Frequency and Timing Synchronization for In-Band Full-Duplex OFDM System

Shaboyan, Sergey; Ahmed, E.; Behbahani, Alireza S.; Younis, W.M.; Eltawil, Ahmed M.

doi:10.1109/glocom.2017.8254928

Cited by 16 publications

(12 citation statements)

References 7 publications

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“…In this work, a WiFi-like frame structure is assumed with a nonoverlapped short preamble, shown in Fig. 2, for IBFD synchronization purposes as discussed in [6]. In order to apply self-interference cancellation, there are two assumptions: a) channel is quasi-static within the frame which is reasonable for low-mobility environments.…”

Section: In-band Full Duplex Systemmentioning

confidence: 99%

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Application of ICA on Self-Interference Cancellation of In-Band Full Duplex Systems

Fouda

Shaboyan

Elezabi

et al. 2020

IEEE Wireless Commun. Lett.

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In this letter, we propose a modified version of Fast Independent Component Analysis (FICA) algorithm to solve the self-interference cancellation (SIC) problem in In-band Full Duplex (IBFD) communication systems. The complex mixing problem is mathematically formulated to suit the real-valued blind source separation (BSS) algorithms. In addition, we propose a method to estimate the ambiguity factors associated with ICA lumped together with the channels and residual separation error. Experiments were performed on an FD platform where FICA-based BSS was applied for SIC in the frequency domain. Experimental results show superior performance compared to least squares SIC by up to 6 dB gain in the SNR.

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Section: In-band Full Duplex Systemmentioning

confidence: 99%

“…b) SI and SOI are synchronized to use the knowledge of the interferer signal in the cancellation. Prior work such as [6] present IBFD synchronization techniques that have been experimentally verified, utilizing nonoverlapped short preamble.…”

Section: In-band Full Duplex Systemmentioning

confidence: 99%

Application of ICA on Self-Interference Cancellation of In-Band Full Duplex Systems

Fouda

Shaboyan

Elezabi

et al. 2020

IEEE Wireless Commun. Lett.

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“…The studies in [1,2] did not consider FOs between the downlink signal and the uplink signals of the other UEs, and therefore, only the intra-SB self-interference (SI) caused by FD was the major performance-limiting factor. Meanwhile, the studies in [3,4] considered FOs in OFDMbased FD. However, they considered the FOs on the BS side [3] or in a two-node system [4].…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, the studies in [3,4] considered FOs in OFDMbased FD. However, they considered the FOs on the BS side [3] or in a two-node system [4]. Hence, the U2D-IU-ISBI was not considered.…”

Section: Introductionmentioning

confidence: 99%

FD-FBMC: A Solution for Multicarrier Full Duplex Cellular Systems

Choi

2021

IEEE Commun. Lett.

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This letter reports on a critical issue with the application of OFDM to a full-duplex (FD) cellular system. With small frequency offsets of uplink signals, the downlink BER increases considerably. This is attributed to the high spectral-leakage-interference from the OFDM waveforms of geographically nearby uplink users. As an alternative, we propose applying the FBMC waveform to the same FD cellular system scenario. We calculate the precise spectral-leakage-interference for OFDM and FBMC, based on which, we set up a semianalytic BER simulation framework. Analysis and numerical results confirm that spectral leakage interference from uplink signals is the critical performance limiting factor. Even with tiny frequency offsets among the users, the performance of FD with OFDM is severely degraded. Although the FDs with the other multicarrier waveforms having lower spectral leakage such as GFDM, UFMC, and f-OFDM overcome this issue to a certain extent, the degradations remain substantial. However, the FBMC-based FD cellular system achieves almost spectralleakage-interference-free performance, and thus, it substantially outperforms the counterparts with other waveforms.

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“…Generally, digital SI cancellation (SIC) exploits the fact that the FD receiver has knowledge of the intended transmit signal in the digital domain, making it possible to reconstruct the SI and then cancel it. However, due to the impacts of the hardware imperfections and the propagation environment, perfect time synchronization between the reconstructed and received SI is almost impossible [3]. The SI propagation channel usually includes the direct path (DP) through the antenna interface device, which has a limited isolation for the high-power transmitted signal, and the multipath reflection paths (RPs) that are created by objects within the environment [4].…”

Section: Introductionmentioning

confidence: 99%

A Time-Robust Digital Self-Interference Cancellation in Full-Duplex Radios: Receiver Design and Performance Analysis

Zhao

Guo

et al. 2020

IEEE Access

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In full-duplex radios, precise time synchronization between the received and reconstructed self-interference (SI) is the basis of the effective SI cancellation (SIC). However, due to the impacts of the hardware imperfections and the propagation environment, perfect time synchronization is impossible. More seriously, the time-varying SI propagation channel aggravates the difficulty of time synchronization. To overcome the above problems, a time-robust digital SIC (TR-DSIC) is proposed in this paper, as a novel scheme to address the time synchronization error (timing error). Firstly, by comprehensively considering nonlinear distortion and multipath propagation with different time delays and time-varying gains, a revised general memory polynomial (RGMP) model of the received SI is presented. Then, based on the RGMP model of the received SI, the TR-DSIC is proposed to cancel the SI in the digital domain, which is robust to arbitrary timing error and no need additional processing for it. Finally, the performance of the proposed TR-DSIC is analyzed under imperfect estimations of the polynomial coefficients. The analytical expression of the variance of the estimation error is presented here, and the closed-form expression of the residual SI power introduced by imperfect estimations of the polynomial coefficients is derived. Simulation results reveal that the TR-DSIC is capable of eliminating the influence of arbitrary timing error. Specially, when the maximum timing error is 0.5T s for the SI multipath channel, the TR-DSIC outperforms the traditional DSIC without considering the timing error between the reconstructed and received SI by 5.2 dB. INDEX TERMS Full-duplex, self-interference cancellation, timing error, nonlinear distortion, multipath.

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Frequency and Timing Synchronization for In-Band Full-Duplex OFDM System

Cited by 16 publications

References 7 publications

Application of ICA on Self-Interference Cancellation of In-Band Full Duplex Systems

Application of ICA on Self-Interference Cancellation of In-Band Full Duplex Systems

FD-FBMC: A Solution for Multicarrier Full Duplex Cellular Systems

A Time-Robust Digital Self-Interference Cancellation in Full-Duplex Radios: Receiver Design and Performance Analysis

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