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In this letter, we study the outage probability (OP) of intelligent reflecting surface (IRS) assisted full duplex two-way (TW) communication systems, which characterizes the performance of overcoming the transmitted data loss caused by long deep fades. To this end, we first derive the probability distribution of the cascaded end-to-end equivalent channel with an arbitrarily given IRS beamformer. Our analysis shows that deriving such probability distribution in the considered case is more challenging than the case with the phase-matched IRS beamformer. Then, with the derived probability distribution of the equivalent channel, we obtain the closed-form expression of the OP. It theoretically shows that the number of reflecting elements has a conspicuous effect on the improvement of the system reliability. Extensive numerical results verify the correctness of the derived results and confirm the superiority of the considered IRS assisted TW communication system comparing to the one-way counterpart. [ABSTRACT FROM AUTHOR]

Although the outage probability of full-duplex relaying communications has been extensively investigated, its outage rate and duration—crucial to the design of effective signaling schemes—remain an open problem. Herein we narrow this gap by analyzing a full-duplex, variable-gain transparent relaying protocol operating in a standard (Nakagami- $m$) fading environment. We obtain exact as well as asymptotic expressions for the outage rate and duration. Also, as a byproduct, we generalize an existing asymptotic solution for the outage probability. Our results reveal that, at high transmission power, the relay-to-destination link’s strength and mobility have a negligible impact on the outage rate and duration of full-duplex relaying. [ABSTRACT FROM AUTHOR]

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 semi-analytic 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 spectral-leakage-interference-free performance, and thus, it substantially outperforms the counterparts with other waveforms. [ABSTRACT FROM AUTHOR]

This letter investigates an adaptive power allocation (APA) scheme for the simultaneous wireless information and power transfer (SWIPT) enabled full duplex (FD) cooperative non-orthogonal multiple access (NOMA) network under time switching (TS) protocol. The proposed APA involves the joint design of power allocation coefficient at the base station and the TS factor at the relay. We derive expressions for the outage probabilities (OP) experienced by the downlink users under APA as well as fixed power allocation (FPA) strategies, considering imperfect successive interference cancellation. By providing the asymptotic OP analysis, we establish that the proposed APA scheme: (i) resolves the zero diversity order problem inherent in FD-NOMA systems under FPA and (ii) significantly improves outage and throughput performance of SWIPT enabled FD-NOMA systems. [ABSTRACT FROM AUTHOR]

We propose a joint optimization of beamforming and time allocation for full-duplex (FD) wireless-powered communication networks (WPCNs). In FD-WPCNs, an FD-enabled hybrid access point (HAP) having multiple antennas broadcasts radio frequency (RF) energy to users, and concurrently each user transmits its own information to the HAP. Due to a lack of fixed power supplies at the users, it is difficult for the HAP to have accurate channel state information (CSI) of all links. Therefore, in this letter, a robust algorithm is proposed to maximize the weighted sum rate of the users against the uncertainty of the CSI using the relationship between the weighted sum rate and the weighted sum of mean-square error. Numerical results demonstrate that the proposed algorithm provides robustness against imperfect channel knowledge and benefits of utilizing multiple antennas in the FD-WPCNs. [ABSTRACT FROM AUTHOR]

Cache hit ratio (CHR) is a common metric to evaluate the performance of an edge caching system. While the CHR is efficient to measure throughput reduction gain, it fails to guarantee user quality of experience since the CHR does not capture the last-mile channel uncertainty. In this letter, we investigate a novel successful delivery probability (SDP) metric of full-duplex-enabled mobile edge caching (FD-MEC) systems, defined as a probability that the user receives the requested file before a tolerable delay. First, the average SDP is derived in a closed-form expression for arbitrary caching policy and network topology, taking into account the wireless fading distribution. Second, based on the derived SDP, a sub-optimal cache placement is proposed to maximize the average SDP, which is analytically shown to surpass both the most popular and uniform caching policies. Finally, the numerical results are presented to verify the accuracy of our analysis and demonstrate the effectiveness of our proposed cache placement design. [ABSTRACT FROM AUTHOR]

Signal relays in power line communication networks are usually implemented using the decode-and-forward protocol, which requires complex relays. In this letter, we propose a real-time amplify-and-forward relay that is mainly based on an analog full-duplex architecture. The speed of analog circuits enables the amplification of the incoming signal without introducing a significant communication delay. Our system-level analysis explains the optimization of the relay design and, based on a measured channel database, shows what increase in communication rate can be achieved by using the proposed solution. [ABSTRACT FROM AUTHOR]

This letter investigates the source and relay precoder design for full-duplex multiple-input multiple-output relay systems, where simultaneous wireless information and power transfer is enabled at the destination. The objective is to design the precoders such that the end-to-end performance can be optimized. Different from existing schemes, a novel dual-objective function is adopted in this letter. The proposed precoders yield closed-form solutions and avoid iterative algorithms. Moreover, our design is applicable when the system suffers from the residual loop-interference. Simulations show that the proposed scheme enables an efficient way to optimize information-decoding and energy-harvesting performances. [ABSTRACT FROM AUTHOR]

Blind known self-interference cancellation (BKSC) is particularly attractive in self-interference (SI) reduction for full-duplex (FD) systems, because it requires no interference channel state information (CSI) and the overhead of capturing the full CSI on SI can be saved. In this letter, a semi-blind SI cancellation method is proposed for FD systems under phase noise. By applying the idea of BKSC in the frequency domain, this method is designed to extract partial CSI of the SI for removing the interference that results from differential operations in BKSC schemes. The closed-form expression for the power of the residual SI is also derived in the presence of phase noise. As a low-complexity method that requires no specific pilot design or complex estimation algorithms, the proposed scheme can effectively suppress the SI signal in the presence of phase noise, which outperforms conventional least-square-based SI cancellation schemes. [ABSTRACT FROM PUBLISHER]

This letter investigates the hybrid duplex wireless peer discovery (Hyb-WPD) that increases the average number of discovered peers (ADP), through arbitrating between half duplex and full duplex (FD) operations. FD allowing simultaneous tranceiving inherently introduces residual self-interference (RSI) due to non-ideal implementation; thus, this impairment yields a new design issue for transmission probability, which determines whether a peer receives or tranceives. This letter proposes the design principles for the Hyb-WPD depending on RSI through mathematically analyzing the ADP, and the numerical results demonstrate their performance. [ABSTRACT FROM PUBLISHER]

Antenna selection for full-duplex communication between two nodes, each equipped with a predefined number of antennae and transmit/receive chains, is studied. Selection algorithms are proposed based on magnitude, orthogonality, and determinant criteria. The algorithms are compared to optimal selection obtained by exhaustive search as well as random selection, and are shown to yield performance fairly close to optimal at a much lower complexity. Performance comparison for a Rayleigh fading symmetric channel reveals that selecting a single transmit antenna is best at low signal-to-noise ratio (SNR), while selecting an equal number of transmit and receive antennae is best at high SNR. [ABSTRACT FROM PUBLISHER]

This letter proposes a security method for wire-line point-to-point communication based on the information theory. The proposed system replaces the conventional receiver by a full-duplex node which can, not only, receive the confidential signal, but also deliver artificial noise to impair the channel of wiretapper observation between the two legitimate partners. The power ratio of the signal to the artificial noise is a key factor for guaranteeing absolute secure communication. The theoretical work is carried out in the model of physical layer security on the assumption that the wiretapper can perform the optimum detection, including with colluding structure. Numerical results are presented for demonstrating the effectiveness of the proposed approach. [ABSTRACT FROM PUBLISHER]

We consider a full-duplex wireless powered communication network, supporting wireless power transfer of a hybrid access point in the downlink and time-division multiple-access devices in the uplink simultaneously. By considering the residual self-interference (SI), we formulate the problems of power allocation (PA) and time allocation (TA) to maximize the sum rate of the uplink subject to the energy causality as well as the peak and average power constraints. The non-convex optimization problems of the joint PA-TA and the PA are approximated as second-order cone programs to be solved with successive convex approximation. The results show that the proposed PA-TA (PA) algorithm outperforms the conventional PA-TA when the SI exists at any (severe) level. [ABSTRACT FROM PUBLISHER]

In this letter, we jointly design the beamformers of relay and source in full-duplex relay-based wireless powered communication networks. Equipped with multiple antennas, the relay/source is designed to transmit information and receive information/energy simultaneously. Furthermore, the hybrid access point (H-AP) acts as relay to assist the information transfer from source to destination. Moreover, source transmits signals only with the energy harvested from H-AP/relay and recycled energy from its own transmitted signals. In this setup, we propose a novel one-phase co-channel protocol and jointly design the beamforming of relay and source to maximize the system throughput. As the problem is non-convex, we first use zero forcing (ZF) method to cancel the self-interference at relay and then propose a low-complexity algorithm to obtain the global optimum when the ZF constraint is assumed. Numerical results show that our proposed optimal beamforming design is superior to other reference schemes. [ABSTRACT FROM PUBLISHER]

In this letter, we consider a multiple-input multiple-output (MIMO) source-relay-destination network, where the relay is a full-duplex MIMO transceiver (FD-MIMO) and uses spatial modulation (SM). We propose a transmission protocol for this system, where the source beamforms to the relay antennas that are not used for transmission, while the remaining antennas in the relay forward the previously decoded information using SM to the destination. We derive the analytical expressions for the bit error rate of the FD-MIMO relaying system. We show from the analytical results and simulations that our proposed FD-MIMO system outperforms the one that uses V-BLAST at relay. This performance advantage is due to the availability of more antennas at the relay dedicated to reception and the use of a lower order quadratic-amplitude modulation in SM, when compared with V-BLAST. [ABSTRACT FROM PUBLISHER]

This letter studies the physical-layer security of a full-duplex (FD) multiple-input multiple-output relay channel. A legitimate source node (Alice) communicates with her destination node (Bob) through an FD relay node in the presence of a cooperative FD jammer and a potential eavesdropper (Eve). The cooperative jammer is assumed to be an FD node that is solely charged by the ambient radio-frequency transmissions. We investigate the self-energy recycling at the cooperative jammer and derive a sufficient condition for the cooperative jammer to operate as a node with reliable energy supply. Without knowing the eavesdropper’s channel state information at the legitimate nodes, we propose a precoded artificial-noise (AN) injection scheme to secure the legitimate transmissions. The numerical results demonstrate that our proposed AN-aided secure scheme achieves a significant average secrecy rate improvement compared with the case of no cooperative jammer. [ABSTRACT FROM PUBLISHER]

This letter investigates self-backhauling with dual antenna selection at multiple small cell base stations. Both half-duplex (HD) and full-duplex (FD) transmissions at the small cell base station are considered. Depending on instantaneous channel conditions, the FD transmission can have higher throughput than the HD transmission, but it is not always the case. Closed-form expressions of the average throughput are obtained and validated by the simulation results. In all cases, the dual receive and transmit antenna selection significantly improves backhaul and data transmission, making it an attractive solution in practical systems. [ABSTRACT FROM PUBLISHER]

This paper provides two optimal power allocation (OPA) strategies for full duplex (FD) relay networks with amplify and forward (AF) protocol. Two strategies are designed based on statistical channel state information (S-CSI) and instantaneous CSI (I-CSI) to minimize the system outage probability under total source and relay power constraint. For the S-CSI scheme, the OPA factor is found through an exhaustive search while, for the I-CSI scheme, the OPA factor is given in a closed-form expression. To evaluate quickly the system performance with two proposed schemes, we derive the tight closed-form lower and upper bounds on the system outage for S-CSI based OPA scheme and the asymptotic performance for I-CSI based OPA scheme. Furthermore, how much difference in performance between AF and decode and forward (DF) relaying with OPA is also verified through our numerical results. [ABSTRACT FROM PUBLISHER]

In this paper a power optimal routing is investigated in fading wireless channels. The fading distribution of the channel is modeled by Nakagami-m, and the outage capacity of full-duplex decode-and-forward (FD-DF) relaying is taken as QoS constraint. In this QoS routing algorithm, the weighted power sum of relay nodes is minimized while the end-to-end link outage probability is kept below a threshold. Firstly, the weighted power sum minimization problem for a static multi-hop route is formulated and solved in closed form for low outage probability. Then a routing metric is extracted from the minimized power sum of a static route which results in optimal routing method, implemented by dynamic programming algorithms like Bellman Ford. The proposed power optimal routing is evaluated by comparing its performance to other strategies with Monte Carlo simulations. [ABSTRACT FROM PUBLISHER]