Interference canceller device and radio communication device

• US 6,904,076 B1
• Filed: 03/02/1999
• Issued: 06/07/2005
• Est. Priority Date: 03/05/1998
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tsutsui, Masafumi, Tanaka, Yoshinori, Kobayakawa, Shuji
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Williams, Lawrence B.
• Application Number:
  US09/260,257
• Time in Patent Office: 2,289 Days
• Field of Search: 375/130, 375142-347, 370/342, 370/335
• US Class Current: 375/130
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation

Abstract

The present invention is directed to an interference canceller for a DS-CDMA communication system and a radio communication device that performs multi-rate transmission and eliminates interference of high-rate channels by a simplified structure. In a DS-CDMA communication system that performs a multi-rate transmission including at least low-rate channels and high-rate channels, there is provided an interference canceller that includes an array antenna interference replicating unit. The interference replicating unit is used in high-rate channels that receive signals received via array antenna elements and creates interference replicas of the high-rate channels. The system also includes an adder 6, which subtracts the interference replicas from the received signal via the array antenna elements. Further a resultant interference-eliminated signal is applied to receivers for the low-rate and high-rate channels.

Claims

1. An interference canceller device for a DS-CDMA communication system including low-rate channels and high-rate channels, comprising:

an interference replicating unit being associated with the high-rate channels for creating interference replicas of the high-rate channels from received signals; and

an adder for subtracting only the interference replicas of the high-rate channels from the received signals.

2. The device of claim 1, which further includes a delay circuit for delaying the received signals to the adder.

3. The device of claim 1, wherein the interference replicating unit includes a despread processing part.

4. The device of claim 3, which further includes a searcher for detecting different paths based on a delay profile of the received signals and allocating the despread processing part of the interference replicating unit to the paths detected.

5. The device of claim 4, wherein the searcher includes a memory for storing a threshold value for detecting paths of the low-rate channels, a path detection unit for detecting paths of the high-rate channels based on the threshold value stored and then allocating the despread processing parts of the interference replicating unit to the paths detected.

6. A radio communication device for a DS-CDMA communication system including low-rate channels and high-rate channels, comprising:

an interference canceller including an interference replicating unit being associated with the high-rate channels for creating interference replicas of the high-rate channels from received signals and an adder for subtracting only the interference replicas of the high-rate channels from the received signals producing interference-eliminated signals; and

a receiver for the low-rate channels for performing demodulation on the interference-eliminated signals.

7. The device of claim 6, which further includes a delay circuit for delaying the received signals to the adder.

8. The device of claim 6, wherein the interference replicating unit includes a despread processing part.

9. The device of claim 8, which further includes a searcher for detecting different paths based on a delay profile of the received signals and allocating the despread processing part of the interference replicating unit to the paths detected.

10. The device of claim 9, wherein the searcher includes a memory for storing a threshold value for detecting paths of the low-rate channels, a path detection unit for detecting paths of the high-rate channels based on the threshold value stored and then allocating the despread processing parts of the interference replicating unit to the paths detected.

11. An interference cancelling method for a DS-CDMA communication system including low-rate channels and high-rate channels, the method comprising the steps of:

creating interference replicas from received signals for the high-rate channels; and

subtracting only the interference replicas of the high-rate channels from the received signals for the high rate channels producing interference-eliminated signals.

12. The method of claim 11, which further includes delaying the received signals before subtracting the interference replicas.

13. The method of claim 11, which further includes demodulating the interference-eliminated signals.

14. An interference replicating unit for a DS-CDMA communication system including low-rate channels and high-rate channels and including a multi-array antenna, comprising:

a plurality of despreading parts for despreading signals received from the multi-array antenna producing despread signals;

a decision part coupled to the despreading parts for providing decision output signals; and

a plurality of respreading parts, coupled to the decision part for respreading the decision output signals,

wherein the interference replicating unit is associated with the high-rate channels for creating only interference replicas of the high-rate channels from received signals.

15. A path searcher for a DS-CDMA communication system including low-rate channels and high-rate channels, comprising:

a memory for storing a delay profile for the low-rate channels and a delay profile for the high-rate channels;

path detection part for setting a first threshold and selecting paths in the delay profile for the low-rate channels exceeding the first threshold;

a second memory for storing the first threshold; and

the path selection part for selecting paths in the delay profile for the high-rate channels exceeding the first threshold.

16. The searcher of claim 15, wherein the path selection part further sets a second threshold and selects paths in the delay profile for the high-rate channels exceeding the second threshold.

17. A path searching method for a DS-CDMA communication system including low-rate channels and high-rate channels, the method comprising the steps of:

storing a delay profile for the low-rate channels and a delay profile for the high-rate channels;

setting a first threshold and selecting paths in the delay profile for the low-rate channels exceeding the first threshold;

storing the first threshold; and

selecting paths in the delay profile for the high-rate channels exceeding the first threshold.

18. The method of claim 17, which further includes setting a second threshold and selecting paths in the delay profile for the high-rate channels exceeding the second threshold.