MIMO Decoding via Interference Signal Modeling
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Solution Overview
Problem
MIMO systems face challenges in decoding signals effectively due to interference from multiple transmitters operating on the same carrier frequency, leading to reduced spectral efficiency and reliability, especially in cellular wireless systems where frequency reuse is limited.
Innovation Solution
A communication device and method that obtain parameters for both intended and interfering streams, allowing for pre-processing and demodulation using equivalent receive signal models to separate intended signals from interference, enabling decoding even in the presence of co-channel interference without requiring non-adjacent cell operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple transmitters operate on the same carrier frequency to increase spectral efficiency, then throughput is improved, but co-channel interference increases leading to decoding reliability deterioration
Solution Approach 1:
The patent introduces an interference signal model as an intermediary component that represents the interfering transmitters. By modeling the interference characteristics (channel responses, modulation schemes, power levels) and incorporating this model into the decoding process, the receiver can distinguish between intended and interfering signals, enabling reliable decoding in high spectral efficiency scenarios without requiring frequency separation.
Solution Approach 2:
The patent changes the decoding approach by transitioning from traditional interference avoidance methods to a model-based interference cancellation method. The receiver obtains parameters characterizing both intended and interfering streams (modulation information, channel responses, power levels) and uses these parameter changes to adjust the decoding process, allowing simultaneous transmission from multiple transmitters on the same frequency while maintaining decoding reliability.
2Reliability
If frequency reuse is restricted to reduce interference, then decoding reliability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The interference signal model acts as a mediator that enables the system to tolerate higher interference levels. By incorporating the modeled interference into the decoding process, the system can reuse frequencies more aggressively without sacrificing reliability, thus improving spectral efficiency while maintaining acceptable error rates through model-based signal separation.
Solution Approach 2:
The patent replaces traditional mechanical frequency separation (using frequency reuse restrictions) with a signal processing approach. Instead of physically separating signals in the frequency domain through restrictive frequency allocation, the system uses model-based signal processing to separate intended signals from interference in the signal processing domain, achieving both high spectral efficiency and reliability.
3Device complexity
If traditional MIMO decoding methods are used without interference modeling, then device complexity is reduced, but performance in high interference environments deteriorates
Solution Approach 1:
The patent applies preliminary action by obtaining parameters characterizing the interfering streams before the actual signal decoding process. The receiver first acquires information about the interference model (channel responses, modulation schemes, power levels) and stores this information for use during decoding. This preliminary characterization of interference enables more effective signal separation without requiring complex real-time interference estimation during the decoding process.
Data Source
AI summary
A method includes obtaining a first set of one or more parameters associated with a plurality of transmitters transmitting a plurality of intended streams and obtaining a second set of one or more parameters associated with an interference source. The first set of parameters includes a first MIMO mode associated with the plurality of transmitters and the second set of parameters includes a second MIMO mode associated with the interference source. The method also includes receiving a plurality of streams, including the plurality of intended streams and a plurality of interfering streams transmitted by the interference source, and selecting a pre-processing scheme based at least in part on the first MIMO mode and the second MIMO mode.