Symbol Cyclic Shift Equalization PAM-OFDM—A Low Complexity CP-Free OFDM Scheme

This work is motivated by growing evidence that the standard Cyclic Prefix (CP) length, adopted in the Long Term Evolution (LTE) physical layer (PHY) specifications, is oversized in propagation environments ranging from indoor to typical urban. Although this ostensibly seems to be addressed by 5G New Radio (NR) numerology, its scalable CP length reduction is proportionally tracked by the OFDM symbol length, which preserves the relative CP overhead of LTE. Furthermore, some simple means to optimize fixed or introduce adaptive CP length arose from either simulations or models taking into account only the bit-oriented PHY transmission performance. On the contrary, in the novel crosslayer analytical model proposed here, the closed-form expression for the optimal CP length is derived such as to minimize the effective average codeblock length, by also considering the error recovery retransmissions through the layers above PHY—the Medium Access Control (MAC) and the Radio Link Control (RLC), in particular. It turns out that, for given protective coding, the optimal CP length is determined by the appropriate rms delay spread of the channel power delay profile part remaining outside the CP span. The optimal CP length values are found to be significantly lower than the corresponding industry-standard ones, which unveils the potential for improving the net throughput.

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“…To solve (15) with respect to τ CP and thus find the optimal CP length, we need to know BER τ CP and then derive dBER(τ CP ) dτ CP , too.…”

Section: Optimal Cp Length For Minimal Codeblock Average Gross Lengthmentioning

confidence: 99%

“…Finally, we substitute BER from (23) and dBER(τ CP ) dτ CP from ( 28) into (15), so the latter becomes:…”

Section: Time-dispersion-only Related Residual Ber For Optimal Cp Lengthmentioning

confidence: 99%

PHY, MAC, and RLC Layer Based Estimation of Optimal Cyclic Prefix Length

Lipovac

Modlic

2021

Sensors

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“…Since the number of sub-carriers used in the OFDM system is 2 6 = 64, it can be absolutely implemented to the system.…”

Section: Fast Walsh Hadamard Transform (Fwht)mentioning

confidence: 99%

“…To achieve this, specially designed alignment signals are used that can cancel mixing of one symbol to another and add an additional signal component that makes the signal circularly convolved with the channel on the receiving side. Liu et al suggested a symbol cyclic shift equalization (SCSE) algorithm for the implementation of a CP-free OFDM system [6]. In this study, they aimed to further reduce the computational complexity of the SCSE algorithm by using PAM modulation.…”

Section: Introductionmentioning

confidence: 99%

A new FWHT‐CMF‐DFE based approach for channel equalization in CP‐free OFDM systems

et al. 2021

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Orthogonal frequency division multiplexing (OFDM) has been widely used in wireless communication systems due to its robustness against the frequency selectivity of fading channels. It provides optimal performance and it also meets the requirements of the next generation communication systems. Although OFDM has these advantages, its spectrum efficiency is usually degraded significantly due to the use of cyclic prefix (CP). In this paper, motivated to deal with this issue, the combined structure of Fast Walsh-Hadamard Transform (FWHT) and Time Domain Equalizer (TDE) is proposed to use in CP-free OFDM systems. The results validated by Monte Carlo simulations decipher the improved performances in terms of spectral efficiencies, bit error rate, peak to average power ratio and out of band emission for using this structure over frequency selective multipath fading channels in CP-free OFDM systems. The acquired simulation results have illustrated that the proposed method provides 20% spectral efficiency without compromising the BER performance.

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“…Hence, m-sequence instead of ZC sequence is adopted as a synchronization signal [13]. M-sequence also has good correlation characteristics as ZC sequence, therefore, some synchronization algorithms [14]- [16] in long term evolution (LTE) can be used. Reference [17] proposed detection algorithms based on auto-correlation and cross-correlation.…”

Section: Introductionmentioning

confidence: 99%

A Novel PSS Timing Synchronization Algorithm for Cell Search in 5G NR System

et al. 2021

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Cell search is the first step to establish downlink synchronization between user equipment (UE) and base station (BS) in the fifth generation (5G) new radio (NR) system. However, frequency offset and noise will cause a massive loss of synchronization performance. To solve this problem, a novel timing synchronization algorithm of primary synchronization signal (PSS) with anti-frequency offset and antinoise is proposed, which includes the improved coarse synchronization algorithm based on Fourier transform and the fine synchronization algorithm based on the triple auto-correlation algorithm. The improved coarse synchronization algorithm not only has a strong frequency offset resistance, especially for large frequency offset, but also obtains the estimated frequency offset. The fine synchronization algorithm is more resistant to noise than the conventional algorithm. Finally, the algorithm analysis and simulation results show that the improved algorithm can work very well even when the normalized frequency offset increases to greater than 0.8, but the conventional algorithm fails to synchronize properly. Meanwhile, when the SNR is as low as -6dB, the detection accuracy of the timing synchronization based on the proposed fine synchronization algorithm is improved by about 31.7% compared with the conventional algorithm.

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Symbol Cyclic Shift Equalization PAM-OFDM—A Low Complexity CP-Free OFDM Scheme

Cited by 19 publications

References 25 publications

PHY, MAC, and RLC Layer Based Estimation of Optimal Cyclic Prefix Length

PHY, MAC, and RLC Layer Based Estimation of Optimal Cyclic Prefix Length

A new FWHT‐CMF‐DFE based approach for channel equalization in CP‐free OFDM systems

A Novel PSS Timing Synchronization Algorithm for Cell Search in 5G NR System

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