Spreading and precoding in OFDM

• US 10,015,034 B1
• Filed: 07/06/2017
• Issued: 07/03/2018
• Est. Priority Date: 05/14/2002
• Status: Expired due to Term

• Current Assignee: Genghiscomm Holdings, LLC
• Original Assignee: Genghiscomm Holdings, LLC
• Inventors: Shattil, Steve
• Primary Examiner(s): Lo, Diane
• Application Number:
  US15/642,850
• Time in Patent Office: 362 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 transform precoder operable to spread 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;

a multiple access resource mapper responsive to an assignment of spectrum resources to the apparatus for selecting a plurality of orthogonal frequency division multiplexing (OFDM) subcarriers corresponding to at least one OFDM symbol interval; and

a signal generator operable to generate an OFDM signal comprising a superposition of the plurality of OFDM subcarriers modulated by the spread symbols, wherein the transform precoder generates the plurality of orthogonal spreading codes to provide the superposition with a reduced peak-to-average-power ratio; and

wherein at least one of the transform precoder and the multiple access resource mapper is configured to weight each of the plurality of OFDM subcarriers with an amplitude scaling factor to adjust gain of the superposition.

2. The apparatus recited in claim 1, wherein one of the plurality of spread symbols is expressed by:

3. The apparatus recited in claim 1, wherein the transform precoder 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.

4. The apparatus recited in claim 1, wherein the multiple access resource mapper is configured to select the plurality of OFDM subcarriers according 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 the signal generator is operable to perform an inverse fast Fourier transform.

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

7. The apparatus recited in claim 1, further comprising a modulator configured to form each of the plurality of data symbols from a plurality of data bits.

8. The apparatus recited in claim 7, further comprising a pseudo-noise scrambler configured to encode the plurality of data bits with a pseudo-noise code.

9. A method for communication, performed by at least one processor, comprising:

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.

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

11. The method recited in claim 9, 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.

12. The method recited in claim 9, 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.

13. The method recited in claim 9, wherein generating the OFDM signal comprises performing an inverse fast Fourier transform on the plurality of spread symbols.

14. The method recited in claim 9, wherein the superposition comprises a time-continuous signal s_l(t) in symbol interval l as a function of time t, expressed by:

15. The method recited in claim 9, 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.

16. An at least one processor configured to perform the method recited in claim 9.

17. A User Equipment configured to perform the method recited in claim 9.

18. A non-transitory computer-readable medium having computer executable program code stored thereon, the computer executable program code comprising:

program code to spread 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;

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

program code to generate an OFDM signal comprising a superposition of the plurality of OFDM subcarriers modulated by 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 the program code to spread and the program code responsive to the assignment provides for multiplying each of the plurality of OFDM subcarriers with an amplitude scaling factor to adjust gain of the superposition.

19. The non-transitory computer-readable medium recited in claim 18, wherein one of the plurality of spread symbols is expressed by:

20. The non-transitory computer-readable medium recited in claim 18, wherein the program code to spread is configured to segment the plurality of data symbols into a plurality of blocks and process each of the plurality of blocks with a DFT.

21. The non-transitory computer-readable medium recited in claim 18, wherein the program code responsive to the assignment is configured to perform according 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.

22. The non-transitory computer-readable medium recited in claim 18, wherein the program code to generate the OFDM signal is configured to provide for performing an inverse fast Fourier transform on the plurality of spread symbols.

23. The non-transitory computer-readable medium recited in claim 18, wherein the superposition is processed to provide a time-continuous signal s_l(t) in symbol interval/as a function of time t, expressed by:

24. The non-transitory computer-readable medium recited in claim 18, further comprising program code to generate the plurality of data symbols from a plurality of data bits, and program code to generate the plurality of data bits by encoding a first plurality of data bits with a pseudo-noise code.