INTERFERENCE CANCELLATION IN A SPREAD SPECTRUM COMMUNICATION SYSTEM

• US 20110228710A1
• Filed: 05/27/2011
• Published: 09/22/2011
• Est. Priority Date: 09/10/1999
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Reznik, Alexander, Mesecher, David K., Grieco, Donald M., Cheung, Gary
• Granted Patent: US 9,036,680 B2
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04B 1/7097 Interference-related aspects
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• 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 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16
• 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 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04J 13/0003 Code application, i.e. aspects relating to how codes are applied to form multiplexed channels

Abstract

A code division multiple access communication system transmits a pilot and traffic signal over a shared spectrum. The pilot and traffic signal have an associated code and are received over the shared spectrum. The received signals are sampled and the samples are delayed to produce a window. A weighted value for each despread pilot code window sample is determined using an adaptive algorithm. Each window sample is despread with a traffic code. Each despread traffic code window sample is weighted according to a weight corresponding to its respective pilot code sample.

Claims

1. A base station comprising:

a plurality of antennas;

circuitry configured produce a plurality of pilot signals;

wherein a different pilot signal of the plurality of pilot signals is transmitted on each of the plurality of antennas;

wherein each of the pilot signals is derived from at least a portion of a pseudo noise (PN) sequence and the at least a portion of the PN sequence bits for each of the pilot signals is different; and

wherein the circuitry is further configured to produce data and split the data into a plurality of data streams;

wherein the data of each of the data streams has data bits combined with at least a portion of a PN sequence and the at least a portion of the PN sequence bits for each stream is different;

wherein the plurality of data streams are transmitted by the plurality of antennas with the different pilot signals.

2. The base station of claim 1 wherein the circuitry is further configured to receive weight information from a user equipment and in response to the weight information, the circuitry is further configured to weight the data streams.

3. The base station of claim 1 wherein the circuitry is further configured to derive weights from uplink signals and the circuitry is further configured to weight the data streams in response to the derived weights.

4. The base station of claim 3 wherein the base station is a time division duplex base station.

5. The base station of claim 1 wherein the plurality of data streams are transmitted to a signal user equipment.

6. A method comprising:

producing, by a base station, a plurality of pilot signals;

transmitting a different pilot signal of the plurality of pilot signals on each of a plurality of antennas;

wherein each of the pilot signals is derived from at least a portion of a pseudo noise (PN) sequence and the at least a portion of the PN sequence bits for each of the pilot signals is different; and

producing, by a base station, data and splitting the data into a plurality of data streams;

wherein the data of each of the data streams has data bits combined with at least a portion of a PN sequence and the at least a portion of the PN sequence bits for each stream is different;

transmitting, by a base station, the plurality of data streams by the plurality of antennas with the different pilot signals.

7. The method of claim 6 further comprising receiving weight information from a user equipment and in response to the weight information, weighting the data streams.

8. The method of claim 6 further comprising deriving weights from uplink signals and weighting the data streams in response to the derived weights.

9. The method of claim 8 wherein the base station is a time division duplex base station.

10. The method of claim 6 wherein the plurality of data streams are transmitted to a signal user equipment.

11. A user equipment comprising:

circuitry configured to receive a downlink signal including a plurality of pilot signals and a plurality of data streams;

wherein a different pilot signal of the plurality of pilot signals was transmitted from a different antenna of a plurality of antennas of a base station;

wherein each of the pilot signals was derived from at least a portion of a pseudo noise (PN) sequence and the at least a portion of the PN sequence bits for each of the pilot signals is different; and

wherein the circuitry is further configured to recover data from the plurality of data streams;

wherein the recovered data was split into the plurality of data streams;

wherein the data of each of the data streams had data bits combined with at least a portion of a PN sequence and the at least a portion of the PN sequence bits for each stream was different;

wherein the plurality of data streams were transmitted by the plurality of antennas of the base station with the different pilot signals.

12. The user equipment of claim 11 wherein the circuitry is further configured to transmit weight information to the base station for use in weighting the data streams.

13. The user equipment of claim 11 wherein the user equipment is a time division duplex user equipment.

14. The user equipment of claim 11 wherein the user equipment is a frequency division duplex user equipment.