Interference eliminating apparatus and method

• US 20050276314A1
• Filed: 10/14/2004
• Published: 12/15/2005
• Est. Priority Date: 06/09/2004
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Furukawa, Hideto, Dateki, Takashi
• Application Number:
  US10/964,748
• Publication Number:
  US 20050276314A1
• Time in Patent Office: Days
• US Class Current: 375/148
• CPC Class Codes: H04B 1/7107 Subtractive interference cancellation

Abstract

A RAKE receiving unit (50) despreads and RAKE-combines a receive signal by a spreading code codel of a desired signal. A correlation calculation unit (61) in a canceling-signal generator (60) calculates a correlation value F between the spreading code codel and a non-orthogonal code code2. An amplitude-ratio acquisition unit (62) acquires an amplitude ratio A between a pilot signal and an undesired signal contained in the receive signal, a RAKE combiner (63) RAKE-combines multipath channel estimation values, and a canceling-signal output unit (64) multiplies the correlation value F, amplitude ratio A and result B of RAKE-combination of the channel estimation values and generates a canceling signal (undesired signal component) X. A signal eliminating unit 70 subtracts the canceling signal X from the RAKE-combined signal R that is output from the RAKE receiving unit (50), thereby outputting the desired signal.

Claims

1. An interference eliminating apparatus in a CDMA radio receiver for eliminating an undesired signal component from a receive signal and outputting a desired signal, comprising:

a correlation output unit for outputting a correlation value between a spreading code for spreading a desired signal and a non-orthogonal code, which is a code that is not orthogonal to the spreading code, for spreading an undesired signal;

an amplitude-ratio acquisition unit for acquiring an amplitude ratio between a pilot signal and an undesired signal contained in the receive signal;

a first RAKE combiner for RAKE-combining and outputting multipath channel estimation values;

a canceling-signal generator for generating a canceling signal, which cancels an undesired signal component, using the correlation value, amplitude ratio and result of RAKE-combination of the channel estimation values; and

a signal eliminating unit for subtracting the canceling signal from the receive signal to thereby eliminate the undesired signal contained in the receive signal.

2. The apparatus according to claim 1, wherein said canceling-signal generator generates the canceling signal by multiplying the correlation value, amplitude ratio and result of RAKE-combination of the channel estimation values.

3. The apparatus according to claim 1, wherein said CDMA radio receiver further includes:

a second RAKE combiner for despreading and RAKE-combining the receive signal by a spreading code of the desired signal;

said signal eliminating unit subtracting the canceling signal from the result of RAKE-combination by said second RAKE combiner and outputting the desired signal.

4. The apparatus according to claim 1, wherein said first RAKE combiner despreads the pilot signal, estimates the channel of each path and RAKE-combines the channel estimation values of respective ones of the paths.

5. The apparatus according to claim 1, wherein said amplitude-ratio acquisition unit acquires the amplitude ratio by using the amplitude ratio between the pilot signal and undesired signal received from the transmitting side, or the transmission power of the pilot signal and of the undesired signal, or the transmission amplitudes of the pilot signal and undesired signal.

6. The apparatus according to claim 1, wherein said amplitude-ratio acquisition unit includes:

means for despreading and obtaining the pilot signal and undesired signal contained in a delayed wave of maximum reception power among a plurality of delayed waves received; and

means for calculating the amplitude ratio based upon result of despreading.

7. A CDMA radio receiver for eliminating an undesired signal component from a receive signal and outputting a desired signal, comprising:

a RAKE receiving unit for despreading the receive signal by a spreading code of a desired signal and performing RAKE combining;

a canceling-signal generator for generating a canceling signal that cancels an undesired signal component contained in the receive signal; and

a signal eliminating unit for subtracting the canceling signal from the RAKE-combination signal and outputting a desired signal;

said canceling-signal generator including;

a correlation output unit for outputting a correlation value between the spreading code for spreading the desired signal and a non-orthogonal code, which is a code that is not orthogonal to the spreading code, for spreading the undesired signal;

an amplitude-ratio acquisition unit for acquiring an amplitude ratio between a pilot signal and an undesired signal contained in the receive signal;

a RAKE combiner for RAKE-combining and outputting multipath channel estimation values; and

a canceling-signal output unit for outputting the signal, which cancels the undesired signal component, using the correlation value, amplitude ratio and result of RAKE-combination of the channel estimation values.

8. The apparatus according to claim 7, wherein said canceling-signal generator generates the canceling signal by multiplying the correlation value, amplitude ratio and result of RAKE-combination of the channel estimation values.

9. A method of eliminating interference in a CDMA radio receiver for eliminating an undesired signal component from a receive signal and outputting a desired signal, said method comprising the steps of:

outputting a correlation value between a spreading code for spreading a desired signal and a non-orthogonal code, which is a code that is not orthogonal to the spreading code, for spreading an undesired signal;

acquiring an amplitude ratio between a pilot signal and an undesired signal contained in the receive signal;

RAKE-combining multipath channel estimation values;

generating a canceling signal, which cancels an undesired signal component, using the correlation value, amplitude ratio and result of RAKE-combination of the channel estimation values; and

subtracting the canceling signal from the receive signal and outputting the desired signal.

10. The method according to claim 9, wherein said step of generating the canceling signal includes generating the canceling signal by multiplying the correlation value, amplitude ratio and result of RAKE-combination of the channel estimation values.

11. The method according to claim 9, further comprising the steps of:

despreading and RAKE-combining the receive signal by a spreading code of the desired signal; and

subtracting the canceling signal from the result of RAKE-combination and outputting the desired signal.