Method and apparatus for mutiplexing reference signal and data in a wireless communication system

• US 9,137,076 B2
• Filed: 10/27/2010
• Issued: 09/15/2015
• Est. Priority Date: 10/30/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Luo, Xiliang, Montojo, Juan, Gaal, Peter, Palanki, Ravi
• Primary Examiner(s): Patel, Jay P
• Application Number:
  US12/913,684
• Publication Number:
  US 20110128909A1
• Time in Patent Office: 1,784 Days
• Field of Search: 370/329, 370/341
• US Class Current: 1/1
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26134 Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal

Abstract

Techniques for efficiently multiplexing a reference signal and data on different sets of subcarriers in the same symbol period are described. In one design, a user equipment (UE) performs a discrete Fourier transform (DFT) on a set of modulation symbols for data to obtain data symbols. The UE also obtains reference symbols generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence. The UE maps the reference symbols to a first set of subcarriers and maps the data symbols to a second set of subcarriers. The UE then generates a transmission symbol based on the mapped reference symbols and the mapped data symbols. The UE may also transmit reference signals and data (i) in multiple symbol periods of a slot or a subframe and/or (ii) from multiple antennas using frequency division multiplexing (FDM) or code division multiplexing (CDM).

Claims

1. A method for wireless communication, comprising:

obtaining reference symbols generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence;

mapping the reference symbols to a first set of subcarriers in a symbol period;

mapping data symbols to a second set of subcarriers in the symbol period; and

generating a transmission symbol based on the mapped reference symbols and the mapped data symbols.

2. The method of claim 1, further comprising:

performing a discrete Fourier transform (DFT) on a set of modulation symbols for data to obtain the data symbols for the second set of subcarriers.

3. The method of claim 1, further comprising:

receiving an assignment of M subcarriers, wherein the first set of subcarriers includes one subcarrier out of every S subcarriers among the M subcarriers, where M is greater than S, and S is greater than one.

4. The method of claim 3, wherein the second set of subcarriers includes at least one subcarrier among the M subcarriers and excludes subcarriers used to transmit reference symbols.

5. The method of claim 1, further comprising:

mapping second reference symbols to a third set of subcarriers in a second symbol period;

mapping second data symbols to a fourth set of subcarriers in the second symbol period; and

generating a second transmission symbol based on the mapped second reference symbols and the mapped second data symbols.

6. The method of claim 5, wherein the symbol period and the second symbol period correspond to two symbol periods of a slot.

7. The method of claim 5, wherein the third set of subcarriers is staggered with respect to the first set of subcarriers.

8. The method of claim 1, further comprising:

mapping second reference symbols to a third set of subcarriers in the symbol period;

mapping second data symbols to a fourth set of subcarriers in the symbol period;

generating a second transmission symbol based on the mapped second reference symbols and the mapped second data symbols;

transmitting the transmission symbol via a first antenna; and

transmitting the second transmission symbol via a second antenna.

9. The method of claim 8, wherein reference signals for the first and second antennas are frequency division multiplexed, and wherein the third set of subcarriers includes subcarriers not included in the first set of subcarriers.

10. The method of claim 8, wherein reference signals for the first and second antennas are code division multiplexed, wherein the second reference symbols are generated based on a second reference signal sequence corresponding to a second cyclic shift of the base sequence, and wherein the first set of subcarriers is equal to the third set of subcarriers.

11. The method of claim 8, further comprising:

receiving an assignment of M subcarriers, wherein the second set of subcarriers is equal to the fourth set of subcarriers, and wherein the second and fourth sets of subcarriers each includes at least one subcarrier among the M subcarriers and excludes subcarriers used to transmit reference symbols.

12. The method of claim 1, wherein the reference symbols are for a demodulation reference signal (DMRS) used to demodulate the data symbols.

13. The method of claim 1, wherein the reference signal sequence has a length of P and includes P reference symbols, where P is the number of subcarriers in the first set of subcarriers.

14. The method of claim 1, wherein the base sequence comprises a Zadoff-Chu sequence or a computer-generated sequence.

15. An apparatus for wireless communication, comprising:

means for obtaining reference symbols generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence;

means for mapping the reference symbols to a first set of subcarriers in a symbol period;

means for mapping data symbols to a second set of subcarriers in the symbol period; and

means for generating a transmission symbol based on the mapped reference symbols and the mapped data symbols.

16. The apparatus of claim 15, further comprising:

means for performing a discrete Fourier transform (DFT) on a set of modulation symbols for data to obtain the data symbols for the second set of subcarriers.

17. The apparatus of claim 15, further comprising:

means for mapping second reference symbols to a third set of subcarriers in a second symbol period, wherein the symbol period and the second symbol period correspond to two symbol periods of a slot;

means for mapping second data symbols to a fourth set of subcarriers in the second symbol period; and

means for generating a second transmission symbol based on the mapped second reference symbols and the mapped second data symbols.

18. The apparatus of claim 15, further comprising:

means for mapping second reference symbols to a third set of subcarriers in the symbol period;

means for mapping second data symbols to a fourth set of subcarriers in the symbol period;

means for generating a second transmission symbol based on the mapped second reference symbols and the mapped second data symbols;

means for transmitting the transmission symbol via a first antenna; and

means for transmitting the second transmission symbol via a second antenna.

19. The apparatus of claim 18, wherein reference signals for the first and second antennas are frequency division multiplexed, and wherein the third set of subcarriers includes subcarriers not included in the first set of subcarriers.

20. The apparatus of claim 18, wherein reference signals for the first and second antennas are code division multiplexed, wherein the second reference symbols are generated based on a second reference signal sequence corresponding to a second cyclic shift of the base sequence, and wherein the first set of subcarriers is equal to the third set of subcarriers.

21. An apparatus for wireless communication comprising:

at least one processor configured to obtain reference symbols generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence, to map the reference symbols to a first set of subcarriers in a symbol period, to map data symbols to a second set of subcarriers in the symbol period, and to generate a transmission symbol based on the mapped reference symbols and the mapped data symbols,

a transceiver configured to transmit the generated transmission symbol.

22. A non-transitory computer-readable medium comprising:

code for causing at least one processor to obtain reference symbols generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence,

code for causing the at least one processor to map the reference symbols to a first set of subcarriers in a symbol period,

code for causing the at least one processor to map data symbols to a second set of subcarriers in the symbol period, and

code for causing the at least one processor to generate a transmission symbol based on the mapped reference symbols and the mapped data symbols.

23. A method for wireless communication, comprising:

receiving a transmission symbol in a symbol period, the transmission symbol comprising reference symbols mapped to a first set of subcarriers and data symbols mapped to a second set of subcarriers, the reference symbols being generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence;

processing the received transmission symbol to obtain received reference symbols from the first set of subcarriers and received data symbols from the second set of subcarriers;

processing the received reference symbols to obtain a channel estimate; and

processing the received data symbols based on the channel estimate to obtain demodulated data symbols.

24. The method of claim 23, further comprising:

performing an inverse discrete Fourier transform (IDFT) on the demodulated data symbols to obtain received modulation symbols; and

processing the received modulation symbols to recover data transmitted on the second set of subcarriers.

25. The method of claim 23, further comprising:

sending an assignment of M subcarriers to a user equipment (UE), wherein the first set of subcarriers includes one subcarrier out of every S subcarriers among the M subcarriers, where M is greater than S, and S is greater than one.

26. The method of claim 25, wherein the second set of subcarriers includes at least one subcarrier among the M subcarriers and excludes subcarriers used to transmit reference symbols.

27. The method of claim 23, further comprising:

receiving a second transmission symbol in a second symbol period, the second transmission symbol comprising second reference symbols mapped to a third set of subcarriers and second data symbols mapped to a fourth set of subcarriers;

processing the received second transmission symbol to obtain received second reference symbols from the third set of subcarriers and received second data symbols from the fourth set of subcarriers;

processing the received second reference symbols to obtain a second channel estimate; and

processing the received second data symbols based on the second channel estimate to obtain demodulated second data symbols.

28. The method of claim 27, wherein the symbol period and the second symbol period correspond to two symbol periods of a slot.

29. The method of claim 27, wherein the third set of subcarriers is staggered with respect to the first set of subcarriers.

30. The method of claim 23, further comprising:

receiving a second transmission symbol in the symbol period, the second transmission symbol comprising second reference symbols mapped to a third set of subcarriers and second data symbols mapped to a fourth set of subcarriers, the transmission symbol being transmitted via a first antenna and the second transmission symbol being transmitted via a second antenna at a user equipment (UE);

processing the received second transmission symbol to obtain received second reference symbols from the third set of subcarriers and received second data symbols from the fourth set of subcarriers;

processing the received second reference symbols to obtain a second channel estimate; and

processing the received data symbols and the received second data symbols based on the channel estimate and the second channel estimate to obtain the demodulated data symbols and demodulated second data symbols.

31. The method of claim 30, wherein reference signals for the first and second antennas at the UE are frequency division multiplexed, and wherein the third set of subcarriers includes subcarriers not included in the first set of subcarriers.

32. The method of claim 30, wherein reference signals for the first and second antennas at the UE are code division multiplexed, wherein the second reference symbols are generated based on a second reference signal sequence corresponding to a second cyclic shift of the base sequence, and wherein the third set of subcarriers is equal to the first set of subcarriers.

33. An apparatus for wireless communication, comprising:

means for receiving a transmission symbol in a symbol period, the transmission symbol comprising reference symbols mapped to a first set of subcarriers and data symbols mapped to a second set of subcarriers, the reference symbols being generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence;

means for processing the received transmission symbol to obtain received reference symbols from the first set of subcarriers and received data symbols from the second set of subcarriers;

means for processing the received reference symbols to obtain a channel estimate; and

means for processing the received data symbols based on the channel estimate to obtain demodulated data symbols.

34. The apparatus of claim 33, further comprising:

means for performing an inverse discrete Fourier transform (IDFT) on the demodulated data symbols to obtain received modulation symbols; and

means for processing the received modulation symbols to recover data transmitted on the second set of subcarriers.

35. The apparatus of claim 33, further comprising:

means for receiving a second transmission symbol in a second symbol period, the second transmission symbol comprising second reference symbols mapped to a third set of subcarriers and second data symbols mapped to a fourth set of subcarriers, the symbol period and the second symbol period corresponding to two symbol periods of a slot;

means for processing the received second transmission symbol to obtain received second reference symbols from the third set of subcarriers and received second data symbols from the fourth set of subcarriers;

means for processing the received second reference symbols to obtain a second channel estimate; and

means for processing the received second data symbols based on the second channel estimate to obtain demodulated second data symbols.

36. The apparatus of claim 33, further comprising:

means for receiving a second transmission symbol in the symbol period, the second transmission symbol comprising second reference symbols mapped to a third set of subcarriers and second data symbols mapped to a fourth set of subcarriers, the transmission symbol being transmitted via a first antenna and the second transmission symbol being transmitted via a second antenna at a user equipment (UE);

means for processing the received second transmission symbol to obtain received second reference symbols from the third set of subcarriers and received second data symbols from the fourth set of subcarriers;

means for processing the received second reference symbols to obtain a second channel estimate; and

means for processing the received data symbols and the received second data symbols based on the channel estimate and the second channel estimate to obtain the demodulated data symbols and demodulated second data symbols.

37. The apparatus of claim 36, wherein reference signals for the first and second antennas at the UE are frequency division multiplexed, and wherein the third set of subcarriers includes subcarriers not included in the first set of subcarriers.

38. The apparatus of claim 36, wherein reference signals for the first and second antennas at the UE are code division multiplexed, wherein the second reference symbols are generated based on a second reference signal sequence corresponding to a second cyclic shift of the base sequence, and wherein the third set of subcarriers is equal to the first set of subcarriers.

39. An apparatus for wireless communication comprising:

a transceiver configured to receive a transmission symbol in a symbol period, the transmission symbol comprising reference symbols mapped to a first set of subcarriers and data symbols mapped to a second set of subcarriers, the reference symbols being generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence,

at least one processor configured to process the received transmission symbol to obtain received reference symbols from the first set of subcarriers and received data symbols from the second set of subcarriers, to process the received reference symbols to obtain a channel estimate, and to process the received data symbols based on the channel estimate to obtain demodulated data symbols.

40. A non-transitory computer-readable medium comprising:

code for causing at least one processor to receive a transmission symbol in a symbol period, the transmission symbol comprising reference symbols mapped to a first set of subcarriers and data symbols mapped to a second set of subcarriers, the reference symbols being generated based on a reference signal sequence corresponding to a cyclic shift of a base sequence,

code for causing the at least one processor to process the received transmission symbol to obtain received reference symbols from the first set of subcarriers and received data symbols from the second set of subcarriers,

code for causing the at least one processor to process the received reference symbols to obtain a channel estimate, and

code for causing the at least one processor to process the received data symbols based on the channel estimate to obtain demodulated data symbols.