OFDMA Frame Offset for Base Station Interference Avoidance
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Solution Overview
Problem
Conventional radio base-station apparatuses using OFDMA with frequency reuse factor 1 experience reduced maximum transmission rates and interference between sectors, leading to decreased transmission efficiency due to the division of the radio frequency band into segments.
Innovation Solution
The radio base-station apparatus configures OFDMA frames for multiple sectors with logical subchannel numbers and OFDMA symbol numbers, ensuring that preambles and frame control information do not overlap, thereby avoiding interference and enhancing transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency reuse factor 1 is used with multiple sectors, then maximum transmission rate is improved, but interference between sectors occurs
Solution Approach 1:
The patent segments the frame structure into distinct regions: a non-overlapping region containing preambles and frame control information, and an overlapping region containing data transmission. This segmentation allows frequency reuse factor 1 to be used for data transmission while preventing interference in the control regions.
Solution Approach 2:
The patent applies different quality requirements to different parts of the frame: the non-overlapping region uses strict time synchronization to prevent interference, while the overlapping region allows flexible frequency reuse. This local differentiation resolves the contradiction between transmission rate and interference avoidance.
2Object-affected harmful factors
If radio frequency band is divided into segments for multiple sectors, then interference is avoided, but transmission rate is reduced
Solution Approach 1:
The patent resolves the frequency division contradiction by introducing a time dimension: frames are configured with specific time offsets so that non-overlapping regions do not coincide in time, while allowing frequency overlap in data regions. This temporal separation maintains frequency reuse efficiency while avoiding interference.
3Device complexity
If preambles and frame control information are arranged sequentially from frame beginnings, then frame structure is simplified, but interference occurs between sectors
Solution Approach 1:
The patent applies preliminary action by configuring time offsets for frame beginnings in advance, ensuring that preambles and frame control information from different sectors do not overlap in time. This preventive measure eliminates interference before it occurs while maintaining the simple sequential arrangement within each frame.
Data Source
AI summary
A radio base-station apparatus with improved frame transmission efficiency by avoiding interference of preambles and frame control information between sectors of a cell or between cells with a frequency reuse factor. In the apparatus OFDMA multiple-access processing is performed for each of a plurality of sectors of a cell, and frames made of logical subchannel numbers and OFDMA symbol numbers are configured in synchronization respectively for the plurality of sectors, and offsets are added to the beginnings of given frames such that the preambles and frame control information arranged sequentially from the beginnings of the frames do not overlap on the OFDMA symbol numbers.