Method of interference cancellation in communication systems

• US 20040192208A1
• Filed: 03/31/2003
• Published: 09/30/2004
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Zou, Jialin, Yang, Yunsong, Kong, Hongwei, Vasudevan, Subramanian, Ye, Henry Hui, Sanwal, Kumud K.
• Granted Patent: US 7,385,944 B2
• Time in Patent Office: Days
• US Class Current: 455/63.1
• CPC Class Codes: H04B 1/71072 Successive interference cancellation
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 1/208 involving signal re-encoding
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

In a method of canceling interference, a base station selects a known highest data rate user transmission from a received first signal containing a group of user transmissions. The known highest rate user transmission may be configured as one or more frames, each frame including a control preamble and a plurality of encoded sub-frames. The control preamble and encoded sub-frames may be decoded, and the decoded sub-frames may be used for removing interference caused by the known highest rate user transmission to all remaining transmissions of the group.

Claims

1. A method a canceling interference in transmissions from a group of users in a communication system, comprising:

selecting a known highest data rate user transmission of the group from a received first signal containing the group'"'"'s transmissions, the highest rate user transmission configured as one or more received frames, each frame including a control preamble and a plurality of encoded sub-frames;

decoding said control preamble and a plurality of encoded sub-frames on a sub-frame basis; and

removing interference due to the highest rate user transmission from the first signal using the decoded sub-frames.

2. The method of claim 1, wherein said control preamble precedes said plurality of encoded sub-frames.

3. The method of claim 1, wherein said control preamble accompanies one or more of said plurality of encoded sub-frames.

4. The method of claim 1, wherein said encoding further includes:

first decoding the control preamble in a first timeslot to determine a channel phase and gain estimate for a first one of the plurality of encoded sub-frames; and

second decoding the first encoded sub-frame in a next timeslot using the determined channel phase and gain estimate to provide a revised channel phase and gain estimate, the second decoding repeated for remaining encoded sub-frames using determined channel phase and gain estimates from all previously decoded sub-frames.

5. The method of claim 1, wherein

said highest rate user transmission represents a second signal composed of one or more frames containing said control preamble and plurality of encoded sub-frames, and

said removing further includes:

re-forming the second signal from the decoded sub-frames; and

subtracting the second signal from the received first signal to remove interference due to the highest rate user transmission from the first signal.

6. The method of claim 5, wherein said re-forming further includes re-encoding, re-modulating, and re-applying the channel gain and phase to each of the decoded sub-frames to form the second signal.

7. The method of claim 5, wherein

said re-forming further includes re-encoding, re-modulating, and re-applying the channel gain and phase to a decode sub-frames to incrementally form a portion of the second signal on a sub-frame basis;

and

said subtracting further includes incrementally subtracting said portion of the second signal from the received first signal.

8. The method of claim 5, wherein said subtracting forms a modified first signal containing voice and data transmissions of a group of scheduled and unscheduled users, the method further comprising:

processing the modified first signal to decode the voice and data transmissions of the group.

9. The method of claim 5, wherein said subtracting yields a modified first signal including all remaining voice and data transmissions of the group and a substantially negligible signal component from the highest data rate user of the group.

10. The method of claim 1, wherein the frame is received over a reverse supplemental channel (R-SCH) as a plurality of encoder blocks preceded by the control preamble, each encoder block being self-decodable.

11. The method of claim 10, wherein each self-decodable encoder block includes a cyclic redundancy code (CRC).

12. The method of claim 1, wherein each frame is encoded with a control preamble and eight encoded sub-frames in ½

Power Control Group (PCG) timeslots.

13. The method of claim 12, wherein the control preamble is subject to code division multiplexing with a encoded sub-frame in one or more of the ½

PCG timeslots.

14. The method of claim 12, where a first and a last ½

PCG timeslot contains a guard time to reduce overlap between successive second signals.

15. The method of claim 1, wherein each frame is encoded with a control preamble and seven encoded sub-frames in ½

Power Control Group (PCG) timeslots.

16. The method of claim 15, wherein the control preamble is subject to time division multiplexing in a first ½

PCG timeslot.

17. The method of claim 15, wherein the first timeslot is a guard time to reduce overlap between two or more second signals.

18. The method of claim 1, wherein said first signal includes a plurality of sequential high date rate user transmissions, the method further comprising:

time-aligning said sequential high date rate user transmissions so as to prevent overlap between leading and trailing edges of sequential high-data rate transmissions.

19. The method of claim 1, wherein said first signal includes a plurality of concurrent high date rate user transmissions, the method further comprising:

time-aligning said concurrent high date rate user transmissions so that only one high date rate user transmission is selected as the second signal during a specified time interval.

20. The method of claim 19, wherein

said group of users are scheduled users, and

said time-aligning further includes transmitting one of a time-advance or time-delay command to scheduled users of said group transmitting one of said concurrent high date rate user transmissions.

21. The method of claim 20, wherein said time-advance and time-delay commands accompanies a scheduling grant message for said group.

22. The method of claim 1, wherein the frame is received over a reverse supplemental channel (R-SCH) as a plurality of encoder blocks with the control preamble, each encoder block including a cyclic redundancy code (CRC) to indicate which encoder blocks have been decoded correctly or incorrectly, the method further comprising:

issuing a response message requesting re-transmission of only those encoder blocks of the frame that have been incorrectly decoded, said re-transmitted encoded blocks to be received with a next frame on the R-SCH.

23. A method of decoding a group of received user transmissions for canceling interference therein, comprising:

selecting a highest data rate user transmission of the group from a received first signal containing the group'"'"'s transmissions, the highest rate user transmission representing a second signal that is configured as one or more received frames, each frame including a control preamble and a plurality of encoded sub-frames;

first decoding the control preamble in a first timeslot to determine a channel phase and gain estimate for a first one of the plurality of encoded sub-frames; and

second decoding the first encoded sub-frame in a next timeslot using the determined channel phase and gain estimate to provide a revised channel phase and gain estimate, the second decoding repeated for remaining encoded sub-frames using determined channel phase and gain estimates from all previously decoded sub-frames.

24. The method of claim 23, wherein

a portion of the second signal is re-formed incrementally as each sub-frame is decoded, and

said portion is subtracted from the received first signal.

25. The method of claim 24, wherein said subtracting of the second signal yields a modified first signal including all remaining voice and data transmissions of the group.

26. The method of claim 23, wherein said selecting further includes selecting and scheduling of a highest data rate user transmission on a per-base station receive antenna basis.

27. A method of encoding transmissions of a group of users within a communication system for canceling interference therein, comprising:

configuring a transmission as one or more frames to be carried over a communication channel, each frame further configured to include a control preamble and a plurality of separately encoded sub-frames, and

transmitting said frames over the communication channel.

28. The method of claim 27, wherein each frame is carried over a reverse supplemental channel (R-SCH) as a control preamble and a plurality of encoder blocks, each encoder block including a cyclic redundancy code (CRC) to indicate which encoder block has errors, the method further comprising:

re-transmitting only those encoder blocks of the frame that contain errors with a next frame on the R-SCH.

29. A method a canceling interference in transmissions encoded in accordance with the method of claim 27 that are received from a group of users in a communication system, comprising:

selecting a highest data rate user transmission of the group from a received first signal containing the group'"'"'s transmissions, the highest rate user transmission representing a second signal that is configured as one or more frames, each frame including a control preamble and a plurality of sub-frames;

decoding said control preamble and a plurality of encoded sub-frames on a sub-frame basis; and

removing interference due to the highest rate user transmission from the first signal using the decoded sub-frames.

30. A method of decoding a group of received user transmissions encoded in accordance with the method of claim 27 for canceling interference therein, comprising:

selecting a highest data rate user transmission of the group from a received first signal containing the group'"'"'s transmissions, the highest rate user transmission representing a second signal that is configured as one or more frames, each frame including a control preamble and a plurality of sub-frames;

first decoding the control preamble in a first timeslot to determine a channel phase and gain estimate for a first one of the plurality of sub-frames; and

second decoding the first sub-frame in a next timeslot using the determined channel phase and gain estimate to provide a revised channel phase and gain estimate, the second decoding repeated for remaining sub-frames using determined channel phase and gain estimates from all previously decoded sub-frames.