In this paper, we investigate a full duplex (FD) multiuser non-orthogonal multiple access (NoMA) communication system, based on the optimization of received signalto-interference-plus-noise ratio (SINR) per unit power. Since the communication system operates in FD mode, co-channel interference (CCI) and self-interference (SI) dominate the system's performance. Accordingly, to combat the CCI, we adopt a gametheoretic approach and propose users clustering algorithms and to suppress the SI, we formulate an optimization problem to maximize the power-normalized SINR (PN-SINR). While the user clustering optimization problem is constrained by i) the successive interference cancellation (SIC) constraint and ii) two binary constraints for the allocations of UL and DL users, the PN-SINR problem is constrained by i) total transmit power budget at the base station and uplink (UL) users, ii) the fundamental condition for the implementation of successive interference cancellation in NoMA, and iii) the minimum fairness condition for UL users. The original PN-SINR problem is non-convex and hence is converted into an equivalent subtractive-form problem, after which we propose an iterative algorithm to find the optimal power allocation policy. Properties of all the proposed algorithms are thoroughly investigated and numerical results are provided. Based on the channel conditions and suppression level of SI and CCI, the superiority of the proposed FD-NoMA system over half duplex NoMA and FD orthogonal multiple access systems is verified.

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The networking paradigm of spectrum sharing is a promising technology to solve the spectrum paucity that has resulted from the exponential increase in the number of wireless devices and ubiquitous services. In light of the novel concept of Authorized/Licensed Shared Access, in this work, we consider the spectrum sharing between a collocated multiple-input-multipleoutput (MIMO) radar and a full-duplex (FD) MIMO cellular communication system consisting of a FD base station (BS) serving multiple downlink and uplink users simultaneously, without hindering the detection probability of the radar. The main objective is to develop an optimization technique at the cellular system for jointly designing the transceiver for the cellular BS and power allocation vectors for uplink users that can maximize the detection probability of radar, while guaranteeing a pre-defined quality-of-service for each user and power budget for the uplink users and BS. The original problem is non-convex and thus, we convert the non-convex problem into a secondorder cone and propose an iterative algorithm to find the optimal solution. Numerical results are then provided to demonstrate the feasibility of the spectral coexistence and show a scalable tradeoff in performance of both systems.

This paper investigates the performance of cooperative spectrum sensing in cognitive radio networks using the stochastic geometry tools. In order to cope with the diversity of received signal-to-noise ratios (SNRs) at secondary users, a practical and efficient cooperative spectrum sensing model is proposed and investigated based on the generalized likelihood ratio test (GLRT) detector. In order to investigate the cooperative spectrum sensing system, the theoretical expressions of the probabilities of false alarm and detection of the local decision are derived. The optimal number of cooperating secondary users is then investigated to achieve the minimum total error rate of the final decision by assuming that the secondary users follow a homogeneous Poisson point process (PPP). Moreover, the theoretical expressions for the achievable ergodic capacity and throughput of the secondary network are derived. Furthermore, the technique of determining an appropriate number of cooperating secondary users is proposed in order to maximize the achievable ergodic capacity and throughput of the secondary network based on a target total error rate requirement. The analytical and simulation results validate the chosen optimal number of collaborating secondary users in terms of spectrum sensing, achievable ergodic capacity and throughput of the secondary network.

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