DAS-Small Cell Downlink Interference Avoidance
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Solution Overview
Problem
Co-channel interference between indoor distributed antenna systems (DAS) and small base stations in heterogeneous networks degrades service quality, particularly in indoor deployments, limiting the practical application and deployment of small base stations.
Innovation Solution
A method that involves determining initial access points, establishing signal strength tables, and using precoding techniques to collaboratively manage downlink interference by selecting and adjusting the number of remote units based on signal-to-interference-plus-noise ratios (SINR) to ensure effective communication while minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-frequency multiplexing is employed to improve spectrum utilization rate, then spectrum efficiency is improved, but co-channel interference between cells increases and service quality degrades
Solution Approach 1:
The system segments the network into macro base stations and small base stations with different coverage areas and transmission characteristics. Small base stations serve specific indoor or localized areas while macro base stations provide broader coverage, allowing frequency reuse without complete overlap and thus reducing co-channel interference while maintaining high spectrum utilization.
Solution Approach 2:
Different transmission parameters and power levels are applied locally to small base stations versus macro base stations. Small base stations use lower power and focused beamforming tailored to their specific coverage zones, which reduces interference to other cells while maintaining high local spectrum efficiency.
2Object-affected harmful factors
If interference coordination mechanisms are implemented between macro base stations and small base stations, then co-channel interference is reduced, but system complexity and coordination overhead increase
Solution Approach 1:
Small base stations autonomously determine their transmission parameters, power levels, and resource allocation based on local channel conditions and detected interference levels from macro base stations. This self-configuration capability eliminates the need for complex centralized coordination mechanisms while effectively managing co-channel interference.
Solution Approach 2:
The system performs preliminary channel estimation and interference measurement before actual data transmission. Small base stations pre-adjust their transmission parameters based on predicted interference conditions, avoiding the need for real-time complex coordination during active communication.
3Productivity
If small base stations are deployed in indoor environments, then indoor coverage and network capacity are improved, but mutual interference with existing indoor DAS systems occurs
Solution Approach 1:
The system introduces an interference measurement and detection mechanism that acts as an intermediary between small base stations and DAS systems. This intermediary monitors the electromagnetic environment, identifies DAS signals, and enables small base stations to adaptively adjust their transmission to coexist with DAS without causing mutual interference.
Solution Approach 2:
Small base stations dynamically change transmission parameters such as frequency offset, power spectral density, and time synchronization when DAS systems are detected in the vicinity. This parameter adaptation allows small base stations to operate in indoor environments with DAS infrastructure without causing harmful interference while maintaining high network capacity.
Data Source
AI summary
Provided in the present invention is a method for avoiding downlink interference between an indoor DAS system and a small base station, the steps comprising: step 1: determining an initial access RU, and establishing a signal strength table; step 2: the DAS system, by means of the chosen RU, attempts to establish a downlink with UE 1, and detects the signal to interference plus noise ratio (SINR) value of the downlink signal of UE 1, and comparing same with a preset threshold value γ1; step 3: UE 1 maintains one or a plurality of RU downlinks assigned thereto by the DAS system, during the communication process continuously detects an SINR value at a set time interval, and on the basis of whether same is greater than γ1, ensures a corresponding service quality.