Sharif Digital Repository

Intercellular coordination is a technique to mitigate intercell interference. In this technique, base stations of different cells coordinate with each other to send data for all users, so each user is serviced by several base stations. Nowadays, with the increasing use of wireless networks, the design of these networks is very important. Most problems in the design of wireless networks are due to limitations such as: interference, the lack of bandwidth and changes of channel. Using all channels in each cell is a suggested method to use the bandwidths efficiently; however it increases intercell interferences hence a method to control interference is needed. Coping with interference can be... 

There is an increasing demand from mobile users for higher bandwidth, lower latency, longer battery life and better quality of service. It is expected that the next generation of mobile networks standards which is called 5G meets most of these demands. It is expected that the enhanced features of the mobile networks can be achieved within the limited bandwidth which is offered by the regulators and therefore, one of the key challenges in the development of these new technologies would be the issue of resource allocation. Efficient allocation of frequency, time and power to different users is an important issue and therefore, one of the important areas of development in these standards has... 

In this thesis, we consider multiple-antenna K-user interference channels with backhaul collaboration in one side (among the transmitters or among the receivers) and investigate the trade-off between the rate in the channel versus the communication load in the backhaul. In this investigation, we focus on a first order approximation result, where the rate of the wireless channel is measured by the degrees of freedom (DoF) per user, and the load of the backhaul is measured by the entropy of backhaul messages per user normalized by log of transmit power, at high power regimes. This trade-off is fully characterized for the case of even values of K, and approximately characterized for the case of... 

In this thesis, interference management techniques, including frequency, power, and space resource managements in two tier femtocell networks are investigated with the aim of increasing the throughput and decreasing the outage probability for both femto and macro users. Previous studies indicate that Fractional Frequency Reuse (FFR) is an effective interference management scheme for OFDMA based two tier femtocell networks. In this thesis, based on FFR scheme, in the first part, a comprehensive method to model the cross tier interference in both uplink and downlink, and for closed access as well as open access femtocells is introduced and by using this model, a static frequency and power... 

To support the increasing data traffic demand in cellular networks, the idea of enabling device-to-device (D2D) communication emerged. Using D2D communication in cellular networks brings significant performance gain in terms of data offload, improved spectral efficiency, increasing network capacity and coverage extension. Along with all these advantages, new challenges emerge in the areas of network design, user admission and interference management. In this study, the focus is on managing the interferences between underlay D2D communications in cellular networks. Hence, the resource allocation approach is used to manage these interferences. In this approach, the goal is allocate an... 

Future mobile networks are expected to not only bring more wireless connectivity and higher data rates, but also to support several high-quality services including low-latency, ultra-reliable, and energy-efficient communications. To support these needs, intelligent reflecting surfaces (IRSs) have recently attracted a lot of attention due to their potential for reconfiguring the wireless channel and are considered as a promising solution for future mobile generations. On the other hand, the exponential growth of network traffic, and its non-uniform distribution result in network congestion during peak-traffic times and network underutilization during off-peak times. Caching or content...