Default Primary Synchronization Code for Cellular Cell Search
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Solution Overview
Problem
In cellular wireless communication systems, the use of multiple Primary Synchronization Channel (PSC) codes degrades cell search performance in asynchronous networks and increases complexity, as User Equipment (UE) struggles to distinguish used PSCs from unused ones, leading to poor detection performance and increased complexity in both synchronous and asynchronous environments.
Innovation Solution
A method and apparatus that designate a default PSC for all cells, with adjacent cells using different PSCs when multiple codes are available, allowing the UE to perform initial cell search using the default PSC and subsequently attempt detection with other PSCs if necessary, thereby simplifying the cell search process and maintaining performance across both network types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PSC codes are used for cells, then cell search performance is improved in synchronous networks, but detection performance degrades and complexity increases in asynchronous networks
Solution Approach 1:
The patent applies local quality by allowing different PSC allocation strategies for different network types: in synchronous networks, multiple PSC codes are allocated to adjacent cells to avoid multipath combining, while in asynchronous networks, a single default PSC is used for all cells. This localized differentiation resolves the contradiction by tailoring the PSC allocation to the specific network synchronization characteristics.
Solution Approach 2:
The patent implements dynamics by enabling the Node B to dynamically determine the number of PSCs to use based on network synchronization status. The system can adapt between using one default PSC for asynchronous networks and multiple PSCs for synchronous networks, allowing the complexity and performance characteristics to vary dynamically with network conditions.
2Object-affected harmful factors
If multiple PSC codes are allocated to adjacent cells, then multipath channel combining is avoided, but UE complexity increases due to difficulty in distinguishing used PSCs
Solution Approach 1:
The patent applies feedback by having the UE report PSC detection results back to the Node B. The Node B uses this feedback information to determine whether to allocate multiple PSCs or use a single default PSC, creating a closed-loop system that adapts PSC allocation based on actual detection performance and network conditions.
Solution Approach 2:
The patent implements preliminary action by having the UE attempt PSC detection using a default PSC before exhaustively searching all possible PSC codes. This preliminary detection step filters out obviously incorrect PSCs and reduces the search space, thereby reducing UE complexity while maintaining the ability to handle multiple PSC scenarios.
3Device complexity
If a single default PSC is used for all cells, then UE complexity is reduced, but cell search performance degrades when multiple PSCs are actually used
Solution Approach 1:
The patent applies partial action by having the UE perform PSC detection using only the default PSC initially, rather than exhaustively searching all possible PSC codes. This partial detection approach reduces complexity while maintaining acceptable performance, as the default PSC is used in the majority of cases and only exhaustive search is performed when necessary.
Data Source
AI summary
A method and apparatus for transmitting and receiving an SCH in a cellular wireless communication system, in which a number of available PSCs among PSCs defined for P-SCH in the system is checked, a default PSC to be used with priority in UEs of the system for cell search is selected and a P-SCH signal is transmitted with the default PSC in each of underlying cells when the number of available PSCs is 1, and PSCs are selected for the cells from among the available PSCs so adjacent cells have different PSCs and P-SCH signals are transmitted using the selected PSCs in the cells when the number of available PSCs is 2 or larger.