SDMA User Selection in MIMO Systems via Channel-Ordered Combination Limiting
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Solution Overview
Problem
Conventional MIMO systems require a large computation volume to select SDMA users by generating all possible user combinations and calculating their capacities, which is inefficient.
Innovation Solution
The method involves reducing the number of user combinations to investigate by ordering users based on channel status and comparing interference-reflected SNR decrements with an investigation threshold, or by setting a maximum investigation number and threshold SNR decrement to limit the computation volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all possible user combinations are generated and their capacities are calculated to select SDMA users, then the user selection accuracy is improved, but the computation volume increases significantly
Solution Approach 1:
The patent segments the user combination selection process into two stages: first, users are sorted based on channel conditions (e.g., channel gain or SNR) to create an ordered list; second, only a limited number of combinations from this ordered list are evaluated. This segmentation reduces the total number of combinations that need full capacity calculation while maintaining selection accuracy by prioritizing combinations with better channel conditions.
Solution Approach 2:
Instead of evaluating all possible user combinations, the patent applies partial action by limiting the evaluation to a subset of combinations that meet certain criteria (e.g., combinations involving users with the best channel conditions). This partial evaluation approach achieves satisfactory user selection without the excessive computation required for exhaustive search.
2Productivity
If the number of users to be serviced (U) increases, then the SDMA system capacity is improved, but the number of user combinations to investigate increases
Solution Approach 1:
The patent performs preliminary sorting of users based on channel conditions before forming user combinations. This preliminary action creates an ordered list of users ranked by their channel quality, which then guides the combination formation process. When U increases, this preliminary sorting remains the same, but the subsequent combination evaluation is streamlined because only combinations involving users from the top of the sorted list need to be considered, reducing the effective search space.
Data Source
AI summary
An apparatus and method for selecting at least two users to be serviced in SDMA in an SDMA wireless communication system are provided. All users are ordered according to a predetermined rule and all possible user combinations each having at least two users are created from the ordered users. An investigation limit number is set using the capacity of a jth user combination. Or a total investigation number is reduced by comparing the interference-reflected SNR decrements of users with an investigation threshold. Therefore, the computation volume for selecting SDMA users is decreased.