Apparatus and method for canceling interference in relay station in a communication system

• US 20090034437A1
• Filed: 07/28/2008
• Published: 02/05/2009
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kwon, Young-Hoon, Yun, Sang-Boh, Shin, Oh-Soon
• Granted Patent: US 7,733,813 B2
• Time in Patent Office: Days
• US Class Current: 370/278
• CPC Class Codes: H04B 7/15585 by interference cancellation
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

A method and apparatus for canceling interference between a transmission signal and a received signal in a full-duplex RS in a communication system are provided, in which an RF/IF signal received from a first node through an antenna is converted to a baseband received signal, demodulated and decoded, a baseband transmission signal is generated by encoding and decoding the decoded data, a baseband interference estimate is calculated using the baseband received signal and the baseband transmission signal, a baseband interference is eliminated from the baseband received signal according to the baseband interference estimate, the baseband transmission signal is converted to an RF/IF transmission signal for a second node, an RF/IF interference estimate is calculated by converting amplitude of the RF/IF transmission signal and delaying it, and an RF/IF interference is eliminated from the RF/IF received signal according to the RF/IF interference estimate.

Claims

1. A method for canceling interference between a transmission signal and a received signal in a full-duplex relay station (RS) in a communication system, comprising:

converting a radio frequency/intermediate frequency (RF/IF) signal received from a first node through an antenna to a baseband received signal;

demodulating and decoding the baseband received signal;

generating a baseband transmission signal by encoding and modulating the demodulated and decoded data;

calculating a baseband interference estimate using the baseband received signal and the baseband transmission signal;

eliminating a baseband interference from the baseband received signal using the baseband interference estimate;

converting the baseband transmission signal to an RF/IF transmission signal to be transmitted to a second node;

calculating an RF/IF interference estimate by converting amplitude of the RF/IF transmission signal and delaying the RF/IF transmission signal with the converted amplitude by a predetermined time period; and

eliminating an RF/IF interference from the RF/IF received signal according to the RF/IF interference estimate.

2. The method of claim 1, wherein the RF/IF interference estimate calculation comprises determining the RF/IF interference estimate according to the RF/IF transmission signal and a control value based on the baseband interference.

3. The method of claim 1, wherein the baseband interference estimate calculation comprises calculating the baseband interference estimate by averaging interference channel estimates calculated for one of a time period and a frequency in which an interference channel is constant.

4. The method of claim 1, wherein the baseband interference estimate calculation comprises calculating the baseband interference estimate by averaging interferences in a current frame k and N frames previous to the current frame k according to the following equation,

${\hat{H}}_1$

( k ) = 1 N + 1 

∑

w = 0 N 

y 

( k - w ) 

x H 

( k - w ) 

x 

( k - w ) 

2 ,

where Ĥ

_I(k) is the baseband interference estimate, y(k) is the baseband received signal, x(k) is the baseband transmission signal, and w is a frame index.

5. The method of claim 1, wherein the baseband interference estimate calculation comprises calculating the baseband interference estimate by averaging interferences in a current frame k, N/2 frames previous to the current frame k, and N/2 frames following the current frame k according to the following equation,

${\hat{H}}_1$

( k ) = 1 N + 1 

∑

w = - N / 2 N / 2 

y 

( k - w ) 

x H 

( k - w ) 

x 

( k - w ) 

2 ,

where Ĥ

_I(k) is the baseband interference estimate, y(k) is the baseband received signal, x(k) is the baseband transmission signal, and w is a frame index.

6. The method of claim 1, further comprising:

obtaining an orthogonal frequency division multiplexing (OFDM) pilot signal by fast Fourier transform (FFT)-processing the baseband received signal;

detecting channel characteristics of each subcarrier using the OFDM pilot signal; and

detecting time-domain channel characteristics by performing inverse discrete Fourier transform (IDFT)-processing on the channel characteristics of each subcarrier, for use in calculating the baseband interference estimate and the RF/IF interference estimate.

7. An apparatus for canceling interference between a transmission signal and a received signal in a full-duplex relay station (RS) in a communication system, comprising:

a receiver for receiving a radio frequency/intermediate frequency (RF/IF) signal from a first node through an antenna;

a first converter for converting the received RF/IF signal to a baseband received signal;

a reception module for demodulating and decoding the baseband received signal;

a transmission module for generating a baseband transmission signal by encoding and modulating the demodulated and decoded data;

a baseband interference controller for calculating a baseband interference estimate using the baseband received signal and the baseband transmission signal;

a second converter for eliminating a baseband interference from the baseband received signal according to the baseband interference estimate and converting the baseband transmission signal to an RF/IF transmission signal to be transmitted to a second node; and

an RF/IF interference controller for calculating an RF/IF interference estimate by converting amplitude of the RF/IF transmission signal and delaying the RF/IF transmission signal with the converted amplitude by a predetermined time period,

wherein the receiver eliminates an RF/IF interference from the RF/IF received signal according to the RF/IF interference estimate.

8. The apparatus of claim 7, wherein the RF/IF interference controller determines the RF/IF interference estimate according to the RF/IF transmission signal and a control value based on the baseband interference.

9. The apparatus of claim 7, wherein the baseband interference controller calculates the baseband interference estimate by averaging interference channel estimates calculated for one of a time period and a frequency in which an interference channel is constant.

10. The apparatus of claim 7, wherein the baseband interference controller calculates the baseband interference estimate by averaging interferences in a current frame k and N frames previous to the current frame k according to the following equation,

${\hat{H}}_1$

( k ) = 1 N + 1 

∑

w = 0 N 

y 

( k - w ) 

x H 

( k - w ) 

x 

( k - w ) 

2 ,

where Ĥ

_I(k) is the baseband interference estimate, y(k) is the baseband received signal, x(k) is the baseband transmission signal, and w is a frame index.

11. The apparatus of claim 7, wherein the baseband interference controller calculates the baseband interference estimate by averaging interferences in a current frame k, N/2 frames previous to the current frame k, and N/2 frames following the current frame k according to the following equation,

${\hat{H}}_1$

( k ) = 1 N + 1 

∑

w = - N / 2 N / 2 

y 

( k - w ) 

x H 

( k - w ) 

x 

( k - w ) 

2 ,

where Ĥ

_I(k) is the baseband interference estimate, y(k) is the baseband received signal, x(k) is the baseband transmission signal, and w is a frame index.

12. The apparatus of claim 7, wherein the reception module obtains an orthogonal frequency division multiplexing (OFDM) pilot signal by fast Fourier transform (FFT)-processing the baseband received signal, detects channel characteristics of each subcarrier using the OFDM pilot signal, and detects time-domain channel characteristics by performing inverse discrete Fourier transform (IDFT) on the channel characteristics of each subcarrier, for use in calculating the baseband interference estimate and the RF/IF interference estimate.

13. A method for canceling interference between a transmission signal and a received signal in a full-duplex relay station (RS) in a communication system, comprising:

converting a radio frequency/intermediate frequency (RF/IF) received signal to a baseband received signal;

demodulating and decoding the baseband received signal;

generating a baseband transmission signal by encoding and modulating the demodulated and decoded baseband received signal;

calculating a baseband interference estimate;

subtracting the baseband interference estimate from the baseband received signal;

converting the baseband transmission signal to an RF/IF transmission signal;

calculating an RF/IF interference estimate; and

substracting the RF/IF interference estimate from the RF/IF received signal.

14. The method of claim 13, wherein the RF/IF interference estimate calculation comprises determining the RF/IF interference estimate according to the RF/IF transmission signal and a control value based on the baseband interference.

15. The method of claim 13, wherein the baseband interference estimate calculation comprises calculating the baseband interference estimate by averaging interference channel estimates calculated for one of a time period and a frequency in which an interference channel is constant.

16. The method of claim 13, wherein the baseband interference estimate calculation comprises calculating the baseband interference estimate by averaging interferences in a current frame k and N frames previous to the current frame k according to the following equation,

${\hat{H}}_1$

( k ) = 1 N + 1 

∑

w = 0 N 

y 

( k - w ) 

x H 

( k - w ) 

x 

( k - w ) 

2 ,

where Ĥ

_I(k) is the baseband interference estimate, y(k) is the baseband received signal, x(k) is the baseband transmission signal, and w is a frame index.

17. The method of claim 13, wherein the baseband interference estimate calculation comprises calculating the baseband interference estimate by averaging interferences in a current frame k, N/2 frames previous to the current frame k, and N/2 frames following the current frame k according to the following equation,

${\hat{H}}_1$

( k ) = 1 N + 1 

∑

w = - N / 2 N / 2 

y 

( k - w ) 

x H 

( k - w ) 

x 

( k - w ) 

2 ,

where Ĥ

_I(k) is the baseband interference estimate, y(k) is the baseband received signal, x(k) is the baseband transmission signal, and w is a frame index.

18. The method of claim 13, further comprising:

obtaining an orthogonal frequency division multiplexing (OFDM) pilot signal by fast Fourier transform (FFT)-processing the baseband received signal;

detecting channel characteristics of each subcarrier using the OFDM pilot signal; and

detecting time-domain channel characteristics by performing inverse discrete Fourier transform (IDFT)-processing on the channel characteristics of each subcarrier, for use in calculating the baseband interference estimate and the RF/IF interference estimate.