Duong Long Le | Hanoi University of Technology (original) (raw)
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National Institute of Technology, Calicut
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Papers by Duong Long Le
2018 IEEE 88th Vehicular Technology Conference (VTC-Fall), 2018
Among many proposed multi-carrier systems, circular filter bank multi-carrier offset quadrature a... more Among many proposed multi-carrier systems, circular filter bank multi-carrier offset quadrature amplitude modulation (CFBMC-OQAM) is one of promising candidates for future wireless networks. This paper studies the impacts of the intrinsic interferences, namely inter-symbol interference (ISI) and inter-carrier interference (ICI), and phase noise (PN) on the performance of CFBMC-OQAM systems. Two types of PN are considered: one is based on a free-running oscillator and the other is based on a phase-locked loop oscillator. Sources of performance degradation are quantified and a closed-form expression is derived for the signal-to-interference ratio (SIR). An algorithm is then applied to mitigate the PN impacts which takes into account the intrinsic interferences. It is observed that while the impact of the self interference can be negligible when there is no PN, the presence of PN significantly degrades performance of CFBMC-OQAM systems. The applied algorithm is shown to effectively remove the PN impacts.
Wireless Personal Communications, 2019
This paper considers a full-duplex wireless communication system in which detection of the desire... more This paper considers a full-duplex wireless communication system in which detection of the desired signal is hindered not only by the self-interference (SI), but also phase noise, in-phase and quadrature-phase imbalance and power amplifier's nonlinearity distortion. An iterative algorithm is proposed in which the processes of SI cancellation and detection of the desired signal aid each other in each iteration. In each iteration, the SI cancellation process performs widely linear estimation of the SI channel and compensates for physical impairments to improve the detection performance of the desired signal. The detected desired signal is in turn removed from the received signal to improve SI channel estimation and SI cancellation in the next iteration. Simulation results show that the proposed algorithm significantly outperforms existing algorithms in SI cancellation and detection of the desired signal.
IET Communications, 2015
This study presents novel strategies to improve the decoding performance through base-station coo... more This study presents novel strategies to improve the decoding performance through base-station cooperation. In the proposed schemes, the soft output of the demapper at a serving base station (SBS) is replaced by a combination of log-likelihood ratio information, which is generated through demodulation by neighbouring base stations (NBSs) as well as the SBS. For the information used in the cooperation, soft information is first considered. Combining the soft information transmitted from all NBSs provides close-to-optimal performance, but it still requires a high amount of overhead to be passed over the backhaul links. In the proposed schemes, the SBS only cooperates with the reliable NBSs, which are identified on the basis of the magnitude of the metrics transmitted from the NBSs, to achieve a trade-off between performance and overhead. In addition, the use of hard information instead of soft information is also proposed to further reduce the backhaul overhead. In this scheme, the metric values as well as the hard information are exploited to generate the updated soft information for the channel decoder. In the simulation results, it is shown that the proposed schemes provide better error performance compared with the conventional schemes under limited backhaul capacities.
2018 IEEE 88th Vehicular Technology Conference (VTC-Fall), 2018
Among many proposed multi-carrier systems, circular filter bank multi-carrier offset quadrature a... more Among many proposed multi-carrier systems, circular filter bank multi-carrier offset quadrature amplitude modulation (CFBMC-OQAM) is one of promising candidates for future wireless networks. This paper studies the impacts of the intrinsic interferences, namely inter-symbol interference (ISI) and inter-carrier interference (ICI), and phase noise (PN) on the performance of CFBMC-OQAM systems. Two types of PN are considered: one is based on a free-running oscillator and the other is based on a phase-locked loop oscillator. Sources of performance degradation are quantified and a closed-form expression is derived for the signal-to-interference ratio (SIR). An algorithm is then applied to mitigate the PN impacts which takes into account the intrinsic interferences. It is observed that while the impact of the self interference can be negligible when there is no PN, the presence of PN significantly degrades performance of CFBMC-OQAM systems. The applied algorithm is shown to effectively remove the PN impacts.
Wireless Personal Communications, 2019
This paper considers a full-duplex wireless communication system in which detection of the desire... more This paper considers a full-duplex wireless communication system in which detection of the desired signal is hindered not only by the self-interference (SI), but also phase noise, in-phase and quadrature-phase imbalance and power amplifier's nonlinearity distortion. An iterative algorithm is proposed in which the processes of SI cancellation and detection of the desired signal aid each other in each iteration. In each iteration, the SI cancellation process performs widely linear estimation of the SI channel and compensates for physical impairments to improve the detection performance of the desired signal. The detected desired signal is in turn removed from the received signal to improve SI channel estimation and SI cancellation in the next iteration. Simulation results show that the proposed algorithm significantly outperforms existing algorithms in SI cancellation and detection of the desired signal.
IET Communications, 2015
This study presents novel strategies to improve the decoding performance through base-station coo... more This study presents novel strategies to improve the decoding performance through base-station cooperation. In the proposed schemes, the soft output of the demapper at a serving base station (SBS) is replaced by a combination of log-likelihood ratio information, which is generated through demodulation by neighbouring base stations (NBSs) as well as the SBS. For the information used in the cooperation, soft information is first considered. Combining the soft information transmitted from all NBSs provides close-to-optimal performance, but it still requires a high amount of overhead to be passed over the backhaul links. In the proposed schemes, the SBS only cooperates with the reliable NBSs, which are identified on the basis of the magnitude of the metrics transmitted from the NBSs, to achieve a trade-off between performance and overhead. In addition, the use of hard information instead of soft information is also proposed to further reduce the backhaul overhead. In this scheme, the metric values as well as the hard information are exploited to generate the updated soft information for the channel decoder. In the simulation results, it is shown that the proposed schemes provide better error performance compared with the conventional schemes under limited backhaul capacities.