Spreading and precoding in OFDM

• US 10,230,559 B1
• Filed: 07/02/2018
• Issued: 03/12/2019
• Est. Priority Date: 05/14/2002
• Status: Expired due to Fees

• Current Assignee: Genghiscomm Holdings, LLC
• Original Assignee: Genghiscomm Holdings, LLC
• Inventors: Shattil, Steve
• Primary Examiner(s): Lo, Diane L
• Application Number:
  US16/026,001
• Time in Patent Office: 253 Days
• Field of Search: None
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04B 7/18506 Communications with or from aircraft, i.e. aeronautical mobile service
• CPC Class Codes: H04J 11/0093 Neighbour cell search
• CPC Class Codes: H04J 13/0003 Code application, i.e. aspects relating to how codes are applied to form multiplexed channels
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/12 Generation of orthogonal codes
• CPC Class Codes: H04L 12/2854 Wide area networks, e.g. public data networks
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/26035 Maintenance of orthogonality, e.g. for signals exchanged between cells or users, or by using covering codes or sequences using different training sequence per antenna H04B7/0684; code allocation H04J13/16
• CPC Class Codes: H04L 27/2614 Peak power aspects
• 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 41/0226 Mapping or translating multiple network management protocols
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 47/10 : Flow control; Congestion control
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0021 : in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/0023 : Time-frequency-space
• CPC Class Codes: H04L 5/0035 : Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0037 : Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0073 : Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04W 52/42 : in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 72/046 : the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/21 : in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 84/18 : Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 88/02 : Terminal devices

Abstract

An OFDM transmitter spreads original data symbols with a complex-valued spreading matrix derived from a discrete Fourier transform. Spread data symbols are mapped to OFDM subcarriers. Spreading and mapping are configured to produce a transmitted spread-OFDM signal with a low peak-to-average power ratio (PAPR) and orthogonal code spaces. In MIMO systems, the complex-valued spreading matrix can comprise a MIMO precoding matrix, and the code spaces can comprise MIMO subspaces. In Cooperative-MIMO, a combination of low code-space cross correlation and low PAPR can be achieved.

Claims

1. An apparatus, comprising:

a processor; and

a non-transitory computer-readable memory communicatively coupled to the processor, the memory including a set of instructions stored thereon and executable by the processor for;

spreading a plurality of data symbols with a plurality of orthogonal spreading codes comprising complex-valued coefficients of a discrete Fourier transform (DFT) to produce a plurality of spread symbols;

responsive to an assignment of spectrum resources for use by a transmitter in an orthogonal frequency division multiplexing (OFDM) network, selecting a plurality of OFDM subcarriers corresponding to at least one OFDM symbol interval; and

generating an OFDM signal comprising a superposition of the plurality of OFDM subcarriers, each modulated by one of the plurality of spread symbols, wherein the plurality of orthogonal spreading codes are selected to provide the superposition with a reduced peak-to-average-power ratio;

wherein at least one of the plurality of spread symbols is expressed by;

2. The apparatus recited in claim 1, wherein the spreading is configured to segment the plurality of data symbols into a plurality of blocks, each of the plurality of blocks being processed by a DFT.

3. The apparatus recited in claim 1, wherein at least one of spreading and selecting provides for multiplying each of the plurality of OFDM subcarriers with an amplitude scaling factor to adjust gain of the superposition.

4. The apparatus recited in claim 1, wherein selecting the plurality of OFDM subcarriers is performed with respect to at least one of a frequency division multiple access scheme, a time division multiple access scheme, a space division multiple access scheme, and a frequency-hopping scheme.

5. The apparatus recited in claim 1, wherein generating the OFDM signal comprises performing an inverse fast Fourier transform on the plurality of spread symbols.

6. The apparatus recited in claim 1, wherein the superposition comprises a time-continuous signal s_I(t) in symbol interval I as a function of time t, expressed by:

7. The apparatus recited in claim 1, wherein each of the plurality of data symbols is generated from a plurality of data bits, the plurality of data bits having been encoded with a pseudo-noise code.

8. An apparatus, comprising:

a processor; and

a non-transitory computer-readable memory communicatively coupled to the processor, the memory including a set of instructions stored thereon and executable by the processor for;

spreading a plurality of data symbols with a plurality of orthogonal spreading codes comprising complex-valued coefficients of a discrete Fourier transform (DFT) to produce a plurality of spread symbols;

responsive to an assignment of spectrum resources for use by a transmitter in an orthogonal frequency division multiplexing (OFDM) network, selecting a plurality of OFDM subcarriers corresponding to at least one OFDM symbol interval; and

generating an OFDM signal comprising a superposition of the plurality of OFDM subcarriers, each modulated by one of the plurality of spread symbols, wherein the plurality of orthogonal spreading codes are selected to provide the superposition with a reduced peak-to-average-power ratio; and

wherein at least one of spreading and selecting provides for multiplying each of the plurality of OFDM subcarriers with an amplitude scaling factor to adjust gain of the superposition.

9. The apparatus recited in claim 8, wherein one of the plurality of spread symbols is expressed by:

10. The apparatus recited in claim 8, wherein the spreading is configured to segment the plurality of data symbols into a plurality of blocks, each of the plurality of blocks being processed by a DFT.

11. The apparatus recited in claim 8, wherein selecting the plurality of OFDM subcarriers is performed with respect to at least one of a frequency division multiple access scheme, a time division multiple access scheme, a space division multiple access scheme, and a frequency-hopping scheme.

12. The apparatus recited in claim 8, wherein generating the OFDM signal comprises performing an inverse fast Fourier transform on the plurality of spread symbols.

13. The apparatus recited in claim 8, wherein the superposition comprises a time-continuous signal s_I(t) in symbol interval I as a function of time t, expressed by:

14. The apparatus recited in claim 8, wherein each of the plurality of data symbols is generated from a plurality of data bits, the plurality of data bits having been encoded with a pseudo-noise code.

15. An apparatus, comprising:

a processor; and

a non-transitory computer-readable memory communicatively coupled to the processor, the memory including a set of instructions stored thereon and executable by the processor for;

spreading a plurality of data symbols with a plurality of orthogonal spreading codes comprising complex-valued coefficients of a discrete Fourier transform (DFT) to produce a plurality of spread symbols;

responsive to an assignment of spectrum resources for use by a transmitter in an orthogonal frequency division multiplexing (OFDM) network, selecting a plurality of OFDM subcarriers corresponding to at least one OFDM symbol interval; and

generating an OFDM signal comprising a superposition of the plurality of OFDM subcarriers, each modulated by one of the plurality of spread symbols, wherein the plurality of orthogonal spreading codes are selected to provide the superposition with a reduced peak-to-average-power ratio; and

wherein the superposition comprises a time-continuous signal s_I(t) in symbol interval I as a function of time t, expressed by;

16. The apparatus recited in claim 15, wherein the spreading is configured to segment the plurality of data symbols into a plurality of blocks, each of the plurality of blocks being processed by a DFT.

17. The apparatus recited in claim 15, wherein at least one of spreading and selecting provides for multiplying each of the plurality of OFDM subcarriers with an amplitude scaling factor to adjust gain of the superposition.

18. The apparatus recited in claim 15, wherein selecting the plurality of OFDM subcarriers is performed with respect to at least one of a frequency division multiple access scheme, a time division multiple access scheme, a space division multiple access scheme, and a frequency-hopping scheme.

19. The apparatus recited in claim 15, wherein generating the OFDM signal comprises performing an inverse fast Fourier transform on the plurality of spread symbols.

20. The apparatus recited in claim 15, wherein each of the plurality of data symbols is generated from a plurality of data bits, the plurality of data bits having been encoded with a pseudo-noise code.

21. An apparatus, comprising:

a processor; and

a non-transitory computer-readable memory communicatively coupled to the processor, the memory including a set of instructions stored thereon and executable by the processor for;

encoding a plurality of data bits with a pseudo-noise code to generate a plurality of coded data bits;

forming a plurality of data symbols from the plurality of coded data bits;

spreading the plurality of data symbols with a plurality of spreading codes comprising complex-valued coefficients of a discrete Fourier transform (DFT) to produce a plurality of spread symbols;

responsive to an assignment of spectrum resources for use by a transmitter in an orthogonal frequency division multiplexing (OFDM) network, selecting a plurality of OFDM subcarriers corresponding to at least one OFDM symbol interval; and

generating an OFDM signal comprising a superposition of the plurality of OFDM subcarriers, each modulated by one of the plurality of spread symbols, wherein the plurality of spreading codes are selected to provide the superposition with a reduced peak-to-average-power ratio.

22. The apparatus recited in claim 21, wherein the superposition comprises a time-continuous signal s_I(t) in symbol interval I as a function of time t, expressed by:

23. The apparatus recited in claim 21, wherein one of the plurality of spread symbols is expressed by:

24. The apparatus recited in claim 21, wherein the spreading is configured to segment the plurality of data symbols into a plurality of blocks, each of the plurality of blocks being processed by a DFT.

25. The apparatus recited in claim 21, wherein at least one of spreading and selecting provides for multiplying each of the plurality of OFDM subcarriers with an amplitude scaling factor to adjust gain of the superposition.

26. The apparatus recited in claim 21, wherein selecting the plurality of OFDM subcarriers is performed with respect to at least one of a frequency division multiple access scheme, a time division multiple access scheme, a space division multiple access scheme, and a frequency-hopping scheme.

27. The apparatus recited in claim 21, wherein generating the OFDM signal comprises performing an inverse fast Fourier transform on the plurality of spread symbols.

28. The apparatus recited in claim 21, wherein the plurality of spreading codes comprises at least one of a set of orthogonal spreading codes and a set of quasi-orthogonal spreading codes.