Synchronization Code Structure for Low-Complexity Frame Timing
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Solution Overview
Problem
In cellular mobile communications, non-hierarchical synchronization channel (SCH) systems face high decoding complexity and increased cell search time due to the need to decode 512 codewords and their cyclic shifts for frame timing and cell ID detection, especially when additional cell-specific information is included, leading to excessive computational resources and prolonged search times.
Innovation Solution
A method is introduced to create and detect codewords with a repetitive structure, where at least one codeword element is repeated in other positions, allowing for efficient systematic decoding by diversity combining and hypothesis testing, reducing the number of decoding metrics needed and achieving performance close to maximum likelihood detection with lower complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-hierarchical SCH decodes all 512 codewords and their cyclic shifts for frame timing and cell ID detection, then detection accuracy is improved, but decoding complexity and cell search time increase significantly
Solution Approach 1:
The patent segments the 512 codewords into multiple groups, where each group contains a subset of codewords. The receiver performs decoding on one group at a time rather than all 512 codewords simultaneously. This segmentation reduces the computational burden per decoding operation while maintaining overall detection accuracy through systematic group-based processing.
2Measurement precision
If non-hierarchical SCH decodes all 512 codewords and their cyclic shifts for frame timing and cell ID detection, then detection accuracy is improved, but cell search time is prolonged
Solution Approach 1:
By dividing the codeword set into manageable groups, the patent enables parallel or sequential processing of smaller subsets. This segmentation allows the cell search procedure to complete faster by processing groups in an organized manner rather than performing exhaustive decoding of all 512 codewords in a single operation.
3Loss of information
If additional cell-specific information is included in the synchronization channel, then information completeness is improved, but decoding complexity increases excessively
Solution Approach 1:
The patent incorporates additional cell-specific information (such as channel bandwidth, number of antennas, cyclic prefix lengths) by encoding it across the grouped codewords. The segmentation approach allows this additional information to be distributed and decoded systematically through group-based processing, avoiding the exponential complexity increase that would result from treating all information in a single exhaustive decoding operation.
Data Source
AI summary
An improved method for conveying data and synchronization information in a telecommunication system is disclosed. The method uses a cyclically permutable code, to which a repetitive structure has been imposed, for carrying the data and synchronization information. The decoding procedure at the receiver then uses this repetitive structure of the code to reduce complexity by first evaluating, by use of hypotheses Hx, the repetitive codeword structure of received codewords and choosing a hypothesis corresponding to the repetitive codeword structure. Then the decoding procedure performs diversity combining of codeword elements of the codewords in accordance with the chosen hypothesis. The received codewords are further detected by comparing the diversity combined codeword elements to all possible codewords fulfilling the hypothesis.