Radio Resource Division for Interference Mitigation in Heterogeneous LTE
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Solution Overview
Problem
In heterogeneous LTE networks, inter-base station interference significantly affects the throughput of low power base stations, particularly due to overlapping data transmission channels, which reduces the connection opportunities and data transmission efficiency for low power base stations.
Innovation Solution
A radio communication system that includes a division ratio determination unit to allocate radio resources between high power and low power base stations, limiting transmission power for specific downlink channels to reduce interference, thereby improving throughput by equalizing the expected throughput of deteriorated terminals connected to both types of base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the coverage of the low power base station is expanded by controlling radio terminals to connect to it even when received power is not highest, then the connection opportunities of the low power base station are improved, but the data transmission channel of the low power base station receives significant interference from the high power base station
Solution Approach 1:
The radio resources are segmented into first radio resources (usable by high power base station) and second radio resources (unusable by high power base station). This segmentation allows the low power base station to transmit data on second radio resources without interference from the high power base station, while the high power base station uses first radio resources. The division ratio determination unit dynamically determines the allocation ratio between first and second radio resources based on throughput requirements of deteriorated terminals.
Solution Approach 2:
Different radio resources are allocated with different transmission power characteristics. First radio resources allow normal transmission power from the high power base station, while second radio resources have limited transmission power from the low power base station. This local quality differentiation ensures that resources are optimized for their specific usage scenarios, reducing interference while maintaining connectivity.
2Productivity
If radio resources used as data transmission channels between neighboring base stations overlap each other, then resource utilization is improved, but the data transmission channel receives interference from neighboring base stations
Solution Approach 1:
The overlapping radio resources are segmented into first radio resources (macro cell usable PDSCH resources) and second radio resources (macro cell unusable PDSCH resources). This segmentation enables the system to utilize all available radio resources while preventing interference by directing high power transmissions only on first radio resources and low power transmissions on second radio resources.
Solution Approach 2:
The transmission power parameter is changed based on the radio resource type. For second radio resources, the transmission power of the low power base station is limited to be lower than for first radio resources. This parameter change allows the system to maintain resource overlap for utilization while controlling interference through power adjustment.
3Productivity
If the transmission power of the low power base station is increased to improve throughput, then the throughput of the low power base station is improved, but the interference to the high power base station's data transmission channel increases
Solution Approach 1:
The system segments radio resources such that second radio resources are exclusively allocated to the low power base station for transmitting to deteriorated terminals. Since the high power base station does not use second radio resources, the low power base station can transmit at higher power on these resources without causing interference to the high power base station's data transmissions.
Solution Approach 2:
The problematic overlapping resources are extracted and separated into distinct first and second radio resource sets. The second radio resources are extracted from the high power base station's usable resources and allocated to the low power base station, eliminating the source of interference while maintaining system throughput.
Data Source
AI summary
A radio communication system 1 according to an embodiment comprises: a pico cell base station PeNB provided in a communication area of a macro cell base station MeNB and having transmission power lower than transmission power of the macro cell base station MeNB. A resource division ratio is determined with respect to radio resources to be usable as a physical downlink shared channel (PDSCH), indicating a ratio of macro cell unusable PDSCH resources and macro cell usable PDSCH resources. The radio resources are assigned to a radio terminal connected to the macro cell base station MeNB, out of the macro cell usable PDSCH resources determined according to the determined resource division ratio. The resource division ratio is determined according to expected throughputs of each of cell edge terminals of the macro cell base station MeNB and the pico cell base station PeNB.