Power control and performance analysis for full‐duplex relay‐assisted D2D communication underlaying fifth generation cellular networks

We investigate power control problem for cooperative relaying in the device-to-device (D2D) system underlaying cellular networks. Specifically, we consider the D2D communication assisted by fixed-location relays in interference existing circumstance. Therefore, an effective power control scheme is of great importance to suppress interference between D2D and cellular communications which can improve the total system throughput and spectral efficiency. In this paper, we formulate a power control optimization problem for cellular communication and a simple on-off power control algorithm for D2D communications. We also obtain analytic expression for the coverage probability of cellular link using stochastic geometry according to proposed algorithm. Simulation results follow to show the rate of both cellular and D2D links in the various number of D2D transceivers.

Mobile cellular communications are experiencing an exponential growth in traffic load on Long Term Evolution (LTE) eNode B (eNB) components. Such load can be significantly contained by directly sharing content among nearby users through device-to-device (D2D) communications, so that repeated downloads of the same data can be avoided as much as possible. Accordingly, for the purpose of improving the efficiency of content sharing and decreasing the load on the eNB, it is important to maximize the number of simultaneous D2D transmissions. Specially, maximizing the number of D2D links can not only improve spectrum and energy efficiency but can also reduce transmission delay. However, enabling maximum D2D links in a cellular network poses two major challenges. First, the interference between the D2D and cellular communications could critically affect their performance. Second, the minimum quality of service (QoS) requirement of cellular and D2D communication must be guaranteed. Therefore, a selection of active links is critical to gain the maximum number of D2D links. This can be formulated as a classical integer linear programming problem (link scheduling) that is known to be NP-hard. This paper proposes to obtain a set of network features via deep learning for solving this challenging problem. The idea is to optimize the D2D link schedule problem with a deep neural network (DNN). This makes a significant time reduction for delay-sensitive operations, since the computational overhead is mainly spent in the training process of the model. The simulation performed on a randomly generated link schedule problem showed that our algorithm is capable of finding satisfactory D2D link scheduling solutions by reducing computation time up to 90% without significantly affecting their accuracy.

Device-to-device (D2D) communication underlaying cellular networks is a promising technology to improve network resource utilization. In D2D-enabled cellular networks, interference generated by D2D communications is usually viewed as an obstacle to cellular communications. However, in this paper, we present a new perspective on the role of D2D interference by taking security issues into consideration. We consider a large-scale D2D-enabled cellular network with eavesdroppers overhearing cellular communications. Using stochastic geometry, we model such a network and analyze the signal-to-interference-plus-noise ratio (SINR) distributions, connection probabilities and secrecy probabilities of both the cellular and D2D links. We propose two criteria for guaranteeing performances of secure cellular communications, namely the strong and weak performance guarantee criteria. Based on the obtained analytical results of link characteristics, we design optimal D2D link scheduling schemes under these two criteria respectively. Both analytical and numerical results show that the interference from D2D communications can enhance physical layer security of cellular communications and at the same time create extra transmission opportunities for D2D users.

Device-to-Device (D2D) communication has become an important technology in future networks, since it can provide advantages such as cell throughput enhancement, user equipment power saving, and increased instantaneous data rate. However, the performance of both D2D and cellular communication can be affected by mutual interferences between them. In this paper, we analyze a resource allocation method for D2D links underlaying cellular networks. A novel method which allows more than one D2D pair to reuse the downlink resource of one cellular user is proposed. In addition, we also present an algorithm to assign a cellular user to each group of D2D pairs, when there are a number of cellular users and D2D users. The proposed algorithm is designed to guarantee that the SINR for both the cellular link and D2D link exceeds acceptable thresholds.

Joint mode selection and power control for D2D underlaid cellular networks

This paper considers a device-to-device (D2D) underlaying cellular network where an uplink cellular user communicates with the base station while multiple direct D2D links share the uplink spectrum. This paper proposes a random network model based on stochastic geometry and develops centralized power control algorithm. The goal of the proposed power control algorithm is two-fold: ensure the cellular users have sufficient coverage probability by limiting the interference created by underlaid D2D users, while also attempting to support as many D2D links as possible. This paper adopts the two level control strategy: Cellular link SINR(signal-to-interference-plus noise ratio) and sum rate maximization, to ensure the cellular communication and improve the coverage probability of D2D and cellular links. Numerical results show the gains of the proposed power control algorithm and accuracy of the analysis.KeywordsPower controlStochastic geometryPoisson point processCoverage probability

Device-to-device (D2D) communication is expected to increase the coverage probability by coexisting along with the conventional cellular systems in 5G technology. As the user equipments are often held closer to the human body, D2D links experience shadowing modelled by the amp;#954;-amp;#956; shadowed fading model. Though the cellular links do not experience amp;#954;-amp;#956; shadowed fading, the same is assumed here as it generalizes many popular fading distributions such as Rayleigh, Rician, Nakagami, amp;#954;-amp;#956; , amp;#951;-amp;#956; , Hoyt etc. Thus the above assumption makes the results obtained here generic. We show that by neglecting shadowing in the D2D link, coverage probability of D2D user is over-estimated at low SIR thresholds and under-estimated at high SIR thresholds. Though cellular links are interfered with by the D2D links, we observe that there is negligible impact on cellular coverage probability due to any change of fading parameters in the D2D links. Also, when all the links are Rayleigh faded, the D2D distance below which D2D mode is preferred to cellular mode of communication is obtained analytically.

The integration of local device-to-device (D2D) communications and cellular connections has been intensively studied to satisfy co-existing D2D and cellular communication demand. In future cellular networks, there will be numerous standby users possessing D2D communication capabilities in close proximity to each other. Considering that these standby users do not necessarily request D2D communications all the time, in this paper we propose a hybrid D2D-cellular scheme to make use of these standby users and to improve the rate performance for cellular users. More specifically, through D2D links, a virtual antenna array can be formed by sharing antennas across different terminals to realize the diversity gain of MIMO channels. This paper considers the use of millimeter wave links to enable high data rate D2D communications. We then design an orthogonal D2D multiple access protocol and formulate the optimization problem of joint cellular and D2D resource allocation for downlink transmissions using the proposed scheme. We obtain a closed-form solution for D2D resource allocation, which reveals useful insights for practical system design. Numerical results from extensive system-level simulations demonstrate that the rate performance of cellular users is significantly improved.

In this paper, we propose a device-to-device (D2D) communication scheme to improve local services in cellular networks. By employing cooperative relay (CR) technology, D2D and cellular communications can operate in orthogonal resource sharing (ORS) mode with the aim of optimizing the data rates for local D2D users while fulfilling the minimum rate requirements for prioritized cellular users. In the proposed CR-based ORS scheme, we consider a cellular communication that is willing to share part of the occupied bandwidth resource with some D2D communications. Hence, the newly-obtained resource can be used by a D2D communication for the following two purposes, i.e., to compensate the rate loss of the cellular communication through cooperative relaying and to communicate its own information so as to increase its own rate. We formulated this CR-based ORS problem as a non-convex optimization problem. Hence, a global maximizer may not exist for the problem. To find the optimal solution for the problem, an effective heuristic algorithm is developed. Simulation results show that the proposed D2D communication scheme can significantly increase the rates of local D2D users and also fulfill the minimum rate requirements of cellular users.

Device-to-device (D2D) communications have been recently proposed as an effective way to increase both spectrum and energy efficiency for future cellular systems. In this paper, joint mode selection, channel assignment, and power control in D2D communications are addressed. We aim at maximizing the overall system throughput while guaranteeing the signal-to-noise-and-interference ratio of both D2D and cellular links. Three communication modes are considered for D2D users: cellular mode, dedicated mode, and reuse mode. The optimization problem could be decomposed into two subproblems: power control and joint mode selection and channel assignment. The joint mode selection and channel assignment problem is NP-hard, whose optimal solution can be found by the branch-and-bound method, but is very complicated. Therefore, we develop low-complexity algorithms according to the network load. Through comparing different algorithms under different network loads, proximity gain, hop gain, and reuse gain could be demonstrated in D2D communications.

Device-to-device (D2D) communication is a potential solution to the incessant increase in data traffic on cellular networks. The greatest problem is how to control the interference between D2D users and cellular mobile users, and between D2D users themselves. This paper proposes a solution for this issue by putting the full control privilege in cellular network using the software-defined networking (SDN) concept. A software virtual switch called Open vSwitch and several components are integrated into mobile devices for data forwarding and radio resource mapping, whereas the control functions are executed in the cellular network via a SDN controller. This allows the network to assign radio resources for D2D communication directly, thus reducing interference. This solution also brings out many benefits, including resource efficiency, energy saving, topology flexibility, etc. The advantages and disadvantages of this architecture are analyzed by both a mathematical method and a simple implementation. The result shows that implementation of this solution in the next generation of cellular networks is feasible.

Device-to-device (D2D) communication exploits the proximity between two devices to enhance the overall spectrum utilization of a crowded cellular network. Two conventional frameworks that are generally used to realize a D2D communication are underlay D2D (U-D2D) and cooperative D2D (C-D2D) communications. Both frameworks have their own merits and demerits in terms of interference management, implementation complexity, and achievable spectral efficiency (SE). For instance, the performance of U-D2D is limited by the amount of interference from the D2D to the cellular user (CU), whereas for C-D2D the performance suffers due to a division of transmission into two orthogonal time phases. In this paper, we propose two novel extensions of conventional D2D communication frameworks, which alleviate their drawbacks and also improves the performance of the overall cellular network. The first proposed framework is an adaptive interference aware U-D2D communication framework. Through this framework, the CU can be protected from the excessive interference of the D2D transmitter (DT), thus maintaining the desired quality of service at CU. The second proposed framework is an adaptive C-D2D communication framework. This framework employs adaptive modulation and coding and bit error rate-based selection and combining to enhance the performance of cellular and D2D users. As a proof-of-concept demonstration and performance assessment, both the frameworks have been implemented on a National Instruments Universal Software Radio Peripheral platform. The measurement results and on-field trials show that the proposed frameworks improve the bit error rate (BER) and the SE of the overall system. Results also interpret that the adaptive C-D2D outperforms the adaptive interference aware U-D2D in terms of BER and SE.

D2D communications can be prone to potential security threats. For example, D2D mobiles need to know who else is located nearby so as to pair up. If the location information is spoofed, the interference caused by wrongly paired D2D users can significantly lower the system performance. Additionally, D2D communications between neighboring D2D nodes provide alternative security approaches (physical-layer security) by using channel statistics. In this chapter, we will study the following two security problems in detail. • Location security: D2D networks need to pair D2D users on the basis of location information so as to use locally available spectrum. This creates a critical loophole for global-positioning-system (GPS)-spoofing attack, where the adversary attacks the GPS signals received by D2D devices, so that D2D devices obtain false available spectrum information with false location information. This security loophole can potentially result in large-scale malfunctioning of mobile D2D networks. • Data transmission security: Security in D2D communications is traditionally implemented using cryptography, as in other wireless communication systems. Alternatively, physical-layer security provides additional security provided by the channel statistics, which fits well the D2D communications scenarios. We will consider physical-layer security in D2D communications as an underlay to cellular networks with an eavesdropper. Benefiting from the underlaid spectrum reuse, D2D users can contribute to the system's secrecy capacity, while D2D users may interfere with cellular users and decrease their secrecy capacity. Location security 8.1.1 Problem overview Dynamic-spectrum-access (DSA) technology has received much attention in industry and academic environments due to its promise of better utilization of spectrum resources compared with the current static spectrum-allocation method. Traditionally, spectrum allocation is static, where FCC assigns communities licenses to use specific frequencies, such as AM, FM, short-wave and citizens' bands, and VHF and UHF television channels, as well as hundreds of less familiar bands that serve cellular and cordless telephones, GPS trackers, air-traffic-control radars, security alarms, radio-controlled toys, and the like. While some of these assigned spectrum bands have been overloaded due to the growth of their users, other spectrum bands are scarcely used.

The development of Device-to-Device (D2D) communication as an alternative communication scheme continues to grow. D2D communication enables each device to communicate directly with other devices without going through the Evolved Node B (eNB). These days, D2D communication can be implemented in conventional cellular communication, and use the same spectrum as the conventional cellular user (underlay). This underlay scheme can improve the cell’s spectrum efficiency, but the interference level that happens in the cell is increased. Because D2D communication and cellular communication use the same spectrum, there will be interference between D2D user equipment (DUE) and Cellular user Equipment (CUE). A well-designed radio resource allocation is needed to reduce the interference level, while maintaining the overall performance of the cell. In this research, Simplified Particle Swarm Optimization (SPSO) is proposed to overcome this problem. SPSO is a PSO-based algorithm with a limited number of iterations designed to halt calculations when the PSO algorithm cannot find a solution. If SPSO exceeds the limit iteration, a greedy algorithm is executed to do the allocation process. From the simulation, the SPSO algorithm can achieve 1.3310 × 108 bps, 12.3239 bps/Hz, 2.1328 × 103 bps/Watt and 92% on total sumrate, spectral efficiency, power efficiency, and system fairness respectively. These number is better if compared with the conventional greedy allocation algorithm. The total sumrate, spectral efficiency, and power efficiency are increased by 0.9%, 0.74%, and 0.95% in average datarate, spectral efficiency, and power efficiency respectively. Meanwhile the SPSO’s system fairness is decreased by 1.65% compared with the conventional greedy algorithm.

With the tremendous increment of traffic in the next generation mobile networks, device to device (D2D) communication is proposed to relieve the traffic burden of the base station and improve the overall network capacity. It supports direct communications between devices and could reuse the resources of cellular users (CUs). Despite the advantages, D2D communications bring great challenges in interference management. In this paper, we study the power control and channel allocation problems in three scenarios: (1) one CU and one D2D pair; (2) one CU and multiple D2D pairs; (3) multiple CUs and multiple D2D pairs. The goal is to coordinate the mutual interferences and maximize the overall network capacity. We derive sufficient conditions to guarantee the efficiency of D2D communications in scenarios with one CU and one D2D pair. We propose the bio-inspired PSO-P power control algorithm for the scenarios with one CU and multiple D2D pairs, and the PSO-CP algorithm for the scenarios with multiple CUs and multiple D2D pairs to jointly assign channels and powers. Simulation results show that the proposed algorithms are efficient in improving the overall network capacity.