IDcell Allocation for Wireless Sector Interference
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Solution Overview
Problem
In IEEE 802.16e broadband wireless communication systems, adjacent sectors often reuse the same IDcell and segment number, leading to subcarrier randomization issues that degrade pilot estimation performance, as the same initialization vectors are used, causing interference and making it difficult for Mobile Stations to distinguish desired signals from interference.
Innovation Solution
An apparatus and method for IDcell allocation in a broadband wireless communication system, where sectors are initially allocated to an N×M IDcell matrix, and a sector pair with the highest proximity is selected to swap IDcells, minimizing the reuse of IDcells and reducing interference by calculating inter-sector proximity using path loss and antenna patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same IDcell is allocated to adjacent sectors to simplify allocation, then device complexity is reduced, but subcarrier randomization performance deteriorates and interference increases
Solution Approach 1:
The patent applies local quality by making IDcell allocation location-dependent. Different IDcells are allocated based on the specific sector's position and its neighboring sectors. The base station determines IDcell allocation locally for each sector by considering the sector index and proximity to other sectors, rather than using a uniform allocation scheme. This ensures that adjacent sectors have different IDcells while maintaining systematic allocation.
Solution Approach 2:
The patent implements preliminary action by pre-defining IDcell allocation rules before actual sector operation. The base station pre-determines the mapping between sector indices and IDcells based on sector proximity relationships. This preliminary allocation strategy prevents IDcell conflicts before they occur, ensuring that sectors are assigned distinct IDcells in advance, thereby avoiding subcarrier randomization conflicts and pilot estimation degradation.
2Productivity
If frequency reuse factor of 1 is used to increase spectral efficiency, then productivity is improved, but interference between adjacent sectors increases
Solution Approach 1:
The patent applies parameter changes by modifying the IDcell parameter specifically for subcarrier randomization purposes while maintaining frequency reuse factor of 1. Although the frequency remains the same across sectors, the IDcell parameter is changed for each sector to generate different initialization vectors for PRBS sequences. This parameter differentiation enables spectral efficiency through frequency reuse while preventing interference through distinct randomization patterns.
3Ease of operation
If the same initialization vector is used in adjacent sectors to simplify processing, then ease of operation is improved, but signal distinction capability deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the initialization vector into multiple components: sector index, sector proximity information, and frame number. Instead of using a single uniform initialization value, the system segments the vector generation process to incorporate sector-specific parameters. This ensures that each sector generates a unique initialization vector while maintaining a systematic and manageable generation process through defined segmentation rules.
Data Source
AI summary
An apparatus and a method for allocating IDcells in a wireless communication system are provided, in which an initial IDcell allocation is performed by allocating entire sectors to elements of an N×M IDcell matrix, a sector pair with the highest proximity is selected for each IDcell in the initial allocation, an IDcell with a sector pair having the highest of the proximities of the selected sector pairs is determined as a target IDcell, one sector of the sector pair with the highest proximity for the target IDcell is selected as a target sector, a predetermined number of sectors are selected for each of the other IDcells except for the target IDcell, from among sectors to which the each of the other IDcells is allocated, and the IDcell of the target sector is swapped with the IDcell of a sector satisfying a first condition among the selected sectors.