Mobile Relay Node Interference Mitigation in Heterogeneous Networks
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Solution Overview
Problem
Heterogeneous wireless networks employing mobile relay nodes experience significant interference between backhaul and radio access links, as well as among backhaul links themselves, which reduces network capacity and can lead to outages, especially in unsynchronized cellular networks.
Innovation Solution
The implementation of fractional frequency reuse and power-controlled targeted beamforming between radio access links and wireless backhaul links associated with mobile relay nodes mitigates interference without requiring explicit synchronization between neighboring cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mobile relay nodes are deployed in heterogeneous networks to increase network capacity and coverage, then network capacity and coverage are improved, but interference between backhaul links and radio access links increases
Solution Approach 1:
The available frequency spectrum is segmented into multiple frequency subsets, with different subsets allocated to backhaul links and radio access links. This frequency division separates the two types of transmissions in the frequency domain, allowing them to operate simultaneously without interfering with each other, thus resolving the contradiction between network capacity improvement and interference reduction
Solution Approach 2:
Different frequency resources are allocated to different spatial locations and transmission types. Specifically, backhaul links and radio access links use different frequency subsets depending on their operational requirements and interference characteristics, optimizing resource allocation locally for each transmission type while maintaining overall network capacity
2Device complexity
If mobile relay nodes are deployed without explicit synchronization between neighboring cells, then deployment complexity and cost are reduced, but interference mitigation becomes difficult
Solution Approach 1:
The frequency spectrum is segmented into dedicated subsets for different links, allowing unsynchronized transmissions to coexist without interference. By assigning non-overlapping frequency resources to backhaul links in different cells, the system eliminates interference without requiring time synchronization between neighboring cells, thus reducing deployment complexity while maintaining interference mitigation
3Area of stationary object
If transmission power of mobile relay nodes is increased to improve coverage, then coverage area is expanded, but interference to macro network increases
Solution Approach 1:
Different frequency subsets are allocated to mobile relay node transmissions based on their function (backhaul vs. radio access). This allows the relay nodes to transmit at higher powers for coverage extension while the frequency division ensures that these transmissions do not interfere with macro network operations, thus achieving both coverage expansion and interference reduction
Data Source
AI summary
Devices, systems and methods for mitigating the interference introduced by mobile relay nodes in a heterogeneous network are described. The techniques described apply fractional frequency reuse and power controlled beamforming to mitigate such interference.