DATA RECEPTION WITH INTERFERENCE CANCELLATION IN A RELAY COMMUNICATION NETWORK

• US 20100105317A1
• Filed: 10/23/2008
• Published: 04/29/2010
• Est. Priority Date: 10/23/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Palanki, Ravi, Agrawal, Avneesh
• Granted Patent: US 8,634,769 B2
• Time in Patent Office: Days
• US Class Current: 455/9
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/03171 Arrangements involving maximum a posteriori probability [MAP] detection
• CPC Class Codes: H04L 25/03318 Provision of soft decisions
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/16 Half-duplex systems; Simplex/duplex switching; Transmission of break signals non-automatically inverting the direction of transmission
• CPC Class Codes: H04W 84/047 using dedicated repeater stations

Abstract

Techniques for transmitting and receiving data in a relay communication network are described. Stations in the relay network may be grouped into multiple depths. Packets may be transmitted in a pipelined manner, with stations at progressively higher depth sending transmissions of a packet in successive frames. In an aspect, a station may receive data with interference cancellation. The station may obtain a received signal containing transmissions of a first packet from stations at a first depth and transmissions of a second packet from stations at a second depth. The first and second stations may be downstream and upstream stations, respectively, or may be upstream stations at different depths. The station may estimate and cancel interference due to the transmissions of the first packet from the received signal to obtain an interference canceled signal. The station may then process the interference canceled signal for the second packet.

Claims

1. A method for wireless communication, comprising:

obtaining a received signal comprising at least one transmission of a first packet from at least one first station at a first depth and at least one transmission of a second packet from at least one second station at a second depth in a relay communication network;

estimating and canceling interference due to the at least one transmission of the first packet from the received signal to obtain an interference canceled signal; and

processing the interference canceled signal for the second packet.

2. The method of claim 1, wherein the first and second packets are broadcast by the first and second stations in the relay network.

3. The method of claim 1, wherein the estimating and canceling interference comprises

estimating interference due to the at least one transmission of the first packet based on a decoded first packet and a channel estimate for the at least one first station, and

subtracting the estimated interference from the received signal to obtain the interference canceled signal.

4. The method of claim 1, wherein the estimating and canceling interference comprises

estimating interference due to the at least one transmission of the first packet based on log-likelihood ratio (LLR) information for the first packet, without decoding the first packet, and

subtracting the estimated interference from the received signal to obtain the interference canceled signal.

5. The method of claim 1, wherein the at least one first station comprises at least one downstream station, wherein the at least one second station comprises at least one upstream station, and wherein the received signal is obtained by a relay station at a third depth between the first and second depths.

6. The method of claim 1, wherein the first and second stations comprise upstream stations at different depths, and wherein the received signal is obtained by a station at a third depth higher than the first and second depths.

7. An apparatus for wireless communication, comprising:

at least one processor configured to obtain a received signal comprising at least one transmission of a first packet from at least one first station at a first depth and at least one transmission of a second packet from at least one second station at a second depth in a relay communication network, to estimate and cancel interference due to the at least one transmission of the first packet from the received signal to obtain an interference canceled signal, and to process the interference canceled signal for the second packet.

8. The apparatus of claim 7, wherein the at least one processor is configured to estimate interference due to the at least one transmission of the first packet based on a decoded first packet and a channel estimate for the at least one first station, and to subtract the estimated interference from the received signal to obtain the interference canceled signal.

9. The apparatus of claim 7, wherein the at least one processor is configured to estimate interference due to the at least one transmission of the first packet based on log-likelihood ratio (LLR) information for the first packet, without decoding the first packet, and to subtract the estimated interference from the received signal to obtain the interference canceled signal.

10. An apparatus for wireless communication, comprising:

means for obtaining a received signal comprising at least one transmission of a first packet from at least one first station at a first depth and at least one transmission of a second packet from at least one second station at a second depth in a relay communication network;

means for estimating and canceling interference due to the at least one transmission of the first packet from the received signal to obtain an interference canceled signal; and

means for processing the interference canceled signal for the second packet.

11. The apparatus of claim 10, wherein the means for estimating and canceling interference comprises

means for estimating interference due to the at least one transmission of the first packet based on a decoded first packet and a channel estimate for the at least one first station, and

means for subtracting the estimated interference from the received signal to obtain the interference canceled signal.

12. The apparatus of claim 10, wherein the means for estimating and canceling interference comprises

means for estimating interference due to the at least one transmission of the first packet based on log-likelihood ratio (LLR) information for the first packet, without decoding the first packet, and

means for subtracting the estimated interference from the received signal to obtain the interference canceled signal.

13. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to obtain a received signal comprising at least one transmission of a first packet from at least one first station at a first depth and at least one transmission of a second packet from at least one second station at a second depth in a relay communication network,

code for causing the at least one computer to estimate and cancel interference due to the at least one transmission of the first packet from the received signal to obtain an interference canceled signal, and

code for causing the at least one computer to process the interference canceled signal for the second packet.

14. A method for wireless communication, comprising:

obtaining a received signal comprising at least one transmission of a first packet from at least one downstream station and at least one transmission of a second packet from at least one upstream station in a relay communication network;

estimating interference due to the at least one transmission of the first packet;

subtracting the estimated interference from the received signal to obtain an interference canceled signal; and

processing the interference canceled signal to recover the second packet from the at least one upstream station.

15. The method of claim 14, further comprising:

obtaining a first received signal comprising at least one transmission of the first packet from the at least one upstream station in a first frame;

processing the first received signal to recover the first packet; and

sending a transmission of the first packet to the at least one downstream station in a second frame, and wherein the received signal is obtained in a third frame.

16. An apparatus for wireless communication, comprising:

at least one processor configured to obtain a received signal comprising at least one transmission of a first packet from at least one downstream station and at least one transmission of a second packet from at least one upstream station in a relay communication network, to estimate interference due to the at least one transmission of the first packet, to subtract the estimated interference from the received signal to obtain an interference canceled signal, and to process the interference canceled signal to recover the second packet from the at least one upstream station.

17. The apparatus of claim 16, wherein the at least one processor is configured to obtain a first received signal comprising at least one transmission of the first packet from the at least one upstream station in a first frame, to process the first received signal to recover the first packet, to send a transmission of the first packet to the at least one downstream station in a second frame, and to obtain the received signal in a third frame.

18. A method for wireless communication, comprising:

obtaining a received signal comprising at least one transmission of a first packet from at least one first station at a first depth and at least one transmission of a second packet from at least one second station at a second depth in a relay communication network;

processing the received signal to recover the first packet;

estimating interference due to the at least one transmission of the first packet based on the recovered first packet;

subtracting the estimated interference from the received signal to obtain an interference canceled signal; and

processing the interference canceled signal for the second packet.

19. The method of claim 18, further comprising:

obtaining a first received signal comprising at least one transmission of the first packet from the at least one second station in a first frame, wherein the received signal is obtained in a second frame, and wherein the processing the received signal comprises processing the first received signal and the received signal to recover the first packet.

20. The method of claim 19, wherein the processing the first received signal and the received signal comprises

computing first log likelihood ratios (LLRs) for the first packet based on the first received signal,

computing second LLRs for the first packet based on the received signal, and

decoding the first and second LLRs to recover the first packet.

21. The method of claim 20, wherein the processing the interference canceled signal comprises computing LLRs for the second packet based on the interference canceled signal.

22. An apparatus for wireless communication, comprising:

at least one processor configured to obtain a received signal comprising at least one transmission of a first packet from at least one first station at a first depth and at least one transmission of a second packet from at least one second station at a second depth in a relay communication network, to process the received signal to recover the first packet, to estimate interference due to the at least one transmission of the first packet based on the recovered first packet, to subtract the estimated interference from the received signal to obtain an interference canceled signal, and to process the interference canceled signal for the second packet.

23. The apparatus of claim 22, wherein the at least one processor is configured to obtain a first received signal comprising at least one transmission of the first packet from the at least one second station in a first frame, to obtain the received signal in a second frame, and to process the first received signal and the received signal to recover the first packet.

24. The apparatus of claim 23, wherein the at least one processor is configured to compute first log likelihood ratios (LLRs) for the first packet based on the first received signal, to compute second LLRs for the first packet based on the received signal, and to decode the first and second LLRs to recover the first packet.

25. The apparatus of claim 24, wherein the at least one processor is configured to compute LLRs for the second packet based on the interference canceled signal.

26. A method for wireless communication, comprising:

sending transmissions of packets from a station at a first depth in a relay communication network, each packet being transmitted in a pipeline by stations at different depths in successive frames; and

periodically sending transmissions of boot-up packets from the station to initialize the pipeline, wherein no transmissions are sent by stations at depths higher than the first depth during the transmissions of the boot-up packets.

27. The method of claim 26, wherein the periodically sending transmissions of boot-up packets comprises sending a transmission of a boot-up packet in a designated frame of each superframe comprising multiple frames.

28. The method of claim 27, wherein the multiple frames in each superframe are assigned sequentially increasing indices starting with 0, and wherein only stations at depth d or lower send transmissions of packets in frame d, where d is a frame index.

29. The method of claim 27, further comprising:

sending no transmissions of packets from the station in at least one frame at the end of each superframe to clear the pipeline.

30. The method of claim 27, further comprising:

sending transmissions of prior packets from the station in at least one frame at the end of each superframe to clear the pipeline.

31. An apparatus for wireless communication, comprising:

at least one processor configured to send transmissions of packets from a station at a first depth in a relay communication network, each packet being transmitted in a pipeline by stations at different depths in successive frames, and to periodically send transmissions of boot-up packets from the station to initialize the pipeline, wherein no transmissions are sent by stations at depths higher than the first depth during the transmissions of the boot-up packets.

32. The apparatus of claim 31, wherein the at least one processor is configured to send a transmission of a boot-up packet in a designated frame of each superframe, wherein each superframe comprises multiple frames assigned sequentially increasing indices starting with 0, and wherein only stations at depth d or lower send transmissions of packets in frame d, where d is a frame index.

33. The apparatus of claim 32, wherein the at least one processor is configured to send either no transmissions of packets or transmissions of prior packets in at least one frame at the end of each superframe to clear the pipeline.