Synchronization Code Structure for Faster Cell ID and Frame Timing
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Solution Overview
Problem
In cellular mobile communications, existing methods for frame timing detection in non-hierarchical synchronization channels require excessive computing resources and time due to the need to decode a large number of codewords and their cyclic shifts, especially when additional cell-specific information is involved, leading to increased complexity and prolonged cell search times.
Innovation Solution
A synchronization code with a repetitive structure is introduced, where each codeword has repeated elements and M distinct cyclic shifts, allowing for efficient decoding by exploiting the repetitive structure through hypothesis testing and diversity combining, reducing the number of decoding metrics needed and maintaining performance close to maximum likelihood detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaustive decoding of all codewords and cyclic shifts is performed for frame timing detection, then detection accuracy is improved, but decoding complexity and cell search time increase significantly
Solution Approach 1:
The patent segments the exhaustive decoding process into two stages: first, correlation-based detection of synchronization signals to identify candidate frame timing positions; second, verification decoding only at these candidate positions. This segmentation avoids the need to decode all 512 codewords and their cyclic shifts, reducing complexity while maintaining detection accuracy.
Solution Approach 2:
The patent performs preliminary correlation detection before actual decoding to identify likely frame timing positions. This preliminary action filters out incorrect positions, so that subsequent decoding operations are performed only at the correct frame timing, eliminating wasted computational resources on incorrect candidates.
2Measurement precision
If multiple synchronization channel signals are multiplexed per radio frame, then symbol timing performance is improved, but frame timing determination becomes indirect and more complex
Solution Approach 1:
The patent uses feedback from correlation detection results to guide the frame timing determination process. The correlation peaks provide feedback about likely frame timing positions, which then directs the decoding verification step, creating a feedback loop that simplifies the overall process compared to direct exhaustive decoding.
Solution Approach 2:
The patent performs preliminary correlation analysis to establish the relationship between multiple SCH signals and frame timing before performing decoding. This preliminary action creates a mapping that simplifies subsequent frame timing determination, avoiding the need for complex indirect inference.
3Loss of information
If cell-specific information is included in the cell search procedure, then information completeness is improved, but the number of codewords to decode increases
Solution Approach 1:
The patent merges cell-specific information transmission with the frame timing detection process by encoding this information into the synchronization channel signals themselves. This merging allows cell-specific information to be detected alongside frame timing using the same correlation-based approach, avoiding the need for separate decoding of additional codewords.
Solution Approach 2:
The patent makes the synchronization channel signals multi-functional by designing them to simultaneously carry frame timing information and cell-specific information. This universality allows a single detection process to extract both types of information, eliminating the need for separate decoding operations for cell-specific data.
Data Source
AI summary
Method and apparatus are provided for encoding cell-specific information in a telecommunication system. Cell-specific information is encoded by a synchronization code. A synchronization signal including the synchronization code is sent, wherein the synchronization code includes a first repetitive cyclically permutable codeword generated from a first codeword(c1,c2,…ci…,c⌈M2⌉),where⌈M2⌉is the smallest integer not less than M/2, 0≦ci≦N, 1≦i≦M for all i, M, N are positive integers, and the repetitive structure of the first repetitive cyclically permutable codeword is given by repeating the value of at least one codeword element of the first repetitive cyclically permutable codeword in at least one other codeword element position within the first repetitive cyclically permutable codeword.