MU-MIMO Beam Selection via Interference-Aware Criteria
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Solution Overview
Problem
Current beamforming techniques in high-frequency communication networks, such as those using millimeter wavelengths, face challenges in achieving optimal beam selection and interference management for multi-user multiple input multiple output (MU-MIMO) systems, leading to suboptimal isolation between co-scheduled terminal devices.
Innovation Solution
A method for beam selection in network nodes that involves transmitting reference signals in a beam sweep and selecting beams based on both the highest received power and a mutual interference criterion, ensuring orthogonality between beams to maximize signal-to-interference ratio (SIR) and reduce mutual interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If beams are selected based only on highest received power, then signal strength is maximized, but interference between co-scheduled terminal devices increases
Solution Approach 1:
The patent changes the selection criterion from a single parameter (received power) to multiple parameters (received power and interference level). The network node evaluates both the signal strength and the interference caused to other terminal devices, selecting beams that optimize the trade-off between these two parameters rather than maximizing only one.
Solution Approach 2:
The patent applies different selection criteria to different beam pairs based on their specific interference characteristics. Instead of using a uniform selection rule for all terminal devices, the network node individually evaluates each terminal device's beam options and selects the optimal beam pair combination that minimizes interference while maintaining signal quality.
2Loss of energy
If narrow beam transmission is used at high frequencies, then propagation loss is compensated, but beam selection complexity increases
Solution Approach 1:
The patent performs preliminary beam sweeping and measurements before actual data transmission. The network node pre-evaluates all candidate beams and their interference characteristics, storing this information for use during scheduling decisions. This preliminary action simplifies the real-time beam selection process by having the complex evaluation already completed.
Solution Approach 2:
The terminal devices assist in the beam selection process by measuring and reporting the received power of reference signals transmitted on different beams. This self-service approach allows the network node to obtain interference and signal quality information without requiring complex measurements and calculations at the network node itself.
Data Source
AI summary
There is provided mechanisms for beam selection. A method is performed by a network node. The method comprises performing a beam management procedure for at least two terminal devices. During the beam management procedure reference signals are transmitted in a beam sweep as performed in a set of beams. During the beam management procedure, each of the at least two terminal devices reports at least two beams in the set of beams for which the reference signals have been received with highest power. The method comprises selecting which beams to serve the at least two terminal devices based jointly on the reports and a mutual interference criterion for the at least two terminal devices.