Sharif Digital Repository

As the achievability of higher rates in wireless channels is a challenging issue, analysis of efficient and practical power allocation policies for different wireless channels such as Multiple Access Channel(MAC), Relay Channel, Interference Channel is one of the research interests for many years. Convex optimization or generally optimization is one of the important problems in communication science. Optimum power allocations are also a discussing argument in information theory which in these problems the objective function is usually the transmitting rate and the problem's constraints are power constraints which must be satisfied. In this thesis, first we investigate convex optimization... 

According to the wide range of applications and numerous implementations, wireless networks are considered as a prominent means of providing data services, and have attracted the attention of many researches in recent years. Performance enhancement of these networks can be very beneficial to industry and wireless data service providers. Manipulation of relays, have been always considered as a proper means for improvement of network performance measures throughput and outage probability.In order to design relay networks efficiently, one should address two following problems: 1- determining transmission policy, and 2- relay location. In this research work, having in mind the optimality of... 

Matrix completion is an emerging field that is proposed after new and attractive field of compressed sensing. Matrix completion is concerned with the problem of recovering an unknown matrix from a small fraction of its entries. In general, accurate recovery of a matrix from a small number of entries is impossible, but the knowledge that the unknown matrix has low rank radically changes this premise, making the search for solutions meaningful. Matrix completion problem comes up in great number of applications,including collaborative filtering, machine learning, control, image processing, sensor networks, system identification and communications (spectrum sensing and network coding). In this... 

As latency reduction is a key objective of upcoming mobile standards such as 5G, control applications over such channels have become of high interest in recent years. In this thesis, we will consider the problem of control over fading channels modeled by finite-state Markov chains. We will combine communication and control theory aspects of the problem and study stability of linear discrete-time plants which communicate with the controller over such fading channels. Two different scenarios are assumed for channel state information availability at encoder side, and the sufficient condition of almost sure asymptotic stabilizability is derived for each scenario. We will then examine the... 

Against the computational security, which guarantees the confidentiality via computational complexity, information theoretic secrecy considers the full information secrecy. The full information secrecy is the case when the mutual information rate between received signal of eavesdropper and the confidential message converges to zero. In this thesis we consider the fundamental limits of transmission security. For this, we first consider basic models with one transmitter, one receiver and one eavesdropper and after investigating previous works, models and performance criteria, we state our owns models and criterion. Since the full knowledge of CSI is an optimistic assumption, we consider the...