Beam Scanning for Interference Avoidance in 5G
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Solution Overview
Problem
In 5G communication systems, beamforming technologies face challenges such as interference between user equipment (UE) devices, limited channel model estimation without reciprocity, and high computational complexity at millimeter wave (mmWave) frequencies, which hinder efficient interference avoidance and capacity optimization.
Innovation Solution
The implementation of a resource-efficient beam scan using cell-specific CSI-RS processes and spatial oversampling to identify and utilize non-interfering beam directions, reducing computational complexity and enabling optimal beamforming without relying on channel reciprocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beamforming is used to improve coverage and reduce interference, then signal strength and capacity are improved, but interference between user equipment still occurs due to beam direction overlap
Solution Approach 1:
The system performs preliminary beam scanning using cell-specific CSI-RS resources before actual data transmission to identify and avoid interfering beam directions. This preliminary action allows the network to schedule transmissions in non-interfering directions, preventing interference before it occurs.
Solution Approach 2:
The patent introduces spatial oversampling to scan beam directions beyond the standard codebook granularity, adding angular resolution dimension to the beamforming process. This enables more precise identification of non-interfering directions by examining beam directions at finer angular intervals.
2Ease of operation
If standard codebook-based beamforming is used, then implementation is straightforward, but beam direction resolution is insufficient to avoid interference
Solution Approach 1:
The patent adds angular resolution by performing beam scans at oversampled directions between standard codebook entries. This creates an enhanced dimensional view of the spatial channel, allowing the system to identify non-interfering directions with finer angular precision while maintaining compatibility with standard codebooks.
Solution Approach 2:
The beam scanning process is segmented into multiple stages: standard codebook-based beamforming for basic operation, and optional spatial oversampling for enhanced resolution. This segmentation allows the system to maintain simplicity when high precision is not needed while enabling improved resolution when interference avoidance requires it.
3Object-generated harmful factors
If beam scanning is performed to identify non-interfering directions, then interference avoidance is improved, but computational complexity increases
Solution Approach 1:
The patent extracts beam direction information from cell-specific CSI-RS resources that are already present in the system for other purposes. By reusing these existing reference signals for beam scanning, the system avoids the computational overhead of generating separate scanning signals while still achieving interference avoidance.
Solution Approach 2:
The cell-specific CSI-RS resources serve multiple functions: they provide reference signals for channel estimation, enable beam scanning for interference avoidance, and support spatial oversampling. This multi-functionality reduces overall system complexity by eliminating the need for dedicated scanning resources.
4Device complexity
If channel reciprocity is assumed for beamforming, then computational complexity is reduced, but accuracy deteriorates at mmWave frequencies
Solution Approach 1:
The system performs self-service beam direction identification by using cell-specific CSI-RS resources transmitted in the downlink to gather channel information directly at the receiver. This eliminates the need for uplink reciprocity assumptions while maintaining practical implementation feasibility through autonomous channel sounding.
Data Source
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AI summary
A scheduling function node (SF) uses the beams available for each WCD to avoid scheduling a transmission that would imply that interference between WCDs is created. In the simplest form such a scheme could be described as follows: (1) avoid scheduling transmission in directions that coincide between WCDs (here, a direction would typically be represented by both azimuth and elevation angles) and (2) when the available beam directions do not allow interference avoidance, accounting for this fact and exploiting other types of orthogonality in the scheduling of time-frequency resources.