Data reception with interference cancellation in a relay communication network

• US 8,634,769 B2
• Filed: 10/23/2008
• Issued: 01/21/2014
• Est. Priority Date: 10/23/2008
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Palanki, Ravi, Agrawal, Avneesh
• Primary Examiner(s): Urban, Edward
• Assistant Examiner(s): Sorowar, Golam
• Application Number:
  US12/257,258
• Publication Number:
  US 20100105317A1
• Time in Patent Office: 1,916 Days
• Field of Search: 455/7, 455/9, 455/10, 455/13.4, 455/13.3, 455/562.1, 455/423, 455/422.1, 455/63.1, 455/501, 370/274, 370/279, 370/293, 370/315, 370/492, 370/203, 370/312, 370/336, 370328-330, 370/342, 375/E1.032, 375/E1.033, 375/E1.001
• US Class Current: 455/13.1
• 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 transmitted in a first frame by at least one first station at a first depth and at least one transmission of a second packet transmitted in the first frame by at least one second station at a second depth in a relay communication network, wherein the second packet is transmitted by the at least one first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one second station in a third frame prior to the first frame;

estimating interference due to the at least one transmission of the first packet transmitted by the at least first station in the first frame to obtain an estimated interference;

canceling the estimated interference from the received signal in the first frame to obtain an interference canceled signal; and

processing the interference canceled signal to recover the second packet from the received signal in the first frame.

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 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 wherein the canceling the estimated interference comprises subtracting the estimated interference from the received signal to obtain the interference canceled signal.

4. The method of claim 1, wherein the estimating 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 wherein the canceling the estimated interference comprises 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 transmitted in a first frame by at least one first station at a first depth and at least one transmission of a second packet transmitted in the first frame by at least one second station at a second depth in a relay communication network, wherein the second packet is transmitted by the at least one first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one second station in a third frame prior to the first frame;

estimate interference due to the at least one transmission of the first packet transmitted by the at least first station in the first frame to obtain an estimated interference;

cancel the estimated interference from the received signal in the first frame to obtain an interference canceled signal; and

process the interference canceled signal to recover the second packet from the received signal in the first frame.

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 transmitted in a first frame by at least one first station at a first depth and at least one transmission of a second packet transmitted in the first frame by at least one second station at a second depth in a relay communication network, wherein the second packet is transmitted by the at least one first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one second station in a third frame prior to the first frame;

means for estimating interference due to the at least one transmission of the first packet transmitted by the at least first station in the first frame to obtain an estimated interference;

means for canceling the estimated interference from the received signal in the first frame to obtain an interference canceled signal; and

mean for processing the interference canceled signal to recover the second packet from the received signal in the first frame.

11. The apparatus of claim 10, wherein the means for estimating 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 wherein the means for canceling the estimated interference comprises 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 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 wherein the means for canceling the estimated interference comprises means for subtracting the estimated interference from the received signal to obtain the interference canceled signal.

13. A computer program product, comprising:

a non-transitory 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 transmitted in a first frame by at least one first station at a first depth and at least one transmission of a second packet transmitted in the first frame by at least one second station at a second depth in a relay communication network, wherein the second packet is transmitted by the at least one first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one second station in a third frame prior to the first frame;

code for causing at least one computer to estimate interference due to the at least one transmission of the first packet transmitted by the at least first station in the first frame to obtain an estimated interference;

code for causing at least one computer to cancel the estimated interference from the received signal in the first frame to obtain an interference canceled signal; and

code for causing at least one computer to process the interference canceled signal to recover the second packet from the received signal in the first frame.

14. A method for wireless communication, comprising:

obtaining a received signal comprising at least one transmission of a first packet transmitted in a first frame by at least downstream station and at least one transmission of a second packet transmitted in the first frame by at least one upstream station in a relay communication network, wherein the second packet is transmitted by the at least downstream first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one upstream station in a third frame prior to the first frame;

estimating interference due to the at least one transmission of the first packet transmitted by the at least downstream station in the first frame to obtain an estimated interference;

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

processing the interference canceled signal to recover the second packet in the first frame 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 third frame prior to the 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 fourth frame prior to the first 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 transmitted in a first frame by at least downstream station and at least one transmission of a second packet transmitted in the first frame by at least one upstream station in a relay communication network, wherein the second packet is transmitted by the at least downstream first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one upstream station in a third frame prior to the first frame;

estimate interference due to the at least one transmission of the first packet transmitted by the at least downstream station in the first frame to obtain an estimated interference;

subtract the estimated interference from the received signal in the first frame to obtain an interference canceled signal; and

process the interference canceled signal to recover the second packet in the first frame 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 third frame prior to the first frame, to process the first received signal to recover the first packet, and to send a transmission of the first packet to the at least one downstream station in a fourth frame prior to the first frame.

18. A method for wireless communication, comprising:

obtaining a received signal comprising at least one transmission of a first packet transmitted in a first frame by at least one first station at a first depth and at least one transmission of a second packet transmitted in the first frame by at least one second station at a second depth in a relay communication network, wherein the second packet is transmitted by the at least one first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one second station in a third frame prior to the first frame;

processing the received signal to recover the first in the first frame;

estimating interference due to the at least one transmission of the first packet transmitted by the at least first station in the first frame to obtain an estimated interference;

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

processing the interference canceled signal to recover the second packet from the received signal in the first frame.

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 third frame prior to the first frame, and wherein the processing the received signal comprises processing the first received signal and the received signal to recover the first packet.

20. A method for wireless communication, comprising:

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

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

processing the first received signal and the second received signal to recover the first packet, the processing comprises

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

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

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

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

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

processing the interference canceled signal for the second 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 transmitted in a first frame by at least one first station at a first depth and at least one transmission of a second packet transmitted in the first frame by at least one second station at a second depth in a relay communication network, wherein the second packet is transmitted by the at least one first station in a second frame subsequent to the first frame and the first packet is transmitted by the at least one second station in a third frame prior to the first frame;

processing the received signal to recover the first in the first frame;

estimate interference due to the at least one transmission of the first packet transmitted by the at least first station in the first frame to obtain an estimated interference;

subtract the estimated interference from the received signal in the first frame to obtain an interference canceled signal; and

process the interference canceled signal to recover the second packet from the received signal in the first frame.

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 third frame prior to the first frame, and to process the first received signal and the received signal to recover the first packet.

24. An apparatus for wireless communication, comprising:

at least one processor is configured to;

obtain a first received signal comprising at least one transmission of a first packet from at least one first station at a first depth in a relay communication network,

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

process the first received signal and the second received signal to recover the first packet,

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

compute second LLRs for the first packet based on the second received signal,

decode the first and second LLRs to recover the first packet,

estimate interference due to the at least one transmission of the first packet from the at least one second station based on the recovered first packet,

subtract the estimated interference from the second received signal to obtain an interference canceled signal, and

process the interference canceled signal for the second 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.