OFDM Subcarrier Region Allocation for Sector Interference Reduction
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Solution Overview
Problem
The existing OFDM/OFDMA communication systems face challenges in minimizing interference between neighboring sectors and cells, leading to performance degradation, especially in the uplink, due to fixed channel allocation and sectorization concepts, which limit frequency reuse efficiency and increase bit error rates.
Innovation Solution
A method for allocating resources in an OFDM mobile communication system by dividing the full subcarrier band into multiple subcarrier regions and allocating subcarriers differently for neighboring sectors, allowing orthogonal resource allocation to minimize interference and enhance frequency reuse, while also redistributing resources between subsectors to balance loads and reduce interference between uplink and downlink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed channel allocation and sectorization concepts are used, then system structure is simplified, but interference between neighboring sectors increases and frequency reuse efficiency decreases
Solution Approach 1:
The patent divides the frequency spectrum into multiple subcarrier regions (first subcarrier region, second subcarrier region, etc.) and allocates different regions to different sectors. This segmentation allows neighboring sectors to use different frequency regions, reducing interference while maintaining a relatively simple sectorized structure.
Solution Approach 2:
The patent applies different subcarrier allocation patterns to different sectors within the same cell. Each sector is allocated specific subcarrier regions based on its location and interference characteristics, creating locally optimized allocation that reduces neighboring sector interference while maintaining overall system simplicity.
2Device complexity
If fixed channel allocation is used, then resource allocation is simple, but frequency reuse efficiency is limited and bit error rate increases
Solution Approach 1:
The patent introduces dynamic subcarrier allocation where the base station can flexibly assign different subcarrier regions to different sectors based on real-time channel conditions and interference levels. This dynamic allocation reduces bit error rates by avoiding fixed, potentially interfering allocations while maintaining manageable complexity through structured allocation patterns.
Solution Approach 2:
The patent changes the allocation parameter from fixed channel assignment to variable subcarrier region assignment. By dynamically adjusting which subcarrier regions are allocated to which sectors based on channel conditions, the system reduces bit error rates while managing allocation complexity through structured parameter changes.
3Productivity
If subcarriers are allocated for neighboring sectors, then frequency reuse is enabled, but interference between uplink and downlink transmissions increases
Solution Approach 1:
The patent segments subcarrier regions and allocates different segments to different sectors in a coordinated manner. By carefully dividing the frequency spectrum and assigning specific segments to specific sectors, the system enables frequency reuse while minimizing uplink-downlink interference through structured segmentation.
Solution Approach 2:
The base station monitors channel conditions and interference levels, using this feedback to dynamically adjust subcarrier region allocations. This feedback mechanism allows the system to maintain frequency reuse efficiency while adapting to changing conditions to reduce uplink-downlink interference.
Data Source
AI summary
In an orthogonal frequency division multiplexing (OFDM) mobile communication system, an apparatus and method allocates resources for data transmission and transmits/receives user data using the allocated resources. A full subcarrier band allocable for one cell is divided into a plurality of subcarrier regions. Subcarriers selected from subcarriers existing in one of the plurality of subcarrier regions are allocated for each of a plurality of sectors constituting the cell. The subcarriers are allocated such that subcarriers existing in different subcarrier regions are allocated for neighboring sectors in the cell.