Channel Sounding in Ofdma System

• US 20080095223A1
• Filed: 09/29/2005
• Published: 04/24/2008
• Est. Priority Date: 09/30/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Rockstar Bidco LP (Rockstar Consortium Inc.)
• Inventors: Xu, Hua, Zhang, Hang, Tong, Wen, Ma, Jianglei, Zhu, Peiying, Jia, Ming, Yu, Dongsheng
• Granted Patent: US 7,924,935 B2
• Time in Patent Office: Days
• US Class Current: 375/228
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0675 characterised by the signaling
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals
• 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 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI

Abstract

Method and apparatus for determining a downlink channel response in an orthogonal frequency division multiplexing access (OFDMA) system. The method and apparatus uses the uplink quality indication channel for determining the downlink channel response, or uses round trip pilot relay channel sounding. The uplink quality indication channel may comprise modified mini-tiles. The subscriber station using round trip pilot relay channel sounding sends composite transponder pilots after receiving the DL pilots.

Claims

1. A method for determining a channel response in an orthogonal frequency division multiplexing access (OFDMA) system comprising the steps of:

a) constructing an OFDMA frame having a quality indication channel;

b) instructing a subscriber station to transmit a quality indication signal in said quality indication channel;

c) determining an uplink channel response based on said quality indication signal; and

d) estimating a downlink channel response based on said uplink channel response.

2. The method according to claim 1, wherein said quality indication channel is a modified quality indication channel, said modified quality indication channel comprising mini-tiles;

said mini-tiles selected from uplink tiles of an uplink subchannel, further comprising the step of;

concatenating a first plurality of uplink subchannels to generate a second plurality of quality indication channels.

3. The method according to claim 2, wherein said system is a multiple-input, multiple-output (MIMO) system.

4. The method according to claim 2, wherein said modified quality indication channel is a channel quality indication channel (CQICH).

5. The method according to claim 2, wherein said uplink subchannel is part of a closed-loop system.

6. The method according to claim 2, wherein said uplink subchannel is a partial usage subchannel (PUSC) channel comprising six uplink tiles, said uplink tile comprising four subcarriers crossing three orthogonal frequency division multiplexing (OFDM) symbols, said uplink tile mapped to four mini-tiles, said first plurality and second plurality are equal to four.

7. The method according to claim 2, wherein said uplink subchannel is optional PUSC channel comprising six uplink tiles, said uplink tile comprising three subcarriers crossing three OFDM symbols, said uplink tile mapped to three mini-tiles, said first plurality is equal to three, and second plurality is equal to four.

8. The method according to claim 3, wherein said uplink subchannel is a MIMO PUSC channel comprising six MIMO uplink tiles, said MIMO uplink tile comprising four subcarriers crossing three OFDM symbols, said MIMO uplink tile mapped to 12 mini-tiles, said first plurality and second plurality are equal to two.

9. The method according to claim 3, wherein said uplink subchannel is optional MIMO PUSC channel comprising three MIMO uplink tiles, said MIMO uplink tile comprising three subcarriers crossing two OFDM symbols, said MIMO uplink tile mapped to six mini-tiles, said first plurality is equal to four, and second plurality is equal to three.

10. The method according to claim 1, wherein said system is a time division duplex (TDD) system.

11. A method for determining a channel response in an orthogonal frequency division multiplexing access (OFDMA) system comprising the steps of:

a) constructing an OFDMA frame having a downlink sounding pilot at a base station;

b) transmitting said downlink sounding pilot over a downlink channel;

c) receiving said downlink sounding pilot at a subscriber station;

d) applying the received downlink sounding pilot as uplink sounding symbol resulting a composite transponder pilot;

e) transmitting said composite transponder pilot and an uplink pilot over an uplink channel;

f) receiving said composite transponder pilot at said base station;

g) receiving said uplink pilot at said base station; and

h) determining a downlink channel response from the received composite transponder pilot and the received uplink pilot.

12. The method according to claim 11, wherein said system is a multiple-input, multiple-output (MIMO) system.

13. The method according to claim 11, wherein said downlink sounding pilot is a mid-amble.

14. The method according to claim 11, wherein said uplink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in an OFDM symbol.

15. The method according to claim 11, wherein said uplink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in different OFDM symbols.

16. The method according to claim 12, wherein said composite transponder pilot and said uplink pilot are arranged in the frequency domain according to the antenna configurations in said base station and said subscriber station.

17. The method according to claim 11, wherein said composite transponder pilot is generated from a subset of downlink (DL) pilots transmitted by a DL sounding symbol.

18. The method according to claim 11, wherein said downlink sounding pilot, said composite transponder pilot and said uplink pilot are in an advanced modulation and coding (AMC) zone.

19. The method according to claim 11, wherein said downlink sounding pilot, said composite transponder pilot and said uplink pilot are in a PUSC zone.

20. The method according to claim 11, further comprising the steps of pre-coding a subsequent pilot by the base station, and transmitting said subsequent pilot to the subscriber station.

21. An orthogonal frequency division multiplexing access (OFDMA) system comprising:

a) a subscriber station being adapted to transmit a quality indication signal in a quality indication channel; and

b) a base station being adapted to receive said quality indication channel;

said base station determining an uplink channel response based on said quality indication signal; and

estimating a downlink channel response based on said uplink channel response.

22. The OFDMA system according to claim 21, wherein the quality indication channel is a modified quality indication channel;

said modified quality indication channel comprising mini-tiles;

said mini-tiles selected from uplink tiles of a uplink subchannel; and

wherein a first plurality of uplink subchannels are concatenated to generate a second plurality of quality indication channels.

23. The OFDMA system according to claim 22, wherein said OFDMA system is a multiple-input, multiple-output (MIMO) system.

24. The OFDMA system according to claim 22, wherein said modified quality indication channel is a channel quality indication channel (CQICH).

25. The OFDMA system according to claim 22, wherein said uplink subchannel is part of a closed-loop system.

26. An orthogonal frequency division multiplexing access (OFDMA) system comprising:

a) a base station being adapted to transmit a downlink sounding pilot; and

to receive a composite transponder pilot and an uplink pilot;

said base station determining a downlink channel response from a received composite transponder pilot and a received uplink pilot; and

b) a subscriber station being adapted to receive said downlink sounding pilot;

said subscriber station applying the received downlink sounding pilot as uplink sounding symbol resulting a composite transponder pilot, and transmitting said composite transponder pilot and an uplink pilot over an uplink channel.

27. The OFDMA system according to claim 26, wherein said system is a multiple-input, multiple-output (MIMO) system.

28. The OFDMA system according to claim 26, wherein said downlink sounding pilot is a mid-amble.

29. The OFDMA system according to claim 26, wherein said uplink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in an OFDM symbol.

30. The OFDMA system according to claim 26, wherein said uplink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in different OFDM symbols.

31. The OFDMA system according to claim 26, wherein said composite transponder pilot and said uplink pilot are arranged in the frequency domain according to the antenna configurations in said base station and said subscriber station.

32. A base station in an orthogonal frequency division multiplexing access (OFDMA) system comprising:

a) a first circuitry for instructing a subscriber station to transmit a quality indication signal in a quality indication channel;

b) receiver for receiving said quality indication signal;

c) a second circuitry for determining an uplink channel response based on said quality indication signal; and

d) a third circuitry for estimating a downlink channel response based on said uplink channel response.

33. The base station according to claim 32, wherein said quality indication channel is a modified quality indication channel, said modified quality indication channel comprising mini-tiles;

said mini-tiles selected from uplink tiles of an uplink subchannel, wherein a first plurality of uplink subchannels is concatenated to generate a second plurality of quality indication channels.

34. The base station according to claim 33, wherein said system is a multiple-input, multiple-output (MIMO) system.

35. The base station according to claim 33, wherein said modified quality indication channel is a channel quality indication channel (CQICH).

36. A base station in an orthogonal frequency division multiplexing access (OFDMA) system comprising:

a) a transmitter for transmitting a downlink sounding pilot over a downlink channel;

b) a receiver for receiving a composite transponder pilot; and

an uplink pilot at said base station;

said composite transponder pilot resulting from said downlink sounding pilot being applied as uplink sounding symbol; and

c) a circuitry for determining a down link channel response from the received composite transponder pilot and the received uplink pilot.

37. The base station according to claim 36, wherein said system is a multiple-input, multiple-output (MIMO) system.

38. The base station according to claim 36, wherein said downlink sounding pilot is a mid-amble.

39. The base station according to claim 36, wherein said uplink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in an OFDM symbol.

40. The base station according to claim 36, wherein said uplink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in different OFDM symbols.

41. A subscriber station in an orthogonal frequency division multiplexing access (OFDMA) system comprising:

a) a transmitter for transmitting a quality indication signal in a quality indication channel;

said quality indication signal for determining an uplink channel response; and

b) a combining circuitry for concatenating a first plurality of uplink subchannels to generate a second plurality of modified quality indication channels.

42. The subscriber station according to claim 41, wherein said quality indication channel is a modified quality indication channel, said modified quality indication channel comprising mini-tiles;

said mini-tiles selected from uplink tiles of an uplink subchannel; and

wherein a first plurality of uplink subchannels is concatenated to generate a second plurality of quality indication channels.

43. The subscriber station according to claim 41, wherein said system is a multiple-input, multiple-output (MIMO) system.

44. The subscriber station according to claim 41, wherein said modified quality indication channel is a channel quality indication channel (CQICH).

45. The subscriber station according to claim 41, wherein said uplink subchannel is part of a closed-loop system.

46. A subscriber station in an orthogonal frequency division multiplexing access (OFDMA) system comprising:

a) a receiver for receiving a downlink sounding pilot;

b) a converter for applying the received downlink sounding pilot as a uplink sounding symbol resulting a composite transponder pilot; and

c) a transmitter for transmitting said composite transponder pilot and an uplink pilot over an uplink channel;

said composite transponder pilot and the received uplink pilot used for determining a down link channel response.

47. The subscriber station according to claim 46, wherein said system is a multiple-input, multiple-output (MIMO) system.

48. The subscriber station according to claim 46, wherein said downlink sounding pilot is a mid-amble.

49. The subscriber station according to claim 46, wherein said downlink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in an OFDM symbol.

50. The subscriber station according to claim 46, wherein said downlink sounding pilot and said composite transponder pilot are transmitted by non-overlap subcarriers in different OFDM symbols.