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cell search algorithms for the 3G long-term evolution

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The Journal of China Universities of Posts and Telecommunications 2007年第2期14卷 33-37页

作者： SU Huan ZHANG Jian-hua Wireless Technology Innovation of Institute Beijing University of Posts and Telecommunications Beijing 100876 China

This article presents downlink initial synchronization and cell identification algorithms for long term evolution （LTE） of third-generation （3G） mobile communication systems, which are based on synchronization channel （SCH） and cell specific pilot symbols, respectively. The key features of the proposed scheme are： it can improve performance of the frequency synchronization through oversampling of the SCH, it can support a large number of target cells by modulating a cell-specific pilot sequence over two symbols within a subframe, and it can guarantee cell identification performance by maximally ratio combining the frequency domain differential cross-correlation. Simulations show that the proposed scheme has a potential use in 3G LTE.

关键词： 3rd generation partnership project （3GPP） LTE orthogonal frequency division multiple access （OFDMA） cell search oversampling

Design and Implementation of Initial cell search in 5G NR Systems

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China Communications 2020年第5期17卷 38-49页

作者： Fatang Chen Xiu Li Yun Zhang Yanan Jiang College of Communication and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China China Telecom Corporation Limited Chongqing Branch Chongqing 400000China

The initial cell search plays an important role during the process of downlink synchronization establishment between the User Equipment(UE) and the base station. In particular, the uncertainty of the synchronization signals on the frequency domain and the flexibility of frame structure configuration have brought great challenges to the initial cell search for the fifth-generation(5G) new radio(NR). To solve this problem, firstly, we analyze the physical layer frame structure of 5G NR systems. Then, by focusing on the knowledge of synchronization signals, the 5G NR cell search process is designed, and the primary synchronization signal(PSS) timing synchronization algorithm is proposed, including a 5G-based coarse synchronization algorithm and conjugate symmetry-based fine synchronization algorithm. Finally, the performance of the proposed cell search algorithm in 5G NR systems is verified through the combination of Digital Signal Processing(DSP) and personal computer(PC). And the MATLAB simulation proves that the proposed algorithm has better performance than the conventional cross-correlation algorithm when a certain frequency offset exists.

关键词： 5G NR systems physical layer cell search PSS timing synchronization algorithm Conjugate symmetry

cell search Algorithm in Beyond 3G Systems

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Journal of Shanghai University(English Edition) 2005年第5期9卷 419-424页

作者：蔡凌云宋文涛罗汉文 Mobile Communication Laboratory Department of Electronic Engineering Shanghai Jiaotong University Shanghai 200030 P. R. China

The downlink frame structure for beyond 3G mobile communication systems is presented. Beyond 3G systems utilize the OFDM technique. However, a problem encountered in OFDM is that channel dispersion destroys orthogonality between carriers, caushag inter-symbol interference. It is also sensitive to high peak to mean power ratio （PAPR）. Therefore it spends much time on obtaining frequency, time, and frame synchronization. This paper proposes to add a frame synchronization channel in the time domain to overcome the shortcoming of OFDM. As transmitter diversity improves the system performance, beyond 3G systems employ space-time block coded （STBC）. Fast cell search algorithm including slot synchronization, frame synchronization and cell ID identification is then discussed, which is based on the frame synchronization channel in transmitter diversity systems. Detection and false alarm probabilities in AWGN and Rayleigh channels are analyzed, and the mean acquisition time is obtained. Computer simulations are conducted to evaluate the performance of the cell search algorithm under different channel conditions.

关键词： mobile communication cell search match filter correlation maximum detection.

Dual-CRC polar codes and dual-SCFlip decoding algorithm for cell search in 5G system

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The Journal of China Universities of Posts and Telecommunications 2021年第6期28卷 82-90页

作者： Li Xiaohui Liu Shuaishuai Fan Tao Fang Kun State Key Laboratory of Integrated Service Networks Xidian UniversityXi'an 710071China School of Communication Engineering Xidian UniversityXi'an 710071China

Polar codes become the coding scheme for control channels of enhanced mobile broadband(eMBB)scenarios in the fifth generation(5 G)communication system due to their excellent decoding performance.For the cell search procedure in 5 G system,some common information bits(CIBs)are transmitted in consecutive synchronization signal blocks(SSBs).In this paper,a dual-cyclic redundancy check(dual-CRC)aided encoding scheme is proposed,and the corresponding dual-successive cancellation flip(dual-SCFlip)algorithm is given to further improve the performance of polar codes in the low signal-to-noise ratio(SNR)environment.In dual-CRC aided encoding structure,the information bits of polar codes in different transmission blocks add cyclic redundancy check(CRC)sequences respectively according to CIBs and different information bits(DIBs).The structure enlarges the size of CIBs to improve the block error ratio(BLER)performance of the system.The dual-SCFlip decoder can perform bit flip immediately once CIBs is decoded completely,and then decode DIBs or terminate decoding in advance according to the CRC result,which reduces the delay of decoding and mitigates the error propagation effect.Simulation results show that the dual-CRC aided encoding scheme and dual-SCFlip decoder have significant performance improvement compared to other existing schemes with low SNR.

关键词： polar codes cell search dual-CRC dual-SCFlip

A robust symbol timing strategy for cellular systems

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Digital Communications and Networks 2023年第3期9卷 757-768页

作者： Yangpeng Dan Jianxin Yi Xianrong Wan Yunhua Rao Yan Liu School of Electronic and Information Wuhan UniversityWuhan430072China Shenzhen Research Institute of Wuhan University Shenzhen518000China

In cellular systems,establishing the initial symbol timing of potential preambles is the first step of a cell search.The envelope fluctuation of the downlink signal hinders the successful timing of conventional symbol timing methods.To solve this problem,a hybrid timing strategy is proposed with two novel detectors,namely the normalized replica-based detector and normalized differential detector.The strategy first detects all potential preambles via the normalized replica-based detector and then employs the normalized differential detector to verify the target preamble,which comes from the target cell and has the highest power.The strategy is unaffected by envelope fluctuation and has computational complexity comparable to that of conventional methods.Simu-lations and real-data tests show that the hybrid timing strategy is robust and practical for initial symbol timing.

关键词： Symbol timing Synchronization Preamble cell search cellular system Envelope fluctuation