D2D Users Research Articles

Resource Allocation and Power Control for D2D Communication Underlaying LTE-Advanced Networks

Device-to-device (D2D) communications has proven to be efficient in improving the network performance and releasing the traffic load of base station. D2D user equipment(DUEs) can share the same LTE resources blocks with the cellular user equipment(CUEs), but it would cause severe co-channel interference. In this paper, a resource allocation and power control scheme is proposed to reduce the impact of co-channel interference. First, adopt a resource allocation scheme based on greedy algorithm on the premise of meeting the minimum rate requirements of devices, then the path loss compensation factor matrix could be calculated according to the distance between DUEs to the base station and CUEs and used to reduce the influence. Simulation results show that the proposed algorithm has better performance in D2D user access rate and system throughput.

Energy efficiency in cognitive radio assisted D2D communication networks

The next generation networks intend to have features like device to device (D2D) connectivity, energy efficiency and spectral efficiency. This paper presents problem formulation for maximization of energy efficiency of cognitive radio assisted D2D networks subject to compliance of transmit powers of cellular users and interference constraints of primary users of broadcast network. Cognitive radio network (CRN) users are cellular users comprising of cellular and D2D users. Cellular users can opt any of the cellular or D2D mode. These CRN users opportunistically utilize spectrum of television (TV) white spaces. The problem thus formulated is NP-complete. Mesh adaptive direct search (MADS) algorithm has been used to find $$\varepsilon $$ -optimal solution. The results of MADS are compared with the global optimal solution obtained by exhaustive search algorithm (ESA). The simulation results reveal that MADS’ performance is equally good as that of ESA in most of the cases. MADS outperforms ESA in terms of energy efficiency comparison. Simulation results compare results of utility value, spectral efficiency and admission of CRN users with two types of utilities, i.e., utility with maximization of energy efficiency and utility without maximization of energy efficiency. Results testify that utility with maximization of energy efficiency outperforms its counterpart utility. MADS is also ideal algorithm as it has low computational complexity as compared to ESA. Computational complexity of ESA increases exponentially as numbers of users increase making MADS obvious choice for real life networks comprising of large number of cellular users.

Optimization-Based Access Assignment Scheme for Physical-Layer Security in D2D Communications Underlaying a Cellular Network

In this paper, we consider physical-layer security for device-to-device (D2D) communications underlaying cellular networks in which cellular users are under threat from multiple eavesdroppers. We propose an access selection scheme for D2D users to protect cellular users against eavesdropping. Specifically, in our proposed scheme, multiple D2D users whose distance to the cellular user is more than the threshold we set will be selected to share the same spectrum as that of the cellular user, and the interference generated by the selected D2D users can be seen as a jamming measure to interrupt the eavesdropping. Then, we consider the secrecy throughput as a standard based on which the security performance of our proposed scheme is quantified, and we derive a closed-form expression for the secrecy throughput of a cellular user with the aid of stochastic geometry. Moreover, by using the optimization method, we prove the existence of optimal threshold and design an iterative algorithm based on the advance-and-retreat method to determine the optimal threshold. Simulation results show that our access selection scheme can effectively improve the physical-layer security of cellular users and that the maximum secrecy throughput can be achieved with the optimal threshold.

Resource Allocation for 5G Heterogeneous Cloud Radio Access Networks With D2D Communication: A Matching and Coalition Approach

Device-to-Device (D2D) communication is a promising technology toward the fifth generation mobile communication. However, when D2D communication is incorporated into heterogeneous cloud radio access network (H-CRAN), the interference management between the D2D users and current users is a challenge. In this paper, we study how to assign the sub-channels of different bandwidth to multiple D2D pairs and the remote radio head users. In such a way, the sub-channels that have been pre-allocated to macro-cell users can be reused, the system performance can be maximized while the quality of service of all users can be guaranteed. Such a resource allocation problem is formulated as a mixed integer nonlinear programming (MINLP) problem which is NP-hard. To obtain the solution, the proposed problem is reformulated into a many-to-one matching sub-game with externality followed by a coalition sub-game. Then, a constrained deferred acceptance algorithm and a coalition formation algorithm are proposed to find solutions to these two sequential sub-games, respectively. Finally, we prove theoretically that both the proposed algorithms can convergent with a low computational complexity. Numerical results demonstrate that compared with existing resource allocation schemes, our proposed scheme can significantly improve the system performance in terms of overall throughput, the total number of admitted users and fairness.

Power Control and Channel Allocation for D2D Underlaid Cellular Networks

Device-to-Device (D2D) communications underlaying cellular networks is a viable network technology that can potentially increase spectral utilization and improve power efficiency for proximity-based wireless applications and services. However, a major challenge in such deployment scenarios is the interference caused by D2D links when sharing the same resources with cellular users. In this paper, we propose a channel allocation (CA) scheme together with a set of three power control (PC) schemes to mitigate interference in a D2D underlaid cellular system modeled as a random network using the mathematical tool of stochastic geometry. The novel aspect of the proposed CA scheme is that it enables D2D links to share resources with multiple cellular users as opposed to one as previously considered in the literature. Moreover, the accompanying distributed PC schemes further manage interference during link establishment and maintenance. The first two PC schemes compensate for large-scale path-loss effects and maximize the D2D sum rate by employing distance-dependent path-loss parameters of the D2D link and the base station, including an error estimation margin. The third scheme is an adaptive PC scheme based on a variable target signal-to-interference-plus-noise ratio, which limits the interference caused by D2D users and provides sufficient coverage probability for cellular users. Closed-form expressions for the coverage probability of cellular links, D2D links, and sum rate of D2D links are derived in terms of the allocated power, density of D2D links, and path-loss exponent. The impact of these key system parameters on network performance is analyzed and compared with previous work. Simulation results demonstrate an enhancement in cellular and D2D coverage probabilities, and an increase in spectral and power efficiency.

Sector-Based Radio Resource Allocation (SBRRA) Algorithm for Better Quality of Service and Experience in Device-to-Device (D2D) Communication

The mounting content sharing among users has resulted in a considerable rise in wireless data traffic, pressurizing the cellular networks to undergo a suitable upheaval. A competent technology of the fifth-generation networks (5G) for efficiently supporting proximity-based applications is Device-to-Device (D2D) communication, underlaying cellular networks. Significant advances have been made till date, for allocating resources to D2D users in cellular networks, such that sharing of spectral resources between cellular and D2D users is carried out in a coordinated manner. In this paper, a sector-based radio resource allocation (SBRRA) algorithm for resource block allocation to D2D pairs has been proposed, where the number of resource blocks (RBs) is allocated to each D2D pair in an adaptive manner, based on the demanded application by each pair. Different applications demand a varying number of RBs, in accordance with their priority. This algorithm focusses on the use of sectored antennas at the base station, for a better performance and low complexity. Extensive simulations are carried out, considering real-time scenario, for ensuring satisfactory Quality of Service (QoS) and Quality of Experience (QoE) by the users. The efficiency of the proposed scheme is proved by comparing it with the RB allocation using Hidden Markov Model (HMM).

Resource Allocation for Underlay D2D Communication With Proportional Fairness

As an emerging paradigm, device-to-device (D2D) communication has the capability to complement and enhance the conventional cellular network by offering high spectral and energy efficiency. However, the problem of cochannel interference makes the resource allocation very complex and challenging in underlay D2D communication networks. This paper proposes a novel joint power control and resource scheduling scheme to enhance both the network throughput and the users’ fairness of the underlay D2D communication networks. Unlike other previous work in this area, our scheme aims at maximizing the sum of all users’ proportional fairness functions, while simultaneously taking into account factors such as fairness, signal-to-interference-plus-noise ratio requirements, and severe interference. The proposed scheme offers a practical solution because it works for lengthy time slots, a realistic scenario for the underlay D2D communication system. We also take into consideration the time-varying feature of user's channel condition in our proposed solution. Numerical results confirm that our proposed scheme not only dramatically improves the system throughput, but also boosts the system fairness while guaranteeing the Quality-of-Service levels of all D2D users and cellular users.

Full-Duplex Relaying for D2D Communication in Millimeter Wave-based 5G Networks

Device-to-device (D2D) communication, which can offload data from base stations by direct transmission between mobile devices, is a promising technology for fifth generation (5G) wireless networks. However, the limited battery capacity of mobile devices is a barrier to fully exploiting the benefits of D2D communication. Meanwhile, high data rate D2D communication is required to support the increasing traffic demand of emerging applications. In this paper, we study relay-assisted D2D communication in millimeter wave (mmWave)-based 5G networks to address these issues. Multiple D2D user pairs are assisted by full-duplex relays that are equipped with directional antennas. To design an efficient relay selection and power allocation scheme, we formulate a multi-objective combinatorial optimization problem, which balances the trade-off between total transmit power and system throughput. The problem is transformed into a weighted bipartite matching problem. We then propose a centralized relay selection and power allocation algorithm and prove that it can achieve a Pareto optimal solution in polynomial time. We further propose a distributed algorithm based on stable matching. Simulation results show that our proposed algorithms substantially reduce the total transmit power and improve the system throughput compared with two existing algorithms in the literature.

Enabling D2D Transmission Mode with Energy Harvesting and Information Transfer in Heterogeneous Networks

The concept of energy harvesting-assisted relay has been introduced to support the relaying transmission using Device-to-Device (D2D) communications for enhancing communication reliability. Motivated by the recent advance in Heterogeneous Network (HetNet) using relaying techniques, we consider the D2D communication provided by Energy Harvesting (EH) assisted relay where signal is forwarded from a Base Station (BS) to the conventional cellular user (non-D2D user) and D2D user. We first derive the outage probability by taking into account the SNR and power allocation parameters, and propose the transmission mode for D2D link as well as non-D2D link. After deriving the outage probability of the D2D-HetNet, we explore the effects of the network parameters on the outage probability and throughput.

Joint mode selection and power allocation for better traffic offloading in D2D communications

Device-to-Device (D2D) technology underlying the cellular network is an attractive solution for future generation network to increase cellular traffic offloading. When two devices are close enough, D2D communication allows a direct communication between them without the mediation of the cellular base station. However, since D2D communication shares the same uplink cellular network radio resource, D2D communication mode selection remains challenging to limit the mutual interference between D2D and cellular links. In this paper, a new D2D mode selection scheme based on a new criterion is proposed aiming at maximizing the cellular traffic offload while respecting the quality of service of cellular users. More precisely, we introduce a noise rise parameter which takes into account the cellular link distance, the D2D link distance, and user’s required throughput. The D2D links are admitted under the constraint of a certain noise rise threshold. To further enhance the achieved throughput of D2D users while respecting the overall interference level in the network, a new power control algorithm is also proposed. Simulation results show that our proposed mode selection scheme provides a tradeoff between traffic offloading and the overall radio capacity in the network. They also prove that the D2D communication mode is more attractive at the cell edge and when D2D users are close enough to each other. In addition, we show the effectiveness of our proposed power control scheme as compared to both static and Rate-Adaptive Water Filling power allocation schemes.

Performance maximization of network assisted mobile data offloading with opportunistic Device-to-Device communications

Mobile data traffic inside mobile operator’s infrastructure is increasing exponentially every year. This increasing demand forces mobile network operators (MNOs) to seek for alternative communication methods in order to relieve the traffic load in base stations, especially in highly populated and crowded environments. Network assisted data offload and Device-to-Device(D2D) communications are two prominent methods to help MNOs solve this problem. In this study, a data offload framework is developed that incorporates network assisted multiple attribute decision making (MADM) for best network selection and D2D communications for exploiting user proximity in crowded environments. The performance of the framework is evaluated with simulation results as well as analytic solutions and performance bounds. The simulation results indicate the superiority of incorporating network-based information besides user-based information in offloading decisions and demonstrates the significant benefits of D2D communications when the density of D2D users is properly adjusted. The simulation results depict that up to 168% and 200% increase in user satisfaction and throughput can be achieved under high network load scenarios at optimal D2D density.

Energy-efficient DRX scheduling for D2D communication in 5G networks

In recent years, intelligent devices such as smart phones and smart tablets are grown and developed rapidly. High-bandwidth media services such as live streaming, gaming and multi-user video conferencing are more and more popular. This results in spectrum resource depletion of the cellular network. To alleviate the problem, the 3rd Generation Partnership Project (3GPP) has proposed a new technology, called device-to-device (D2D) communications. However, D2D devices and direct link cellular users all share and access the same spectrum resource, thus degrading the network performance significantly due to the interference. In addition, due to the frequent communication nature of streaming and gaming services, the power consumption of devices is increasing dramatically. To mitigate above problems, this paper investigates how to improve the spectrum efficiency by well scheduling and allocating radio resource to more concurrent D2D and cellular users on the uplink direction and reduce unnecessary power consumption of devices via Discontinuous Reception (DRX) scheduling while guaranteeing users' Quality of Service (QoS). We propose an energy-efficient resource and sleep scheduling scheme. This scheme first establishes a conflict graph to maintain the transmission and interference relationship, and then tries to maximize concurrent D2D and mobile users by resource reuse. At the same time, the method also exploits DRX technology to further decrease possible interference and conserve devices’ power consumption through optimizing their sleep operation. Simulation results show that our scheme can achieve better performance on system throughput, network capacity, and power saving compared to the existing schemes.

Improving physical layer security and efficiency in D2D underlay communication

Device-to-device (D2D) communication is a core technology for expanding the next generation wireless cellular network. To deal with the security challenges and optimize the system communication quality, this paper investigates the security and efficiency problem of D2D underlay communication in a base station cell area with the presence of malicious eavesdroppers. Fairness and strategy space of both D2D User Equipment and Cellular User Equipment are taken into consideration under the control of Efficiency Functions. The optimization problems are formulated as a game model series of utility functions built on the unit price of jamming power and the amount of jamming service. We extracting the system into a price bargain game with a buyer and a seller both desiring maximum profits, a bargaining game approach is adopted to solve this problem by reaching an agreement of unit price. The step number of bargain process is also a restriction under consideration. For the non-steps model, an Evaluation Function and a Comprehensive Utility Function are demonstrated to analyze the bargain process. For steps-contained model, the step number of iteration is involved and an attenuation function is introduced to modify the bargaining game. The algorithms of two models are proposed to derive the equilibrium point for reaching an agreement. Finally, extensive simulations are illustrated for verifying proposed theory.

Socially Aware Caching Strategy in Device-to-Device Communication Networks

As a response to the challenge of data traffic explosion in wireless networks, content caching in device-to-device (D2D) communication networks has emerged as a promising solution. However, in practical deployment, D2D content caching has its own problems. In particular, not all of the user devices are willing to share the content with others due to numerous concerns, such as security, battery life, and social relationship. In this paper, we consider the factor of social relationship in the deployment of D2D content caching. First, we apply stochastic geometry theory to derive an analytical expression of downloading performance for the D2D caching network. Specifically, a social relationship model with respect to the physical distance is adopted in our analysis to obtain the average download delay performance using random and deterministic caching strategies. Second, to achieve a better performance in more practical and specific scenarios, we develop a socially aware distributed caching strategy based on a decentralized learning automaton, to optimize the cache placement operation in D2D networks. Different from the existing caching schemes, the proposed algorithm not only considers the file request probability and the closeness of devices as measured by their physical distance but also takes into account the social relationship between D2D users. Our simulation results show that the proposed algorithm can converge quickly and outperforms the random and deterministic caching strategies. With these results, our work sheds insights on the design of D2D caching in the practical deployment of 5G networks.

Energy-Efficient D2D Communications Underlaying NOMA-Based Networks With Energy Harvesting

This letter investigates the resource allocation problem in device-to-device (D2D) communications underlaying a nonorthogonal multiple access based cellular network, where both cellular users (CUs) and D2D users harvest energy from the hybrid access point in the downlink and transmit information in the uplink. We propose a low-complexity iterative algorithm to maximize the energy efficiency of the D2D pair while guaranteeing the quality of service of CUs. In each iteration, by analyzing the Karush–Kuhn–Tucker conditions, the globally optimal solution can be derived in the closed form despite the nonconvexity. Simulation results validate the superiority of the proposed scheme over the existing schemes.

Greedy Heuristic Resource Allocation Algorithm for Device-to-Device Aided Cellular Systems with System Level Simulations

Resource allocation in device-to-device (D2D) aided cellular systems, in which the proximity users are allowed to communicate directly with each other without relying on the intervention of base stations (BSs), is investigated in this paper. A new uplink resource allocation policy is proposed by exploiting the relationship between D2D-access probability and channel gain among variant devices, such as cellular user equipments (CUEs), D2D user equipments (DUEs) and BSs, etc., under the constraints of their minimum signal to interference-plus-noise ratio (SINR) requirements. Furthermore, the proposed resource-allocation problem can be formulated as the cost function of “maximizing the number of simultaneously activated D2D pairs subject to the SINR constraints at both CUEs and DUEs”. Numerical results relying on system-level simulations show that the proposed scheme is capable of substantially improving both the D2D-access probability and the network throughput without sacrificing the performance of conventional CUEs.

Asynchronous Device Detection for Cognitive Device-to-Device Communications

Dynamic spectrum sharing will facilitate the interference coordination in device-to-device (D2D) communications. In the absence of network level coordination, the timing synchronization among D2D users will be unavailable, leading to inaccurate channel state estimation and device detection, especially in time-varying fading environments. In this paper, we design an asynchronous device detection/discovery framework for cognitive-D2D applications, which acquires timing drifts and dynamical fading channels when directly detecting the existence of a proximity D2D device (e.g. or primary user). To model and analyze this, a new dynamical system model is established, where the unknown timing deviation follows a random process, while the fading channel is governed by a discrete state Markov chain. To cope with the mixed estimation and detection problem, a novel sequential estimation scheme is proposed, using the conceptions of statistic Bayesian inference and random finite set. By tracking the unknown states (i.e. varying time deviations and fading gains) and suppressing the link uncertainty, the proposed scheme can effectively enhance the detection performance. The general framework, as a complimentary to a network-aided case with the coordinated signaling, provides the foundation for development of flexible D2D communications along with proximity-based spectrum sharing.

Impact of connecting to the n th nearest node in dedicated device‐to‐device communications

Device-to-device (D2D) communication is a proximity-based data transmission technique where users communicate directly with each other, when bypassing evolved node base station. The most common assumption in the literature is that every D2D user connects to its nearest node. However, in many situations connection to the first nearest node for a D2D user is not possible due to the channel conditions or user's decline in joining in a D2D connection. The impact of connecting to the nth nearest node in a dedicated D2D enabled network is investigated. The coverage probability and average data rate of a typical D2D link in the network, where users connect to their nth nearest node are studied. The results show that considering the first nearest node is an ideal assumption and investigating the connection to the other farther nodes is of great importance.

Energy-Efficient Device-to-Device Communications for Green Smart Cities

To afford effective service of real-time monitoring and responses for smart cities, it is desired to provide ubiquitous network connections and high data rate services. However, the huge demands for ubiquitous high data rate wireless communications have caused a sharp increase in energy consumption and green house gas emission. In order to realize a sustainable smart city, it is critical to incorporate green communication technique into smart city developments. Device-to-device (D2D) communication has been recognized as one of the key technologies to improve data rate and reduce power consumption, which allows two physically nearby located user equipments to communicate directly with each other. In this paper, with the target of achieving green communications through D2D, we investigate the joint optimization of uplink subcarrier assignment (SA) and power allocation (PA) in D2D underlying cellular networks. Specifically, the problem formulation is to minimize the energy cost of all users in the system while guaranteeing the required data rate of both the D2D user equipments (DUEs) and cellular user equipments. Such an optimization problem is in general a mixed-integer nonlinear programming problem that is NP-hard. To make this problem tractable, we decompose it into the SA and PA subproblems. In particular, we design a heuristic algorithm to assign subcarrier by assuming that the transmit power is evenly allocated over all subcarriers. After that, we solve the PA subproblem by exploiting the difference between the concave function (D.C.) structure of the constraints and transform it into a convex optimization problem. Simulation results demonstrate the remarkable improvement in terms of power consumption by using our algorithms.

An intra–inter-cell device-to-device communication scheme to enhance 5G network throughput with delay modeling

As the number of mobile users is growing, so is the demand for more bandwidth. It becomes important that the required bandwidth and spectral resources do not scale with traffic in the next generation of wireless networks [i.e. fifth generation (5G)]. Device-to-device (D2D) communication underlaying cellular networks has been recognized as an essential technique in 5G networks. By applying definite principles and strategies, D2D communication not only increases the spectral and energy efficiency, but also enhances network throughput, network coverage and reduces delay. In this paper, we present an intra–inter-cell D2D communication scheme to enhance throughput of 5G networks. We study call setup delay of two developed communication scenarios and throughput gain comparing three systems. Firstly, we show the enhancements required in current cellular architectures to support inter-cell D2D communication. We develop protocols for two scenarios and demonstrate how architecture entities cooperate for the call setup between D2D users. We measure the overall call setup time for the developed protocols and derive a closed-form delay formula to estimate call setup time probability. Secondly, we perform simulations using a topology similar to that found in realistic urban environments to study throughput gains of the proposed intra–inter-cell D2D communication scheme. We compare three systems in terms of throughput: (1) pure cellular system (with cellular users only), (2) pure cellular system with intra-cell D2D users sharing the same cellular resource, and (3) pure cellular system with intra–inter-cell D2D users sharing the same cellular resource. Simulation results show that the proposed scheme substantially increases the network throughput and spectrum efficiency.