Apparatus for removing interference between neighbor cells in a radio communication system, and method for same

• US 8,583,051 B2
• Filed: 08/04/2009
• Issued: 11/12/2013
• Est. Priority Date: 08/04/2008
• Status: Active Grant

• Current Assignee: Seoul National University R&DB Foundation (Seoul National University)
• Original Assignee: Seoul National University R&DB Foundation (Seoul National University)
• Inventors: Lee, Yong Hwan, Lee, Seung Hwan
• Primary Examiner(s): Alam, Fayyaz
• Application Number:
  US13/057,581
• Publication Number:
  US 20110183692A1
• Time in Patent Office: 1,561 Days
• Field of Search: 455/522, 455 69- 70, 455/13.4, 455/67.11, 455/63.1, 455436-442, 370315-320
• US Class Current: 455/67.11
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336

Abstract

The present invention relates to an apparatus for removing interference between neighbor cells in a radio communication system, and to a method for same. The apparatus according to the present invention includes a receiving unit which receives receiving power information and signal-to-noise ratio information of a neighbor cell base station from multiple receiving antennas, a first determination unit for determining the number of major neighbor cell interference signals by using the received receiving power information and the signal-to-noise ratio information, a second determination unit for determining a candidate signal vector of a target signal in accordance with the determined number of major neighbor cell interference signals, the received signal-to-noise ratio, and the number of the multiple receiving antennas, a third determination unit for determining a candidate signal matrix of the major neighbor cell interference signals on the basis of the determined candidate signal vector of the target signal, and an estimation unit for estimating signals transmitted from the target base station or the neighbor base station by applying the determined candidate signal matrix of the major neighbor cell interference signals to the method of maximum likelihood.

Claims

1. An apparatus for cancelling interference between neighboring cells, comprising:

a receiving unit for receiving reception power information and Signal-to-Noise power Ratio (SNR) information of a neighboring cell base station from multiple receiving antennas;

a first determination unit for determining a number of dominant neighboring cell interference signals using the received reception power information and SNR information;

a second determination unit for fixing a candidate signal vector of a target signal depending on the determined number of dominant neighboring cell interference signals, the received SNR information, and a number of the multiple receiving antennas;

a third determination unit for fixing a candidate signal matrix of the dominant neighboring cell interference signals based on the fixed candidate signal vector of the target signal; and

an estimation unit for cancelling interference from signals transmitted from the neighboring cell base station by applying the fixed candidate signal matrix of the dominant neighboring cell interference signals to a reception signal vector in accordance with a Maximum Likelihood (ML) technique,

wherein the second determination unit

selects C₀ candidate signal values of the target signal in an ascending order of Euclidean distances of the candidate signal values when the SNR is less than a threshold value required to determine the dominant neighboring cell interference signals or when the number of the dominant neighboring cell interference signals is equal to or greater than the number of the receiving antennas, and

fixes a candidate signal vector of the target signal, which includes the selected C₀ candidate signal values of the target signal.

2. The apparatus according to claim 1, wherein the receiving unit receives the reception power information and the SNR information of the neighboring cell base station through a downlink preamble signal, and receives signals which have been transmitted from the target base station and have been estimated using the ML technique.

3. The apparatus according to claim 1, wherein the first determination unit obtains the number of the dominant neighboring cell interference signals based on the received reception power information and the received SNR information using equation

4. The apparatus according to claim 1, wherein the second determination unit:

selects a single candidate signal value of the target signal when the SNR is equal to or greater than the threshold value required to determine the dominant neighboring cell interference signals and when the number of the dominant neighboring cell interference signals is less than the number of the receiving antennas, and

fixes a candidate signal vector of the target signal, which includes the selected single candidate signal value of the target signal.

5. The apparatus according to claim 1, wherein the third determination unit:

selects C_i candidate signal values of the neighboring cell interference signals based on the fixed candidate signal vector of the target signal when an SNR of an i-th base station signal is less than the threshold value or when the number of the dominant neighboring cell interference signals is equal to or greater than the number of the receiving antennas, and fixes a candidate signal matrix of the neighboring cell interference signals, which includes the selected C, candidate signal values of the neighboring cell interference signals.

6. The apparatus according to claim 5, wherein the third determination unit:

selects a single candidate signal value of the neighboring cell interference signals based on the fixed candidate signal vector of the target signal when the SNR of the i-th base station signal is equal to or greater than the threshold value and when the number of the dominant neighboring cell interference signals is less than the number of the receiving antennas, and

fixes a candidate signal matrix of the neighboring cell interference signals, which includes the selected single candidate signal value of the neighboring cell interference signals.

7. The apparatus according to claim 1, wherein the estimation unit:

estimates signals transmitted from the target or neighboring cell base station using equation

8. The apparatus according to claim 7, wherein the estimation unit determines signals transmitted from the target base station using equation {tilde over (x)}=┌

{tilde over (x)}┐

₁, where ┌

{tilde over (x)}┐

₁ denotes a first column vector of {tilde over (x)}.

14. The method according to claim 5, wherein the fixing the candidate signal matrix of the dominant neighboring cell interference signals is configured to:

select a single candidate signal value of the neighboring cell interference signals based on the fixed candidate signal vector of the target signal when the SNR of the i-th base station signal is equal to or greater than the threshold value and when the number of the dominant neighboring cell interference signals is less than the number of the receiving antennas, and

fix a candidate signal matrix of the neighboring cell interference signals, which includes the selected single candidate signal value of the neighboring cell interference signals.

9. A method of cancelling interference between neighboring cells, comprising:

receiving reception power information and Signal-to-Noise power Ratio (SNR) information of a neighboring cell base station from multiple receiving antennas;

determining a number of dominant neighboring cell interference signals using the received reception power information and SNR information;

fixing a candidate signal vector of a target signal depending on the determined number of dominant neighboring cell interference signals, the received SNR information, and a number of the multiple receiving antennas;

fixing a candidate signal matrix of the dominant neighboring cell interference signals based on the fixed candidate signal vector of the target signal; and

estimating signals transmitted from the neighboring cell base station and cancelling interference by applying the fixed candidate signal matrix of the dominant neighboring cell interference signals to a reception signal vector in accordance with a Maximum Likelihood (ML) technique,

wherein the fixing the candidate signal vector of the target signal is configured to

select a single candidate signal value of the target signal when the SNR is equal to or greater than the threshold value required to determine the dominant neighboring cell interference signals and when the number of the dominant neighboring cell interference signals is less than the number of the receiving antennas, and

fix a candidate signal vector of the target signal, which includes the selected single candidate signal value of the target signal.

10. The method according to claim 9, wherein the receiving is configured to receive the reception power information and the SNR information of the neighboring cell base station through a downlink preamble signal.

11. The method according to claim 9, wherein the determining the number of the dominant neighboring cell interference signals is configured to determine the number of the dominant neighboring cell interference signals based on the received reception power information and the received SNR information using equation

12. The method according to claim 9, wherein the fixing the candidate signal vector of the target signal is configured to:

select C₀ candidate signal values of the target signal in an ascending order of Euclidean distances of the candidate signal values when the SNR is less than a threshold value required to determine the dominant neighboring cell interference signals or when the number of the dominant neighboring cell interference signals is equal to or greater than the number of the receiving antennas, and

fix a candidate signal vector of the target signal, which includes the selected C₀ candidate signal values of the target signal.

13. The method according to claim 9, wherein the fixing the candidate signal matrix of the dominant neighboring cell interference signals is configured to:

select C_i candidate signal values of the neighboring cell interference signals based on the fixed candidate signal vector of the target signal when an SNR of an i-th base station signal is less than the threshold value or when the number of the dominant neighboring cell interference signals is equal to or greater than the number of the receiving antennas, and

fix a candidate signal matrix of the neighboring cell interference signals, which includes the selected C_i candidate signal values of the neighboring cell interference signals.

15. The method according to claim 9, wherein the estimating signals transmitted from the target or neighboring cell base station is configured to:

estimate signals transmitted from the target or neighboring cell base station using equation

16. The method according to claim 15, wherein the estimating the signals transmitted from the target or neighboring cell base station is configured to determine signals transmitted from the target base station using equation {tilde over (x)}=┌

{tilde over (x)}┐

₁, where ┌

{tilde over (x)}┐

₁ denotes a first column vector of {tilde over (x)}.