Method and system for estimating co-channel interference in a frame of a block transmission system

Abstract

A method and system for estimating Co-Channel Interference (CCI) at each pilot sub-carrier of each symbol in a frame of a block transmission system is provided. The method includes determining the CCI at each pilot sub-carrier of a predetermined number of symbols (L). The predetermined number of symbols is equal to the periodicity of the pilot pattern of the frame. The method includes using the CCI at each pilot sub-carrier of the predetermined number of symbols to estimate the CCI at each pilot sub-carrier of remaining symbols in the frame.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart for estimating co-channel interference (CCI) at each pilot sub-carrier of each symbol in a frame of a block transmission system, in accordance with an embodiment.

FIG. 2 is a flowchart for performing channel estimation, in accordance with an embodiment.

FIG. 3 is a flowchart for estimating CCI at each pilot sub-carrier of each symbol in a frame of the block transmission system, in accordance with another embodiment.

FIG. 4 is a flowchart for performing channel estimation, in accordance with another embodiment.

FIG. 5 is a block diagram of a system for performing channel estimation in a block transmission system, in accordance with an embodiment. [To Rick: Please note that, in light of your comments we have changed FIG. 5 to represent a block diagram. Further, a block transmission system represents an OFDM communication system. In light of this, FIG. 5A recommended by you would not be required.]

FIG. 6 is a comparison between Mean Square Error (MSE) performance of the method of an embodiment and a single channel estimator without interference cancellation known in the art.

Claims

1. A method for estimating co-channel interference at each pilot sub-carrier of each symbol in a frame of a block transmission system, the block transmission system being a frequency reuse system, the method comprising: a. determining the co-channel interference at each pilot sub-carrier of a predetermined number of symbols (L), the predetermined number of symbols being equal to the periodicity of the pilot pattern of the frame; andb. using the co-channel interference at each pilot sub-carrier of the predetermined number of symbols to estimate the co-channel interference at each pilot sub-carrier of remaining symbols in the frame.

2. The method of claim 1, wherein the co-channel interference at a pilot sub-carrier of a ‘k+L’ symbol is approximately equal to the co-channel interference at the corresponding pilot sub-carrier of a ‘k’ symbol.

3. The method of claim 1, wherein the frame is an uplink frame.

4. The method of claim 1, wherein the frame is a downlink frame.

5. A method for performing channel estimation, the channel estimation being performed by a receiver in a block transmission system, the block transmission system being a frequency reuse system, the method comprising: a. estimating a channel response of a training symbol;b. estimating co-channel interference at each pilot sub-carrier of each symbol in a frame of the block transmission system, the frame being transmitted by at least one transmit antenna, wherein estimating co-channel interference comprises: i. determining the co-channel interference at each pilot sub-carrier of a predetermined number of symbols (L) by using the channel response of the training symbols, the predetermined number of symbols being equal to the periodicity of the pilot pattern of the frame; andii. using the co-channel interference at each pilot sub-carrier of the predetermined number of symbols to estimate the co-channel interference at each pilot sub-carrier of remaining symbols in the frame; andc. calculating a channel response of each pilot sub-carrier of the remaining symbols of the frame based on the corresponding estimated co-channel interference.

6. The method of claim 5, wherein the training symbol is a preamble symbol if the number of transmit antennas is equal to one.

7. The method of claim 5, wherein the training symbol is a mid-amble symbol if the number of transmit antennas is at least two.

8. The method of claim 7, wherein the mid-amble is a reuse-⅓ mid-amble symbol.

9. The method of claim 5, wherein the co-channel interference at each pilot sub-carrier of the predetermined number of symbols (L) is determined using a product of the channel response of the training symbols and a predetermined function of fader rate of the receiver and difference in number of symbols from the training symbol.

10. The method of claim 5, wherein the co-channel interference at a pilot sub-carrier of a ‘k+L’ symbol is approximately equal to the co-channel interference at a corresponding pilot sub-carrier of a ‘k’ symbol.

11. The method of claim 5, wherein the co-channel interference at a pilot sub-carrier of a ‘k+L’ symbol is approximately equal to a product of the fader rate of the receiver and the co-channel interference at the corresponding pilot sub-carrier of a ‘k’ symbol.

12. The method of claim 10, further comprising: a. updating the channel response of the pilot sub-carrier of the ‘k+L’ symbol based on the channel response of the corresponding pilot sub-carrier of a ‘k+L−1’ symbol; andb. updating the co-channel interference of the pilot sub-carrier of the ‘k+L’ symbol based on the updated the channel response.

13. A system for performing channel estimation, the channel estimation being performed by a receiver in a block transmission system, the block transmission system being a frequency reuse system, the system comprising: a. a training-channel-response estimator, the training-channel-response estimator configured to estimate a channel response of a training symbol;b. a co-channel interference estimator, the co-channel interference estimator configured to estimate co-channel interference at each pilot sub-carrier of each symbol in a frame of the block transmission system, the frame being transmitted by at least one transmit antenna, wherein the co-channel interference estimator comprises a processor that is configured to: i. determine the co-channel interference at each pilot sub-carrier of a predetermined number of symbols (L) by using the channel response of the training symbols, the predetermined number of symbols being equal to the periodicity of the pilot pattern of the frame; andii. use the co-channel interference at each pilot sub-carrier of the predetermined number of symbols to estimate the co-channel interference at each pilot sub-carrier of remaining symbols in the frame; andc. a symbol-channel-response calculator, the symbol-channel-response calculator configured to calculate a channel response of each pilot sub-carrier of the remaining symbol of the frame based on the corresponding estimated co-channel interference.

14. The system of claim 13, wherein each pilot sub-carrier in the frame is a Maximum Length Shift Register (MLSR) sequence.

15. The system of claim 13, wherein the co-channel interference at a pilot sub-carrier of a ‘k+L’ symbol is approximately equal to the co-channel interference at the corresponding pilot sub-carrier of a ‘k’ symbol.

16. The system of claim 15, further comprising: a. a channel response updating module configured to update the channel response of the pilot sub-carrier of the ‘k+L’ symbol based on the channel response of the corresponding pilot sub-carrier of a ‘k+L−1’ symbol; andb. a co-channel interference updating module configured to update the co-channel interference of the pilot sub-carrier of the ‘k+L’ symbol based on the updated the channel response.

17. The system of claim 13, wherein the co-channel interference at a pilot sub-carrier of a ‘k+L’ symbol is approximately equal to the product of the fader rate of the receiver and the co-channel interference at the corresponding pilot sub-carrier of a ‘k’ symbol.

18. The system of claim 13, wherein the co-channel interference at each pilot sub-carrier of the predetermined number of symbols (L) is determined by using a product of the channel response of the training symbols and a predetermined function of fader rate of the receiver and difference in number of symbols from the training symbols.

19. The system of claim 13, wherein the block transmission system is a frequency reuse-1 system.

20. The system of claim 13, wherein the training-channel-response estimator, the co-channel interference estimator and the symbol-channel-response calculator are integrated into a single module.