• ETRI Journal
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• v.42 no.1
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• pp.17-25
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• 2020

Multiple-input multiple-output systems can achieve a full sum rate (SR) via full duplex (FD). However, its performance is degraded by self-interference (SI) that occurs between the transmitter and receiver at the same node and thus is constrained by error floors. Conversely, half duplex (HD) can avoid the SI albeit at lower spectral efficiency, and the slope of its error curve is determined by the diversity order. In this study, a link selection scheme based on switching between FD and HD is examined as a simple method to improve the bit error rate (BER) performance of FD systems. In the proposed link selection algorithm, either FD or HD is selected based on the received minimum distance and signal-to-interference plus noise ratio. Simulation results indicate that the proposed hybrid FD/HD switching system offers significant BER performance improvement when compared with that of the conventional FD and FD based on only the received minimum distance under the same fixed SR. Under relatively sufficient SI cancellation, it is demonstrated to outperform the HD with a diversity advantage in low and medium signal-to-noise ratio region.

• 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.40 no.3
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• pp.451-458
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• 2015

The deployment density of AP increases as well as the density WLAN stations due to increase of WLAN use and the real performance of WLAN is degraded. To improve the performance, there are many PHY/MAC technologies and OFDMA and full duplex are promising technologies among them. In conventional OFDMA WLAN MAC relate works, there are some limitations in terms of channel utilization and collision probability. Thus, it need to research for effective channel allocation protocol. Full duplex can transmit data on the same time and same frequency resource so it can allocate channel more flexible than half duplex. In this paper, we prose the OFDMA FD-MAC(Full Duplex MAC) protocol that it allocates the sub-channels based on the idle channel information for full duplex pair. In addition, it shows the throughput improvement by performance analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.3000-3022
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• 2019

Full-duplex (FD) technologies enable wireless nodes to simultaneously transmit and receive signal using the same frequency-band. The FD modes could improve their physical layer throughputs. However, in the wireless ad hoc networks, the FD communications also produce new interference risks. On the one hand, the interference ranges (IRs) of the nodes are enlarged when they work in the FD mode. On the other hand, for each FD pair, the FD communication may cause the potential hidden terminal problems to appear around the both sides. In this paper, to avoid the interference risks, we first model the IR of each node when it works in the FD mode, and then analyze the conditions to be satisfied among the transmission ranges (TRs), carrier-sensing ranges (CSRs), and IRs of the FD pair. Furthermore, in the media access control (MAC) layer, we propose a specific method and protocol for collision avoidance. Based on the modified Omnet++ simulator, we conduct the simulations to validate and evaluate the proposed FD MAC protocol, showing that it can reduce the collisions effectively. When the hidden terminal problem is serious, compared with the existing typical FD MAC protocol, our protocol can increase the system throughput by 80%~90%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3887-3907
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• 2015

This paper introduces a full duplex single secondary user multiple-input multiple-output (FD-SSU-MIMO) cognitive radio network, where secondary user (SU) opportunistically accesses the authorized spectrum unoccupied by primary user (PU) and transmits data based on FD-MIMO mode. Then we study the network achievable average sum-rate maximization problem under sum transmit power budget constraint at SU communication nodes. In order to solve the trade-off problem between SU's sensing time and data transmission time based on opportunistic spectrum access (OSA) and the power allocation problem based on FD-MIMO transmit mode, we propose a simple trisection algorithm to obtain the optimal sensing time and apply an alternating optimization (AO) algorithm to tackle the FD-MIMO based network achievable sum-rate maximization problem. Simulation results show that our proposed sensing time optimization and AO-based optimal power allocation strategies obtain a higher achievable average sum-rate than sequential convex approximations for matrix-variable programming (SCAMP)-based power allocation for the FD transmission mode, as well as equal power allocation for the half duplex (HD) transmission mode.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.568-576
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• 2010

In this paper, we analyze the outage probability of full duplex relay (FDR) with decode-and-forward (DF) protocol is derived under fading channels. The fading channel for source-relay link is assumed to be Rician fading to consider the infrastructured fixed relay with line of sight (LOS) propagation, and the other fading channels are assumed to be Rayleigh fading. Based on this analytical result, we provide the criterion that FDR shows a lower outage probability than HDR to consider the interference problem and the resource efficiency improvement by full duplex (FD) operation. The accuracy of the analysis is confirmed throughout the simulation results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3908-3920
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• 2015

In this paper, performance analysis of full-duplex (FD) relay selection under decode-and-forward (DF) relaying mode is carried out by taking into account several critical factors, including the distributions of the received signal-to-noise ratio (SNR) and the outage probability of wireless links. The tradeoff between the FD and half-duplex (HD) modes for relay selection techniques is also analyzed, where the former suffers from the impact of residual self-interference, but the latter requires more channel resources than the former (i.e., two orthogonal channels are required). Furthermore, the impact of optimal power allocation (OPA) on the proposed relay-selection scheme is analyzed. Particularly, the exact closed-form expressions for outage probability of the proposed scheme over Rayleigh fading channels are derived, followed by validating the proposed analysis using simulation. Numerical results show that the proposed FD based scheme outperforms the HD based scheme by more than 4 dB in terms of coding gain, provided that the residual self-interference level in the FD mode can be substantially suppressed to the level that is below the noise power.

• 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.

• 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.

• 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.