Spatial pilot structure for multi-antenna wireless communication

• US 8,498,192 B2
• Filed: 02/20/2007
• Issued: 07/30/2013
• Est. Priority Date: 02/21/2006
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bhushan, Naga, Kadous, Tamer, Fan, Mingxi, Wei, Yongbin
• Primary Examiner(s): Rinehart, Mark
• Assistant Examiner(s): Crompton, Christopher R
• Application Number:
  US11/677,000
• Publication Number:
  US 20070195688A1
• Time in Patent Office: 2,352 Days
• Field of Search: 370/203, 370/334
• US Class Current: 370/203
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04J 13/0044 OVSF [orthogonal variable spreading factor]
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0028 Formatting
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/1671 the supervisory signal being transmitted together with control information
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26132 using repetition
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/18 : Negotiating wireless communication parameters
• CPC Class Codes: H04W 48/08 : Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

Spatial pilot to support MIMO receivers in a multi-antenna and multi-layer transmission communication system. A first layer pilot for a single layer transmission is repeated across subbands in a first OFDM symbol and the first layer pilot is also repeated offset from the first OFDM symbol in an adjacent second OFDM symbol. Additional transmission layers may also be transmitted each include a separate pilot generated and repeated in the first symbol and repeated offset form the separate pilot in an adjacent second symbol. The first and second OFDM symbols are then transmitted and received to characterize the receive channels.

Claims

1. A method of transmitting a pilot in a wireless communication system, comprising:

generating a first layer pilot for a single layer transmission;

repeating the first layer pilot across non-adjacent subbands of a first orthogonal frequency division multiplex (OFDM) symbol;

repeating, offset from the first layer pilot of the first OFDM symbol, the first layer pilot across non-adjacent subbands of an adjacent second OFDM symbol; and

transmitting the first and second OFDM symbols in the single layer transmission, wherein the first and second OFDM symbols are placed in a slot that supports backward compatibility by retaining pilot and media access control (MAC) segments within the slot and modifying traffic segments within the slot in at least one legacy channel while pilot and MAC segments are not retained in at least one non-legacy channel.

2. The method of claim 1, further comprising:

generating a second layer pilot for a two layer transmission;

repeating offset from the first layer pilot the second layer pilot across subbands of a first OFDM symbol;

repeating offset from the second layer pilot of the first OFDM symbol the second layer pilot across subbands of an adjacent second OFDM symbol; and

transmitting the first and second OFDM symbols in the two layer transmission.

3. The method of claim 2, further comprising:

generating a third layer pilot for a three layer transmission;

repeating offset from the first and second layer pilots the third layer pilot across subbands of a first OFDM symbol;

repeating offset from the third layer pilot of the first OFDM symbol the third layer pilot across subbands of an adjacent second OFDM symbol; and

transmitting the first and second OFDM symbols in the three layer transmission.

4. The method of claim 3, further comprising:

generating a fourth layer pilot for a four layer transmission;

repeating offset from the first, second and third layer pilots the fourth layer pilot across subbands of a first OFDM symbol;

repeating offset from the fourth layer pilot of the first OFDM symbol the fourth layer pilot across subbands of an adjacent second OFDM symbol; and

transmitting the first and second OFDM symbols in the four layer transmission.

5. The method of claim 2, wherein the first and second layer pilots are alternatingly positioned in the same subbands across the first and second OFDM symbols.

6. The method of claim 3, wherein the first, second and third layer pilots are alternatingly positioned in the same subbands across the first, second and a third OFDM symbols adjacent to at least one of the first and second OFDM symbols.

7. The method of claim 6, wherein the first, second, third and fourth layer pilots are alternatingly positioned in the same subbands across the first, second, third and a fourth OFDM symbols adjacent to at least one of the first, second and third OFDM symbols.

8. The method of claim 1, wherein the first layer pilot occupies approximately 5 percent of the subbands of each of the first and second OFDM symbols.

9. The method of claim 2, wherein the first and second layer pilots occupy approximately 10 percent of the subbands of each of the first and second OFDM symbols.

10. The method of claim 3, wherein the first, second and third layer pilots occupy approximately 10 percent of the subbands of each of the first and second OFDM symbols.

11. The method of claim 4, wherein the first, second, third and fourth layer pilots occupy approximately 20 percent of the subbands of each of the first and second OFDM symbols.

12. An apparatus in a wireless communication system, comprising:

a pilot generator operative to generate at least one pilot based on a number of layers of transmission, each of the at least one pilot being repeated across non-adjacent subbands of a first orthogonal frequency division multiplex (OFDM) symbol and further being repeated, offset from others of the at least one pilot of the first OFDM symbol, across non-adjacent subbands of an adjacent second OFDM symbol; and

a plurality of transmitter units operative to transmit each of the first and second OFDM symbols in a respective number of layer transmission via a plurality of transmit antennas, wherein the first and second OFDM symbols are placed in a slot that supports backward compatibility by retaining pilot and media access control (MAC) segments within the slot and modifying traffic segments within the slot in at least one legacy channel while pilot and MAC segments are not retained in at least one non-legacy channel.

13. The apparatus of claim 12, wherein the at least one pilot includes a first layer pilot for a single layer transmission and wherein the first layer pilot is offset across subbands of the first and second OFDM symbols.

14. The apparatus of claim 12, wherein the at least one pilot includes a first layer pilot and a second layer pilot for a two layer transmission and wherein the first and second layer pilots are offset across subbands of the first and second OFDM symbols.

15. The apparatus of claim 12, wherein the at least one pilot includes a first layer pilot, a second layer pilot and a third layer pilot for a three layer transmission and wherein the first, second and third layer pilots are offset across subbands of the first and second OFDM symbols.

16. The apparatus of claim 12, wherein the at least one pilot includes a first layer pilot, a second layer pilot, a third layer pilot and a fourth layer pilot for a four layer transmission and wherein the first, second, third and fourth layer pilots are offset across subbands of the first and second OFDM symbols.

17. The apparatus of claim 14, wherein the first and second layer pilots are alternatingly positioned in the same subbands across the first and second OFDM symbols.

18. The apparatus of claim 15, wherein the first, second and third layer pilots are alternatingly positioned in the same subbands across the first, second and a third OFDM symbols adjacent to at least one of the first and second OFDM symbols.

19. The apparatus of claim 16, wherein the first, second, third and fourth layer pilots are alternatingly positioned in the same subbands across the first, second, third and a fourth OFDM symbols adjacent to at least one of the first, second and third OFDM symbols.

20. The apparatus of claim 13, wherein the first layer pilot occupies approximately 5 percent of the subbands of each of the first and second OFDM symbols.

21. The apparatus of claim 14, wherein the first and second layer pilots occupy approximately 10 percent of the subbands of each of the first and second OFDM symbols.

22. The apparatus of claim 15, wherein the first, second and third layer pilots occupy approximately 10 percent of the subbands of each of the first and second OFDM symbols.

23. The apparatus of claim 16, wherein the first, second, third and fourth layer pilots occupy approximately 20 percent of the subbands of each of the first and second OFDM symbols.

24. An apparatus in a wireless communication system, comprising:

means for generating a first layer pilot for a single layer transmission;

means for repeating the first layer pilot across non-adjacent subbands of a first orthogonal frequency division multiplex (OFDM) symbol;

means for repeating, offset from the first layer pilot of the first OFDM symbol, the first layer pilot across non-adjacent subbands of an adjacent second OFDM symbol; and

means for transmitting the first and second OFDM symbols in the single layer transmission, wherein the first and second OFDM symbols are placed in a slot that supports backward compatibility by retaining pilot and media access control (MAO segments within the slot and modifying traffic segments within the slot in at least one legacy channel while pilot and MAC segments are not retained in at least one non-legacy channel.

25. The apparatus of claim 24, further comprising:

means for generating a second layer pilot for a two layer transmission;

means for repeating offset from the first layer pilot the second layer pilot across subbands of a first OFDM symbol;

means for repeating offset from the second layer pilot of the first OFDM symbol the second layer pilot across subbands of an adjacent second OFDM symbol; and

means for transmitting the first and second OFDM symbols in the two layer transmission.

26. The apparatus of claim 25, further comprising:

means for generating a third layer pilot for a three layer transmission;

means for repeating offset from the first and second layer pilots the third layer pilot across subbands of a first OFDM symbol;

means for repeating offset from the third layer pilot of the first OFDM symbol the third layer pilot across subbands of an adjacent second OFDM symbol; and

means for transmitting the first and second OFDM symbols in the three layer transmission.

27. The apparatus of claim 26, further comprising:

means for generating a fourth layer pilot for a four layer transmission;

means for repeating offset from the first, second and third layer pilots the fourth layer pilot across subbands of a first OFDM symbol;

means for repeating offset from the fourth layer pilot of the first OFDM symbol the fourth layer pilot across subbands of an adjacent second OFDM symbol; and

means for transmitting the first and second OFDM symbols in the four layer transmission.

28. A method of performing channel estimation in a wireless communication system, comprising:

obtaining, via a plurality of receive antennas, received symbols each including a first layer pilot with adjacent ones of the received symbols including the first layer pilot repeated in non-adjacent subbands, wherein the first layer pilot is offset in the adjacent ones of the received symbols; and

processing the received symbols based on the first layer pilot to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas, wherein the received symbols are placed in a slot that supports backward compatibility by retaining pilot and media access control (MAC) segments within the slot and modifying traffic segments within the slot in at least one legacy channel while pilot and MAC segments are not retained in at least one non-legacy channel.

29. The method of claim 28, further comprising:

obtaining, via a plurality of receive antennas, received symbols each further including a second layer pilot with adjacent ones of the received symbols including the second layer pilot offset in the subbands from each other; and

processing the received symbols based on the first and second layer pilots to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas.

30. The method of claim 29, further comprising:

obtaining, via a plurality of receive antennas, received symbols each further including a third layer pilot with adjacent ones of the received symbols including the third layer pilot offset in the subbands from each other; and

processing the received symbols based on the first, second and third layer pilots to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas.

31. The method of claim 30, further comprising:

obtaining, via a plurality of receive antennas, received symbols each further including a fourth layer pilot with adjacent ones of the received symbols including the fourth layer pilot offset in the subbands from each other; and

processing the received symbols based on the first, second, third and fourth layer pilots to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas.

32. An apparatus in a wireless communication system, comprising:

a plurality of receiver units operative to provide received symbols each including a first layer pilot with adjacent ones of the received symbols including the first layer pilot repeated in non-adjacent subbands, wherein the first layer pilot is offset in the adjacent ones of the received symbols; and

a channel estimator operative to process the received symbols based on the first layer pilot to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas, wherein the received symbols are placed in a slot that supports backward compatibility by retaining pilot and media access control (MAC) segments within the slot and modifying traffic segments within the slot in at least one legacy channel while pilot and MAC segments are not retained in at least one non-legacy channel.

33. The apparatus of claim 32, wherein the received symbols each further including a second layer pilot with adjacent ones of the received symbols including the second layer pilot offset in the subbands from each other and wherein the first and second layer pilots are processed to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas.

34. The apparatus of claim 33, wherein the received symbols each further including a third layer pilot with adjacent ones of the received symbols including the third layer pilot offset in the subbands from each other and wherein the first, second and third layer pilots are processed to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas.

35. The apparatus of claim 34, wherein the received symbols each further including a fourth layer pilot with adjacent ones of the received symbols including the fourth layer pilot offset in the subbands from each other and wherein the first, second, third and fourth layer pilots are processed to obtain estimates of a plurality of channels between the plurality of transmit antennas and the plurality of receive antennas.

36. A computer-program product for transmitting a pilot in a wireless communication system, the computer-program product comprising a non-transitory computer-readable medium having instructions thereon, the computer-readable medium comprising:

code that is executable by a processor for generating a first layer pilot for a single layer transmission;

code that is executable by the processor for repeating the first layer pilot across non-adjacent subbands of a first orthogonal frequency division multiplex (OFDM) symbol;

code that is executable by the processor for repeating, offset from the first layer pilot of the first OFDM symbol, the first layer pilot across non-adjacent subbands of an adjacent second OFDM symbol; and

code that is executable by the processor for transmitting the first and second OFDM symbols in the single layer transmission, wherein the first and second OFDM symbols are placed in a slot that supports backward compatibility by retaining pilot and media access control (MAC) segments within the slot and modifying traffic segments within the slot in at least one legacy channel while pilot and MAC segments are not retained in at least one non-legacy channel.