FLEXIBLE TIME-FREQUENCY MULTIPLEXING STRUCTURE FOR WIRELESS COMMUNICATION

• US 20070195690A1
• Filed: 02/20/2007
• Published: 08/23/2007
• Est. Priority Date: 02/21/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gorokhov, Alexei, Bhushan, Naga
• Granted Patent: US 8,077,595 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• 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 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated

Abstract

Techniques for efficiently sending data in a wireless communication system are described. Code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) may be selected for each traffic segment, which may correspond to specific time frequency resources. An output waveform comprised of traffic and overhead segments may be generated. Each traffic segment may carry CDM data at a chip rate if CDM is selected or OFDM data if OFDM is selected. OFDM symbols may be generated at a sample rate that may be an integer ratio of the chip rate and may have a duration that may be determined based on the traffic segment duration. The output waveform may carry CDM data and/or OFDM data on subcarriers corresponding to at least one carrier in a spectral allocation and may further carry OFDM data on remaining usable subcarriers in the spectral allocation.

Claims

1. An apparatus comprising:

at least one processor to select code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) for each of at least one traffic segment, and to generate an output waveform comprised of the at least one traffic segment, each traffic segment carrying CDM data if CDM is selected for the traffic segment or OFDM data if OFDM is selected for the traffic segment; and

a memory coupled to the at least one processor.

2. The apparatus of claim 1, wherein the at least one processor generates at least one overhead segment with overhead data and generates the output waveform comprised of the at least one traffic segment and the at least one overhead segment.

3. The apparatus of claim 1, wherein the at least one processor selects CDM or OFDM for each of first and second traffic segments and generates the output waveform comprised of the first and second traffic segments and an overhead segment, each of the first and second traffic segments carrying CDM data or OFDM data, and the overhead segment carrying overhead data.

4. The apparatus of claim 1, wherein the at least one processor selects CDM or OFDM for each of multiple traffic segments for multiple carriers, and generates the output waveform comprised of the multiple traffic segments for the multiple carriers, each traffic segment carrying CDM data or OFDM data.

5. The apparatus of claim 4, wherein the at least one processor generates multiple overhead segments with overhead data for the multiple carriers, and generates the output waveform comprised of the multiple traffic segments and the multiple overhead segments for the multiple carriers.

6. The apparatus of claim 1, wherein the at least one processor generates a first waveform comprised of traffic segments carrying CDM data, generates a second waveform comprised of traffic segments carrying OFDM data, and generates the output waveform based on the first and second waveforms.

7. The apparatus of claim 1, wherein the at least one processor maps CDM data to subcarriers used for traffic segments carrying CDM data, maps OFDM data to subcarriers used for traffic segments carrying OFDM data, and generates the output waveform based on the mapped CDM data and OFDM data.

8. The apparatus of claim 1, wherein each traffic segment carries CDM data or OFDM data for unicast data sent to at least one terminal.

9. A method comprising:

selecting code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) for each of at least one traffic segment; and

generating an output waveform comprised of the at least one traffic segment, each traffic segment carrying CDM data if CDM is selected for the traffic segment or OFDM data if OFDM is selected for the traffic segment.

10. The method of claim 9, wherein the selecting CDM or OFDM comprises selecting CDM or OFDM for each of first and second traffic segments, and wherein the generating the output waveform comprises generating the output waveform comprised of the first and second traffic segments and an overhead segment, each of the first and second traffic segments carrying CDM data or OFDM data, and the overhead segment carrying overhead data.

11. An apparatus comprising:

means for selecting code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) for each of at least one traffic segment; and

means for generating an output waveform comprised of the at least one traffic segment, each traffic segment carrying CDM data if CDM is selected for the traffic segment or OFDM data if OFDM is selected for the traffic segment.

12. The apparatus of claim 11, wherein the means for selecting CDM or OFDM comprises means for selecting CDM or OFDM for each of first and second traffic segments, and wherein the means for generating the output waveform comprises means for generating the output waveform comprised of the first and second traffic segments and an overhead segment, each of the first and second traffic segments carrying CDM data or OFDM data, and the overhead segment carrying overhead data.

13. An apparatus comprising:

at least one processor to select code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) for a traffic interval, to generate CDM data at a chip rate and to send the CDM data in the traffic interval if CDM is selected, and to generate at least one OFDM symbol at a sample rate and to send the at least one OFDM symbol in the traffic interval if OFDM is selected, the sample rate being related to the chip rate by an integer ratio, and each OFDM symbol having a duration determined based on duration of the traffic interval; and

a memory coupled to the at least one processor.

14. The apparatus of claim 13, wherein the at least one processor generates the CDM data at a chip rate of 1.2288 mega chips/second (Mcps) if CDM is selected, and generates the at least one OFDM symbol at a sample rate of 1.2288×

n mega samples/second (Msps) if OFDM is selected, where n is the integer ratio.

15. The apparatus of claim 13, wherein the at least one processor generates multiple OFDM symbols for the traffic interval if OFDM is selected, each OFDM symbol having a duration that is an integer divisor of the duration of the traffic interval.

16. The apparatus of claim 15, wherein the traffic interval spans 400 chips, and wherein each OFDM symbol has duration of 400/m chips, where m is the integer divisor.

17. The apparatus of claim 13, wherein each OFDM symbol covers K subcarriers, where K is an integer that is not a power of two.

18. The apparatus of claim 13, wherein the at least one processor generates overhead data in accordance with CDM at the chip rate and time division multiplexes the overhead data in an overhead interval and the CDM data or the at least one OFDM symbol in the traffic interval.

19. The apparatus of claim 13, wherein the at least one processor generates CDM data at the chip rate for at least one carrier in a spectral allocation, and generates the at least one OFDM symbol at the sample rate for remaining usable subcarriers in the spectral allocation.

20. The apparatus of claim 19, wherein the at least one processor generates overhead data in accordance with CDM at the chip rate, generates at least one long OFDM symbol at the sample rate, each long OFDM symbol having a duration determined based on duration of an overhead interval, and sends the overhead data and the at least one long OFDM symbol in the overhead interval.

21. The apparatus of claim 19, wherein the at least one processor generates a first waveform comprising the CDM data for the at least one carrier, generates a second waveform comprising the at least one OFDM symbol for the remaining usable subcarriers, and generates an output waveform based on the first and second waveforms.

22. A method comprising:

selecting code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) for a traffic interval;

generating CDM data at a chip rate and sending the CDM data in the traffic interval if CDM is selected; and

generating at least one OFDM symbol at a sample rate and sending the at least one OFDM symbol in the traffic interval if OFDM is selected, the sample rate being related to the chip rate by an integer ratio, and each OFDM symbol having a duration determined based on duration of the traffic interval.

23. The method of claim 22, further comprising:

generating overhead data in accordance with CDM at the chip rate;

generating at least one long OFDM symbol at the sample rate, each long OFDM symbol having a duration determined based on duration of an overhead interval; and

sending the overhead data and the at least one long OFDM symbol in the overhead interval.

24. An apparatus comprising:

means for selecting code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) for a traffic interval;

means for generating CDM data at a chip rate and sending the CDM data in the traffic interval if CDM is selected; and

means for generating at least one OFDM symbol at a sample rate and sending the at least one OFDM symbol in the traffic interval if OFDM is selected, the sample rate being related to the chip rate by an integer ratio, and each OFDM symbol having a duration determined based on duration of the traffic interval.

25. The apparatus of claim 24, further comprising:

means for generating overhead data in accordance with CDM at the chip rate;

means for generating at least one long OFDM symbol at the sample rate, each long OFDM symbol having a duration determined based on duration of an overhead interval; and

means for sending the overhead data and the at least one long OFDM symbol in the overhead interval.

26. An apparatus comprising:

at least one processor to determine a first set of subcarriers corresponding to at least one carrier in a spectral allocation, to determine a second set of subcarriers corresponding to remaining usable subcarriers in the spectral allocation, and to generate an output waveform comprising code division multiplexing (CDM) data or orthogonal frequency division multiplexing (OFDM) data or both CDM data and OFDM data on the first set of subcarriers and further comprising OFDM data on the second set of subcarriers; and

a memory coupled to the at least one processor.

27. The apparatus of claim 26, wherein the at least one processor generates the output waveform comprising CDM data or OFDM data on subcarriers corresponding to each of the at least one carrier and further comprising OFDM data on the second set of subcarriers.

28. The apparatus of claim 27, wherein the at least one processor generates the output waveform further comprising overhead data for the at least one carrier in an overhead interval.

29. The apparatus of claim 28, wherein the at least one processor determines a third set of subcarriers corresponding to remaining usable subcarriers in the overhead interval, and generates the output waveform further comprising OFDM data on the third set of subcarriers in the overhead interval.

30. The apparatus of claim 26, wherein the at least one carrier comprises multiple carriers, and wherein the at least one processor generates the output waveform comprising CDM data or OFDM data on subcarriers corresponding to each of the multiple carriers and further comprising OFDM data on the second set of subcarriers.

31. The apparatus of claim 30, wherein the at least one processor determines at least one null subcarrier between a carrier with CDM data and an adjacent carrier with OFDM data, and wherein the first set of subcarriers excludes null subcarriers between the multiple carriers.

32. A method comprising:

determining a first set of subcarriers corresponding to at least one carrier in a spectral allocation;

determining a second set of subcarriers corresponding to remaining usable subcarriers in the spectral allocation; and

generating an output waveform comprising code division multiplexing (CDM) data or orthogonal frequency division multiplexing (OFDM) data or both CDM data and OFDM data on the first set of subcarriers and further comprising OFDM data on the second set of subcarriers.

33. The method of claim 32, wherein the generating the output waveform comprises generating the output waveform further comprising overhead data for at least one carrier and OFDM data on a third set of subcarriers in an overhead interval.

34. An apparatus comprising:

means for determining a first set of subcarriers corresponding to at least one carrier in a spectral allocation;

means for determining a second set of subcarriers corresponding to remaining usable subcarriers in the spectral allocation; and

means for generating an output waveform comprising code division multiplexing (CDM) data or orthogonal frequency division multiplexing (OFDM) data or both CDM data and OFDM data on the first set of subcarriers and further comprising OFDM data on the second set of subcarriers.

35. The apparatus of claim 34, wherein the means for generating the output waveform comprises means for generating the output waveform further comprising overhead data for at least one carrier and OFDM data on a third set of subcarriers in an overhead interval.

36. An apparatus comprising:

at least one processor to generate a first set of at least one orthogonal frequency division multiplexing (OFDM) symbol in accordance with a first OFDM symbol numerology for a first terminal, and to generate a second set of at least one OFDM symbol in accordance with a second OFDM symbol numerology for a second terminal; and

a memory coupled to the at least one processor.

37. The apparatus of claim 36, wherein the at least one processor generates overhead data in accordance with code division multiplexing (CDM), and time division multiplexes the first set of at least one OFDM symbol in a first time interval, the second set of at least one OFDM symbol in a second time interval, and the overhead data in a third interval.

38. The apparatus of claim 36, wherein the first and second OFDM symbol numerologies are associated with different OFDM symbol durations.

39. The apparatus of claim 36, wherein the first and second OFDM symbol numerologies are associated with different numbers of subcarriers.

40. The apparatus of claim 36, wherein the first and second OFDM symbol numerologies are associated with different cyclic prefix lengths.

41. A method comprising:

generating a first set of at least one orthogonal frequency division multiplexing (OFDM) symbol in accordance with a first OFDM symbol numerology for a first terminal; and

generating a second set of at least one OFDM symbol in accordance with a second OFDM symbol numerology for a second terminal.

42. The method of claim 41, further comprising:

generating overhead data in accordance with code division multiplexing (CDM); and

time division multiplexing the first set of at least one OFDM symbol in a first time interval, the second set of at least one OFDM symbol in a second time interval, and the overhead data in a third interval.

43. An apparatus comprising:

means for generating a first set of at least one orthogonal frequency division multiplexing (OFDM) symbol in accordance with a first OFDM symbol numerology for a first terminal; and

means for generating a second set of at least one OFDM symbol in accordance with a second OFDM symbol numerology for a second terminal.

44. The apparatus of claim 43, further comprising:

means for generating overhead data in accordance with code division multiplexing (CDM); and

means for time division multiplexing the first set of at least one OFDM symbol in a first time interval, the second set of at least one OFDM symbol in a second time interval, and the overhead data in a third interval.

45. An apparatus comprising:

at least one processor to determine whether code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) is used for a traffic segment, to process received samples to recover CDM data sent in the traffic segment if CDM is used, and to process the received samples to recover OFDM data sent in the traffic segment if OFDM is used; and

a memory coupled to the at least one processor.

46. The apparatus of claim 45, wherein the at least one processor processes the received samples to recover overhead data in an overhead segment that is time division multiplexed with the traffic segment.

47. The apparatus of claim 45, wherein to recover the OFDM data the at least one processor processes the received samples to obtain received symbols for subcarriers used for the traffic segment, and processes the received symbols to recover the OFDM data sent in the traffic segment.

48. The apparatus of claim 45, wherein to recover the CDM data the at least one processor filters the received samples to obtain filtered samples for subcarriers used for the traffic segment, processes the filtered samples to obtain input samples for the traffic segment, decovers the input samples with multiple orthogonal codes to obtain received symbols, and processes the received symbols to recover the CDM data sent in the traffic segment.

49. The apparatus of claim 45, wherein to recover the CDM data the at least one processor processes the received samples to obtain frequency-domain symbols for a plurality of subcarriers, processes frequency-domain symbols for subcarriers used for the traffic segment to obtain time-domain samples, decovers the time-domain samples with multiple orthogonal codes to obtain received symbols, and processes the received symbols to recover the CDM data sent in the traffic segment.

50. A method comprising:

determining whether code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) is used for a traffic segment;

processing received samples to recover CDM data sent in the traffic segment if CDM is used; and

processing the received samples to recover OFDM data sent in the traffic segment if OFDM is used.

51. The method of claim 50, further comprising:

processing the received samples to recover overhead data in an overhead segment that is time division multiplexed with the traffic segment.

52. An apparatus comprising:

means for determining whether code division multiplexing (CDM) or orthogonal frequency division multiplexing (OFDM) is used for a traffic segment;

means for processing received samples to recover CDM data sent in the traffic segment if CDM is used; and

means for processing the received samples to recover OFDM data sent in the traffic segment if OFDM is used.

53. The apparatus of claim 52, further comprising:

means for processing the received samples to recover overhead data in an overhead segment that is time division multiplexed with the traffic segment.