MIMO Receiver Additional Path Reduces Co-Channel Interference
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Solution Overview
Problem
Conventional MIMO-OFDM WLAN systems face co-channel interference due to poor channel selectivity and interference from adjacent channel signals, which affects the recovery of desired signals.
Innovation Solution
A MIMO-OFDM WLAN system with an M-antenna transmitter and (M+1) receive paths, where each receive path includes a filterbank and a processor to separate and process subcarrier signals, reducing co-channel interference by using additional receive paths and advanced signal processing techniques like maximum-ratio combining and interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional MIMO-OFDM WLAN systems use M receive paths for M transmit antennas, then the system structure is simple and cost-effective, but co-channel interference from adjacent channel signals cannot be effectively reduced
Solution Approach 1:
The patent introduces an additional receive path beyond the conventional M paths for M transmit antennas. This extra dimension in the receive path configuration enables the system to separately process and cancel co-channel interference from adjacent channels, transforming the interference problem into a solvable mathematical problem through increased dimensional capacity.
Solution Approach 2:
The received signal is segmented and processed through different receive paths, with the additional path specifically dedicated to capturing and processing interference signals. This segmentation allows the system to separate desired signals from co-channel interference, enabling targeted interference cancellation while maintaining simple processing for the main signal paths.
2Measurement precision
If the receiver uses standard M receive paths, then the processing complexity is low, but channel selectivity is poor and adjacent channel signals fold into the channel of interest
Solution Approach 1:
By adding one more receive path to the conventional M-path configuration, the system gains an additional dimensional space for signal separation. This extra dimension provides the mathematical degrees of freedom needed to achieve perfect channel selectivity and eliminate adjacent channel folding, transforming a filtering problem into a spatial separation problem.
Solution Approach 2:
The additional receive path acts as an intermediary that specifically captures adjacent channel interference signals. By having a dedicated path for interference capture, the system can process and cancel interference without affecting the main signal paths, achieving high channel selectivity through this intermediary component.
Data Source
AI summary
In a multiple-input, multiple-output (MIMO) system, a receiver is implemented with at least one additional receive path beyond the number of transmit antennas used to transmit the signals (e.g., wireless OFDM signals) received at the receiver. In one embodiment, the additional receive path is used to reduced co-channel interference (CCI) in the recovered OFDM signals. In particular, each receive path applies recursive filtering to generate separate subcarrier signals. A processor converts the separate subcarrier signals from the different receive paths into a first set of subcarrier signals corresponding to each transmitted OFDM signal, where each first set of subcarrier signals has desired signal and possibly CCI. The processor also generates a second set of subcarrier signals corresponding to the CCI. The processor subtracts portions of the second set of subcarrier signals from each first set of subcarrier signals to generate recovered OFDM signals having reduced CCI.