Synchronization Channel Multiplexing for Mobile Cell Search
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Solution Overview
Problem
Current E-UTRA mobile communication systems require a 3-step cell search process for sector identification, which increases processing time and memory requirements, and are prone to interference and fading, especially near sector boundaries, leading to decreased accuracy in cell and sector identification.
Innovation Solution
A multicarrier communication system that multiplexes sector and cell specific information on the synchronization channel (SCH) using orthogonal codes, allowing for 2-step cell search by despreading with sector specific codes and demodulating cell specific information concurrently, reducing processing load and memory needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the 3-step cell search method is used for sector identification, then cell and sector can be identified, but the processing time and memory requirements increase
Solution Approach 1:
The patent merges sector identification and cell search into a concurrent 2-step process. The synchronization channel (SCH) is multiplied by both sector-specific orthogonal codes and cell-specific spreading codes, allowing the mobile station to perform despreading for sector identification and correlation detection for cell search simultaneously in the third step, rather than sequentially as in the traditional 3-step method.
Solution Approach 2:
The synchronization channel serves multiple functions: it provides time synchronization (first step), frame timing and scramble code group identification (second step), and sector identification (third step). By multiplying the SCH by both sector-specific orthogonal codes and cell-specific spreading codes, the same channel carries information for both sector and cell identification, eliminating the need for separate processing steps.
2Measurement precision
If the 3-step cell search method is used for sector identification, then cell and sector can be identified, but memory capacity requirements increase
Solution Approach 1:
The patent merges sector identification and cell search into a concurrent 2-step process. The synchronization channel (SCH) is multiplied by both sector-specific orthogonal codes and cell-specific spreading codes, allowing the mobile station to perform despreading for sector identification and correlation detection for cell search simultaneously in the third step, rather than sequentially as in the traditional 3-step method.
3Productivity
If the same SCH data is transmitted concurrently for each sector, then sector identification can be performed, but interference and fading occur near sector boundaries
Solution Approach 1:
The patent applies local quality by making the synchronization channel sector-specific through multiplication with orthogonal codes that are unique to each sector. This allows the mobile station to distinguish signals from different sectors even when transmitted concurrently on the same frequency, reducing interference near sector boundaries. Each sector's SCH signal has distinct local characteristics (orthogonal code) that enable reliable identification despite spatial overlap.
Data Source
AI summary
To reduce the process of a cell search including sector identification without increasing loads on a transmission/reception apparatus. A synchronization channel (SCH) included on downlink in a multicarrier mobile communication system is multiplied by a sector specific code and a cell specific code (step S1), assigned to subcarriers on the frequency axis (step S2), subjected to spreading processing and IFFT processing (steps S3, S4), and further subjected to insertion of GI and D/A conversion processing (steps S5, S6), and multicarrier is transmitted from a directional antenna of each sector (step S7). The receiving side specifies a SCH position by auto-correlation method or cross-correlation method, performs FFT, and then, concurrently performs identification of a sector by detection of the sector specific code, and acquisition of cell specific information by demodulation of the cell specific code.