In the next generation cellular networks, device-to-device (D2D) communication is already considered a fundamental feature. A problem of multi-hop D2D networks is on how to define forwarding algorithms that achieve, at the same time, high delivery ratio and low network overhead. In this paper we aim to understand group meetings' properties by looking at their structure and regularity with the final goal of applying such knowledge in the design of a forwarding algorithm for D2D multi-hop networks. We introduce a forwarding protocol, namely GROUPS-NET, which is aware of social group meetings and their evolution over time. Our algorithm is parameter-calibration free and does not require any knowledge about the social network structure of the system. In particular, different from the state of the art algorithms, GROUPS-NET does not need communities detection, which is a complex and expensive task. We validate our algorithm using different publicly available data-sources. In real large scale scenarios, our algorithm achieves approximately the same delivery ratio of the state-of-art solution with up to 40 less network overhead.
In this work we explore group meetings to enable opportunistic routing in multihop D2D networks. Previous efforts explore D2D in several ways to provide different applications. @cite_10 propose a D2D protocol for public safety use cases, such as natural disasters with massive people concentration. The protocol includes device discovery through beacon broadcast using encryption keys to set up secure D2D communication links. Some works have shown the potential of using LTE-D2D to provide communication in infrastruture-less settings, such as in wearable networks @cite_1 and in the internet of things @cite_32 . Vehicular networks may also benefit from the adoption of D2D. @cite_22 , the authors propose a traffic flow model based on a dynamic resource allocation algorithm to deal with the problem of vehicular communication, sharing the same licensed frequency spectrum as D2D communications, in a single LTE cell. @cite_15 , the combination of LTE-D2D with MIMO is proposed to achieve low latency and better reliability in vehicular communication.
@cite_22 @cite_1 @cite_32 @cite_15 @cite_10
2515199124 2470257024 2560441157 1994347094
Device-to-Device (D2D) communication is an important feature for many kinds of mobile networks and in particular for the UMTS Long Term Evolution Advanced (LTE-A) cellular technology, where an underlay network can be created between User Equipments (UEs) without the support of an evolved Node B (eNB). The possibility to allow direct links between UEs plays an important role when the commercial LTE infrastructure is subject to failures or becomes unavailable after a disaster. Project ABSOLUTE, in scenarios for public safety, proposes raising in the sky a balloon with attached a 4G eNB (AeNB) to restore temporarily connectivity. In all cases in which UEs are out-of-coverage of the AeNB like in indoors, D2D becomes crucial. In this work, we propose to establish direct links employing a communication protocol that relies on the transmission of beacon frames sent in broadcast mode by selected UEs. We delve security aspects of this D2D protocol suitable for Public Safety (PS) users with out-of-coverage UEs based on sharing encryption keys. We pursue a network connectivity analysis of the secure protocol whereby we are able to show the existence of tradeoff points between connectivity and the increased overhead added by security for different values of the system parameters. In this paper the possibility of device-to-device (D2D) communications as an underlay of an LTE-A network is introduced. The D2D communication enables new service opportunities and reduces the eNB load for short range data intensive peer-to-peer communication. The cellular network may establish a new type of radio bearer dedicated for D2D communications and stay in control of the session setup and the radio resources without routing the user plane traffic. The paper addresses critical issues and functional blocks to enable D2D communication as an add-on functionality to the LTE SAE architecture. Unlike 3G spread spectrum cellular and OFDM WLAN techniques, LTE-A resource management is fast and operates in high time-frequency resolution. This could allow the use of non-allocated time-frequency resources, or even partial reuse of the allocated resources for D2D with eNB controlled power constraints. The feasibility and the range of D2D communication, and its impact to the power margins of cellular communications are studied by simulations in two example scenarios. The results demonstrate that by tolerating a modest increase in interference, D2D communication with practical range becomes feasible. By tolerating higher interference power the D2D range will increase. The Internet-of-Things (IoT) is promising to inter-connect physical objects and machines in an intelligent network. In this context, scalable and resilient Machine-to-Machine (M2M) communication protocols are required, and the new Device-to-Device (D2D) feature of the 4G system constitutes an appealing solution. Standardization activities are still in progress, but the rapid diffusion of both LTE and IoT devices and applications leads to development of experimental proposals aimed at merging these two technologies. We contribute in this work with a novel D2D communication protocol, which enables user equipments (UEs) to become the hubs of machine-type traffic by means of a suitable radio interface and upload data in the Web via the mobile network, thus opening to new cloud services. The protocol we propose is designed for multi-hop communications between D2D-enabled terminals and it is equipped with a light-weight security mechanism. It is meant to address the communication needs of UEs inside mobile network coverage, and those of UEs that suffer from scarce radio coverage. In terms of performance, we analyse connectivity and security in the multi-hop D2D network, taking into account the interference created by the transmission of beacon signals during the discovery phase of the wide network. We resort to stochastic geometry to model the end-to-end delay and communication resilience of the multi-hop D2D network. Device-to-device (D2D) communication is developed as a new paradigm to enhance network performance according to LTE and WiMAX advanced standards. The D2D communication may have dedicated spectrum (overlay) or shared spectrum (underlay). However, the allocated dedicated spectrum may not be effectively used in the overlay mode, while interference between the D2D users and cellular users cause impairments in the underlay mode. Can the resource allocation of a D2D system be optimized using the cognitive approach where the D2D users opportunistically access the underutilized radio spectrum? That is the focus of this paper. In this paper, the transmission rate of the D2D users is optimized while simultaneously satisfying five sets of constraints related to power, interference, and data rate, modeling D2D users as cognitive secondary users. Furthermore, a two-stage approach is considered to allocate the radio resources efficiently. A new adaptive subcarrier allocation scheme is designed first, and then, a novel power allocation scheme is developed utilizing geometric water-filling approach that provides optimal solution with low computation complexity for this nonlinear problem. Numerical results show that the proposed approach achieved significant performance enhancement than the existing schemes.