Cell Search Method Using Successive Interference Cancellation
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Solution Overview
Problem
Conventional cell search methods in wireless communication systems, particularly in TDD-LTE mode, face challenges with frame synchronization due to overlapping synchronization signals, leading to interference and reduced detection probability of weak signals.
Innovation Solution
The method involves performing a reception timing detection procedure to obtain possible reception times for the primary synchronization signal (PSS), generating frequency-domain PSS sequences based on root indexes, and conducting coherent detection of the secondary synchronization signal (SSS) to determine physical layer cell identities, while employing successive interference cancellation (SIC) in the frequency domain to mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cell search methods are used in TDD-LTE mode, then the detection procedure follows standard protocol, but overlapping synchronization signals cause interference and reduce detection probability of weak signals
Solution Approach 1:
The patent segments the cell search process into distinct phases: initial synchronization signal detection, channel estimation, and successive interference cancellation. By dividing the detection procedure into separate stages with specific functions, the system can process strong and weak signals differently at each stage, reducing mutual interference and improving overall detection reliability
Solution Approach 2:
The patent introduces channel estimation as an intermediary step between signal reception and final detection. The estimated channel characteristics serve as a mediator that helps distinguish between strong and weak synchronization signals, enabling the successive interference cancellation algorithm to effectively separate and detect signals that would otherwise be obscured by interference
2Productivity
If conventional cell search is performed without reception timing detection, then the procedure follows standard steps, but cell search time is extended due to sequential processing
Solution Approach 1:
The patent performs reception timing detection as a preliminary action before the main cell search procedure. By determining the timing of synchronization signals in advance, the system can align subsequent processing operations more efficiently, reducing the overall cell search time while maintaining detection accuracy
Solution Approach 2:
The patent implements continuous processing throughout the cell search procedure by overlapping operations such as correlation computation, channel estimation, and interference cancellation. This continuous action eliminates idle processing intervals and maintains productive computation throughout the entire cell search timeframe
3Reliability
If successive interference cancellation is applied in frequency domain, then interference between strong and weak signals is eliminated, but computational complexity increases
Solution Approach 1:
The patent transforms the interference cancellation operation from time domain to frequency domain by applying Fast Fourier Transform. This parameter change in the computational domain allows the use of efficient frequency-domain filtering and cancellation algorithms, reducing computational complexity while maintaining the ability to eliminate interference between signals
Data Source
AI summary
A method of cell search for a mobile device in a wireless communication system is provided. The method comprises performing a reception timing detection procedure, to obtain at least a possible reception time for a primary synchronization signal (PSS), performing a PSS hypothesis procedure, to generate three frequency-domain PSS sequences according to three root indexes each corresponding to a physical layer identity, and performing a secondary synchronization signal (SSS) coherent detection procedure, to calculate a SSS sequence according to each of the at least a possible reception time with the three frequency-domain PSS sequences, to obtain a physical layer cell identity group corresponding to the SSS sequence.