Multichannel CDMA subtractive interference cancellation method employed by a remote unit

• US 20020172173A1
• Filed: 06/06/2002
• Published: 11/21/2002
• Est. Priority Date: 04/22/1993
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Schilling, Donald L., Kowalski, John
• Granted Patent: US 7,167,464 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation

Abstract

A method employed by a remote unit wherein a plurality of channels are received as a received signal. Each channel is associated with a code. For each of the plurality of channels, others of the plurality of channels are subtracted from the received signal and a result of that subtracting is despread as data for that channel.

Claims

1. A method employed by a remote unit for recovering data transmitted over a plurality of channels employing a wireless code division multiple access communication technique, comprising:

a) receiving the plurality of channels as a received signal, each channel associated with a code;

b) subtracting for each of the plurality of channels others of the plurality of channels from the received signal; and

c) despreading a result of that subtraction as data for that channel.

2. The method of claim 1 wherein step (b) includes, for each channel:

despreading the received signal with the others channel codes;

respreading the despread others channel codes using the other channel codes; and

subtracting from the received signal the respread other channels.

3. The method of claim 2 wherein the despreading is performed by a mixer.

4. The method of claim 2 wherein the despreading is performed by a matched filter.

5. The method of claim 1 wherein dispreading the result further comprises passing the result of the subtraction through a mixer together with a code of the channel excluded from the subtraction operation.

6. The method of claim 5 wherein dispreading the result further comprises filtering the result of the subtraction employing a code which is matched to a code of the channel excluded from the subtraction operation.

7. The method of claim I wherein steps (a) through (c) are repeated employing the despread result obtained during initial performance of steps (a) through (c).

8. The method of claim 7 further comprising combining the result from the repeated operation of steps (a) through (c) and passing the combined results through a decision device.

9. A method employed by a remote unit for recovering data transmitted over a plurality of channels employing wireless code division multiple access communication, comprising:

a) despreading a spread spectrum signal employing a detector for generating despread, spread spectrum outputs for each channel;

b) receiving the plurality of channels as a received signal, each channel being associated with a code; and

c) subtracting for each of the plurality of channels others of the plurality of channels from the received signal and despreading a result of that subtraction as data for that channel.