Non-Uniform Synchronization Transmission Spacing for Wireless Cell Search
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless communication systems face inefficiencies in cell search processes due to uniform spacing of synchronization transmissions, which increases overhead and complexity in detecting base stations and acquiring timing information for user equipment (UEs).
Innovation Solution
Implementing non-uniform spacing of synchronization transmissions, including primary synchronization codes (PSCs) and secondary synchronization codes (SSCs), across subframes and symbol periods to convey different types of information, such as cell IDs and cyclic prefix lengths, while using coherent detection with channel estimates derived from adjacent transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform spacing of synchronization transmissions is used, then the system structure is simple, but the overhead increases and detection performance deteriorates
Solution Approach 1:
The patent applies asymmetry by using non-uniform spacing between synchronization transmissions instead of uniform spacing. The first synchronization transmission is placed at a first location and the second synchronization transmission is placed at a second location in the frame, creating asymmetric intervals that convey information about cell ID and cyclic prefix length while reducing overhead compared to uniform spacing schemes.
2Loss of information
If multiple synchronization transmissions are sent with non-uniform spacing, then information conveyance capability improves, but the device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the non-uniform spacing pattern to simultaneously convey multiple types of information: cell identity, cyclic prefix length, and frame timing. The same synchronization transmission structure serves multiple purposes, reducing the need for separate signaling channels and minimizing overall system complexity despite the non-uniform spacing.
3Measurement precision
If non-uniform spacing of synchronization transmissions is implemented, then detection performance improves, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by performing channel estimation using the first synchronization transmission before detecting the second synchronization transmission. This preliminary channel estimate is used to compensate for channel effects in the second transmission, improving detection performance while managing computational complexity through a structured two-stage process rather than requiring complex joint detection algorithms.
4Reliability
If synchronization transmissions are sent more frequently, then cell search robustness improves, but system overhead increases
Solution Approach 1:
The patent extracts information about cell ID and cyclic prefix length from the spacing pattern itself rather than requiring separate overhead signaling. By encoding this information in the temporal separation between synchronization transmissions, the system achieves robust cell search capability without increasing overall transmission overhead, as the information is conveyed through the structure of existing transmissions rather than additional signals.
Data Source
AI summary
To support cell search, multiple (e.g., two) synchronization transmissions are sent in a frame with non-uniform spacing. Information is conveyed via the non-equal distances between consecutive synchronization transmissions. Multiple levels of non-uniform spacing may be used to convey different types of information. In one design, the multiple synchronization transmissions are sent in different subframes of a frame, and each synchronization transmission is sent in one of multiple symbol periods in a respective subframe. The synchronization transmissions may be sent in non-evenly spaced subframes to convey frame boundary. One synchronization transmission may be sent in one of multiple possible symbol periods depending on the information, e.g., a particular group of cell IDs, being conveyed. The distances between synchronization transmissions may also be used to convey cyclic prefix length. A secondary synchronization transmission carrying a cell ID may be sent at a predetermined offset from one of the multiple synchronization transmissions.