Codebook Precoder Synchronization Signal Transmission in mmWave Systems
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Solution Overview
Problem
In ultrahigh frequency wireless communication systems, particularly mmWave systems, synchronization signal transmission is hindered by path loss and deep-null phenomena, leading to inefficiencies in synchronization procedures and increased complexity for user equipment (UE) due to high-frequency oscillators and Doppler effects.
Innovation Solution
A method is introduced to enhance synchronization efficiency by designing a codebook for precoders applied to synchronization signals, allowing for repeated transmission and beamforming techniques to improve signal diversity and minimize complexity for UE, using weighted sums of basic precoders and subarray concepts to optimize beamforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization signal is transmitted using conventional methods in mmWave systems, then path loss and deep-null phenomena occur, but synchronization efficiency deteriorates and UE complexity increases
Solution Approach 1:
The antenna array is divided into multiple subarrays, each transmitting synchronization signals with different precoding vectors. This segmentation allows the system to overcome deep-null phenomena by providing diverse transmission paths, improving reliability while maintaining efficiency through parallel processing of subarray signals
Solution Approach 2:
The patent employs codebook-based precoding with carefully selected precoding vectors that change parameters such as beam directions and weights. By optimizing these parameters, the system achieves better signal coverage and reliability in mmWave environments without increasing UE complexity
2Measurement precision
If codebook-based precoding is applied to synchronization signals, then synchronization performance improves, but UE processing complexity increases
Solution Approach 1:
The patent applies partial codebook-based precoding where only essential precoding operations are performed at the UE side. The base station handles most of the complex precoding calculations, while the UE performs simplified processing, thereby maintaining synchronization accuracy without significantly increasing UE complexity
3Area of stationary object
If beamforming techniques are used to overcome path loss, then signal coverage improves, but system complexity increases
Solution Approach 1:
The antenna array is segmented into multiple subarrays that transmit synchronized signals with different precoding vectors. This segmentation enables wide coverage through diverse beam patterns while maintaining manageable system complexity through standardized subarray processing and codebook-based precoding
Solution Approach 2:
The codebook-based precoding framework provides universal applicability across different subarrays and transmission scenarios. The same codebook structure and selection criteria can be used for various coverage requirements, reducing overall system complexity through standardized multi-functional processing
Data Source
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AI summary
Disclosed are a method for transmitting a synchronization signal and a base station therefor, the method comprising: generating a codebook including a second precoder defined by concatenation of first precoders, which corresponds to a plurality of antenna subarrays, respectively; generating a synchronization sequence by multiplying, by a weight, the same reference sequence input over a plurality of time intervals, for each antenna subarray; and repeatedly transmitting a synchronization signal generated by applying the second precoder to the generated synchronization sequence, through the plurality of antenna subarrays, wherein the reference sequence is different for each of the plurality of antenna subarrays, and a combination of the reference sequence and the weight indicates additional information transmitted to a terminal.