Multi-Antenna Soft Decoding for Co-Channel Interference Cancellation
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Solution Overview
Problem
Current wireless communication systems face limitations in data transmission rates due to the need to decompose frequency bands into multiple channels to avoid interference, which reduces bandwidth and efficiency.
Innovation Solution
The system computes soft information by estimating channel and modulation information for both intended and interfering signals, allowing mobile stations to decode intended signals effectively without requiring separate frequency channels, thereby enabling efficient data transmission across the full available bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency bands are decomposed into multiple channels to avoid interference, then interference between signals is reduced, but bandwidth is reduced and data transmission rate is limited
Solution Approach 1:
The patent converts the harmful interference from co-channel signals into useful information by estimating the interference channel and subtracting it from the received signal. The interference that was previously detrimental is now characterized and removed, allowing full-bandwidth transmission without frequency decomposition.
Solution Approach 2:
The patent changes the approach from frequency domain separation to time domain interference cancellation. By estimating interference parameters (channel impulse response, signal power) and subtracting them in the time domain, the system achieves both high reliability and high data transmission rate using the full bandwidth.
2Reliability
If frequency decomposition is used to avoid interference, then signal reliability is maintained, but spectral efficiency decreases
Solution Approach 1:
The patent transforms the harmful co-channel interference into a characterizable and removable component. By estimating the interference signal parameters and subtracting them, the system achieves frequency reuse with full bandwidth utilization while maintaining communication reliability.
Solution Approach 2:
The patent transitions from frequency domain multiplexing to time domain interference cancellation. This dimensional change allows the system to use the full frequency spectrum simultaneously while separating desired and interfering signals in the time domain through channel estimation and subtraction.
3Object-affected harmful factors
If conventional matched filtering or linear equalization is used for interference cancellation, then some interference mitigation is achieved, but effectiveness is insufficient when interference strength is comparable or greater than background noise
Solution Approach 1:
The patent introduces an interference channel estimator as an intermediary component that characterizes the interference path between the interfering transmitter and the receiver. This estimator provides accurate interference signal reconstruction even when interference strength exceeds background noise, enabling effective subtraction and improving decoding accuracy.
Solution Approach 2:
The patent performs preliminary estimation of the interference channel impulse response and signal parameters before the actual decoding process. This preliminary characterization of the interference allows for accurate interference subtraction, making the subsequent decoding robust even in high-interference environments where conventional methods fail.
Data Source
AI summary
Apparatus and methods are provided for computing soft information at a receiver having a plurality of receive antennas. The receiver may be a mobile station or a base station, and can receive a signal vector that includes an intended signal from a first source as well as interfering signals from one or more other, interfering sources. The receiver can determine modulation information, such as the modulation scheme, used by each of the interfering sources. The mobile station can also estimate channel information, such as channel gain information, associated with each interfering source. Using the modulation and channel information, the receiver can compute soft information, such as a log-likelihood ratio. In some embodiments, the receiver can adaptively determine which interference sources and which receive antennas to use when computing the soft information.