Weak User Detection in Massive MIMO Beam Selection
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Solution Overview
Problem
Massive MIMO systems face challenges in real-time processing and hardware requirements due to the large number of parallel data streams from multiple antennas, leading to complexity in beam selection and processing, particularly in detecting weak users and achieving optimal beamforming gains.
Innovation Solution
A method for operating a receiver arrangement that transforms collected signals into beam space using a transform base, selects a subset of beams based on quality requirements, and iteratively adjusts the subset or transform base to ensure quality thresholds are met, allowing for efficient detection and processing of weak signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a very large number of antennas are used in massive MIMO to achieve narrow beams and large focusing gain, then reception sensitivity and beamforming gain are improved, but processing complexity and hardware requirements increase exponentially
Solution Approach 1:
The patent segments the massive MIMO system into two distinct processing stages: beam space processing (transforming antenna signals into beam domain) and symbol processing (detecting user symbols). This segmentation allows the system to handle large numbers of antennas by first converting the problem into a lower-dimensional beam space, reducing the complexity of subsequent processing while maintaining reception sensitivity.
Solution Approach 2:
The patent introduces beam space as an intermediary domain between the antenna domain and the symbol detection domain. By transforming signals into beam space using a transform base (such as DFT or codebook-based beams), the system creates an intermediate representation that preserves signal quality while reducing the dimensionality of subsequent processing operations.
2Measurement precision
If all beams from a very large number of antennas are processed to ensure detection of weak users, then detection accuracy is improved, but real-time processing becomes infeasible due to exponential complexity scaling
Solution Approach 1:
The patent performs preliminary beam space transformation before symbol detection, organizing the signal energy into concentrated beams in advance. This preliminary action groups signal power from multiple antennas into fewer beam domains, making subsequent detection more efficient and enabling real-time processing while maintaining accuracy for weak users.
Solution Approach 2:
The patent changes the processing parameter from antenna-domain signals to beam-domain signals through a transform operation. This parameter change (from N antenna elements to M beams where M < N) reduces the computational dimensionality while preserving the essential signal characteristics needed for accurate detection of weak users.
3Productivity
If beam selection is used to reduce processing complexity, then processing efficiency is improved, but weak users may be missed due to selective beam processing
Solution Approach 1:
The patent employs iterative detection with feedback where initial symbol estimates are used to cancel interference, and the process is repeated to improve detection accuracy. This feedback mechanism allows the system to reliably detect weak users even when processing a reduced set of beams, as the iterative refinement compensates for the initial beam selection limitations.
Solution Approach 2:
The patent converts the potential harm of beam selection (missing weak users) into a benefit by using strong users as interference sources that can be estimated and cancelled. The selected beams provide sufficient signal strength for accurate symbol estimation, which then enables interference cancellation that improves weak user detection in subsequent iterations.
Data Source
AI summary
There is disclosed a method of operating a receiver arrangement in a radio access network. The receiver arrangement is adapted for receiving a plurality of antenna signals from a plurality of antennas, wherein the plurality of signals is collected to form a collected signal. The method includes transforming the collected signal into beam space based on a transform base, to provide a set of beams, selecting a subset of beams from the set of beams and evaluating the subset of beams for a quality requirement. If evaluating results in the quality requirement not being fulfilled, either the subset of selected beams is changed and it is returned to evaluating or the transform base is changed and it is returned to transforming. The disclosure also pertains to related methods and devices.