Frequency division multiple access schemes for wireless communication

• US 20070115795A1
• Filed: 01/04/2006
• Published: 05/24/2007
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Palanki, Ravi, Gore, Dhananjay
• Granted Patent: US 8,582,548 B2
• Time in Patent Office: Days
• US Class Current: 370/203
• CPC Class Codes: H04B 1/00 Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 7/2621 using frequency division multiple access [FDMA] H04B7/2615 takes precedence
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

Techniques for transmitting data using single-carrier frequency division multiple access (SC-FDMA) multiplexing schemes are described. In one aspect, data is sent on sets of adjacent subbands that are offset from one another to achieve frequency diversity. A terminal may be assigned a set of N adjacent subbands that is offset by less than N (e.g., N/2) subbands from another set of N adjacent subbands assigned to another terminal and would then observe interference on only subbands that overlap. In another aspect, a multi-carrier transmission symbol is generated with multi-carrier SC-FDMA. Multiple waveforms carrying modulation symbols in the time domain on multiple sets of subbands are generated. The multiple waveforms are pre-processed (e.g., cyclically delayed by different amounts) to obtain pre-processed waveforms, which are combined (e.g., added) to obtain a composite waveform. A cyclic prefix is appended to the composite waveform to generate the multi-carrier transmission symbol.

Claims

1. An apparatus comprising:

at least one processor configured to generate a transmission symbol carrying a set of modulation symbols in time domain on a first set of N adjacent subbands assigned to a first terminal, wherein the first set of N subbands is offset by less than N subbands from a second set of N adjacent subbands assigned to a second terminal, and wherein N is an integer greater than one; and

a memory coupled to the at least one processor.

2. The apparatus of claim 1, wherein the first set of N subbands is offset by N/2 subbands from the second set of N subbands.

3. The apparatus of claim 1, wherein the first set of N subbands is offset by less than N subbands from a third set of N adjacent subbands assigned to a third terminal, and wherein the second set of N subbands is offset by less than N subbands from the third set of N subbands.

4. The apparatus of claim 1, wherein the first and second terminals are in two sectors in a communication system.

5. The apparatus of claim 1, wherein the first and second terminals are in a single sector in a communication system.

6. The apparatus of claim 1, wherein the at least one processor is configured to transform the set of modulation symbols to frequency domain to obtain a first sequence of frequency domain values, to map the frequency domain values in the first sequence on the N subbands in the first set to obtain a second sequence, and to generate the transmission symbol with the second sequence.

7. The apparatus of claim 1, wherein the at least one processor is configured to map the set of modulation symbols to evenly spaced sample locations in a first sequence, to transform the first sequence to frequency domain to obtain a second sequence of frequency domain values, to zero out frequency domain values in the second sequence for subbands not included in the first set to obtain a third sequence, and to generate the transmission symbol with the third sequence.

8. A method comprising:

determining a first set of N adjacent subbands assigned to a first terminal, wherein the first set of N subbands is offset by less than N subbands from a second set of N adjacent subbands assigned to a second terminal, and wherein N is an integer greater than one; and

generating a transmission symbol carrying a set of modulation symbols in time domain on the first set of N subbands.

9. The method of claim 8, wherein the generating the transmission symbol comprises

transforming the set of modulation symbols to frequency domain to obtain a first sequence of frequency domain values,

mapping the frequency domain values in the first sequence on the N subbands in the first set to obtain a second sequence, and

generating the transmission symbol with the second sequence.

10. An apparatus comprising:

means for determining a first set of N adjacent subbands assigned to a first terminal, wherein the first set of N subbands is offset by less than N subbands from a second set of N adjacent subbands assigned to a second terminal, and wherein N is an integer greater than one; and

means for generating a transmission symbol carrying a set of modulation symbols in time domain on the first set of N subbands.

11. The apparatus of claim 10, wherein the means for generating the transmission symbol comprises

means for transforming the set of modulation symbols to frequency domain to obtain a first sequence of frequency domain values,

means for mapping the frequency domain values in the first sequence on the N subbands in the first set to obtain a second sequence, and

means for generating the transmission symbol with the second sequence.

12. An apparatus comprising:

at least one processor configured to generate multiple waveforms carrying modulation symbols in time domain on multiple sets of subbands, to pre-process the multiple waveforms to obtain multiple pre-processed waveforms, and to generate a transmission symbol with the multiple pre-processed waveforms; and

a memory coupled to the at least one processor.

13. The apparatus of claim 12, wherein the at least one processor is configured to cyclically delay the multiple waveforms by different amounts.

14. The apparatus of claim 12, wherein the at least one processor is configured to generate two waveforms carrying modulation symbols on two sets of subbands.

15. The apparatus of claim 14, wherein the two waveforms include first and second waveforms, and wherein the at least one processor is configured to cyclically delay the first waveform by zero sample and to cyclically delay the second waveform by K/(2N) samples, where K is the total number of subbands and N is the number of subbands in each of the two sets.

16. The apparatus of claim 12, wherein the at least one processor is configured to filter the multiple waveforms with a set of at least one filter.

17. The apparatus of claim 16, wherein the at least one processor is configured to select the set of at least one filter from among multiple sets of at least one filter.

18. The apparatus of claim 16, wherein the at least one processor is configured to select the set of at least one filter to achieve a low peak-to-average power ratio (PAPR) for the transmission symbol.

19. The apparatus of claim 12, wherein the at least one processor is configured to transform multiple sets of modulation symbols to frequency domain to obtain multiple sets of frequency domain values, to map the multiple sets of frequency domain values to the multiple sets of subbands to generate multiple sequences, and to transform the multiple sequences to time domain to generate the multiple waveforms.

20. The apparatus of claim 12, wherein the at least one processor is configured to combine the multiple pre-processed waveforms to obtain a composite waveform, and to append a cyclic prefix to the composite waveform to generate the transmission symbol.

21. The apparatus of claim 12, wherein each of the multiple sets of subbands includes multiple adjacent subbands.

22. The apparatus of claim 12, wherein each of the multiple sets of subbands includes multiple subbands distributed across a plurality of subbands.

23. The apparatus of claim 12, wherein each of the multiple sets of subbands includes multiple groups of subbands.

24. A method comprising:

generating multiple waveforms carrying modulation symbols in time domain on multiple sets of subbands;

pre-processing the multiple waveforms to obtain multiple pre-processed waveforms; and

generating a transmission symbol with the multiple pre-processed waveforms.

25. The method of claim 24, wherein the generating the multiple waveforms comprises

transforming multiple sets of modulation symbols to frequency domain to obtain multiple sets of frequency domain values,

mapping the multiple sets of frequency domain values to the multiple sets of subbands to generate multiple sequences, and

transforming the multiple sequences to time domain to generate the multiple waveforms.

26. The method of claim 24, wherein the pre-processing the multiple waveforms comprises

cyclically delaying the multiple waveforms by different amounts.

27. The method of claim 24, wherein the generating the transmission symbol comprises

combining the multiple pre-processed waveforms to obtain a composite waveform, and

appending a cyclic prefix to the composite waveform to generate the transmission symbol.

28. An apparatus comprising:

means for generating multiple waveforms carrying modulation symbols in time domain on multiple sets of subbands;

means for pre-processing the multiple waveforms to obtain multiple pre-processed waveforms; and

means for generating a transmission symbol with the multiple pre-processed waveforms.

29. The apparatus of claim 28, wherein the means for generating the multiple waveforms comprises

means for transforming multiple sets of modulation symbols to frequency domain to obtain multiple sets of frequency domain values,

means for mapping the multiple sets of frequency domain values to the multiple sets of subbands to generate multiple sequences, and

means for transforming the multiple sequences to time domain to generate the multiple waveforms.

30. The apparatus of claim 28, wherein the means for pre-processing the multiple waveforms comprises

means for cyclically delaying the multiple waveforms by different amounts.

31. The apparatus of claim 28, wherein the means for generating the transmission symbol comprises

means for combining the multiple pre-processed waveforms to obtain a composite waveform, and

means for appending a cyclic prefix to the composite waveform to generate the transmission symbol.

32. An apparatus comprising:

at least one processor configured to receive a transmission symbol comprised of multiple waveforms carrying multiple sets of modulation symbols on multiple sets of subbands, wherein the multiple waveforms are pre-processed and combined to form the transmission symbol, to transform the received transmission symbol to frequency domain to obtain multiple sets of frequency-domain values for the multiple sets of subbands, and to transform the multiple sets of frequency-domain values to time domain to obtain estimates for the multiple sets of modulation symbols; and

a memory coupled to the at least one processor.

33. The apparatus of claim 32, wherein the at least one processor is configured to filter the multiple sets of frequency-domain values with a set of at least one filter.

34. An apparatus comprising:

means for receiving a transmission symbol comprised of multiple waveforms carrying multiple sets of modulation symbols on multiple sets of subbands, wherein the multiple waveforms are pre-processed and combined to form the transmission symbol;

means for transforming the received transmission symbol to frequency domain to obtain multiple sets of frequency-domain values for the multiple sets of subbands; and

means for transforming the multiple sets of frequency-domain values to time domain to obtain estimates for the multiple sets of modulation symbols.

35. An apparatus comprising:

at least one processor configured to receive a transmission symbol carrying a set of modulation symbols in time domain on a first set of N adjacent subbands assigned to a first terminal, and to process the received transmission symbol to recover the set of modulation symbols from the first set of N subbands, wherein the first set of N subbands is offset by less than N subbands from a second set of N adjacent subbands assigned to a second terminal, and wherein N is an integer greater than one; and

a memory coupled to the at least one processor.

36. The apparatus of claim 35, wherein the at least one processor is configured to transform the received transmission symbol to frequency domain to obtain a set of frequency-domain values for the first set of N subbands, and to transform the set of frequency-domain values to time domain to recover the set of modulation symbols.