Iterative interference suppressor for wireless multiple-access systems with multiple receive antennas

• US 9,425,855 B2
• Filed: 10/26/2015
• Issued: 08/23/2016
• Est. Priority Date: 04/07/2005
• Status: Active Grant

• Current Assignee: III Holdings 1, LLC (Intellectual Ventures LLC)
• Original Assignee: III Holdings 1, LLC (Intellectual Ventures LLC)
• Inventors: Guess, Tommy, McCloud, Michael L., Nagarajan, Vijay, Lamba, Gagandeep Singh
• Primary Examiner(s): Lugo, David B.
• Application Number:
  US14/922,600
• Publication Number:
  US 20160043770A1
• Time in Patent Office: 302 Days
• US Class Current: 1/1
• 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 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0894 using different delays between antennas
• CPC Class Codes: H04J 11/0063 of multipath interference, e.g. Rake receivers

Abstract

This invention teaches to the details of an interference suppressing receiver for suppressing intra-cell and inter-cell interference in coded, multiple-access, spread spectrum transmissions that propagate through frequency selective communication channels to a multiplicity of receive antennas. The receiver is designed or adapted through the repeated use of symbol-estimate weighting, subtractive suppression with a stabilizing step-size, and mixed-decision symbol estimates. Receiver embodiments may be designed, adapted, and implemented explicitly in software or programmed hardware, or implicitly in standard RAKE-based hardware either within the RAKE (i.e., at the finger level) or outside the RAKE (i.e., at the user or sub channel symbol level). Embodiments may be employed in user equipment on the forward link or in a base station on the reverse link. It may be adapted to general signal processing applications where a signal is to be extracted from interference.

Claims

1. A wireless terminal, comprising:

a plurality of antennas configured to receive multiple-access communication signals from a plurality of transmission sources;

a plurality of RAKE receivers configured to separate the multiple-access communication signals into a plurality of constituent signals for each transmission source;

a plurality of constituent-signal analyzers configured to generate a plurality of initial symbol estimates from the plurality of constituent signals; and

one or more interference suppression units configured to generate, from the plurality of initial symbol estimates, a synthesized received signal for each antenna of the plurality of antenna, subtract the respective synthesized received signal from the multiple-access communication signal received by each antenna to obtain a plurality of residual signals for the plurality of antenna, combine the plurality of residual signals with the plurality of constituent signals to obtain interference-suppressed constituent signals, and generate a plurality of updated symbol estimates based on the interference-suppressed constituent signals.

2. The wireless terminal of claim 1, wherein an interference suppression unit of the one or more interference suppression units is configured to generate, from the plurality of initial symbol estimates, multipath constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas, and generate, for the antenna, a residual signal of the plurality of residual signals based on the multipath constituent signals.

3. The wireless terminal of claim 1, wherein an interference suppression unit of the one or more interference suppression units, comprises:

a multipath constituent generator configured to generate, from the plurality of initial symbol estimates, multipath constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

a plurality of subtractive suppressors, each configured to combine the multipath constituent signals for a respective transmission source to obtain a combined multipath signal for the respective transmission source, and combine a residual signal of the plurality of residual signals with the multipath constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals; and

a processor configured to combine the combined multipath signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna, and subtract the synthesized received signal from the multiple-access communication signal received by the antenna to obtain the residual signal.

4. The wireless terminal of claim 1, wherein an interference suppression unit of the one or more interference suppression units, comprises:

a multipath constituent generator configured to generate, from the plurality of initial symbol estimates, multipath constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

a plurality of subtractive suppressors, each configured to combine the multipath constituent signals for a respective transmission source to obtain a combined multipath signal for the respective transmission source, and combine a scaled residual signal with the multipath constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals; and

a processor configured to combine the combined multipath signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna, subtract the synthesized received signal from the multiple-access communication signal received by the antenna to obtain a residual signal of the plurality of residual signals, and scale the residual signal by a stabilizing step size to obtain the scaled residual signal.

5. The wireless terminal of claim 1, wherein an interference suppression unit of the one or more interference suppression units, is configured to generate, from the plurality of initial symbol estimates, subchannel constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas, and generate the plurality of residual signals based on the subchannel constituent signals.

6. The wireless terminal of claim 1, wherein an interference suppression unit of the one or more interference suppression units, comprises:

a subchannel constituent generator configured to generate, from the plurality of initial symbol estimates, subchannel constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

a plurality of subtractive suppressors, each configured to combine the subchannel constituent signals for a respective transmission source to obtain a combined subchannel signal for the respective transmission source, and combine a residual signal of the plurality of residual signals with the subchannel constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals; and

a processor configured to combine the combined subchannel signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna, and subtract the synthesized receive signal from the multiple-access communication signal received by the antenna to obtain the residual signal.

7. The wireless terminal of claim 1, wherein an interference suppression unit of the one or more interference suppression units, comprises:

a subchannel constituent generator configured to generate, from the plurality of initial symbol estimates, subchannel constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

a plurality of subtractive suppressors, each configured to combine the subchannel constituent signals for a respective transmission source to obtain a combined subchannel signal for the respective transmission source, and combine a scaled residual signal with the subchannel constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals; and

a processor configured to combine the combined subchannel signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna, subtract the synthesized receive signal from the multiple-access communication signal received by the antenna to obtain a residual signal of the plurality of residual signals, and scale the residual signal by a stabilizing step size to obtain the scaled residual signal.

8. The wireless terminal of claim 1, wherein:

the one or more interference suppression units comprise at least a first interference suppression unit and a second interference suppression unit;

the first interference suppression unit is configured to receive the plurality of initial symbol estimates and generate a first plurality of updated symbol estimates; and

the second interference suppression unit is configured to receive the first plurality of updated symbol estimates from the first interference suppression unit as its plurality of initial symbol estimates and generate a second plurality of updated symbol estimates.

9. The wireless terminal of claim 1, wherein the one or more interference suppression units consists of a single interference suppression configured to iteratively update the plurality of initial symbol estimates to obtain the plurality of updated symbol estimates.

10. A wireless terminal, comprising:

a plurality of antennas configured to receive multiple-access communication signals from a plurality of transmission sources;

a plurality of RAKE receivers configured to separate the multiple-access communication signals into a plurality of constituent signals for each transmission source;

a computer-readable memory with stored firmware; and

a processor configured to execute the stored firmware of the computer-readable memory, wherein the processor, in response to executing the stored firmware, is configured to;

generate a plurality of initial symbol estimates from the plurality of constituent signals;

generate, from the plurality of initial symbol estimates, a synthesized received signal for each antenna of the plurality of antenna;

subtract the respective synthesized received signal from the multiple-access communication signal received by each antenna to obtain a plurality of residual signals for the plurality of antenna;

combine the plurality of residual signals with the plurality of constituent signals to obtain interference-suppressed constituent signals; and

generate a plurality of updated symbol estimates based on the interference-suppressed constituent signals.

11. The wireless terminal of claim 10, wherein the processor, in response to executing the stored firmware, is further configured to:

generate, from the plurality of initial symbol estimates, multipath constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas; and

generate, for the antenna, a residual signal of the plurality of residual signals based on the multipath constituent signals.

12. The wireless terminal of claim 10, wherein the processor, in response to executing the stored firmware, is further configured to:

generate, from the plurality of initial symbol estimates, multipath constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

combine the multipath constituent signals for a respective transmission source to obtain a combined multipath signal for the respective transmission source;

combine a residual signal of the plurality of residual signals with the multipath constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals;

combine the combined multipath signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna; and

subtract the synthesized received signal from the multiple-access communication signal received by the antenna to obtain the residual signal.

13. The wireless terminal of claim 10, wherein the processor, in response to executing the stored firmware, is further configured to:

generate, from the plurality of initial symbol estimates, multipath constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

combine the multipath constituent signals for a respective transmission source to obtain a combined multipath signal for the respective transmission source;

combine a scaled residual signal with the multipath constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals;

combine the combined multipath signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna;

subtract the synthesized receive signal from the multiple-access communication signal received by the antenna to obtain a residual signal of the plurality of residual signals; and

scale the residual signal by a stabilizing step size to obtain the scaled residual signal.

14. The wireless terminal of claim 10, wherein the processor, in response to executing the stored firmware, is further configured to:

generate, from the plurality of initial symbol estimates, subchannel constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas; and

generate the plurality of residual signals based on the subchannel constituent signals.

15. The wireless terminal of claim 10, wherein the processor, in response to executing the stored firmware, is further configured to:

generate, from the plurality of initial symbol estimates, subchannel constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

combine the subchannel constituent signals for a respective transmission source to obtain a combined subchannel signal for the respective transmission source;

combine a residual signal of the plurality of residual signals with the subchannel constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals;

combine the combined subchannel signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna; and

subtract the synthesized receive signal from the multiple-access communication signal received by the antenna to obtain the residual signal.

16. The wireless terminal of claim 10, wherein the processor, in response to executing the stored firmware, is further configured to:

generate, from the plurality of initial symbol estimates, subchannel constituent signals for each transmission source of the plurality of transmission sources relative to an antenna of the plurality of antennas;

combine the subchannel constituent signals for a respective transmission source to obtain a combined subchannel signal for the respective transmission source;

combine a scaled residual signal with the subchannel constituent signals for the respective transmission source to obtain the interference-suppressed constituent signals;

combine the combined subchannel signals for the plurality of transmission sources relative to the antenna of the plurality of antennas to obtain the synthesized received signal for the antenna;

subtract the synthesized received signal from the multiple-access communication signal received by the antenna to obtain a residual signal of the plurality of residual signals; and

scale the residual signal by a stabilizing step size to obtain the scaled residual signal.

17. The wireless terminal of claim 10, wherein the processor, in response to executing the stored firmware, is further configured to iteratively update the plurality of initial symbol estimates to obtain the plurality of updated symbol estimates.