A Novel Device-to-Device Discovery Scheme for Underlay Cellular Networks

Tremendous growing demand for high data rate services such as video, gaming and social networking in wireless cellular systems, attracted researchers' attention to focus on developing proximity services. In this regard, device-to-device (D2D) communications as a promising technology for future cellular systems, plays crucial rule. The key factor in D2D communication is providing efficient peer discovery mechanisms in ultra dense networks. In this paper, we propose a centralized D2D discovery scheme by employing a signaling algorithm to exchange D2D discovery messages between network entities. In this system, potential D2D pairs share uplink cellular users' resources with collision detection, to initiate a D2D links. Stochastic geometry is used to analyze system performance in terms of success probability of the transmitted signal and minimum required time slots for the proposed discovery scheme. Extensive simulations are used to evaluate the proposed system performance.Comment: Accepted for publication in 25'th Iranian Conference on Electrical Engineering (ICEE2017

Probabilistic Analysis of Operating Modes in Cache-Enabled Full-Duplex Device-to-Device Communications

RÉSUMÉ Les communications Device-to-Device (D2D) activées par le cache, reconnues comme l’un des principaux catalyseurs du réseau cellulaire de cinquième génération (5G), sont une solution prometteuse pour alléger la lourde charge pesant sur les réseaux centraux mobiles et les liaisons terrestres. La mise en cache, cependant, impose un nouvel indice de performance clé (KPI) à l’utilisateur réseau qui est la probabilité de satisfaction de l’utilisateur. En d’autres termes, quelle est la probabilité que l’utilisateur obtienne les informations nécessaires du réseau? Cette probabilité dépend du type de transmission (c’est-à-dire semi-duplex ou duplex intégral) et de nombreux éléments liés au système de mise en cache, tels que la manière dont les informations sont mises en cache ou la popularité des informations mises en cache. L’analyse de ces éléments donne lieu à différents modes de fonctionnement. Afin d’évaluer le nouveau KPI, les probabilités de chaque mode de fonctionnement doivent être extraites des conditions de transmission et de mise en cache. Cette thèse présente une analyse approfondie de ces probabilités mettant en pertinence la relation entre les politiques de mise en cache, la popularité des contenus et les types de transmission. De telles relations permettent une évaluation fluide de la satisfaction des utilisateurs dans différentes conditions.----------ABSTRACT Cache-enabled D2D (Device-to-Device) communications, recognized as one of the key enablers of the fifth generation (5G) cellular network, is a promising solution to alleviate the great burden on mobile core networks and backhaul links. Caching, however, imposes a new networking user Key Performance Index (KPI) that is the probability of user satisfaction. In other words, how likely is the user to get the needed information from the network? Such probability depends on the type of transmission, (i.e. half duplex or full duplex) and on many elements related to the caching system, such as the way the information is cached, or the popularity of the cached information. The analysis of those elements gives rise to different modes of operation. In order to evaluate the new KPI, the probabilities of each mode of operation must be extracted from the transmission and caching conditions. This thesis presents a thorough analysis of those probabilities putting in relevance the relationship between caching policies, content popularity and transmission types. Such relationships allow the smooth evaluation of user satisfaction under different conditions

Delay Analysis in Full-Duplex Heterogeneous Cellular Networks

Heterogeneous networks (HetNets) as a combination of macro cells and small cells are used to increase the cellular network's capacity, and present a perfect solution for high-speed communications. Increasing area spectrum efficiency and capacity of HetNets largely depends on the high speed of backhaul links. One effective way which is currently utilized in HetNets is the use of full-duplex (FD) technology that potentially doubles the spectral efficiency without the need for additional spectrum. On the other hand, one of the most critical network design requirements is delay, which is a key representation of the quality of service (QoS) in modern cellular networks. In this paper, by utilizing tools from the stochastic geometry, we analyze the local delay for downlink (DL) channel, which is typically defined as the mean number of required time slots for a successful communication. Given imperfect self-interference (SI) cancellation in practical FD communications, we utilize duplex mode (half-duplex (HD) or FD) for each user based on the distance from its serving base station (BS). Further, we aim to investigate the energy efficiency (EE) for both duplexing modes, i.e., HD and FD, by considering local delay. We conduct extensive simulations to validate system performance in terms of local delay versus different system key parameters.Comment: This paper has been accepted for publication in the IEEE Transactions on Vehicular Technolog