Base Station Synchronization Signals With Repetitive CP Codewords
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Solution Overview
Problem
In mobile communication systems, the existing synchronization methods require excessive computing resources and time for cell search due to the need to decode and compute metrics for a large number of codewords, especially in non-hierarchical synchronization channels, where both cell ID and frame synchronization are detected from SCH signals within a frame.
Innovation Solution
A method is introduced that uses cyclically permutable codewords with a repetitive structure, allowing for efficient decoding by reducing the number of decoding metrics needed, achieved through the use of repetitive cyclically permutable (RCP) codewords, where each codeword element is repeated, facilitating diversity combining and hypothesis testing to determine frame synchronization and cell ID.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaustive decoding of 512 codewords and their cyclic shifts is performed for cell ID detection, then detection accuracy is improved, but computing resources and power consumption increase significantly
Solution Approach 1:
The patent segments the exhaustive codeword decoding process into two stages: first, rapid identification of candidate codewords using correlation-based methods; second, refined decoding only for these candidates. This segmentation reduces the number of codewords requiring full decoding from 512 to a much smaller subset, thereby reducing power consumption while maintaining detection accuracy.
Solution Approach 2:
Instead of performing complete exhaustive decoding on all 512 codewords, the patent applies partial action by first performing a reduced-complexity screening step that identifies likely candidates, then applying full decoding only to these candidates. This partial approach achieves sufficient detection accuracy without the excessive computational burden of complete exhaustion.
2Measurement precision
If exhaustive decoding of 512 codewords and their cyclic shifts is performed for cell ID detection, then detection accuracy is improved, but cell search time increases
Solution Approach 1:
The patent segments the cell search process into rapid candidate identification followed by focused decoding of only those candidates. This time-efficient segmentation avoids the need to decode all 512 codewords exhaustively, thereby reducing cell search time while preserving detection accuracy through the two-stage approach.
Solution Approach 2:
The patent performs preliminary action by conducting a fast correlation-based screening before the actual decoding process. This preliminary step identifies candidate codewords that are likely to be correct, allowing the system to skip unnecessary decoding operations and significantly reduce overall cell search time.
3Measurement precision
If synchronization signals are multiplexed several times in a radio frame to improve symbol timing performance, then symbol timing accuracy is improved, but frame timing determination becomes indirect and more complex
Solution Approach 1:
The patent employs feedback mechanisms where the detected symbol timing information is used to guide and constrain the frame timing determination process. The correlation results from multiple synchronized signals provide feedback that narrows down possible frame timing options, reducing complexity while maintaining the accuracy benefits of signal multiplexing.
Data Source
AI summary
Methods and apparatus are provided for facilitating synchronization between a base station (BS) and a user equipment (UE) in a mobile communication system. The UE receives a synchronization signal originated by the BS. The synchronization signal is encoded with a selected cyclically permutable (CP) codeword, the selected CP codeword being selected from a set of CP codewords. Encoding of the synchronization signal is facilitated by a repetitive cyclically permutable (RCP) codeword derivable from the selected CP codeword. The RCP codeword has a plurality of codeword elements each associated with a value, the value of at least one codeword element in the RCP codeword being repeated in another codeword element position in the RCP codeword. And the synchronization signal is decoded in accordance with repetitive structure of the RCP codeword.