Base Station-UE Synchronization Using Repetitive CP Codewords

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 frame timing and cell ID detection are performed simultaneously.

Innovation Solution

The introduction of a repetitive cyclically permutable (RCP) codeword structure, where each codeword has distinct cyclic shifts and repetitive elements, allows for efficient decoding by reducing the number of metrics to be computed and utilizing diversity combining, thereby simplifying the detection of frame synchronization and cell ID.

Engineering Contradictions & Design Principles

VSEngineering 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

Engineering Contradiction:

Improvecell ID detection accuracyVSAvoidUE power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The cell search procedure is divided into two independent stages: first detecting frame timing by correlating with primary synchronization signals (PSS), then detecting cell ID by correlating with secondary synchronization signals (SSS). This segmentation allows the UE to perform simpler operations sequentially rather than exhaustive decoding of all 512 codewords simultaneously, significantly reducing power consumption while maintaining detection accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Frame timing is acquired first using PSS before cell ID detection using SSS. This preliminary action establishes the correct timing reference, which is then used to properly correlate with SSS sequences. By performing this preliminary timing acquisition, the system avoids the need to test all possible cyclic shifts of all codewords, thereby reducing computational complexity and power consumption.

Inventive Principle:

Principle #10Preliminary action

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

Engineering Contradiction:

Improvecell ID detection accuracyVSAvoidcell search time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The cell search procedure is divided into two independent stages: first detecting frame timing by correlating with primary synchronization signals (PSS), then detecting cell ID by correlating with secondary synchronization signals (SSS). This segmentation allows the UE to perform simpler operations sequentially rather than exhaustive decoding of all 512 codewords simultaneously, significantly reducing power consumption while maintaining detection accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Frame timing is acquired first using PSS before cell ID detection using SSS. This preliminary action establishes the correct timing reference, which is then used to properly correlate with SSS sequences. By performing this preliminary timing acquisition, the system avoids the need to test all possible cyclic shifts of all codewords, thereby reducing computational complexity and power consumption.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If a non-hierarchical SCH is used for simultaneous timing acquisition and cell ID detection, then synchronization procedure is simplified, but decoding complexity increases

Engineering Contradiction:

Improvesynchronization channel structureVSAvoiddecoding complexity

Core Design Contradiction:

Device complexityVSDifficulty of detecting and measuring

Solution Approach 1:

The synchronization channel is segmented into two separate signal types: Primary Synchronization Signal (PSS) for frame timing acquisition and Secondary Synchronization Signal (SSS) for cell ID detection. Although transmitted in a non-hierarchical structure within the same frame, the functional segmentation allows each signal to be processed independently with optimized correlation operations, reducing overall decoding complexity compared to a unified approach.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different local properties are assigned to different synchronization signals: PSS uses specific sequence structures optimized for timing acquisition, while SSS uses different sequences optimized for cell ID detection. This local optimization of signal properties allows each detection task to use the most efficient processing method for its specific purpose, reducing overall computational complexity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10674462B2Facilitating synchronization between a base station and a user equipment

Publication Date: 2020.06.02 HUAWEI TECH CO LTD

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. 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.