Device-to-Device Communication

Although Internet of Things (IoT) brings significant advantages over traditional communication technologies for smart grid and smart home applications, these implementations are still very rare. Relying on a comprehensive literature review, this paper aims to contribute towards narrowing the gap between the existing state-of-the-art smart home applications and the prospect of their integration into an IoT enabled environment. We propose a holistic framework which incorporates different components from IoT architectures/frameworks proposed in the literature, in order to efficiently integrate smart home objects in a cloud-centric IoT based solution. We identify a smart home management model for the proposed framework and the main tasks that should be performed at each level. We additionally discuss practical design challenges with emphasis on data processing, as well as smart home communication protocols and their interoperability. We believe that the holistic framework ascertained in this paper can be used as a solid base for the future developers of Internet of Things based smart home solutions.

In this paper, a novel non-orthogonal multiple access (NOMA) enhanced device-to-device (D2D) communication scheme is considered. Our objective is to maximize the system sum rate by optimizing subchannel and power allocation. We propose a novel solution that jointly assigns subchannels to D2D groups and allocates power to receivers in each D2D group. For the subchannel assignment, a novel algorithm based on the many-to-one two-sided matching theory is proposed for obtaining a suboptimal solution. Since the power allocation problem is non-convex, sequential convex programming is adopted to transform the original power allocation problem to a convex one. The power allocation vector is obtained by iteratively tightening the lower bound of the original power allocation problem until convergence. Numerical results illustrate that: i) the proposed joint subchannel and power allocation algorithm is an effective approach for obtaining near-optimal performance with acceptable complexity; and ii) the NOMA enhanced D2D communication scheme is capable of achieving promising gains in terms of network sum rate and number of accessed users, compared to traditional orthogonal multiple access (OMA) based D2D communication scheme.

This paper proposes linear precoder-decoder schemes
for a multiple-input multiple-output (MIMO) underlay deviceto-
device (D2D) communication system by considering two D2D
modes: two-way relaying based D2D and direct D2D. The D2D
communication takes place in the same spectrum as the cellular
communication. In the two-way relaying based D2D mode, the
relay uses physical layer network coding (PNC). The precoderdecoder
design is based on minimizing mean square errors (MSE),
which is useful to mitigate interference and to improve the performance
of both D2D and cellular communications. Distributed and
centralized algorithms are proposed considering bi-directional
communication in both D2D and cellular communications. In the
direct D2D mode, a similar MSE procedure is adopted, and exact
solutions are derived for precoder-decoder matrices. In the numerical
results, the optimality and convergence properties of the
proposed algorithms are analyzed. Additionally, the system performances
are investigated with interference thresholds and maximum
available power at the nodes. Two transmit mode selection
schemes are considered as dynamic and static selection schemes.
Finally, these selection schemes are investigated over an XY grid
by varying the position of a given device. The results reveal that the
PNC two-way relaying based D2D mode extends the coverage area
of D2D communication.

In this work, we consider Quality of Service (QoS)
guarantee for Device to Device (D2D) users co-existing with
a cellular system where the D2D communication links are
sharing radio spectrum resources with macrocell users in the
downlink. Despite the lofty advantages associated with D2D
communications, one major concern is the resulting interference
from the D2D users, which should not infringe on the service
quality requirements of the User Equipments (UEs). In this
work, we investigate the scenario in which D2D communications
operates simultaneously with downlink transmissions from the
Evolved Node B (eNB). Power control problem for the D2D
users is formulated in order to optimize the energy efficiency
of the eNB users as well as to ensure that QoS of D2D devices
and UEs does not fall below the acceptable target. The feasible
conditions of the power control problem are derived and then the
centralized and the distributed solutions are obtained. We further
suggest jointly designed dynamic power control and channel reallocation
algorithm that will guarantee the priority of the UEs.
Effectiveness of the proposed scheme is demonstrated through
extensive simulations.

In post-disaster scenarios, such as after floods, earthquakes, and in war zones, the cellular communication infrastructure may be destroyed or seriously disrupted. In such emergency scenarios, it becomes very important for first aid responders to communicate with other rescue teams in order to provide feedback to both the central office and the disaster survivors. To address this issue, rapidly deployable systems are required to re-establish connectivity and assist users and first responders in the region of incident. In this work, we describe the design, implementation, and evaluation of a rapidly deployable system for first response applications in post-disaster situations, named RDSP. The proposed system helps early rescue responders and victims by sharing their location information to remotely located servers by utilizing a novel routing scheme. This novel routing scheme consists of the Dynamic ID Assignment (DIA) algorithm and the Minimum Maximum Neighbor (MMN) algorithm. The DIA algorithm is used by relay devices to dynamically select their IDs on the basis of all the available IDs of networks. Whereas, the MMN algorithm is used by the client and relay devices to dynamically select their next neighbor relays for the transmission of messages. The RDSP contains three devices; the client device sends the victim's location information to the server, the relay device relays information between client and server device, the server device receives messages from the client device to alert the rescue team. We deployed and evaluated our system in the outdoor environment of the university campus. The experimental results show that the RDSP system reduces the message delivery delay and improves the message delivery ratio with lower communication overhead.

In this letter, we aim at solving the resource allocation problem for device-to-device (D2D) communications underlaying cellular networks. Particularly, multiple D2D pairs are allowed to reuse the same resource block (RB), and one D2D pair is allowed to use the spectrum of multiple RBs. Our objective is to maximize the system sum rate by satisfying the signal-to-interference-plus-noise ratio (SINR) constraints for both D2D and cellular user equipments (UEs). In order to solve this non-deterministic polynomial-time (NP) hard optimization problem, we propose a novel algorithm for obtaining a sub-optimal solution based on the many-to-many two-sided matching game with externalities. To characterize the properties of the proposed algorithm, we prove that it converges to the two-sided exchange stability within limited number of iterations. Additionally, simulation results show that the proposed algorithm can achieve the near-optimal system sum rate and significantly outperforms a one-to-one matching algorithm.

Device-to-device (D2D) communications play a significant role in increasing the capacity of cellular networks. D2D enables direct interaction between mobile users without traversing the base station (BS) and at the same time causes interference between D2D and cellular links which can affect the system performance. To ensure efficient and reliable D2D operations within a cellular network, the related quality of service (QoS) requirement needs to be met in the design of such a system involving both D2D and cellular users in a same network. In this study, we have investigated three different transmission schemes (cellular, D2D and cooperative D2D modes) by deriving the closed-form expressions of key QoS performance such as system reliability, achievable data rate, and energy efficiency for these three transmission schemes. Based on this establishment, we have also examined the effects of using different numbers of parallel relay branches and different number of relays within each branch on the network performance to reveal how effectively the cooperative D2D can enhance QoS in comparison with other transmission methods. The proposed approach can be optimised through adaptively selecting appropriate transmission schemes and, as a result, good trade-offs between system reliability and efficiency can also be achieved under various environmental conditions.

In this letter, we investigate the context-aware resource allocation for device-to-device communications accounting for the quality-of-service (QoS) requirements and priorities of different applications based on users' requests. We formulate a context-aware optimization problem and implement the matching theory to solve the problem. We propose a novel algorithm where the D2D user equipments and resource blocks (RBs) act as two opposite sets of players and interact with each other to obtain the optimal matching. We analytically prove that the algorithm converges to a two-sided exchange stability within limited number of swap operations. We also demonstrate that the proposed algorithm significantly outperforms the context-unaware resource allocation algorithm by around 62.2%.

Underlaying Device-to-Device (D2D) communications can increase the spectral efficiency of cellular networks when sharing part of the spectrum with cellular users. This requires radio resource allocation policies capable to limit and control the interference between D2D and cellular communications. Many of the proposed policies are centralized, and require the base station to decide which resources should be allocated to each D2D transmission. Centralized schemes can efficiently control interference levels, but their feasibility can be compromised by their complexity and signaling overhead. To address this constraint, this paper proposes DiRAT, a distributed radio resource allocation scheme for D2D communications underlaying cellular networks. With DiRAT, the D2D nodes locally select their radio resources from a pool created by the cellular network in order to control the interference generated to the primary cellular users. DiRAT includes a control mechanism to ensure that the user QoS requirements are satisfied. This study demonstrates that DiRAT can increase the network capacity while avoiding or limiting the degradation of the performance of the primary cellular users. DiRAT also significantly reduces the complexity and overhead compared to existing centralized and distributed schemes.

Device-to-Device (D2D) communications in Long Term Evolution (LTE) networks has been proposed as a promising concept as part of the LTE-Advanced (LTE-A) framework, whose aim is to improve user experiences and resource utilization, taking advantage of users' proximity to each other. In order to extend the current LTE-A system to support D2D communication, there is a need to work on enhancements on the network architecture level. In this paper, we survey the work proposed so far by researchers and propose a design that extends the Third Generation Partnership Project's (3GPP) definition of proximity based services, describing by this the necessary supporting elements.

5G networks mainly rely on infrastructure-centric cellular solutions to address data traffic and service demands. Continuously scaling infrastructure-centric cellular networks is not exempt from challenges, and beyond 5G networks should consider the active coexistence and coordination of infrastructure-centric and device-centric wireless networks. Device-centric wireless networks will build from D2D and MCNs. Device-centric wireless networks can push the limits of edge computing and networking to smart devices (including smartphones, vehicles, machines and robots), and exploit their mobile computing, storage and connectivity capabilities. These capabilities can be more efficiently utilized using demand-driven opportunistic networking that establishes the connections between devices and nodes not just based on their presence, but also on their capacity to support the requested demand and services. This article presents results from experimental field tests that demonstrate the cellular spectral efficiency gains that can be achieved from the combined use of device-centric wireless communications and demand-driven opportunistic networking. The field trials demonstrate that these technologies can improve the cellular spectral efficiency of conventional cellular communications by up to a factor of 4.7 and 12 in outdoor pedestrian and vehicular scenarios, respectively, under the evaluated scenarios and conditions. These gains have been obtained using 4G and IEEE 802.11 technologies. However, the potential of device-centric wireless networks is not constrained to any particular radio interface. The results presented in this article provide empirical evidences that further motivate progressing toward a new paradigm where edge networking capabilities are moved to smart mobile devices that become part of the network fabric, and can opportunistically and locally integrate network management functions to ensure that sufficient resources are placed where the demand arises.

Traditional single-hop cellular architectures fail to provide high and homogeneous quality of service levels throughout a cell area due to the strong signal attenuation
with the distance. In this context, multi-hop cellular networks that utilize mobile relays and device-to-device communications have been proposed to overcome the physical limitations of conventional cellular architectures. One of the key building blocks of multi-hop cellular networks is the multi-hop routing of information from the source to the destination. This paper investigates the performance and energy
signaling benefits of location-based multi-hop routing protocols. In particular, the paper demonstrates the benefits of a contextual optimization of this type of protocols in order to achieve a high end-to-end performance, while reducing the energy and signaling implementation cost.

—Device-to-Device (D2D) communication is a promising technology for LTE-A and future 5G cellular systems to provide proximity services especially for public safety and emergency scenarios. We investigate here the underlay mode where Cellular Users (CUEs) and D2Ds can transmit on the same sub-channels inside a cell thus interfering each other. This paper provides a model to evaluate the performance of D2D communications (sharing uplink resources with CUEs) and proposes a heuristic resource management scheme (combining a scheduler and a pairing strategy) to improve cell capacity while guaranteeing low outage probability. This scheme (denoted as PF 2-OUT) adopts a proportional fairness scheduler for both CUEs and D2Ds and modifies the allocations to D2Ds in case these are causing outage for CUEs. The goodness of this heuristic scheme has been validated showing how its performance is quite close to an optimized scheme in the literature.

We propose a multiple-input multiple-output
(MIMO) two-way relaying based underlay device-to-device (D2D)
communication system, in which relay uses physical layer network
coding (PNC). Both cellular and D2D communication take
place in the same spectrum. D2D communication is based on
PNC, and a joint transceiver design is required to facilitate PNC
mapping with MIMO channels. A joint precoder-decoder scheme
is also considered in the cellular communication to mitigate
interference, and improve the error performance. Mean square
errors at nodes are considered as the objective function, and
interference threshold limits and power constraints are also
used in joint precoder-decoder design problems. These turn out
to be non-convex optimization problems, and we propose two
algorithms in both phases of D2D and cellular communication.
Distributed optimization methods are used in the proposed
algorithms. We analyze the convergence of proposed algorithms,
and the system performances are investigated with different D2D
pair locations, interference constraint thresholds, and maximum
available power at nodes.

Up to date, Social Internet of Things (SIoT) and Fog Computing (FC) are two standing-alone technological paradigms under the realm of the Future Internet. SIoT relies on the self-establishment and self-management of inter-thing social relationships, in order to guarantee scalability to large IoT networks composed by both human and non-human agents. FC extends cloud capabilities to the access network, in order to allow resource-poor IoT devices to support delay-sensitive applications. Motivated by these complementary features of the SIoT and FC models, in this position paper, we propose their integration into the novel paradigm of the Social Fog of IoT (SoFT). Specifically, we provide the following three main contributions: (i) after formalizing the SoFT paradigm, we motivate its introduction through a number of exemplary use cases; (ii) we describe the architecture and the main resource-management functions of the resulting virtualized SoFT technological platform. It merges the physical things at the IoT layer and their virtual clones at the Fog layer into a cyber-physical overlay network of social clones; and, (iii) as a proof-of-concept, we present the simulated performance of a small-scale SoFT prototype, and compare its energy-vs.-delay performance with the corresponding one of a state-of-the-art virtualization-free technological platform, that relies only on Device-to-Device (D2D) inter-thing communication. THE INCOMING ERA OF THE SOCIAL THINGS U NDER the vision of the Future Internet, the IoT paradigm aims at connecting anything, to be accessed at anytime from anywhere by using the Internet as basic network infrastructure. According to this vision, future IoT networks will be composed by a large number (e.g., an order of magnitude greater than the current one) of IP-enabled and resource-limited wireless (possibly, mobile) devices, that will cooperate for attaining common goals and/or providing composite target services [1]. Hence, due to scalability and energy consumption issues, the centralized management of future large-scale IoT networks is not a viable option. In order to address this challenge, the Social Internet of Things (SIoT) paradigm is quickly gaining momentum [2]. It integrates Social Networking (SN) principles into the native IoT model, in order to enforce distributed self-cooperation and self-management in physical networks composed by human and non-human agents. Specifically, in the SIoT vision, human and non-human entities interact according to the Peer-to-Peer (P2P) model by autonomously building up inter-thing social relationships with respect to the rules enforced by their owners. In so doing, the resulting social network of " friend " things: (i) is capable to self-evolve without any human centralized supervision and/or control; and, (ii) similarly to human social networks (like Facebook), it may be self-navigated by the involved things, in order to perform information and/or service discovery [2]. Hence, the SIoT model effectively addresses the scalability issue of the native IoT paradigm by enforcing the convergence of social and communication networks. However, it also opens the question about the network technology and protocol layer to be selected, in order to implement the SIoT network in an energy-efficient way. For this purpose, the Social Device-to-Device (S-D2D) paradigm has been recently proposed [3]. It aims at implementing the inter-thing social network at the Physical layer of the underlying protocol stack by directly exploiting D2D short-range wireless (possibly, mobile) connections. The main pro of this paradigm is that it operates in an " ad hoc " (e.g., infrastructure-free) way. However, its main con is that it forces the involved things to exploit their native (limited) resources, in order to support the resulting social network [3]. Motivations and main idea of the paper In principle, the emerging paradigm of Fog Computing (FC) [4] exhibits the right features for coping with the aforementioned technological issues. Shortly, Fog Nodes (FNs) are small-size virtualized interconnected resource-equipped data centers. They are hosted by wireless access points at the edge of the network, in order to build up a three-tier Cloud-Fog-Thing hierarchical architecture. FC natively supports three main services, namely, thing virtualization, Thing-to-Fog task offloading and inter-Fog resource pooling. In principle, these services could be efficiently exploited, in order to implement the SIoT social network as an overlay network of thing clones, that entirely relies on the bandwidth/computing resources of the supporting FNs. So doing, the native resources of the physical things could be employed only for the synchronization with the corresponding Fog-hosted clones. This is, indeed, the main idea behind the proposed SoFT paradigm. According to these considerations, the remaining part of this paper is organized into two main parts. First, after shortly reviewing and comparing the basic features of the FC and Cloud Computing (CC) paradigms, we introduce the IoT-SIoT-Fog interplay induced by SN principles through an illustrative example. Afterwards, we pass to describe a number of actual use cases that motivate the SIoT-Fog integration and point out its added value. Second, as main technical contributions of the paper: (i) we formalize the main building blocks and functionalities of the proposed SoFT technological platform; and, then, (ii) we compare the energy-vs.-delay performance of a SoFT test-bed with the corresponding one of a state-of-the-art S-D2D test-bed. Finally, we conclude the paper by addressing some future research directions.

This work considers an analytical approach to evaluate the outage behavior of the device-to-device (D2D) communication, that is underlaid with cellular networks, as an enabling technology for Internet-of-Things (IoTs). In such an architecture, a group of IoT devices (IoTDs) communicate with an IoT gateway (GW) by reusing the resources of cellular users (CUEs) to enhance the spectral efficiency of the fifth-generation (5G) networks. Two interference management schemes are widely used in the literature for the sharing of D2D spectrum, namely the fixed-power margin (FPM) and the cooperative pairing (CooP) schemes. We investigate and compare the performance of the two schemes from the perspective of outage probability (OP). While satisfying the minimal performance of the system, the OP of an arbitrary pair (i.e., one IoTD and one CUE) under both schemes are derived in closed form in terms of hyper-geometric functions via the Mellin transform technique. Moreover, for the CooP scheme, an iterative alternating Dinkelbach (IAD) algorithm is proposed as an outage-optimal power allocation scheme. Analytical and simulation results reveal that the CooP scheme is the outage-optimum for the high SNR regime while the FPM scheme is the optimal one for the low SNR regime. Simulation results also show that the suitable power margin of the FPM scheme lies in between 2 and 3 dB. Under these two interference management schemes, the accuracy of the analytical results is verified through numerical simulation and it turns out that these are well matched.

Device-to-Device (D2D) communications can increase the spectral efficiency of future cellular networks when sharing part of the cellular spectrum. Radio resource allocation mechanisms are then necessary to control the interference that D2D and cellular transmissions can generate to each other. Most of the existing allocation schemes rely on the knowledge of the channel gain of all possible links between cellular and D2D nodes. This paper proposes to reduce the complexity cost and signalling overhead of the allocation process by using location information available at the network level. Using this information, the base station assigns radio resources to new D2D transmissions with the objective to control and limit the interference to the primary cellular users and existing D2D transmissions. The proposed radio resource allocation scheme continuously monitors that the user QoS requirements are satisfied. If it is not the case, it dynamically modifies the resource allocation to the interfering D2D transmissions. The proposed scheme achieves performance levels similar to that obtained with an optimized centralized allocation scheme, but with a significantly lower complexity cost and signaling overhead.

This paper presents a secure beamforming design
to prevent eavesdropping on multiple-input multiple-output
(MIMO) device-to-device (D2D) communication. The devices
communicate via a trusted relay which performs physical layer
network coding (PNC), and multiple eavesdroppers are trying
to intercept the device information. The beamforming design is
based on minimizing mean square error of the D2D communication
while employing signal-to-interference-plus-noise ratio
(SINR) threshold constraints to prevent possible eavesdropping.
The channel state information of the device-to-eavesdropper and
relay-to-eavesdropper channels is imperfect at the devices and
relay. The channel estimation errors are assumed with Gaussian
Markov uncertainty model. Consequently, robust optimization
problems are formulated considering the multiple access and
broadcasting stages of the D2D communication. These problems
are non-convex, and two algorithms are proposed to solve them.
In the numerical analysis, we discuss the convergence of the
proposed algorithms, impact of the number of eavesdroppers on
the performance, and the SINR distributions at eavesdroppers.

Abstract—Device-to-Device (D2D) communications, which al-
low direct communication among mobile devices, have been
proposed as an enabler of local services in 3GPP LTE-Advance
(LTE-A) cellular networks. This work investigates a hierarchical
LTE-A network framework consisting of multiple D2D operators
at the upper layer and a group of devices at the lower layer.
We propose a cooperative model that allows the operators to
improve their utility in terms of revenue by sharing their devices, and the devices to improve their payoff in terms of end-to-end throughput by collaboratively performing multi-path routing. To help understanding the interaction among operators and devices, we present a game-theoretic framework to model the cooperation behavior, and further, we propose a layered coalitional game (LCG) to address the decision making problems among them. Specifically, the cooperation of operators is modeled as an overlapping coalition formation game (CFG) in a partition form, in which operators should form a stable coalitional structure. Moreover, the cooperation of devices is modeled as a coalitional graphical game (CGG), in which devices establish links among each other to form a stable network structure for multi-path routing. We adopt the extended recursive core, and Nash network, as the stability concept for the proposed CFG and CGG, respectively. Numerical results demonstrate that the proposed LCG yields notable gains compared to both the non-cooperative case and a LCG variant and achieves good convergence speed.

Future Fifth Generation (5G) cellular systems will be characterized by ultra-dense areas, where users are gradually asking for new multimedia applications and hungry-bandwidth services. Therefore, a promising solution to boost and optimize this future wireless heterogeneous networks is represented by the Cloud Radio Access Network (C-RAN) with the joint use of Software Defined Networking (SDN) and Network Function Virtualization (NFV). In such a scenario, low power base stations and device-to-device communications (D2D), involved into traditional cellular network, represented a possible solution to offload the heavy traffic of macrocells, while guaranteeing user experience as well. Nevertheless, the high centralization and the limited-capacity backhauls makes it difficult to perform centralized control plane functions on a large network scale. To address this issue, we investigate the integration of two enabling technologies for C-RAN (i.e., SDN and NFV) in the current 5G heterogeneous wireless architecture in order to exploit properly proximity-based transmissions among devices. Then, in order to validate the applicability of our proposed architecture, we consider the case of D2D pair handover where we show that our solution is able to decrease the number of signaling messages needed to handoff the D2D pair from a source to a target base station and, at the same time, the time execution for the entire handover process.

Background: The wireless networks make it easier for users to connect with each other in the sense of the Internet of Things (IoT) system. The cloud and MANET convergence offer the services for cloud access within MANET of devices connected. Objective: The main objective of this research is to establish a cloud-based ad-hoc network architecture for the communication among smart devices under the 5G based Internet of Things architecture. Methods: The methods are applied to discover the smart devices using probability-based model, hidden Markov model and gradient-based model. Results: A cloud-MANET architecture of the smart device is constructed with cloud and MANET computation. The framework allows MANET users to access and deliver cloud services through their connected devices, where all simulations, error handling, and resource management are implemented. Conclusion: The MANET service has been launched as well as linked to the cloud by the mobile device. The author used the amazon cloud storage service. This research produces a conceptual model that is based on the ubiquitous method. It is shown the success in this area and expectations for future scope.

—The quantitative study of bibliographic material is referred to as bibliometric analysis. It presents a general overview of a research area where the published works can be classified based on countries, authors, publication years, keywords, and fields of research. This study aims to provide a bibliometric analysis of the research carried out in the field of device to device (D2D) communications in the past decade. The primary objective of this study is to find some of the most relevant and influential research papers in this field and define the newest trends as per the information available in the Web of Science database. During the course of this study, numerous classifications have been made based on different parameters such as the most productive and influential authors, and the most influential keywords and journals. The conclusions of this study are in line with the common wisdom, although certain deviations have been found.

Like in other multilingual contexts, code-switching has gained a foothold as a verbal mode of communication among Malaysian bilingual speakers. It occurs in both formal and informal contexts of communication. Empirical research has shown that the practice of alternating or mixing languages is not only common, but serves important communication strategies . This study examines the purposes of code-switching and how it is used to achieve the speakers' communicative intents in Bahasa Melayu (BM)-English bilingual conversations Data were collected through audio-recording of speakers' speech during organizational training sessions. The data were analyzed according to the situations that triggered the code-switching. The findings show that speakers employed code-switching to organize, enhance and enrich their speech.

With the current development of mobile communication services, people need personal communication of high speed, excellent service, high quality and low latencyhowever, limited spectrum resources become the most important factor to hamper improvement of cellular systems. As big amount of data traffic will cause greater local consumption of spectrum resources, future networks are required to have appropriate techniques to better support such forms of communication. D2D (Device-to-device) communication technology in a cellular network makes full use of spectrum resources underlaying, reduces the load of the base station, minimizes transmit power of the terminals and the base stations, thereby enhances the overall throughput of the networks. Due to the use of multiplexing D2D UE (User equipment) resources and spectrum, and the interference caused by the sharing of resources between adjacent cells, it has become a major factor affecting coexisting of cellular subscribers and D2D users. When D2D communication multiplexes the uplink resources, the base-stations are easily to be disturbed; when the downlink resources are multiplexed, the users of downlink are susceptible to interference. In order to build a high-efficient mobile network, we can meet the QoS requirements by controlling the power to suppress the interference between the base station and a terminal user.

In the emerging Fifth Generation (5G) systems mobile social networks will play an important role for disseminating information and multimedia contents. In such a scenario, short range transmissions and multicast services are considered as promising technologies in order to disseminate contents as fast as possible. This paper proposes a viral information diffusion approach for improving the information diffusion time among a large number of users. A novel expected information diffusion time is considered by taking into account system metrics on both network and social side. In particular, we defined a new metric named social network contact time which describes the social interaction time between a generic user and the social platform. We compared the proposed approach with conventional multicast scheme and social information diffusion approach based on distance. Results show that the proposed viral algorithm achieves considerable gains in term of information diffusion time and data rate per UE. In particular, the gain experienced by the users in term of content dissemination varies between the 14% and 48%.

Centralized social networking and media sharing portals provide inadequate support for preserving user privacy, content ownership and control. These problems can be mitigated through distributed Web services as demonstrated by a number of academic projects and industrial deployments. In general, these distributed services do not assign globally recognized, persistent names to the user devices. As a result, these solutions work in isolation and also cannot inter-operate with traditional Web technology. In this work, we present a decentralized and scalable platform, named pWeb, for distributing web services, like online social networks and media streaming, across end user devices. pWeb assigns Internet compatible names to end user devices, and provides name resolution and directory services. A user can retain ownership, and make the services and contents in his devices searchable and accessible at different privacy levels, e.g., friends, family and public. New services can be easily developed and deployed over the pWeb platform. We have developed a working prototype of the platform, and to demonstrate its effectiveness we have implemented a video streaming application for Android and Windows platforms. We also present performance results from our prototype implementation.

Device-to-Device (D2D) communications in cellular networks allow devices to communicate directly without going through the base station. The D2D underlaying cellular networks method is aimed to increase network energy efficiency, as specified for Long-Term Evolution Advanced (LTE-A) and 5G systems. In this paper, we examine the performance of both cooperative and non-cooperative communications modes based on the energy models we establish, within a mobile network where both user equipment (UE) to base station and D2D transmission links co-exist. We show that the source-destination distance is an important factor to decide whether to use the cooperative or non-cooperative transmission scheme in order to achieve better energy efficiency. We have also investigated the effects of choosing different numbers of relaying branches and relays in each branch on the performance of the network. This investigation leads to identifying optimal transmission schemes for maximizing energy efficiency under varying environmental conditions.

A vital technology in the next-generation cellular network is device-to-device (D2D) communication. Cellular user enabled with D2D communication provides high spectral efficiency and further increases the coverage area of the cell, especially for the end-cell users and blind spot areas. However, the implementation of D2D communication increases interference among the cellular and D2D users. In this paper, we proposed a radio resource allocation (RRA) algorithm to manage the interference using fractional frequency reuse (FFR) scheme and Hungarian algorithm. The proposed algorithm is divided into three parts. First, the FFR scheme allocates different frequency bands among the cell (inner and outer region) for both the cellular and the D2D users to reduce the interference. Second, the Hungarian weighted bipartite matching algorithm is used to allocate the resources to D2D users with the minimum total system interference, while maintaining the total system sum rate. The cellular users share the resources with more than one D2D pair. Lastly, the local search technique of swapping is used for further allocation to minimize the interference. We implemented two types of assignments, fair multiple assignment, and restricted multiple assignment. We compared our results with existing algorithms which verified that our proposed algorithm provides outstanding results in aspects like interference reduction and system sum rate. For restricted multiple assignment, 60-70% of the D2D users are allocated in average cases. This is an open access article under the CC BY-SA license.

Next generation cellular networks require high capacity, enhanced efficiency of energy and guaranteed quality of service (QoS). To reach these goals, device-to device (D2D) communication is a candidate technologie for future 5th Generation especially applications that require the reuse, the hop and the proximity gain. The present paper studies the energy efficient power control for the uplink of an OFDMA (orthogonal frequency-division multiple access) system composed of both regular cellular users and device-to-device (D2D) pairs. First, we analyze and model mathematically the prerequisites for D2D communications and classical cellular links in terms of minimum rate and maximum power requirement. Second, we use fractional programming in order to convert the initial problem into a concave one and we apply non-cooperative game theory in order to characterize the equilibrium. Then, we got the solution of the problem from the results of a water-filling power allocation. Moreover, we employ a distributed design for power allocation by means of three methods: a) Theory of fractional programming b) Closed form expression (the novelty is the use of Wright Omega function). c) Inverse water filling. Finally, simulations in both static and dynamic channel setting are realized to demontrate the enhanced gain in term of EE, SE (spectral efficiency) and time of execution of the iterative algorithm (Dinkelbach) than the closed form algorithms.

In the present day, 5G and beyond networks are being designed to support the future increase of data traffic and service demands. To support such increase, 5G networks will incorporate device-centric technologies with adequate mechanisms to scale and handle the growing and very large number of connected devices and traffic demands. Device-centric technologies include Device-to-Device (D2D) communications and Multi-hop Cellular Networks (MCNs). In device-centric wireless networks, devices will be able to connect to the network using two different connection modes: through a traditional cellular connection, or through a multi-hop cellular connection based on D2D communications with intermediate mobile devices. Device-centric technologies will therefore provide new connectivity options and significant opportunities to enhance the capacity and efficiency of 5G networks. However, new challenges will need to be addressed. One of them is the selection of the most adequate connection mode for each mobile device, because it will be key to improve the network performance and efficiency. This work proposes a context-aware mode selection scheme capable of identifying and selecting the most adequate connection mode for each device under a wide range of deployment and operating conditions. The proposed scheme estimates the benefits and risks of each connection mode based on context information available at the base station guaranteeing low signaling overhead. The obtained results show that the proposed mode selection scheme helps achieving throughput gains higher than 200% compared to traditional single-hop cellular communications for devices at the cell edge, and significant gains are also achieved compared to other mode selection schemes implemented and evaluated.