• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4957-4976
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• 2016

This paper investigates the error performance of the amplify-and-forward (AF) relaying systems in the context of full-duplex (FD) communication. In addition to the inherent self-interference (SI) due to simultaneous transmission and reception, coexistent FD terminals may cause crosstalk. In this paper, we utilize the information exchange via the crosstalk channel to construct a particular distributed space-time code (DSTC). The residual SI is also considered. Closed-form pairwise error probability (PEP) is first derived. Then we obtain the upper bound of PEP in high transmit power region to provide more insights of diversity and coding gain. The proposed DSTC scheme can attain full cooperative diversity if the variance of SI is not a function of the transmit power. The coding gain can be improved by lengthening the frame and proper power control. Feasibility and efficiency of the proposed DSTC are verified in numerical simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1374-1379
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• 2016

In almost all schemes of cooperative cognitive radio networks (CCRN), the users transmit and receive signals in half-duplex mode. In this paper, a design of CCRN adopting the full-duplex (FD) technique is addressed. In order to enable FD communication among users in the CCRN, simultaneous transmitting and receiving antennas are employed for the secondary users. Preliminary results from analysis and numerical evaluation indicate that the proposed FD multiple-input-multiple-output CCRN framework can provide a performance gain over the conventional CCRN frameworks.

• ETRI Journal
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• v.39 no.2
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• pp.245-254
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• 2017

In-band full-duplex (IFD) communication has recently attracted a great deal of interest because it potentially provides a two-fold spectral efficiency increase over half-duplex communications. In this paper, we propose a novel digital self-interference cancelation (DSIC) algorithm for an IFD communication system in which two nodes exchange orthogonal frequency-division multiplexing (OFDM) symbols. The proposed DSIC algorithm is based on the least-squares estimation of a self-interference (SI) channel with block processing of multiple OFDM symbols, in order to eliminate the fundamental and harmonic components of SI induced through the practical radio frequency devices of an IFD transceiver. In addition, the proposed DSIC algorithm adopts discrete Fourier transform processing of the estimated SI channel to further enhance its cancelation performance. We provide a minimum number of training symbols to estimate the SI channel effectively. The evaluation results show that our proposed DSIC algorithm outperforms a conventional algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5338-5359
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• 2017

In-band full-duplex (IBFD) wireless communication supports symmetric dual transmission between two nodes and asymmetric dual transmission among three nodes, which allows improved throughput for distributed IBFD wireless networks. However, inter-node interference (INI) can affect desired packet reception in the downlink of three-node topology. The current Half-duplex (HD) medium access control (MAC) mechanism RTS/CTS is unable to establish an asymmetric dual link and consequently to suppress INI. In this paper, we propose a medium access control mechanism for use in distributed IBFD wireless networks, FD-DMAC (Full-Duplex Distributed MAC). In this approach, communication nodes only require single channel access to establish symmetric or asymmetric dual link, and we fully consider the two transmission modes of asymmetric dual link. Through FD-DMAC medium access, the neighbors of communication nodes can clearly know network transmission status, which will provide other opportunities of asymmetric IBFD dual communication and solve hidden node problem. Additionally, we leverage FD-DMAC to transmit received power information. This approach can assist communication nodes to adjust transmit powers and suppress INI. Finally, we give a theoretical analysis of network performance using a discrete-time Markov model. The numerical results show that FD-DMAC achieves a significant improvement over RTS/CTS in terms of throughput and delay.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.1941-1960
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• 2019

Unmanned aerial vehicles (UAVs), acting as mobile base stations (BSs), can be deployed in the typical fifth-generation mobile communications (5G) scenarios for the purpose of substantially enhancing the radio coverage. Meanwhile, UAV aided underlay device-to-device (D2D) communication mode can be activated for further improving the capacity of the 5G networks. However, this UAV aided D2D communication system is more vulnerable to eavesdropping attacks, resulting in security risks. In this paper, the D2D receivers work in full-duplex (FD) mode, which improves the security of the network by enabling these legitimate users to receive their useful information and transmit jamming signal to the eavesdropper simultaneously (with the same frequency band). The security communication under the UAV coverage is evaluated, showing that the system's (security) capacity can be substantially improved by taking advantage of the flexible radio coverage of UAVs. Furthermore, the closed-form expressions for the coverage probabilities are derived, showing that the cellular users (CUs)' secure coverage probability in downlink transmission is mainly impacted by the following three factors: its communication area, the relative position with UAV, and its eavesdroppers. In addition, it is observed that the D2D users or DUs' secure coverage probability is relevant to state of the UAV. The system's secure capacity can be substantially improved by adaptively changing the UAV's position as well as coverage.

• ETRI Journal
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• v.40 no.2
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• pp.207-217
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• 2018

As implementation of the in-band full duplex (IFD) transceiver becomes feasible, research interest is growing with respect to using IFD communication with cellular networks. However, the cellular network in which the IFD communication is applied inevitably suffers from an increase of the co-channel interference (CCI) due to IFD simultaneous transmission and reception. In this paper, we analyze the performance of a cellular network based on uni-directional IFD (UD-IFD) communication, wherein an IFD base station simultaneously supports downlink and uplink transmissions of half-duplex (HD) users. In addition, a multi-pair CCI cancellation (MP-CCIC) method combining CCIC and user pairing is proposed to improve the performance of the UD-IFD network. Simulation results showed that, compared to a conventional HD cellular network without using CCIC, capacity gain was not obtained in the UD-IFD cellular network. On the other hand, when applying the proposed MP-CCIC, the capacity of the UD-IFD cellular network greatly improved compared to that of an HD cellular network.

• ETRI Journal
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• v.39 no.6
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• pp.794-802
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• 2017

In this paper, a wireless powered communication network (WPCN) consisting of a hybrid access point (H-AP) and multiple user equipment (UE), all of which operate in full-duplex (FD), is described. We first propose a transceiver structure that enables FD operation of each UE to simultaneously receive energy in the downlink (DL) and transmit information in the uplink (UL). We then provide an energy usage model in the proposed UE transceiver that accounts for the energy leakage from the transmit chain to the receive chain. It is shown that the throughput of an FD WPCN using the proposed FD UE (FD-WPCN-FD) can be maximized by optimal allocation of the UL transmission time to the UE by solving a convex optimization problem. Simulation results reveal that the use of the proposed FD UE efficiently improves the throughput of a WPCN with a practical self-interference cancellation capability at the H-AP. Compared to the WPCN with FD H-AP and half-duplex (HD) UE, FD-WPCN-FD achieved an 18% throughput gain. In addition, the throughput of FD-WPCN-FD was shown to be 25% greater than that of WPCN in which an H-AP and UE operated in HD.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.8
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• pp.921-923
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• 2016

In this letter, massive MIMO and full-duplex communication are considered together for high efficiency next generation WLAN systems. The proposed scheme allocates different carrier sensing thresholds by applying the joint spatial division and reuse (JSDR) scheme and is able to enhance the efficiency of MU-MIMO protocols by reducing the protocol overhead. Finally, full-duplex communication is applied to improve the spectral efficiency of WLAN systems.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.240-245
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• 2014

How well the self-interference cancellation (SIC) technique performs is a primary issue in realizing an in-band full-duplex (FD) wireless communication system. One factor affecting its performance is channel estimation error on the self-interference channel. We propose a new analog SIC scheme which is robust to channel estimation error. It uses phase rotators in the radio frequency (RF) chain. We also derive closed-form equations for the residual self-interference of the proposed and the conventional schemes. The analytical and numerical results show that the residual self-interference under the proposed SIC scheme is less than that using the conventional scheme, even though channel estimation error is present.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2389-2391
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• 2015

The feasibility condition of interference alignment (IA) for full-duplex (FD) multiple-input multipleoutput (MIMO) cellular networks is considered. The necessary and sufficient condition on the IA feasibility is established, characterizing the achievable sum degrees of freedom (DoF). The results demonstrate that FD operation with appropriate IA is able to improve the sum DoF on the conventional half-duplex operation.