Patent EA-001051-B1 (EA)
Title: Method and system for substractive multiple access interference cancellation
Inventor: BENDER PAUL E
IPC: H04W88/02
Filed: 1996-08-23
Abstract: 1. A method for processing the forward link portion of a wireless telecommunication system communication comprising the steps of: (a) receiving a first forward link signal and second forward link signal; (b) estimating a data value being transmitted via said first forward link signal; (c) generated an ideal waveform based on said data valve; (d) subtracting said ideal waveform from said second forward link signal; and (e) determining a data value being transmitted via said second forward link signal. 2. The method as set forth in claim 1 wherein said first forward link signal has a plurality of channels generated by summing a set of data types modulated with a corresponding set of channel codes, and step (b) is comprised of the step of performing a fast Hadamard transform on said first forward link signal. 3. The method as set forth in claim 1 wherein said first forward link signal has a plurality of channels generated by summing a set of data types modulated with a corresponding set of channel codes, and step (b) is comprised of the step of demodulating said first forward link signal with a channel code associated with a pilot channel. 4. The method as set forth in claim 1 wherein said first forward link signal and said second forward link signal are generated by the same base transceiver station. 5. The method as set forth in claim 1 wherein said first forward link signal is transmitted from a first base transceiver station, and said second forward link signal is transmitted from a second base transceiver station. 6. The method as set forth in claim 1 where in step (b) is comprised of the steps of: (b.l) determining a set of data values being transmitted via said first forward link signal; (b.2) calculating a set of ideal waveforms bases on said set of data values; and (b.3) summing said set of ideal waveforms. 7. A wireless telephone system subscriber unit comprising: means for receiving a first forward link signal and second forward link signal; means for estimating a data being transmitted via said first forward link signal; means for generating an ideal waveform in response to said data; means for removing said ideal waveform from said second forward link signal; and means for determining a data value being transmitted via said second forward link signal. 8. The wireless telephone system subscriber unit as set forth in claim 7 wherein said first forward link signal has a plurality of channels generated by summing a set of data types modulated with a corresponding set of channel codes, and said means for estimating is comprised of means for performing a fast Hadamard transform on said first forward link signal. 9. The wireless telephone system subscriber unit as set forth in claim 7 wherein said first forward link signal has a plurality of channels generated by summing a set of data types modulated with a corresponding set of channel codes, and said means for determining is comprised of a means for demodulating said first forward link signal with a channel code associated with a pilot channel. 10. The wireless telephone system subscriber unit as set forth in claim 7 wherein said first and second forward Jmk generated by a first base transceiver station. 11. The wireless telephone system subscriber unit as set forth in claim 8 wherein said means for generating is comprised of: means for generating a set of ideal waveforms based on a set of estimates from said means for performing a data value being transmitted via said first forward link signal; and means for summing said set of ideal waveforms. 12. The wireless telephone system subscriber unit as set forth in claim 7 wherein said first forward link signal is received from a first base transceiver station, and said second forward link signal is received from a second base transceiver station. 13. A wireless telecommunications system for transmitting data comprising: first base transceiver station for transmitting a first forward link signal; second base transceiver station for transmitted a second forward link signal; and subscriber unit for estimating data being transmitted via said first forward link signal, for generating an ideal waveform in response to said data for subtracting said ideal waveform from said second forward link signal, and for determining a data value being transmitted via said second forward link signal after said ideal waveform has been subtracted. 14. The wireless telecommunications system as set forth in claim 13 wherein said first forward link signal has a plurality of channels generated via direct sequence modulation using a set of channel codes, and said means for determining is comprised of means for performing a fast Hadamard transform. 15. The wireless telecommunications system as set forth in claim 13 wherein said first forward link signal has a plurality of channels generated via direct sequence modulation using a set of channel codes, and said wireless subscriber unit is comprised of a means for demodulating said first forward link signal with a channel code associated with a pilot channel. 16. The wireless telecommunications system as set forth in claim 13 wherein said first and second forward link signals are received simultaneously.