Wireless communications systems and methods for virtual user based multiple user detection utilizing vector processor generated mapped cross-correlation matrices

• US 20030091058A1
• Filed: 03/14/2002
• Published: 05/15/2003
• Est. Priority Date: 03/14/2001
• Status: Active Grant

• Current Assignee: Mercury Systems, Incorporated
• Original Assignee: Mercury Computer Systems Incorporated
• Inventors: Oates, John H., Greene, Jonathan E.
• Granted Patent: US 7,218,668 B2
• Time in Patent Office: Days
• US Class Current: 370/442
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/7105 Joint detection techniques, e.g. linear detectors
• CPC Class Codes: H04B 1/71052 using decorrelation matrix
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 2201/70707 Efficiency-related aspects
• CPC Class Codes: H04B 2201/70711 with modular structure

Abstract

The invention provides methods and apparatus for multiple user detection (MUD) processing that have application, for example, in improving the capacity CDMA and other wireless base stations. One aspect of the invention provides a multiprocessor, multiuser detection system for detecting user transmitted symbols in CDMA short-code spectrum waveforms. A first processing element generates a matrix (hereinafter, “gamma matrix”) that represents a correlation between a short-code associated with one user and those associated with one or more other users. A set of second processing elements generates, e.g., from the gamma matrix, a matrix (hereinafter, “R-matrix”) that represents cross-correlations among user waveforms based on their amplitudes and time lags. A third processing element produces estimates of the user transmitted symbols as a function of the R-matrix.

Claims

8. A system for detecting user transmitted symbols encoded in spread spectrum waveforms (hereinafter “

physical user waveforms”

) comprising

one or more processors coupled with apparatus that receives the physical user waveforms, the one or more processors generating one or more virtual user waveforms representing each of the transmitted physical user waveforms, each virtual user waveform representing at least a portion of a symbol encoded in its respective physical user waveform,

one or more vector processors coupled with the one or more processors, the vector processor generating cross-correlations among the virtual user waveforms as a function of one or more characteristics of the respective physical user waveforms,

the one or more processors generating estimates of the symbols encoded in the physical user waveforms as a function of the cross-correlations.

9. The system of claim 8, wherein the one or more processors generate the virtual user waveforms each comprising one or more control or data bits of the symbol encoded in the respective physical user waveform.

10. The system of claim 8, wherein the one or more vector processors generate the cross-correlations among the virtual user waveforms, and store those cross-correlations in a first matrix.

11. The system of claim 10, wherein the one or more vector processors generate the cross-correlations as a function of block-floating integer representations of one or more characteristics of the virtual user waveforms.

12. The system of claim 8, wherein the one or more processors generate a second matrix representing a cross-correlation of the physical user waveforms as a function of the first matrix.

13. The system of claim 12, wherein the one or more processors generate the estimates of the symbols as a function of the second matrix.

14. The system of claim 12, wherein the one or more processors generate the second matrix as a function of the first matrix and a function of a mapping of virtual user waveforms to physical user waveforms.

15. The system of claim 14, comprising one or more vectors storing the mapping and storing identifications of the physical user waveforms and associated virtual user waveforms.

16. In a system for detecting user transmitted symbols encoded in spread spectrum waveforms, the improvement comprising a processor that generates cross-correlations among the waveforms as a function of block-floating integer representations of one or more characteristics of those waveforms.

1. A method for detecting user transmitted symbols encoded in spread spectrum waveforms (hereinafter “

physical user waveforms”

) comprising

decomposing each of one or more physical user waveforms into one or more respective virtual user waveforms, each virtual user waveform representing at least a portion of a symbol encoded in the respective physical user waveform,

determining cross-correlations among the virtual user waveforms as a function of one of more characteristics of the respective physical user waveforms,

generating estimates of the symbols encoded in the physical user waveforms as a function of the cross-correlations.

2. The method of claim 1, wherein the decomposing step comprises generating the virtual user waveforms each as representing one or more respective control or data bits of a symbol encoded in the respective physical user waveform.

3. The method of claim 1, wherein the determining step includes generating a first matrix that stores the cross-correlations among the virtual user waveforms.

4. The method of claim 3, comprising generating, from the first matrix, a second matrix representing a cross-correlation of the physical user waveforms.

5. The method of claim 4, wherein the step of generating the estimates of the symbols includes generating those estimates from the second matrix.

6. The method of claim 4, wherein the generating step includes generating the second matrix as a function of the first matrix and as a function of a mapping of virtual user waveforms to physical user waveforms.

7. The method of claim 6, wherein the mapping is reflected in a vector storing at least an identification of each of the physical user waveforms and an identification of each of the associated virtual user waveforms.

17. In the system of claim 16, wherein the processor is a vector processor.

18. In the system of claim 17, the further improvement comprising a further processor that transforms floating-point representations of the one or more characteristics into the block-floating integer representations.

19. In the system of claim 18, the further improvement comprising a further processor that transforms the block-floating integer representations to floating-point form.

18-1. In the system of claim 17, the further improvement wherein the vector processor generates the cross-correlations in as a plurality of block-floating integer representations.