Code division multiplexing in a single-carrier frequency division multiple access system

• US 20070041404A1
• Filed: 05/10/2006
• Published: 02/22/2007
• Est. Priority Date: 08/08/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Palanki, Ravi, Sutivong, Arak, Khandekar, Aamod
• Granted Patent: US 8,885,628 B2
• Time in Patent Office: Days
• US Class Current: 370/479
• CPC Class Codes: H04B 1/692 Hybrid techniques using combinations of two or more spread spectrum techniques
• CPC Class Codes: H04J 1/00 Frequency-division multiplex systems H04J14/00 takes precedence
• CPC Class Codes: H04J 11/00 Orthogonal multiplex systems, e.g. using WALSH codesH04J13/00 takes precedence
• CPC Class Codes: H04J 13/10 Code generation
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 25/03866 using scrambling
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/2615 Reduction thereof using coding
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/2643 using symbol repetition, e.g. time domain realization of distributed FDMA
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management

Abstract

In a single-carrier frequency division multiple access (SC-FDMA) system that utilizes interleaved FDMA (IFDMA) or localized FDMA (LFDMA), a transmitter generates modulation symbols for different types of data (e.g., traffic data, signaling, and pilot) and performs code division multiplexing (CDM) on at least one data type. For example, the transmitter may apply CDM on signaling and/or pilot sent on frequency subbands and symbol periods that are also used by at least one other transmitter. To apply CDM to a given data type (e.g., signaling), the transmitter performs spreading on the modulation symbols for that data type with an assigned spreading code. CDM may be applied across symbols, samples, samples and symbols, frequency subbands, and so on. The transmitter may perform scrambling after the spreading. The transmitter generates SC-FDMA symbols of the same or different symbol durations for traffic data, signaling, and pilot and transmits the SC-FDMA symbols.

Claims

1. An apparatus comprising:

a processor operative to generate modulation symbols, to perform code division multiplexing (CDM) with a spreading code, and to generate single-carrier frequency division multiple access (SC-FDMA) symbols for the modulation symbols; and

a memory coupled to the processor.

2. The apparatus of claim 1, wherein the processor is operative to perform CDM for at least one symbol period used by at least two transmitters for transmission.

3. The apparatus of claim 1, wherein the processor is operative to perform scrambling with a scrambling code.

4. The apparatus of claim 3, wherein different sectors are assigned different scrambling codes.

5. The apparatus of claim 1, wherein the processor is operative to perform CDM across symbols.

6. The apparatus of claim 1, wherein the processor is operative to replicate a sequence of modulation symbols L times, to multiply L replicated sequences of modulation symbols with L chips of the spreading code to form L sequences of scaled modulation symbols, and to generate L SC-FDMA symbols for the L sequences of scaled modulation symbols, where L is the length of the spreading code.

7. The apparatus of claim 1, wherein the processor is operative to replicate each SC-FDMA symbol L times and to multiply L replicated SC-FDMA symbols with L chips of the spreading code, where L is the length of the spreading code.

8. The apparatus of claim 1, wherein the processor is operative to perform CDM across samples.

9. The apparatus of claim 1, wherein the processor is operative to replicate a sequence of at least one modulation symbol L times, to multiply L replicated sequences of at least one modulation symbol with L chips of the spreading code to form L sequences of scaled modulation symbols, and to generate an SC-FDMA symbol for the L sequences of scaled modulation symbols, where L is the length of the spreading code,.

10. The apparatus of claim 1, wherein the processor is operative to perform CDM across both symbols and samples.

11. The apparatus of claim 1, wherein the processor is operative to replicate a modulation symbol L times, to multiply the L replicated modulation symbols with L chips of the spreading code to obtain L scaled modulation symbols, and to generate at least two SC-FDMA symbols for the L scaled modulation symbols, where L is the length of the spreading code.

12. The apparatus of claim 1, wherein the processor is operative to perform CDM across frequency subbands.

13. The apparatus of claim 1, wherein at least one spreading code is not assigned to any transmitter and is reserved for interference estimation.

14. The apparatus of claim 1, wherein the processor is operative to generate modulation symbols for at least two types of data and to perform CDM for at least one type of data among the at least two types of data.

15. The apparatus of claim 1, wherein the processor is operative to generate modulation symbols for traffic data and signaling and to perform CDM for signaling.

16. The apparatus of claim 1, wherein the processor is operative to generate SC-FDMA symbols having at least two different durations.

17. The apparatus of claim 1, wherein the processor is operative to generate modulation symbols for traffic data and signaling, to generate SC-FDMA symbols having a first duration for traffic data, and to generate SC-FDMA symbols having a second duration for signaling, the second duration being shorter or longer than the first duration.

18. The apparatus of claim 1, wherein the processor is operative to generate modulation symbols for traffic data and pilot, to generate SC-FDMA symbols having a first duration for traffic data, and to generate SC-FDMA symbols having a second duration for pilot, the second duration being shorter or longer than the first duration.

19. The apparatus of claim 1, wherein the processor is operative to generate SC-FDMA symbols having a first duration for data sent without CDM and to generate SC-FDMA symbols having a second duration for data sent with CDM, the second duration being shorter or longer than the first duration.

20. The apparatus of claim 1, further comprising:

a controller operative to determine different sets of subbands to use for transmission in different time slots based on a frequency hopping pattern.

21. A method comprising:

generating modulation symbols;

performing code division multiplexing (CDM) with a spreading code; and

generating single-carrier frequency division multiple access (SC-FDMA) symbols for the modulation symbols.

22. The method of claim 21, further comprising:

performing scrambling with a scrambling code.

23. The method of claim 21, wherein the performing CDM with the spreading code comprises

performing CDM with the spreading code across symbols, across samples, or across both samples and symbols.

24. The method of claim 21, wherein the performing CDM with the spreading code comprises

performing CDM with the spreading code for at least one type of data among at least two types of data being transmitted.

25. The method of claim 21, wherein the generating the SC-FDMA symbols comprises

generating SC-FDMA symbols having at least two different durations for at least two types of data being transmitted.

26. An apparatus comprising:

means for generating modulation symbols;

means for performing code division multiplexing (CDM) with a spreading code; and

means for generating single-carrier frequency division multiple access (SC-FDMA) symbols for the modulation symbols.

27. The apparatus of claim 26, further comprising:

means for performing scrambling with a scrambling code.

28. The apparatus of claim 26, wherein the means for performing CDM with the spreading code comprises

means for performing CDM with the spreading code across symbols, across samples, or across both samples and symbols.

29. The apparatus of claim 26, wherein the means for performing CDM with the spreading code comprises

means for performing CDM with the spreading code for at least one type of data among at least two types of data being transmitted.

30. The apparatus of claim 26, wherein the means for generating the SC-FDMA symbols comprises

means for generating SC-FDMA symbols having at least two different durations for at least two types of data being transmitted.

31. An apparatus comprising:

a processor operative to receive single-carrier frequency division multiple access (SC-FDMA) symbols, to perform SC-FDMA demodulation on the SC-FDMA symbols, and to perform despreading with a spreading code for SC-FDMA symbols transmitted with code division multiplexing (CDM); and

a memory coupled to the processor.

32. The apparatus of claim 31, wherein multiple transmitters transmit SC-FDMA symbols with CDM in at least one symbol period assigned to the transmitters for transmission.

33. The apparatus of claim 31, wherein the processor is operative to perform despreading across symbols, across samples, or across both symbols and samples for the SC-FDMA symbols transmitted with CDM.

34. The apparatus of claim 31, wherein the processor is operative to perform descrambling with a scrambling code.

35. The apparatus of claim 31, wherein the processor is operative to derive an interference estimate based on at least one spreading code not assigned to any transmitter.

36. The apparatus of claim 35, wherein the processor is operative to perform data detection based on the interference estimate.

37. The apparatus of claim 35, wherein the processor is operative to derive a channel estimate with the interference estimate and to perform data detection based on the channel estimate and the interference estimate.

38. The apparatus of claim 31, wherein the processor is operative to obtain despread symbols for multiple antennas, to combine the despread symbols across the multiple antennas, and to perform data detection after combining across the multiple antennas.

39. The apparatus of claim 31, wherein the processor is operative to perform receiver spatial processing for SC-FDMA symbols transmitted without CDM by at least two transmitters in a symbol period.

40. The apparatus of claim 31, further comprising:

a controller operative to determine different sets of subbands used for transmission in different time slots based on a frequency hopping pattern.

41. A method comprising:

receiving single-carrier frequency division multiple access (SC-FDMA) symbols;

performing SC-FDMA demodulation on the SC-FDMA symbols; and

performing despreading with a spreading code for SC-FDMA symbols transmitted with code division multiplexing (CDM).

42. The method of claim 41, wherein the performing despreading with the spreading code comprises

performing despreading with the spreading code across symbols, across samples, or across both symbols and samples for the SC-FDMA symbols transmitted with CDM.

43. The method of claim 41, further comprising:

performing descrambling with a scrambling code.

44. The method of claim 41, further comprising:

deriving an interference estimate based on at least one spreading code not assigned to any transmitter.

45. An apparatus comprising:

means for receiving single-carrier frequency division multiple access (SC-FDMA) symbols;

means for performing SC-FDMA demodulation on the SC-FDMA symbols; and

means for performing despreading with a spreading code for SC-FDMA symbols transmitted with code division multiplexing (CDM).

46. The apparatus of claim 45, further comprising:

means for performing descrambling with a scrambling code.

47. The apparatus of claim 45, wherein the means for performing despreading with the spreading code comprises

means for performing despreading with the spreading code across symbols, across samples, or across both symbols and samples for the SC-FDMA symbols transmitted with CDM.

48. The apparatus of claim 45, further comprising:

means for deriving an interference estimate based on at least one spreading code not assigned to any transmitter.