Sharif Digital Repository

To support the increasing data traffic demand in wireless communications networks, a multi-tier architecture that consists of multiple small cells is adopted in traditional (macro) cellular networks. Nevertheless, due to the expansion of various wireless devices and services, there is still a need to increase the network capacity in new generation networks such as 5G. Hence, the integration of Device-to-Device (D2D) communication as a promising technology with heterogeneous networks has been proposed. This integration not only increases network capacity but also improves spectral efficiency and alleviates the traffic load of base stations. However, the co/cross-tier interferences between D2D... 

In this paper, we report our evaluation of the strength of random number generator and RSA key-pair generator of some commercially available constrained hardware modules, i.e., tokens and smart cards. That was motivated after recent related attacks to RSA public keys, which are generated by constrained network devices and smart cards, and turned out to be insecure due to low-quality randomness. Those attacks are mostly computing pair-wise GCD between the moduli in public keys, and resulted in breaking several thousands of these keys. Our results show that most of the tested hardware modules behave well. However, some have abnormal or weak random generators which seem to be unsuitable for... 

Improvement of energy efficiency in Software Defined Networking (SDN) is a challenging problem. In order to achieve higher energy efficiency, the routing and scheduling in software defined networks should be planned robustly based on the topological specifications of the SDN. The topological specifications of the SDN depends on the size of the network graph which changes rapidly as the virtualized network devices in the network turned on and off by the controller. Therefore, modelling the SDN graph is an important issue in designing a reliability aware energy efficient SDN. In this paper we propose a new algorithm for reliable energy efficient traffic engineering in SDN. In the proposed... 

In this paper, we introduce novel mechanisms for measuring and evaluating the performance of a network and its devices, configured especially for Voice over IP (VoIP). We study the effects of different configurations on final voice quality by enabling or changing the related equipment features. In our study we quantify quality changes based on different router configurations and discuss precisely to what extent and how much this quality is improved versus features or special configurations of network devices. These results can be used for two purposes: compare and benchmark different routers in order to know which one is proper for a typical VoIP network, and select the best configurations....