MULTIPLEXING AND POWER CONTROL OF UPLINK CONTROL CHANNELS IN A WIRELESS COMMUNICATION SYSTEM

• US 20080287155A1
• Filed: 05/08/2008
• Published: 11/20/2008
• Est. Priority Date: 05/18/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Xu, Hao, Malladi, Durga Prasad, Wang, Rachel
• Granted Patent: US 8,750,917 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0039 Frequency-contiguous, i.e. with no allocation of frequencies for one user or terminal between the frequencies allocated to another
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 52/48 during retransmission after error or non-acknowledgment

Abstract

Techniques for transmitting control information in a wireless communication system are described. The system may support acknowledgement (ACK) channels and channel quality indicator (CQI) channels, which may have different target signal-to-noise ratios (SNRs). The ACK and CQI channels from different user equipments (UEs) may be multiplexed on the same resource block. In one design, the transmit power of a CQI channel may be set to achieve a nominal target SNR for CQI when not multiplexed with the ACK channels and may be reduced to achieve a lower target SNR when multiplexed with the ACK channels. In another design, the transmit power of an ACK channel may be set to achieve a nominal target SNR for ACK when not multiplexed with the CQI channels and may be boosted to achieve a higher target SNR when multiplexed with the CQI channels. The CQI channel may randomly hop to mitigate performance degradation.

Claims

1. A method for wireless communication, comprising:

sending a first control channel at a first transmit power level if the first control channel is not multiplexed with second control channels from other user equipments (UEs); and

sending the first control channel at a second transmit power level different from the first transmit power level if the first control channel is multiplexed with the second control channels from the other UEs.

2. The method of claim 1, wherein the first control channel comprises a channel quality indicator (CQI) channel, wherein the second control channels comprise acknowledgement (ACK) channels, and wherein the second transmit power level is lower than the first transmit power level.

3. The method of claim 2, wherein the first transmit power level achieves a first target signal-to-noise ratio (SNR) for the CQI channel if not multiplexed with the ACK channels from the other UEs, and wherein the second transmit power level achieves a second target SNR for the CQI channel if multiplexed with the ACK channels from the other UEs, the second target SNR being lower than the first target SNR.

4. The method of claim 1, wherein the first control channel comprises an acknowledgement (ACK) channel, wherein the second control channels comprise channel quality indicator (CQI) channels, and wherein the second transmit power level is higher than the first transmit power level.

5. The method of claim 4, wherein the first transmit power level achieves a first target signal-to-noise ratio (SNR) for the ACK channel if not multiplexed with the CQI channels from the other UEs, and wherein the second transmit power level achieves a second target SNR for the ACK channel if multiplexed with the CQI channels from the other UEs, the second target SNR being higher than the first target SNR.

6. The method of claim 1, wherein the first control channel comprises an acknowledgement (ACK) channel carrying a first number of bits, and wherein the second control channels comprise ACK channels carrying a second number of bits different from the first number of bits.

7. The method of claim 4, wherein the sending the first control channel at the first transmit power level comprises sending an ACK at the first transmit power level or a negative acknowledgement (NAK) at a third transmit power level if the ACK channel is not multiplexed with the CQI channels from the other UEs, the third transmit power level being higher than the first transmit power level, and wherein the sending the first control channel at the second transmit power level comprises sending the ACK at the second transmit power level or the NAK at a fourth transmit power level if the ACK channel is multiplexed with the CQI channels from the other UEs, the fourth transmit power level being higher than the second transmit power level.

8. The method of claim 1, further comprising:

hopping the first control channel to randomize multiplexing of the first control channel with the second control channels from the other UEs.

9. The method of claim 1, wherein spreading is used for one of the first and second control channels and is not used for other one of the first and second control channels.

10. The method of claim 1, wherein the first and second control channels have different target signal-to-noise ratios (SNRs) and further have different received signal levels when multiplexed together.

11. The method of claim 1, further comprising:

receiving signaling indicating whether or not the first control channel is multiplexed with the second control channels from the other UEs; and

selecting the first or second transmit power level for the first control channel based on the signaling.

12. The method of claim 1, further comprising:

adjusting transmit power of a user equipment (UE) based on power control; and

determining the first or second transmit power level based on first or second power offset, respectively, and the adjusted transmit power of the UE.

13. An apparatus for wireless communication, comprising:

at least one processor configured to send a first control channel at a first transmit power level if the first control channel is not multiplexed with second control channels from other user equipments (UEs), and to send the first control channel at a second transmit power level different from the first transmit power level if the first control channel is multiplexed with the second control channels from the other UEs.

14. The apparatus of claim 13, wherein the first control channel comprises a channel quality indicator (CQI) channel, wherein the second control channels comprise acknowledgement (ACK) channels, and wherein the second transmit power level is lower than the first transmit power level.

15. The apparatus of claim 13, wherein the first control channel comprises an acknowledgement (ACK) channel, wherein the second control channels comprise channel quality indicator (CQI) channels, and wherein the second transmit power level is higher than the first transmit power level.

16. The apparatus of claim 13, wherein the at least one processor is configured to hop the first control channel to randomize multiplexing of the first control channel with the second control channels from the other UEs.

17. The apparatus of claim 13, wherein the at least one processor is configured to adjust transmit power of a user equipment (UE) based on power control, and to determine the first or second transmit power level based on first or second power offset, respectively, and the adjusted transmit power of the UE.

18. An apparatus for wireless communication, comprising:

means for sending a first control channel at a first transmit power level if the first control channel is not multiplexed with second control channels from other user equipments (UEs); and

means for sending the first control channel at a second transmit power level different from the first transmit power level if the first control channel is multiplexed with the second control channels from the other UEs.

19. The apparatus of claim 18, wherein the first control channel comprises a channel quality indicator (CQI) channel, wherein the second control channels comprise acknowledgement (ACK) channels, and wherein the second transmit power level is lower than the first transmit power level.

20. The apparatus of claim 18, wherein the first control channel comprises an acknowledgement (ACK) channel, wherein the second control channels comprise channel quality indicator (CQI) channels, and wherein the second transmit power level is higher than the first transmit power level.

21. The apparatus of claim 18, further comprising:

means for hopping the first control channel to randomize multiplexing of the first control channel with the second control channels from the other UEs.

22. The apparatus of claim 18, further comprising:

means for adjusting transmit power of a user equipment (UE) based on power control; and

means for determining the first or second transmit power level based on first or second power offset, respectively, and the adjusted transmit power of the UE.

23. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to send a first control channel at a first transmit power level if the first control channel is not multiplexed with second control channels from other user equipments (UEs); and

code for causing the at least one computer to send the first control channel at a second transmit power level different from the first transmit power level if the first control channel is multiplexed with the second control channels from the other UEs.

24. A method for wireless communication, comprising:

sending a channel quality indicator (CQI) channel at a first transmit power level if the CQI channel is not multiplexed with acknowledgement (ACK) channels from other user equipments (UEs); and

sending the CQI channel at a second transmit power level lower than the first transmit power level if the CQI channel is multiplexed with the ACK channels from the other UEs.

25. The method of claim 24, further comprising:

generating multiple data sequences for the CQI channel without spreading, wherein the sending the CQI channel at the second transmit power level comprises sending the multiple data sequences in multiple symbol periods of a resource block at the second transmit power level, and wherein the ACK channels from the other UEs are sent with spreading in the resource block.

26. The method of claim 24, further comprising:

generating multiple data sequences for the CQI channel based on a reference signal sequence, wherein the sending the CQI channel at the second transmit power level comprises sending the multiple data sequences in multiple symbol periods of a resource block at the second transmit power level, wherein data sequences for the ACK channels from the other UEs are generated with at least one other reference signal sequence, and wherein the reference signal sequence and the at least one other reference signal sequence correspond to different cyclic shifts of a base sequence.

27. An apparatus for wireless communication, comprising:

at least one processor configured to send a channel quality indicator (CQI) channel at a first transmit power level if the CQI channel is not multiplexed with acknowledgement (ACK) channels from other user equipments (UEs), and to send the CQI channel at a second transmit power level lower than the first transmit power level if the CQI channel is multiplexed with the ACK channels from the other UEs.

28. The apparatus of claim 27, wherein the at least one processor is configured to generate multiple data sequences for the CQI channel without spreading, and to send the multiple data sequences in multiple symbol periods of a resource block at the second transmit power level, wherein the ACK channels from the other UEs are sent with spreading in the resource block.

29. The apparatus of claim 27, wherein the at least one processor is configured to generate multiple data sequences for the CQI channel based on a reference signal sequence, and to send the multiple data sequences in multiple symbol periods of a resource block at the second transmit power level, wherein data sequences for the ACK channels from the other UEs are generated with at least one other reference signal sequence, and wherein the reference signal sequence and the at least one other reference signal sequence correspond to different cyclic shifts of a base sequence.

30. A method for wireless communication, comprising:

receiving a first control channel from a user equipment (UE) at a first received signal-to-noise ratio (SNR) if the first control channel is not multiplexed with second control channels from other UEs; and

receiving the first control channel at a second received SNR different from the first received SNR if the first control channel is multiplexed with the second control channels from the other UEs.

31. The method of claim 30, wherein the first control channel comprises a channel quality indicator (CQI) channel, wherein the second control channels comprise acknowledgement (ACK) channels, and wherein the second received SNR is lower than the first received SNR.

32. The method of claim 31, further comprising:

performing erasure detection for the CQI channel if multiplexed with the ACK channels from the other UEs; and

skipping the erasure detection for the CQI channel if not multiplexed with the ACK channels from the other UEs.

33. The method of claim 31, further comprising:

determining whether the CQI channel is reliable based on a metric;

using a CQI report received from the CQI channel if the CQI channel is deemed reliable, and

discarding the CQI report if the CQI channel is deemed unreliable.

34. The method of claim 30, wherein the first control channel comprises an acknowledgement (ACK) channel, wherein the second control channels comprise channel quality indicator (CQI) channels, and wherein the second received SNR is higher than the first received SNR.

35. The method of claim 30, further comprising:

performing detection for the first and second control channels with interference cancellation if the first and second control channels are multiplexed together.

36. An apparatus for wireless communication, comprising:

at least one processor configured to receive a first control channel from a user equipment (UE) at a first received signal-to-noise ratio (SNR) if the first control channel is not multiplexed with second control channels from other UEs, and to receive the first control channel at a second received SNR different from the first received SNR if the first control channel is multiplexed with the second control channels from the other UEs.

37. The apparatus of claim 36, wherein the first control channel comprises a channel quality indicator (CQI) channel, wherein the second control channels comprise acknowledgement (ACK) channels, and wherein the second received SNR is lower than the first received SNR.

38. The apparatus of claim 37, wherein the at least one processor is configured to perform erasure detection for the CQI channel if multiplexed with the ACK channels from the other UEs, and to skip the erasure detection for the CQI channel if not multiplexed with the ACK channels from the other UEs.

39. The apparatus of claim 37, wherein the at least one processor is configured to determine whether the CQI channel is reliable based on a metric, to use a CQI report received from the CQI channel if the CQI channel is deemed reliable, and to discard the CQI report if the CQI channel is deemed unreliable.

40. The apparatus of claim 36, wherein the first control channel comprises an acknowledgement (ACK) channel, wherein the second control channels comprise channel quality indicator (CQI) channels, and wherein the second received SNR is higher than the first received SNR.

41. The apparatus of claim 36, wherein the at least one processor is configured to perform detection for the first and second control channels with interference cancellation if the first and second control channels are multiplexed together.