In this paper, we assess the effect of full-duplex (FD) radio in the context of millimeter-wave (mmWave) communications. Particularly, we propose an analytical framework, based on stochastic geometry, to evaluate the performance of heterogeneous FD-mmWave cellular networks for two user location-based classifications, namely cell-center users (CCUs) and cell-edge users (CEUs). Moreover, we evaluate the performance of the considered networks with successive interference cancellation (SIC) capabilities. Based on the proposed framework, analytical expressions for the coverage and sum-rate performance are derived. We investigate the impact of FD-mmWave communications on the network performance of CCUs/CEUs and quantify the associated performance gains under different network parameter settings. Our results demonstrate the beneficial combination of FD radio with heterogeneous mmWave cellular networks, since it increases the spectral efficiency but also alleviates the effects of the multi-user interference. Furthermore, we present the trade-off between the coverage and sum-rate performance of heterogeneous FD-mmWave cellular networks for the considered user classifications. The results show that half-duplex mode is beneficial for the CEUs to achieve better network performance, as opposed to the CCUs for which FD mode is more efficient. Finally, we show the effectiveness of SIC on the network performance, with significant performance gains for the CEUs. Index TermsFull-duplex, heterogeneous networks, millimeter-wave, successive interference cancellation, stochastic geometry.Christodoulos Skouroumounis, Constantinos Psomas and Ioannis Krikidis are with the communications due to its abundant spectrum resources, which can lead to multi-Gbps rates [14]. As a result of their unique features such as directivity, sensitivity to blockages, and higher path losses, mmWave communications have fundamental differences with the current sub-6 GHz communications [14]. Due to these differences, the unique features of mmWave communications are required to be considered in the design of network architectures and protocols to fully exploit the potentials of mmWave communications. Network densification is proposed to address the large path-loss attenuation of mmWave frequencies, by bringing the transmitter closer to the receiver. This results in increased reliability, improved spectrum efficiency, and increased network capacity. Another important technique to compensate the large path-loss attenuation is the employment of directional antennas, which becomes feasible due to the short wavelength of mmWave signals. In addition to the difficulties caused by the unique features of the mmWave signals, recent studies have shown that these features also cause a positive effect on the network performance, which is the mitigation of the overall interference [15], [16], [18], [19]. Thus, the co-design of FD radio and mmWave networks is of critical importance in order to combat the severe multi-user interference caused by the FD technology by exploiting...

In this paper, we study the performance of next-generation cellular networks in the context of a low complexity base station (BS) selection scheme. In contrast to existing BS cooperation approaches, where multiple BSs jointly transmit to the user, by using our proposed low-complexity technique, a user communicates with the BS that provides the maximum signal-to-interference-plus-noise-ratio from a set formed according to a pre-selection policy. We consider three pre-selection policies based on: 1) the Euclidean distance, 2) the averaged received power, and 3) a random selection. Moreover, we consider the case where the users have the ability to employ the successive interference cancellation (SIC) scheme.Despite its high computational complexity, SIC can potentially decode and remove strong interfering signals from the aggregate received signal which can significantly boost the user's performance. By using stochastic geometry tools, analytical expressions for the coverage performance are derived for each policy, by taking into account spatial randomness and blockage effects. Our proposed technique provides low computational and implementation complexity due to the two-level selection scheme. Furthermore, we show that our proposed scheme does not lose in diversity compared to existing cooperation techniques and that all policies can benefit by the employment of the SIC scheme.

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In this letter, we propose a novel hybrid cooperation scheme in the context of heterogeneous sub-6 GHz/millimeterwave cellular networks, where users are classified either as cellcenter or cell-edge users. Using stochastic geometry tools, we propose an analytical framework to investigate the achieved performance of our proposed scheme. Specifically, analytical expressions for the moments of the conditional success probability are derived and a simple approximation of the meta-distribution is calculated, leveraging the moment-matching method with the Beta-distribution. Our results show that the proposed scheme is beneficial for the cell-edge users, and therefore, the overall network performance is significantly enhanced.

Full-duplex (FD) radio can potentially provide a higher spectral efficiency provided the self-interference (SI) at a terminal can be substantially mitigated and the multiuser interference, in the case of a large-scale scenario, is restricted. In this paper, we investigate the positive impact directional antennas can have on the reduction of these two types of interference. We study a two-dimensional geometric channel model in order to understand and acquire insight regarding the multipath effects on the SI caused by scatterers. Moreover, we provide a performance analysis for the uplink in large-scale FD cellular networks and model the impact of passive suppression on the network's performance. The derived results show the significant performance gains that can be achieved by the employment of directional antennas.

In this paper, we study the co-design of full-duplex (FD) radio with joint communication and radar sensing (JCAS) techniques in millimeter-wave (mmWave) heterogeneous networks (HetNets). Spectral co-existence of radar and communication systems causes mutual interference between the two systems, compromising both the data exchange and sensing capabilities. Focusing on the detection performance, we propose a cooperative detection technique, which exploits the sensing information from multiple base stations (BSs), aiming at enhancing the probability of successfully detecting an object. Three combining rules are considered, namely the OR, the Majority and the AND rule. In real-world network scenarios, the locations of the BSs are spatially correlated, exhibiting a repulsive behavior. Therefore, we model the spatial distribution of the BSs as a β-Ginibre point process (β-GPP), which can characterize the repulsion among the BSs. By using stochastic geometry tools, analytical expressions for the detection performance of β-GPP-based FD-JCAS systems are expressed for each of the considered combining rule. Furthermore, by considering temporal interference correlation, we evaluate the probability of successfully detecting an object over two different time slots. Our results demonstrate that our proposed technique can significantly improve the detection performance when compared to the conventional non-cooperative technique.

Extremely high reliability and energy efficiency are crucial in sixth generation (6G) mobile networks to accommodate the diverse range of end-user devices in the era of the Internet of Everything. The concept of simultaneous wireless information and power transfer (SWIPT) has been emerged as a promising solution to boost the reliability of wireless communication systems through prolonging the battery lifetime by harvesting energy from the received radio-frequency signals.In this paper, we propose a low complexity threshold-based pair switching (TbPS) technique for SWIPT in the context of large-scale cellular networks, where the multiple-antenna mobile users (MUs) employ maximum ratio combining technique and adopt the random waypoint model. Under the TbPS technique, a subset of MU's antennas is allocated for information decoding (ID), only when their post-combiner signal-to-interference ratio, exceeds a certain threshold, while the remaining antennas are allocated for energy harvesting (EH). Contrary to traditional approaches which assume the existence of either uncorrelated or fully correlated interference, our proposed technique takes into consideration the interference correlation between nearby antennas. In order to further alleviate the inter-cell interference and energy consumption, we propose a traffic load-based sleeping (TLbS) technique in the context of finite-area network deployments, where lightly-loaded cells switch into sleep mode. By leveraging tools from stochastic geometry, we derive analytical expressions for the ID, EH as well as joint ID and EH success probability of MUs based on the proposed techniques. Our results demonstrate the optimal parameters (i.e., antenna selection and traffic load threshold) of our proposed techniques, that maximize the joint ID and EH success probability. Finally, it is shown that, by properly selecting the threshold values, both the proposed TbPS scheme and TLbS mechanism outperform the conventional techniques in terms of the SWIPT capability of the MUs.