Multi-hop D2D Communications Research Articles

Cellular throughput optimization by game-based power adjustment and outband D2D communication

Device-to-device (D2D) communication is a promising option for the fifth generation (5G) mobile communication network to reduce energy consumption and increase throughput, which makes high throughput applications possible. Also, the improvement for energy and spectrum efficiency is critical in such applications. Without occupation of cellular spectrum resources, outband D2D communication is increasingly applied to high throughput applications to increase spectrum supply. However, energy efficiency is still a key issue that needs to be addressed. Moreover, the overall energy efficiency in cellular networks is severely limited by cell-edge devices. Therefore, in this paper, we apply multi-hop relay-aided outband D2D communication to cellular networks and propose a game-based power adjustment method to address throughput optimization problem. Firstly, we model an interaction relationship of power adjustment for each transmission path as a potential game, where a new utility function is designed for each player (i.e., the receiving end of a transmission path) to evaluate its action gain and to determine whether taking action or not. And then, it is proved that the utility function is an ordinal potential function (OPF) and the game of power adjustment is an ordinal potential game (OPG), which guarantees the convergence of game decision process. Moreover, we propose a new game decision algorithm, which has quicker convergence speed than the existing typical algorithm. In addition, we design a network-assisted distributed processing architecture for solving throughput optimization problem, including receiving mode selection, verification for relay selection, and transmission power adjustment, which can ease the burden of centralized processing. The experimental results show that our scheme is superior to the existing typical work in terms of throughput, delay, energy efficiency, continuous service ability, and convergence performance.

FINDER: A D2D based critical communications framework for disaster management in 5G

Public Safety Network communications technologies are at crossroads with next-generation networks to render better solutions and applications that can manage disaster efficiently. The fifth generation (5G) network is poised to have a guaranteed network connection, even in the case of partial dysfunction of cellular infrastructure due to disaster. In this paper, we have designed a framework named FINDER (Finding Isolated Nodes using D2D for Emergency Response) to locate-and-reconnect the isolated Mobile Nodes (MNs) in the disaster zone, so that the damage to assets and loss of life can be minimized. If the cellular link is non-existent over a disaster, the MNs under the impaired Base Station (BS) switch to the Device-to-Device (D2D) communications mode, and a critical D2D network is formed. The MNs in the disaster zone can reach an active network through a neighboring BS or a Wi-Fi access point. A multi-hop D2D communications based on hybrid Ant Colony Optimization is adopted to increase the energy efficiency of individual nodes and the overall network lifetime. Further, dynamic clustering curtails the numbers of active participating nodes, and data aggregation shrinks the number of packets in the network. Assistance from the Software-Defined Networking (SDN) controller at the BS benefits to have an intelligent and reliable connectivity to the MNs in the disaster zone. Our proposal FINDER is implemented using MATLAB, and the simulation results show that our framework extends the network lifetime with improved message delivery probability.

Hybrid Resource Allocation Scheme in Multi-hop Device-to-Device Communication for 5G Networks

The 5G communication paradigm provides architecture of coexistence of device-to-device (D2D) communication with the current cellular communication. Direct D2D communication offloads the major traffic by enabling the localized communication between the users with the advantage of close proximity by reusing cellular resource block. However, direct D2D communication suffers from limited proximity constraint. In order to increase the proximity, direct D2D communication can be extended to multi-hop D2D communication. By sharing the cellular resource with multi-hop D2D pairs, a significant interference may occur that further reduces the system throughput. In order to reduce the interference and to increase the throughput of the network, a hybrid resource allocation scheme for the multi-hop D2D communication is proposed in this work. This scheme is divided into two parts. In first part, an interference matrix is constructed by using graph-based technique. Particle swarm optimization (PSO) algorithm is applied in second part. The application of PSO not only reduces the interference at significant level but also harvests true potential gains of each resource block with improved overall throughput of the system. The extensive simulation results demonstrate the effectiveness of the proposed scheme with the random resource allocation scheme and graph-based resource allocation scheme. In addition, proposed scheme performs better in case of increased proximity and supports the minimum data rate compared to the orthogonal sharing-based resource allocation and cellular-oriented resource allocation schemes.

Energy- and Spectral-Efficient Adaptive Forwarding Strategy for Multi-Hop Device-to-Device Communications Overlaying Cellular Networks

Device-to-device (D2D) communications in cellular networks enable direct transmissions between user equipments (UEs). If the source UE (SUE) and the destination UE (DUE) are far away from each other or the channel between them is too weak for direct transmission, then multi-hop D2D communications, where relay UEs (RUEs) forward the SUE’s data packets to the DUE, can be used. In this paper, we propose an energy-efficient optimal adaptive forwarding strategy (OAFS) for multi-hop D2D communications. OAFS adaptively chooses between the best relay forwarding (BRF) mode and the cooperative relay beamforming (CRB) mode with the optimal number of RUEs, depending on which of them provides the higher energy efficiency (EE). To reduce the computational complexity for selecting the optimal RUEs for CRB mode, we propose a low-complexity sub-optimal adaptive forwarding strategy (SAFS) that selects between the BRF and the CRB with two RUEs by comparing their EE. Furthermore, a distributed forwarding mode selection approach is proposed to reduce the overhead for forwarding mode selection. The analytical and simulation results show that OAFS and SAFS exhibit significantly higher EE and spectral efficiency than BRF, CRB, direct D2D communications, and conventional cellular communications. SAFS is almost as energy- and spectral-efficient as OAFS.

Enabling Relay-Assisted D2D Communication for Cellular Networks: Algorithm and Protocols

Recently, there is a growing emphasis on device-to-device (D2D) communication, which is the key component of the Internet-of-Things ecosystem. D2D communication can operate on the licensed spectrum of cellular networks so as to improve the spectrum utilization. In this paper, we focus on the resource allocation problem for general multihop D2D communication and introduce users’ mobility into D2D communication underlaying cellular networks. Maximizing the total end-to-end data rate involves complex tasks, such as resource allocation and routing. By leveraging on the square tessellation technique, we propose an efficient square-division-based resource allocation scheme . Furthermore, we design a relay-assisted D2D communication protocol that addresses the challenges in enabling multihop D2D communications, namely, spectrum resource allocation, users’ mobility, and relay incentive. Through extensive simulations, we show that our relay-assisted D2D communication protocol improves the system throughput up to 55% and the user access rate up to four times in typical scenarios, as compared with state-of-the-art schemes.

A Power-Efficient and Social-Aware Relay Selection Method for Multi-Hop D2D Communications

Due to the short communication range, users are selected as relays to support multi-hop transmission for content sharing/downloading in D2D communications. In this letter, we first exploit social relationships from interacts and contributions, and then formulate an optimal relay selection problem to enhance cooperative multi-hop D2D communications. A Power-efficient and Social-aware Relay Selection (PSRS) algorithm is provided to solve the above problem. Simulation results show that our method has the lowest average power consumption compared to the existing methods.

Multi-Hop Cooperative Caching in Social IoT Using Matching Theory

It is envisioned that the Internet of Things (IoT) will provide promising opportunities to users, manufacturers, and service providers with a wide applicability in many fields. By employing social networking and device-to-device (D2D) communications in the IoT, the resulting social IoT can potentially provide services more effectively and efficiently. This paper focuses on content sharing among smart objects (devices) in the social IoT with D2D-based cooperative coded caching. Generally, complete content items or coded fragments are allowed to be delivered via multi-hop cooperative D2D communications. First, aiming at maximizing the overall success rate of multi-hop-based content sharing, the interplay between coding parameter optimization and wireless resource allocation is investigated by considering both physical and social characteristics. Moreover, a Roth and Vande Vate-based distributed scheme is proposed to solve the dynamic matching problem between the content helpers and content requesters. Numerical results demonstrate that the proposed scheme can achieve a good tradeoff between system performance and computational complexity.

Reachability Analysis of Multi-Hop D2D Communications at Disaster

Reachability Analysis of Multi-Hop D2D Communications at Disaster

Recent Advances on Cellular D2D Communications

Device-to-device (D2D) communications have attracted a great deal of attention fromresearchers in recent years.[...]

Multi-Hop Relay-Aided Underlay D2D Communications for Improving Cellular Coverage Quality

The future wireless networks need to improve spectrum and energy efficiency to satisfy the increasing demand for high data rate. Device-to device (D2D) communications have the ability to address this problem. This paper focuses on the underlay D2D relay function to improve cellular coverage quality. Although there are a few relevant works in this aspect, there is room for further improvement. For example, there is the constraint on the number of relays in a transmission path, which hardly meets the requirement of the cell-edge devices to fully improve their cellular throughput. Also, there is little energy constraint for underlay D2D relay selection, which is difficult to guarantee the service life of underlay D2D relaying links. Furthermore, without careful regulation of transmission power in terms of cellular coverage improvement, it is not conducive to the improvement of spectrum and energy efficiency in this aspect. Therefore, this paper proposes the improved scheme to deal with these problems, which can: 1) improve spectrum efficiency by using underlay spectrum sharing mode and alleviating its weakness (e.g., co-channel interference); 2) enhance comprehensive performance of underlay D2D relaying links by jointly considering multiple Quality-of-Service (QoS) metrics; 3) reduce overhead of relay selection by proposing a greedy algorithm based on a distributed local search; and 4) improve both energy efficiency and convergence time by designing a new power adjustment scheme based on the improved potential game decision algorithm. The theoretical analysis proves the existence of Nash equilibrium, and the simulation results show that the proposed game decision algorithm accelerates convergence and the proposed whole scheme improves cellular coverage quality.

Successful transmission probability of cognitive device-to-device communications underlaying cellular networks in the presence of hardware impairments

This paper studies the cognitive wireless powered device-to-device (D2D) communication underlaying a cellular network, where there are two types of communications, including peer-to-peer (P2P) communication and a multi-hop D2D communication, which are assumed to be affected by hardware impairments (HWIs). We investigate the one-hop P2P communication and the multi-hop D2D communication, where the relay node helps other two user equipments (UEs) exchange information with a two-time-slot physical-layer network coding scheme. To examine the system performance, we derive closed-form expressions for the average energy efficiency (EE) and spectral efficiency (SE). Besides that, we also obtain the successful transmission probability (STP) for the two considered communications, and the optimal values of time switching (TS) and power splitting (PS) ratios are achieved with the help of a genetic algorithm (GA)-based optimization algorithm in our proposed energy harvesting (EH) protocol so-called Hybrid TS-PS (HTPS) relaying protocol. Comparisons between amplify-and-forward (AF) and decode-and-forward (DF) transmission schemes are provided. The simulation results give evidence that the STP is significantly improved regardless of the presence of HWIs thanks to the derived parameters, i.e., average EE, SE, and the optimal TS and PS ratios.

Improving cellular downlink throughput by multi-hop relay-assisted outband D2D communications

One goal of the fifth-generation (5G) cellular network is to support much higher data capacity (e.g., 1000 times higher than today), where device-to-device (D2D) communication is one of the key enabling technologies. In this paper, we focus on the D2D relaying functionality to improve cellular downlink throughput. Based on the shortages of the latest relevant work, we propose a new scheme that leverages multi-hop relay-assisted outband D2D communications. First of all, by extending two-hop connection to three-hop connection, our scheme can cut down receiving bit error ratio (BER) of cell edge nodes far away from a cellular base station (BS), which improves cellular downlink throughput. Then, it balances network lifetime and throughput by the proposed ratio of income and expenditure (RIE) metric with respect to remaining energy and throughput. Moreover, it reduces the computational overhead of searching relay and also ensures that the optimal relay is selected by the adjustment of searching scope. Compared with the most relevant work, our scheme outperforms it in terms of throughput, delay, and network lifetime.

Coverage and Rate Analysis for Facilitating Machine-to-Machine Communication in LTE-A Networks Using Device-to-Device Communication

With a wide range of applications, Machine-to-Machine (M2M) communication has become an emerging technology for connecting generic machines to the Internet. To ensure ubiquity in connections across all machines, it is necessary to have a standard infrastructure, such as 3GPP LTE-A network infrastructure, that facilitates such type of communications. However, owing to the huge scale of ?> machines to be deployed in near future and the nature of data transactions, ensuring ubiquitous connections among all the machines will be difficult. Solutions that not only maintain connectivity but also route machine data in a cost effective manner are the need of the hour. In this context, it has been suggested that Device-to-Device (D2D) communication can play a very important role in expanding network coverage and routing the data between source-destination machine pairs. In this paper, we conduct a feasibility study to highlight the impact of multi-hop D2D communication in increasing the network coverage and average rate of a Machine Type Communication (MTC) device. We present a stochastic geometry based framework to analyze the coverage probability and average data rate of a three-hop M2M network deployed along with User Equipments (UEs) and conduct extensive simulations to study the system performance. Our simulation results show that the three-hop M2M network formed from out-of-range MTC devices and UEs can significantly improve the coverage and average rate of the entire network. Due to the mobility of users in the network, design of robust routing mechanisms in such a time evolving network becomes difficult. Hence, we suggest the use of space-time graph built from the predicted user locations to design a cost efficient multi-hop D2D topology that enables routing of MTC data to its destination.

Radio resource management scheme and outage analysis for network-assisted multi-hop D2D communications

In a cellular network it's very difficult to make spectrum resource more efficiently. Device-to-Device (D2D) technology enables new service opportunities, and provides high throughput and reliable communication while reducing the base station load. For better total performance, short-range D2D links and cellular links share the same radio resource and the management of interference becomes a crucial task. Here we argue that single-hop D2D technology can be used to further improve cellular networks performance if the key D2D radio resource management algorithms are suitably extended to support multi-hop D2D communications. Aiming to establish a new paradigm for the analysis and design of multi-hop D2D communications, We propose a radio resource allocation for multi-hop D2D routes based on interference avoidance approach in LTE-A networks. On top of that, we investigate the outage probability of D2D communication. We first introduce a new definition of outage probability by considering the maximum distance to be allowable for single-hop transmission. Then we study and analyze the outage performance of a multi-hop D2D route. We derive the general closed form expression of outage probability of the multi-hop D2D routes. The results demonstrate that the D2D radio, sharing the same resources as the cellular network, provide higher capacity compared to pure cellular communication where all the data is transmitted through the base station. They also demonstrate that the new method of calculation of D2D multi hop outage probability has better performance than classical method defined in the literature.

On the Performance of Device-to-Device Communications With Delay Constraint

Device-to-device (D2D) communication permits direct communication between devices, thereby it provides performance gain for traditional cellular networks. In this paper, we investigate how to improve the performance of D2D communication while satisfying the delay constraint for practical applications. Closed-form expressions are derived for trade-offs among system performance, such as successful transmission probability, transmission capacity, delay constraint, and energy consumption. In addition, two schemes are proposed to improve the performance for D2D communication under a given delay constraint. First, an optimal transmission scheme is proposed in which the transmission of user equipment (UE) can be scheduled adaptively to have the best successful transmission probability, whereas the D2D link satisfies the delay constraint. Second, a delay assignment scheme is proposed in which delay is adaptively assigned for each hop to achieve the maximum capacity when the network employs multihop D2D communication. Simulation results show that the adaptive transmission scheme improves the successful transmission probability (e.g., increased by 13 times when the source density is $\text{10}^{-4}$ ) compared with the fixed-probability transmission scheme, although it can satisfy the delay constraints for different applications. Furthermore, compared with the fixed delay assignment scheme, the network capacity can be improved up to 50% by the proposed scheme with proper delay assignment for each hop.

Social-Community-Aware Long-Range Link Establishment for Multihop D2D Communication Networks

With the ever-increasing demands for local area services of popular content sharing, device-to-device (D2D) communication is conceived to be a key component of the next-generation cellular networks. D2D communications consume low energy and provide high capacity via proximity range transmissions, where multihop transmissions are needed for real-time content sharing. Aiming to solve the challenging problem for multihop D2D communication networks, existing studies only consider communication domain information to create long-range links (LLs) to reduce multihop transmission delay. In contrast, in this paper, we propose a novel social-community-aware LLs establishment strategy, which exploits the interplay between social network features and communication domain constraints. We first formulate the LLs establishment strategy as a cost-minimization problem and then propose an efficient greedy algorithm to solve the formulated problem, which is suitable for scenarios of both single-sink and distributed content sharing. To decrease the computational complexity, we model the optimization problem as a coalition graph game and propose a dynamic algorithm based on local best response and a near-optimal algorithm based on switching operation, which both run in the distributed approach. Numerical results demonstrate that our proposed solution decreases the average path length significantly with low computational complexity compared with other state-of-the-art schemes.

Iunius: A Cross-Layer Peer-to-Peer System With Device-to-Device Communications

Device-to-device (D2D) communications utilizing licensed spectrum have been considered a promising technology to improve cellular network spectral efficiency and offload local traffic from cellular base stations (BSs). In this paper, we develop Iunius: a peer-to-peer (P2P) system based on harvesting data in a community utilizing multi-hop D2D communications. The Iunius system optimizes D2D communications for P2P local file sharing, improves user experience, and offloads traffic from the BSs. The Iunius system features cross-layer integration of: 1) a wireless P2P protocol based on the BitTorrent protocol in the application layer; 2) a simple centralized routing mechanism for multi-hop D2D communications; 3) an interference cancellation technique for conventional cellular (CC) uplink communications; and 4) a radio resource management scheme to mitigate the interference between CC and D2D communications that share the cellular uplink radio resources while maximizing the throughput of D2D communications. Simulation results show that the proposed Iunius system can increase the cellular spectral efficiency, reduce the traffic load of BSs, and improve the data rate and energy saving for mobile users.

Energy Efficiency and Spectrum Efficiency of Multihop Device-to-Device Communications Underlaying Cellular Networks

Device-to-device (D2D) communications are usually considered to be two user equipment units (UEs) communicating directly without going through the central base station (BS). In fact, they can be further broadened to multihop D2D communications in which a UE may help other UEs communicate with each other or assist other UEs to communicate with the BS. In this paper, the authors investigate a scenario of multihop D2D communications where one UE may help other two UEs to exchange information with a two-time-slot physical-layer network coding scheme. The authors analyze the average energy efficiency and spectral efficiency of multihop D2D communications under Rayleigh fading channels and get close analytical approximations based on Taylor series expansion. Comparisons with direct D2D communications and traditional cellular communications through BS are provided. The optimal UE transmission powers of these three different modes to maximize the energy efficiency are also derived.

An Overview of Device-to-Device Communications Technology Components in METIS

As the standardization of network-assisted device-to-device (D2D) communications by the Third Generation Partnership Project progresses, the research community has started to explore the technology potential of new advanced features that will largely impact the performance of 5G networks. For 5G, D2D is becoming an integrative term of emerging technologies that take an advantage of the proximity of communicating entities in licensed and unlicensed spectra. The European 5G research project Mobile and Wireless Communication Enablers for the 2020 Information Society (METIS) has identified advanced D2D as a key enabler for a variety of 5G services, including cellular coverage extension, social proximity, and communicating vehicles. In this paper, we review the METIS D2D technology components in three key areas of proximal communications—network-assisted multi-hop, full-duplex, and multi-antenna D2D communications—and argue that the advantages of properly combining cellular and ad hoc technologies help to meet the challenges of the information society beyond 2020.

Outage Probability for Multi-Hop D2D Communications With Shortest Path Routing

In this letter, we provide a tractable theoretical framework for analysing the performance of device-to-device (D2D) communications in the presence of co-channel interference from other D2D and conventional cellular (CC) transmissions. In particular, we consider multi-hop D2D using the shortest-path-routing (SPR) algorithm in both the uplink (UL) and the downlink (DL) channels. Closed-form expressions for the number of hops and the outage probability are presented. Our analytical and numerical results both show that while the D2D links are reasonably reliable (outage probability <; 5%), they can severely degrade the performance of CC transmissions (outage probability > 25%). Accordingly, we exploit and provide insights into the trade-off between D2D and CC transmission reliability.