Preamble Sequence Design for Spectral Compactness and Initial Synchronization in OFDM

Chung, Char-Dir; Chen, Wei-Chang

doi:10.1109/tvt.2017.2759092

Cited by 20 publications

(5 citation statements)

References 40 publications

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“…When compared with the existing alternative methods, this novel scheme achieved competitive performance and significantly reduced computational complexity. In 2018, Chung et al [ 28 ] developed new CAZAC and near CAZAC sequences to enable robust fine timing and frequency synchronization, which endowed OFDM preamble waveforms with a compact spectrum and a low peak-to-mean envelope power ratio (PMEPR). In the same year, Lin et al [ 29 ] proposed a new near-CAZAC sequence to construct spectrally compact OFDM preamble waveforms.…”

Section: Related Workmentioning

confidence: 99%

Timing and Frequency Synchronization Using CAZAC Sequences for OFDM Systems

Peng

et al. 2023

Sensors

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Since orthogonal frequency division multiplexing (OFDM) systems are very susceptible to symbol timing offset (STO) and carrier frequency offset (CFO), which cause inter-symbol interference (ISI) and inter-carrier interference (ICI), accurate STO and CFO estimations are very important. In this study, first, a new preamble structure based on the Zadoff–Chu (ZC) sequences was designed. On this basis, we proposed a new timing synchronization algorithm, called the continuous correlation peak detection (CCPD) algorithm, and its improved algorithm: the accumulated correlation peak detection (ACPD) algorithm. Next, the correlation peaks that were obtained during the timing synchronization were used for the frequency offset estimation. For this, the quadratic interpolation algorithm was adopted as the frequency offset estimation algorithm, which was better than the fast Fourier transform (FFT) algorithm. The simulation results showed that when the correct timing probability reached 100%, under the parameters of m = 8 and N = 512, the performance of the CCPD algorithm was 4 dB higher than that of Du’s algorithm, and that of the ACPD algorithm was 7 dB. Under the same parameters, the quadratic interpolation algorithm also had a great performance improvement in both small and large frequency offsets, when compared with the FFT algorithm.

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Section: Related Workmentioning

confidence: 99%

Timing and Frequency Synchronization Using CAZAC Sequences for OFDM Systems

Peng

et al. 2023

Sensors

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“…The guard interval is selected from the set of a well-known PN sequence

, which exhibits the constant amplitude and zero cross-correlation properties in the time domain [ 32 , 33 , 34 , 35 ]. The unique feature of eOFDM is the selection of

, which is based on

s carried by the subcarriers with indices from

, where

and

for each

.…”

Section: System Modelmentioning

confidence: 99%

BER Reduction and Capacity Enhancement with Novel Guard Sequence Selection for Multi-Carrier Communication

Ologun

Shah

et al. 2022

Sensors

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Orthogonal frequency division multiplexing (OFDM) is an efficient multicarrier scheme that uses different types of guard intervals such as cyclic prefix (CP) and known symbol padding (KSP) (zero padding (ZP), unique word (UW), etc.) in block formation. Among these guard intervals, CP varies for each block, while other guard intervals remain fixed from block to block. These guard intervals efficiently perform channel estimation, synchronization and remove inter-block interference (IBI); nevertheless, none of the existing schemes develop any relationship between the guard interval (sequence) and the data symbols on different subcarriers of the OFDM block. We present a new idea of selecting the guard interval based on the data symbols of a subset of subcarriers in the block and exploit the high auto-correlation of the selected guard sequence to improve the bit error rate (BER) performance of the system. The results based on a fair comparison show that our enhanced orthogonal frequency division multiplexing (eOFDM) scheme inherits significant improvements in BER and the capacity of a multicarrier system as compared to the existing techniques.

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“…Since the AoD of a UE in DL channel might land on any SC across the wideband, we employ pseudorandom noise (PN) sequences instead of Zadoff-Chu sequences that are used in 4G narrowband internet of things (NB-IoT). PN sequences have low peak to average power ratio, zero auto-correlation with its time-shifted version, and do not require fixed narrowband reception for completeness [17]. The preamble sequence is assumed to be known at UEs.…”

Section: A Rainbow Beam DL Synchronizationmentioning

confidence: 99%

Rainbow-link: Beam-Alignment-Free and Grant-Free mmW Multiple Access using True-Time-Delay Array

Li,

Yan,

Cabric

2021

Preprint

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In this paper we propose a novel millimeter wave (mmW) multiple access method that exploits unique frequency dependent beamforming capabilities of True Time Delay (TTD) array architecture. The proposed protocol combines a contentionbased grant-free access and orthogonal frequency-division multiple access (OFDMA) scheme for uplink machine type communications. By exploiting abundant time-frequency resource blocks in mmW spectrum, we design a simple protocol that can achieve low collision rate and high network reliability for short packets and sporadic transmissions. We analyze the impact of various system parameters on system performance during synchronization and contention period. We exploit unique advantages of frequency dependent beamforming, referred as rainbow beam, to eliminate beam training overhead and analyze its impact on rates, latency, and coverage. The proposed system and protocol can flexibly accommodate different low latency applications with moderate rate requirements for a very large number of narrowband single antenna devices. By harnessing abundant resources in mmW spectrum and beamforming gain of TTD arrays rainbow link based system can simultaneously satisfy ultra-reliability and massive multiple access requirements.

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Preamble Sequence Design for Spectral Compactness and Initial Synchronization in OFDM

Cited by 20 publications

References 40 publications

Timing and Frequency Synchronization Using CAZAC Sequences for OFDM Systems

Timing and Frequency Synchronization Using CAZAC Sequences for OFDM Systems

BER Reduction and Capacity Enhancement with Novel Guard Sequence Selection for Multi-Carrier Communication

Rainbow-link: Beam-Alignment-Free and Grant-Free mmW Multiple Access using True-Time-Delay Array

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