MIMO-NOMA User Matching via Channel Correlation
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Solution Overview
Problem
Current user matching methods in MIMO-NOMA downlink communication systems degrade system performance in scenarios with low channel correlation between users, leading to unfair data rates and increased inter-cluster interference for weak users.
Innovation Solution
A user matching method that sorts users by channel gain and calculates correlation coefficients to group strong and weak users, optimizing power distribution using a Lagrange multiplier method to ensure fair data rates and minimize inter-cluster interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If users are matched based on channel gain difference to maximize system throughput, then strong users achieve high rates, but weak users suffer sharp rate decrease in low channel correlation scenarios
Solution Approach 1:
The patent changes the matching parameter from channel gain difference alone to a composite metric that includes both channel gain difference and channel correlation coefficient. This parameter change allows the system to adapt to different channel correlation scenarios, preventing weak user rate degradation while maintaining system throughput.
Solution Approach 2:
The patent introduces dynamic user matching that adapts to channel correlation conditions. When channel correlation is low, the system dynamically adjusts matching criteria to pair strong users with weak users having sufficiently different channel characteristics, preventing rate collapse while optimizing overall throughput.
2Productivity
If Zero Forcing precoding is used to eliminate inter-cluster interference for strong users, then strong user performance improves, but weak users experience increased interference and rate degradation
Solution Approach 1:
The patent applies different precoding strategies to different user groups within the same cluster. Strong users receive ZF precoding for interference elimination, while weak users receive matched-filter or other precoding that considers their specific channel conditions and correlation characteristics, optimizing performance for each user type locally.
Solution Approach 2:
The patent segments users into strong and weak user groups and applies different interference management strategies to each segment. This segmentation allows ZF precoding to be optimized for strong users while separate mechanisms protect weak users from inter-cluster interference.
3Productivity
If user matching prioritizes channel gain difference, then NOMA throughput is maximized, but fairness between users in low correlation scenarios deteriorates
Solution Approach 1:
The patent creates a composite user matching criterion that combines channel gain difference and channel correlation coefficient into a unified matching metric. This composite approach balances throughput optimization with fairness consideration, ensuring both strong and weak users achieve reasonable rates while maintaining high system throughput.
Data Source
AI summary
A user matching and power distribution methods for a MIMO-NOMA downlink communication system is provided. The user matching method includes: dividing all users into a strong user group and a weak user group according to a channel gain sorting result; and sequentially selecting a user in the strong user group, calculating a correlation coefficient between the user and each user in the weak user group, selecting a weak user with the highest correlation coefficient as a weak user in a cluster where the strong user is located, and excluding matched users from respective user groups, until the matching between all strong users and weak users are completed. The present invention enables weak users in a cluster to experience less inter-cluster interference in scenarios where the channel correlation between users is relatively low, thereby improving the total throughput of the communication system.