at least one access terminal.

4. The method of claim 1, wherein the signal comprises at least one of a pilot, an overhead channel and a traffic channel.

5. The method of claim 1, wherein the demodulated, decoded information comprises at least one of decoded data bits, re-encoded data bits, modulated symbols, and modulated/interleaved symbols.

6. The method of claim 1, further comprising using the demodulated, decoded information to estimate channel parameters at the second base station.

7. The method of claim 6, wherein the channel parameters comprise at least one of multipath delays and channel coefficients.

8. The method of claim 6, wherein the channel parameters comprise at least one of amplitude and phase of an orthogonal frequency division multiplexing (OFDM) tone.

9. The method of claim 1, wherein reconstructing the signal at the second base station comprises coding, modulation and filtering.

10. The method of claim 1, wherein reconstructing the signal at the second base station comprises coding, modulation and a Fourier transform.

11. The method of claim 1, wherein sending the demodulated, decoded information to the second base station uses a direct link between the first base station and the second base station.

12. The method of claim 1, wherein sending the demodulated, decoded information to the second base station uses a base station controller in communication with the first base station and with the second base station.

13. The method of claim 1, wherein the signal is a code division multiple access signal.

14. The method of claim 1, wherein the signal is an orthogonal frequency division multiplexing signal.

15. A system for reducing interference, the system comprising:

a first base station comprising;

a receiver configured to demodulate and to decode a signal sent from at least one access terminal, wherein the signal comprises an interlace of time-separated subpackets corresponding to a packet; and

a transmitter configured to send, during a time interval associated with receiving data that is interlaced between the time-separated subpackets, demodulated, decoded information of the signal to a second base station, wherein the transmitter is configured to send the demodulated, decoded information of the signal to the second base station between receiving two subpackets of the interlace; and

wherein the first base station is configured to send an acknowledgement signal for a successfully decoded packet and to send a negative acknowledgement signal for a non-successfully decoded packet,

wherein the receiver is further configured to demodulate the time-separated subpackets and to decode packets from subpackets sent from a plurality of access terminals and received by the first base station in a same time frame, and

wherein the second base station comprises a signal reconstruction unit configured to reconstruct the signal at the second base station and a subtracter configured to subtract the reconstructed signal from a buffer output at the second base station.

16. The system of claim 15, wherein the second base station further comprises a second receiver to receive at least a portion of the signal from the at least one access terminal.

17. The system of claim 15, wherein the second base station is within a communication range of the at least one access terminal.

18. The system of claim 15, wherein the signal comprises at least one of a pilot, an overhead channel and a traffic channel.

19. The system of claim 15, wherein the demodulated, decoded information comprises at least one of decoded data bits, re-encoded data bits, modulated symbols, and modulated/interleaved symbols.

20. The system of claim 15, wherein the second base station is configured to use the demodulated, decoded information to estimate channel parameters.

21. The system of claim 20, wherein the channel parameters comprise at least one of multipath delays and channel coefficients.

22. The system of claim 20, wherein the channel parameters comprise at least one of amplitude and phase of an orthogonal frequency division multiplexing (OFDM) tone.

23. The system of claim 15, wherein reconstructing the signal at the second base station comprises coding, modulation and filtering.

24. The system of claim 15, wherein reconstructing the signal at the second base station comprises coding, modulation and performing a Fourier transform.

25. The system of claim 15, wherein sending the demodulated, decoded information to the second base station uses a direct link between the first base station and the second base station.

26. The system of claim 15, wherein sending the demodulated, decoded information to the second base station uses a base station controller in communication with the first base station and with the second base station.

27. The system of claim 15, wherein the signal is a code division multiple access signal.

28. The system of claim 15, wherein the signal is an orthogonal frequency division multiplexing signal.

29. A system for reducing interference, the system comprising:

a plurality of stationary units configured to receive signals from at least one access terminal and to transmit the signals to a central processor that is external to the plurality of stationary units, wherein the signals comprise an interlace of time-separated subpackets corresponding to a packet; and

the central processor, wherein the central processor comprises a buffer configured to store samples of the signals, wherein the central processor is configured to demodulate and decode the samples that are stored at the buffer, to reconstruct the demodulated, decoded samples to generate reconstructed samples, and to subtract the reconstructed samples from samples stored at the buffer,

wherein particular samples are selected for decoding at the buffer in an order that is based on a probability of decoding the particular samples,

wherein the central processor is further configured to attempt to send an acknowledgement signal for a successfully decoded packet and to send a negative acknowledgement signal for a non-successfully decoded packet, and

wherein demodulating and decoding the samples comprises demodulating the time-separated subpackets and decoding the time-separated subpackets.

30. The system of claim 29, wherein the stationary units are spatially distributed over a geographical area such that each unit receives signals from a cell that is substantially distinct from other cells of other units.

31. The system of claim 29, wherein the signals transmitted by the stationary units to the central processor are modulated, coded signals.

32. The system of claim 29, further comprising one or more optical fibers coupled to the plurality of units and the central processor.

33. The system of claim 29, wherein each of the stationary units comprises an antenna, an amplifier, a filter and a sampler.

34. The system of claim 29, wherein the buffer comprises a plurality of sub-buffers, each sub-buffer being configured to store samples of signals from a specific unit.

35. The system of claim 29, wherein the central processor is configured to combine multipath signals from two or more of the stationary units.

36. The system of claim 29, wherein the central processor is configured to subtract the reconstructed samples from samples received by one of the stationary units that did not receive signals above a power threshold from the at least one access terminal.

37. The system of claim 29, wherein the central processor is configured to perform channel estimation for one of the stationary units that did not receive signals above a power threshold from the at least one access terminal.

38. The system of claim 29, wherein the signals comprise at least one of a pilot, an overhead channel and a traffic channel.

39. The system of claim 29, wherein reconstructing the demodulated, decoded samples at the central processor comprises coding, modulation and filtering.

40. The system of claim 29, wherein reconstructing the demodulated, decoded samples at the central processor comprises coding, modulation and performing a Fourier transform.

41. The system of claim 29, wherein the signals are code division multiple access signals.

42. The system of claim 29, wherein the signals are orthogonal frequency division multiplexing signals.

43. A method to reduce interference, the method comprising:

at a plurality of stationary units, receiving signals transmitted by at least one access terminal and transferring the received signals to a central processor that is external to the plurality of stationary units, wherein the signals comprise an interlace of time-separated subpackets corresponding to a packet;

at the central processor, storing samples of the received signals;

at the central processor, demodulating and decoding the samples, wherein demodulating and decoding the samples comprises demodulating the time-separated subpackets and decoding the time-separated subpackets, wherein decoding the time-separated subpackets includes at least one of sending an acknowledgement signal for a successfully decoded packet and sending a negative acknowledgement signal for a non-successfully decoded packet;

at the central processor, reconstructing the demodulated, decoded samples to generate reconstructed samples; and

at the central processor, subtracting the reconstructed samples from the samples,

wherein the samples are selected for decoding in an order that is based on a probability of decoding the samples.

44. The method of claim 43, wherein the signals transferred by the stationary units to the central processor are modulated, coded signals.

45. The method of claim 43, further comprising combining multipath signals from two or more of the plurality of stationary units.

46. The method of claim 43, further comprising subtracting the reconstructed samples from samples received by one of the stationary units that did not receive signals above a power threshold from the at least one access terminal.

47. The method of claim 43, further comprising performing channel estimation for one of the stationary units that did not receive signals above a power threshold from the at least one access terminal.

48. The method of claim 43, wherein the signals comprise at least one of a pilot, an overhead channel and a traffic channel.

49. The method of claim 43, wherein reconstructing at the central processor comprises coding, modulation and filtering.

50. The method of claim 43, wherein reconstructing at the central processor comprises coding, modulation and performing a Fourier transform.

51. The method of claim 43, wherein the signals are code division multiple access signals.

52. The method of claim 43, wherein the signals are orthogonal frequency division multiplexing signals.

53. A computer-readable non-transitory medium comprising processor-executable instructions to cause at least one processor to:

at a first base station, demodulate and decode a signal sent from at least one access terminal and received by the first base station, wherein the signal comprises an interlace of time-separated subpackets corresponding to a packet;

during a time interval associated with receiving data that is interlaced between the time-separated subpackets, send, by the first base station, demodulated, decoded information of the signal to a second base station;

reconstruct the signal at the second base station; and

subtract the reconstructed signal at a buffer of the second base station,

wherein sending the demodulated, decoded information of the signal to the second base station occurs between receiving two subpackets of the interlace,

wherein decoding the signal comprises at least one of sending an acknowledgement signal for a successfully decoded packet and sending a negative acknowledgement signal for a non-successfully decoded packet, and

wherein demodulating and decoding the signal comprises demodulating the time-separated subpackets and decoding packets from subpackets sent from a plurality of access terminals and received by the first base station in a same time frame.

54. A system comprising:

means for demodulating and decoding, at a first base station, a signal sent from at least one access terminal and received by the first base station, wherein the signal comprises an interlace of time-separated subpackets corresponding to a packet;

means for sending, during a time interval associated with receiving data that is interlaced between the time-separated subpackets, demodulated, decoded information of the signal from the first base station to a second base station;

means for reconstructing the signal at the second base station; and

means for subtracting the reconstructed signal at a buffer of the second base station,

wherein sending the demodulated, decoded information of the signal to the second base station occurs between receiving two subpackets of the interlace,

wherein decoding the signal comprises at least one of sending an acknowledgement signal for a successfully decoded packet and sending a negative acknowledgement signal for a non-successfully decoded packet, and

wherein demodulating and decoding the signal comprises demodulating the time-separated subpackets and decoding packets from subpackets sent from a plurality of access terminals and received by the first base station in a same time frame.