Iterative interference suppressor for wireless multiple-access systems with multiple receive antennas
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 subchannel 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.
1. A base station configured to process signals received from a plurality of wireless terminals, the base station comprising:
a memory;
one or more computer programs stored in the memory; and
one or more processors that, in response to executing the one or more computer programs:
combine a plurality of constituent signals to produce a synthesized received signal;
subtract the synthesized received signal from a received signal to produce a residual signal;
scale the residual signal to produce a scaled residual signal;
combine the scaled residual signal with each of the plurality of constituent signals to form a plurality of interference suppressed constituent signals;
time-advance the plurality of interference suppressed constituent signals to produce a plurality of time-advanced signals; and
combine the plurality of time-advanced signals corresponding to a first user to produce a first combined user signal.
2. The base station of claim 1 , further comprising a Rake receiver configured to generate the plurality of constituent signals based on signals received from the plurality of wireless terminals.
3. The base station of claim 1 , wherein the one or more processors, in response to executing the one or more computer programs:
multiply the synthesized received signal by complex conjugates of a plurality of users' coded waveforms; and
integrate resultant products to despread the synthesized received signal.
4. The base station of claim 1 , wherein the plurality of constituent signals corresponds to a plurality of users.
5. The base station of claim 1 , wherein the plurality of constituent signals corresponds to a plurality of rake fingers.
6. The base station of claim 1 , wherein the plurality of constituent signals corresponds to a plurality of users' code waveforms.
7. A base station configured to process signals received from a plurality of wireless terminals, the base station comprising:
a memory;
one or more computer programs stored in the memory; and
one or more processors that, in response to executing the one or more computer programs:
combine a plurality of constituent signals to produce a synthesized received signal;
subtract the synthesized received signal from a received signal to produce a residual signal;
scale the residual signal to produce a scaled residual signal;
combine the scaled residual signal with a subset of the plurality of constituent signals to form a plurality of interference suppressed constituent signals;
time-advance the plurality of interference suppressed constituent signals to produce a plurality of time-advanced signals;
weight the plurality of time-advanced signals to produce a plurality of weighted, time-advanced signals; and
combine the plurality of weighted, time-advanced signals corresponding to a first user to produce a first combined user signal.
8. The base station of claim 7 , further comprising a Rake receiver configured to generate the plurality of constituent signals based on signals received from the plurality of wireless terminals.
9. The base station of claim 7 , wherein the one or more processors, in response to executing the one or more computer programs:
multiply the synthesized received signal by complex conjugates of a plurality of users' coded waveforms; and
integrate resultant products to despread the synthesized received signal.
10. The base station of claim 7 , wherein the plurality of constituent signals corresponds to a plurality of users.
11. The base station of claim 7 , wherein the plurality of constituent signals corresponds to a plurality of rake fingers.
12. The base station of claim 7 , wherein the plurality of constituent signals corresponds to a plurality of users' code waveforms.