Transmitter incorporating spatio-temporal processing

• US 6,377,631 B1
• Filed: 11/05/1999
• Issued: 04/23/2002
• Est. Priority Date: 08/29/1996
• Status: Expired due to Term

• Current Assignee: Cisco Systems, Inc.
• Original Assignee: Cisco Systems, Inc.
• Inventors: Raleigh, Gregory G.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Fan, Chieh M.
• Application Number:
  US09/435,246
• Time in Patent Office: 900 Days
• Field of Search: 375/219, 375/260, 375/285, 375/296, 375/299, 375/316, 375/346, 375/347, 375/348, 375/349, 375/350, 370/203, 370/210, 370/342, 455/63, 455/64, 455/65, 708/403, 708/404, 708/405
• US Class Current: 375/299
• CPC Class Codes: H04B 1/1081 Reduction of multipath noise by equalising H04B7/005
• CPC Class Codes: H04B 7/0443 utilizing "waterfilling" technique
• CPC Class Codes: H04B 7/0469 taking special antenna structures, e.g. cross polarized antennas into account
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0658 Feedback reduction
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606
• CPC Class Codes: H04B 7/0842 Weighted combining
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0606 Space-frequency coding
• CPC Class Codes: H04L 1/0618 : Space-time coding
• CPC Class Codes: H04L 1/18 : Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 1/1812 : Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 2025/03414 : Multicarrier
• CPC Class Codes: H04L 2025/03426 : transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03802 : Signalling on the reverse channel
• CPC Class Codes: H04L 25/0204 : of multiple channels
• CPC Class Codes: H04L 25/021 : Estimation of channel covariance
• CPC Class Codes: H04L 25/0212 : of impulse response
• CPC Class Codes: H04L 25/0242 : using matrix methods
• CPC Class Codes: H04L 25/03305 : Joint sequence estimation and interference removal joint detection of several desired signals H04L25/03331
• CPC Class Codes: H04L 25/03331 : Arrangements for the joint estimation of multiple sequences
• CPC Class Codes: H04L 25/03343 : Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2601 : Multicarrier modulation systems
• CPC Class Codes: H04L 27/2626 : Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2647 : Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0023 : Time-frequency-space
• CPC Class Codes: H04L 5/0028 : Variable division signaling therefor H04L5/0092
• CPC Class Codes: H04L 5/0046 : Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04W 16/28 : using beam steering
• CPC Class Codes: H04W 72/00 : Local resource management
• CPC Class Codes: H04W 88/02 : Terminal devices
• CPC Class Codes: H04W 88/08 : Access point devices

Abstract

A space-time signal processing system with advantageously reduced complexity. The system may take advantage of multiple transmitter antenna elements and/or multiple receiver antenna elements, or multiple polarizations of a single transmitter antenna element and/or single receiver antenna element. The system is not restricted to wireless contexts and may exploit any channel having multiple inputs or multiple outputs and certain other characteristics. Multi-path effects in a transmission medium cause a multiplicative increase in capacity.

Claims

1. In a digital communication system, a method for transmitting via a plurality of inputs to a channel, said method comprising:

providing a time domain substantially orthogonalizing procedure to divide said channel into input bins;

providing one or more spatial directions for communication defined by corresponding weightings among said channel inputs wherein each input bin has at least one associated spatial direction, said weightings defining said one or more spatial directions so that each spatial direction corresponds to communication via more than one channel input; and

transmitting said information in subchannels of said channel by employing at least two independent parallel applications of an inverse of said time domain substantially orthogonalizing procedure, said subchannels being defined by a combination of input bin and spatial direction.

2. The method of claim 1 wherein transmitting said information comprises:

providing a group of input symbols wherein each input symbol corresponds to a particular input bin of said time domain substantially orthogonalizing procedure;

applying ones of said weightings corresponding to each of said input bins to each of said input symbols to develop for each of said input symbols a vector of spatially processed symbols, each element of said vector corresponding to a single channel input of said plurality of channel inputs;

applying said inverse of said time domain substantially orthogonalizing procedure independently for each of said channel inputs to said spatially processed symbols; and

transmitting time domain symbols via said channel inputs responsive to results of said inverse of said time domain substantially orthogonalizing procedure.

3. The method of claim 1 wherein each input bin has at least two associated spatial directions, said spatial directions being chosen independently for each input bin signal.

4. The method of claim 3 wherein said at least two spatial directions are mutually orthogonal for each of said input bins.

5. The method of claim 3 wherein transmitting comprises:

providing a group of input symbols wherein each input symbol corresponds to a particular input bin of said time domain substantially orthogonalizing procedure and a particular one of said at least two spatial directions;

for each of said spatial directions applying one of said weightings to define contributions to each of said channel inputs;

for each channel input, independently applying said inverse of said time domain substantially orthogonalizing procedure to results of applying said weightings; and

transmitting via said channel inputs responsive to results of applying said inverse of said time domain substantially orthogonalizing procedure.

6. The method of claim 5 wherein said weightings are selected according to singular value decompositions of matrices characterizing communication via each input bin of said channel.

7. The method of claim 5 further comprising applying a coding procedure to develop said group of input symbols.

8. The method of claim 3 wherein said at least two spatial directions are not mutually orthogonal for each of said input bins.

9. The method of claim 8 wherein transmitting comprises:

coding said information to develop symbols corresponding to each of said subchannels, said coding being optimized to take advantage of multiple spatial directions;

applying said inverse of said time domain substantially orthogonalizing procedure independently to symbols corresponding to each of said at least two spatial directions;

applying said weightings to results of said independent applications of said inverse of said time domain substantially orthogonalizing procedure; and

transmitting via said channel inputs responsive to results of applying said weightings.

10. The method of claim 9 wherein said inverse of said time domain substantially orthogonalizing procedure belongs to one of a group consisting of an inverse Fast Fourier Transform and a Fast Fourier Transform.

11. The method of claim 10 wherein said Fast Fourier Transform or said inverse Fast Fourier transform is followed by addition of a cyclic prefix.

12. The method of claim 1 wherein said channel comprises a wireless channel and said plurality of channel inputs are associated with a corresponding plurality of transmitter antenna elements.

13. The method of claim 12 wherein said plurality of transmitter antenna elements are co-located.

14. The method of claim 12 wherein said plurality of transmitter antenna elements are at disparate locations.

15. The method of claim 1 further comprising:

allocating bit loading and power among said plurality of subchannels.

16. A transmitter system for transmitting via a plurality of inputs to a channel, said transmitter system comprising:

at least one processing element that applies an inverse of a time domain substantially orthogonalizing procedure to divide said channel into input bins;

a spatial processor employing weightings among said channel inputs to define spatial directions wherein each input bin has at least one associated spatial direction, said weightings defining said one or more spatial directions so that each spatial direction corresponds to communication via more than one channel input; and

wherein said transmitter system transmits information in subchannels of said channel, each of said subchannels being defined by a combination of input bin and spatial direction, by employing said at least one processing element for at least two independent applications of said inverse of said time domain substantially orthogonalizing procedure.

17. The transmitter system of claim 16 comprising:

a system input that receives a group of input symbols wherein each input symbol corresponds to a particular input bin of said time domain substantially orthogonalizing procedure; and

wherein

said spatial processor applies ones of said weightings corresponding to each of said input bins to each of said input symbols to develop for each of said input symbols a vector of spatially processed symbols, each element of said vector corresponding to a single channel input of said plurality of channel inputs; and

wherein

said at least one processing element applies said inverse of said time domain substantially orthogonalizing procedure independently for each of said channel inputs to said spatially processed symbols; and

wherein

said transmitter system transmits via said channel inputs responsive to results of said inverse of said time domain substantially orthogonalizing procedure.

18. The transmitter system of claim 16 wherein information is transmitted in subchannels defined by said input bins and at least two spatial directions associated with each of said input bins, said spatial directions being chosen independently for each of said input bins.

19. The transmitter system of claim 18 wherein said at least two spatial directions are mutually orthogonal for each of said input bins.

20. The transmitter system of claim 19 comprising:

a system input that receives a group of input symbols wherein each input symbol corresponds to a particular input bin of said time domain substantially orthogonalizing procedure and a particular one of said at least two spatial directions; and

wherein

said spatial processor, for each of said spatial directions, applies one of said weightings to define contributions to each of said channel inputs; and

wherein

said at least one processing element independently applies said inverse of said time domain substantially orthogonalizing procedure to results of applying said weightings; and

wherein

said transmitter system transmits via said channel inputs responsive to results of applying said inverse of said time domain substantially orthogonalizing procedure.

21. The transmitter system of claim 20 wherein said weightings are selected according to singular value decompositions of matrices characterizing communication via each input bin of said channel.

22. The transmitter system of claim 20 further comprising an encoding system that applies a coding procedure to develop said group of input symbols.

23. The transmitter system of claim 18 wherein said at least two spatial directions are not mutually orthogonal for each of said input bins.

24. The transmitter system of claim 23 further comprising:

an encoding system that encodes said information to develop symbols corresponding to each of said subchannels, said coding being optimized to take advantage of multiple spatial directions; and

wherein

said at least one processing element applies said inverse of said time domain substantially orthogonalizing procedure independently to symbols corresponding to each of said at least two spatial directions; and

wherein

said spatial processor applies said weightings to results of said independent applications of said inverse of said time domain substantially orthogonalizing procedure; and

wherein

said transmitter system transmits via said plurality of channel inputs responsive to results of applying said weightings.

25. The transmitter system of claim 16 wherein said inverse of said time domain substantially orthogonalizing procedure belongs to one of a group consisting of an inverse Fast Fourier Transform and a Fast Fourier Transform.

26. The transmitter system of claim 25 wherein said Fast Fourier Transform or said inverse Fast Fourier transform is followed by addition of a cyclic prefix.

27. The transmitter system of claim 16 wherein said channel comprises a wireless channel and said plurality of channel inputs are associated with a corresponding plurality of transmitter antenna elements.

28. The transmitter system of claim 27 wherein said plurality of transmitter antenna elements are co-located.

29. The transmitter system of claim 27 wherein said plurality of transmitter antenna elements are at disparate locations.

30. The transmitter system of claim 16 further comprising:

a bit loading system that allocates bit loading and power among said plurality of subchannels.