Relay Station Frequency Assignment for Interference Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The introduction of relay technology in cellular systems complicates intercell interference coordination, particularly in LTE-Advanced networks, as relay stations can interfere with adjacent cells due to increased power at cell edges, leading to reception issues for mobile stations using central frequencies of adjacent cells.
Innovation Solution
Implementing a communication system that restricts frequency bands assigned to relay stations in one cell to avoid interfering with adjacent cells by using restricted bands or lowering priority, and employing multi-cell frequency repetition to manage central and boundary frequencies, allowing frequency hopping for relay stations to mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If relay stations are installed in cell edges to improve throughput, then coverage and throughput at cell edges are improved, but interference with adjacent cells increases
Solution Approach 1:
The patent applies local quality by differentiating frequency band assignment between relay stations and mobile stations in different cell regions. Boundary frequencies are assigned to relay stations in boundary regions while central frequencies are assigned to mobile stations in center regions, creating localized frequency usage patterns that reduce inter-cell interference while maintaining edge throughput.
Solution Approach 2:
The patent segments the frequency spectrum into boundary frequencies and central frequencies, and segments the cell into boundary regions and center regions. This segmentation allows relay stations and mobile stations to operate on different frequency subsets, reducing interference between adjacent cells while improving edge throughput.
2Area of stationary object
If boundary frequencies are assigned to relay stations to improve edge coverage, then coverage in boundary regions is improved, but interference with central frequencies of adjacent cells occurs
Solution Approach 1:
The patent implements local quality by assigning boundary frequencies specifically to relay stations operating in boundary regions, while mobile stations in center regions use central frequencies. This localized frequency assignment ensures that relay transmissions in boundary areas do not interfere with central frequency operations in adjacent cells.
Solution Approach 2:
The patent uses frequency bands as intermediaries to separate relay station transmissions from mobile station transmissions. By introducing boundary frequencies as a mediator resource, the system allows relay stations to extend coverage in boundary regions without directly interfering with the central frequencies used by mobile stations and base stations.
3Object-affected harmful factors
If frequency bands are restricted for relay stations to reduce interference, then interference with adjacent cells is reduced, but frequency utilization efficiency decreases
Solution Approach 1:
The patent segments the frequency spectrum into distinct boundary frequencies and central frequencies, allocating them to different user types and locations. This segmentation reduces interference by spatial-frequency mapping while maintaining high utilization efficiency through OFDMA's flexible resource allocation capabilities.
Solution Approach 2:
The patent employs dynamic resource allocation through OFDMA, allowing the system to adaptively assign frequency resources based on channel conditions, user location, and traffic demands. This dynamic approach ensures that frequency bands are utilized efficiently while maintaining interference reduction through coordinated frequency assignment.
Data Source
AI summary
By deciding positions of frequencies used via a relay station by a system in advance for assignment of boundary frequencies, frequencies of a central frequency more likely to be affected by the relay station are also mapped by avoiding a signal thereof. Alternatively, an adjacent cell whose central frequency is affected changes depending on a position of the relay station and thus, locations set to be highly likely to interfere with the central frequency of the adjacent cell is reduced by setting a region of the boundary frequencies permitted to the relay station in accordance with the position of the relay station.