Cell Search in Wireless Networks Using Phase-Rotated Sequences
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Solution Overview
Problem
Current wireless communication networks face challenges in efficiently detecting and synchronizing multiple base stations, especially those not time-synchronized, which affects the performance and interference management in heterogeneous networks, leading to reduced spectrum efficiency.
Innovation Solution
A method for operating a multicarrier communication receiver that includes detecting primary and secondary synchronization signals, estimating coarse and fine time offsets, and using phase-rotated reference sequences to identify and synchronize with multiple base stations, even when they are not time-aligned, through a cell search procedure that enhances cell detection and channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If distributed small base stations are added to increase network capacity, then network capacity and coverage are improved, but interference between base stations increases and detection becomes more difficult
Solution Approach 1:
The patent segments the cell search process into multiple stages: initial cell detection using reference signals, followed by time offset estimation, and finally synchronization signal detection. This segmentation allows the system to handle multiple base stations systematically, reducing interference effects at each stage while maintaining high network capacity.
Solution Approach 2:
The patent performs preliminary time offset estimation using reference signals before detecting synchronization signals from neighboring base stations. This preliminary action removes the harmful effect of time misalignment and asynchronous operations, enabling reliable detection of multiple base stations without mutual interference.
2Adaptability or versatility
If base stations operate without time synchronization to enable self-organization, then deployment flexibility is improved, but detection reliability and synchronization accuracy deteriorate
Solution Approach 1:
The patent performs preliminary time offset estimation using reference signals before detecting synchronization signals. This preliminary action enables reliable detection of base stations operating without time synchronization, maintaining detection reliability while preserving deployment flexibility for self-organizing networks.
Solution Approach 2:
The patent introduces reference signals as an intermediary mechanism that facilitates time offset estimation between asynchronous base stations. These reference signals act as a mediator that enables reliable detection and synchronization without requiring strict time synchronization, thus maintaining both flexibility and reliability.
3Device complexity
If conventional cell search procedures are used without time offset estimation, then system complexity is reduced, but detection probability and accuracy of neighboring cells decrease
Solution Approach 1:
The patent segments the cell search procedure into distinct stages: reference signal-based time offset estimation, followed by synchronization signal detection. This segmentation improves detection accuracy by addressing time misalignment separately, while keeping each individual stage relatively simple and manageable.
Solution Approach 2:
The patent performs preliminary time offset estimation using reference signals before the main synchronization signal detection. This preliminary action significantly improves detection probability and accuracy of neighboring cells, while adding only moderate complexity that is justified by the substantial performance improvement.
Data Source
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AI summary
The present application relates to an orthogonal frequency division multiplexing (OFDM) receiver and a method of operating the receiver for performing a cell search. A coarse correlator block is provided to detect one cell out of a plurality of wireless communication cells by determining first correlation values by applying a partial correlation comprising part-wise correlating sample data with each one of a first set of phase-rotated reference sequences and non-coherent combining. The maximum of the first correlation values yields to a cell identifier value. A fine correlator block is provided to estimate a fine time offset value for the one wireless communication cell by determining second correlation values by applying a correlation comprising correlating the sample data with each one of a second set of phase-rotated reference sequences. The maximum of the second correlation values yields to a fine time offset.