Interference Cancellation in Wireless Receiver Systems
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Solution Overview
Problem
In next-generation communication systems, particularly in IEEE 802.16e-based Broadband Wireless Access systems, interference between neighbor cells significantly reduces the Carrier-to-Interference and Noise Ratio (CINR) for Mobile Stations located at cell boundaries, leading to decreased system performance due to inadequate interference cancellation techniques.
Innovation Solution
A method and system for data reception that employs a maximum likelihood decoding algorithm to improve reception performance by canceling interference signals from multiple transmission antennas using multiple reception antennas, reducing system complexity through efficient Log Likelihood Ratio (LLR) calculation by estimating interference signals and canceling desired signals before decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency reuse factor=1 is used to increase frequency resource efficiency, then frequency resource efficiency is improved, but interference between neighbor cells increases causing CINR degradation at cell boundaries
Solution Approach 1:
The patent extracts and separately processes the desired signal and interference signal from the composite received signal. By using channel state information to identify and separate the interference component, the system can cancel it out, thereby resolving the CINR degradation caused by frequency reuse factor=1 while maintaining resource efficiency
Solution Approach 2:
The patent converts the harmful interference signal into a beneficial component by using it to calculate interference cancellation metrics. The interference signal, initially degrading performance, is now utilized to generate cancellation information that improves reception quality at cell boundaries
2Reliability
If interference canceller is used to cancel interference signals, then system performance is improved, but interference signals cannot be correctly canceled or desired signals cannot be correctly restored
Solution Approach 1:
The patent performs preliminary channel estimation and signal separation before interference cancellation. By pre-calculating channel state information and identifying desired vs. interference signals in advance, the system establishes accurate baseline metrics that enable precise interference cancellation and desired signal restoration
Solution Approach 2:
The patent implements feedback mechanisms where channel state information is continuously updated based on received signals, and cancellation accuracy is monitored and adjusted. This feedback loop ensures that interference cancellation remains precise even as channel conditions vary, maintaining high measurement precision
3Reliability
If maximum likelihood decoding algorithm is used to improve reception performance, then reception performance is improved, but system complexity increases
Solution Approach 1:
The patent segments the complex maximum likelihood decoding process into manageable stages: channel estimation, signal separation, interference metric calculation, and iterative cancellation. By dividing the overall decoding task into discrete segments, the system achieves high reception performance while keeping implementation complexity可控 through modular processing
Data Source
AI summary
A method and apparatus for receiving data in a communication system is disclosed. Receiving a first signal from a transmitter, a first canceller cancels from the received first signal a second signal desired to be received from the transmitter. A second canceller detects and cancels an interference signal from the second signal-canceled first signal. A calculator calculates a Log Likelihood Ratio (LLR) of the interference signal-canceled first signal.