Sharif Digital Repository

Data gathering is a common but critical operation in many applications of wireless sensor networks. Innovative techniques that improve energy efficiency to prolong the network lifetime are highly required. Clustering is an effective topology control approach in wireless sensor networks, which can increase scalability and lifetime. These networks require robust wireless communication protocols that are energy efficient and provide low latency. In this paper, we develop and analyze an efficient cooperative transmission protocol with robust clustering (RCCT) for sensor networks that considers a fault-tolerant and energy-efficient distributed clustering with minimum overhead. RCCT distributes... 

We introduce a model of a non-Gaussian quantum channel that stems from the composition of two physically relevant processes occurring in open quantum systems, namely, amplitude damping and dephasing. For it we find input states approaching zero output entropy while respecting the input energy constraint. These states fully exploit the infinite dimensionality of the Hilbert space. Upon truncation of the latter, the minimum output entropy remains finite, and optimal input states for such a case are conjectured thanks to numerical evidence  

In this paper, we consider the problem of scheduling the power of a sensor when transmitting over an unknown Gilbert-Elliott (GE) channel for remote state estimation. The sensor supports two power modes, namely low power and high power, which are to be selected for transmission over the channel in order to minimize a cost on the error covariance, while satisfying the energy constraints. The remote estimator provides error-free acknowledgement/negative-acknowledgement (ACK/NACK) messages to the sensor only when low power is utilized. We first consider the Partially Observable Markov Decision Process (POMDP) problem for the case of known GE channels and derive conditions for optimality of a... 

With the emergence of various battery operated technologies in different computing domains and the challenge of heating in such technologies, the issue of energy dissipation has become more critical than ever before. In such systems, energy constraints in one hand, and heat generation, on the other hand, necessitates the employment of energy efficient technologies in the fabrication of digital circuits. One possible solution for mitigating the energy dissipation in digital circuits is the use of adiabatic families in the process of designing computing devices. Adiabatic circuits are designed mainly based on the principles of thermodynamics and provide a paradigm shift in the design of... 

In this paper, we evaluate the effect of energy constraints on the performance of a simple network comprised of wireless nodes with energy harvesting capability. In this scenario, wireless nodes contend with each other based on slotted Aloha protocol in order to transmit a packet. Packet transmission occurs provided that enough energy exists in the energy buffer. We propose an analytical model based on a closed queueing network (QN) to include details of data and energy buffers as well as random access MAC protocol. We show how energy limitation affects the MAC design parameters, e.g., contention window size, in order to optimize the performance of the network. Moreover, we evaluate the... 

Data aggregation is an effective technique which is introduced to conserve energy by reducing packet transmissions in wireless sensor networks (WSNs). In addition, it is possible to consume less energy by using the spatial correlation and redundancy of data in dense networks to form clusters of nodes sensing similar values and, in turn, transmit one data packet per cluster. In this paper, we propose a Data-Aware Clustering and Aggregation scheme (DACA) to manage the energy constraint in a query-driven WSN. The DACA selects cluster head nodes by forming a new factor as a function of three parameters including the residual energy, the data value, and the number of neighbors at each node.... 

Two important objectives in wireless sensor networks are reliability and reducing energy consumption. Hence, overcoming energy constraints and utilizing error control schemes such as Automatic Repeat Request (ARQ) and Forward Error Correction (FEC) are necessary to improve the energy efficiency and reliability. However, these two concerns are at odds, so there is a trade-off between them. Considering this point, the impact of various error control schemes on these objectives and the trade-off between them has been considered in Bluetooth networks recently. However, all these works consider ideal assumptions (e.g., perfect error detection) only. This work evaluates the energy-efficiency of... 

Energy constraint is the most critical problem in wireless sensor networks (WSNs). To address this issue, clustering has been introduced as an efficient way for routing. However, the available clustering algorithms do not efficiently consider the geographical information of nodes in cluster-head election. This leads to uneven distribution of cluster-heads and unbalanced cluster sizes that brings about uneven energy dissipation in clusters. In this paper, an Efficient Distributed Cluster-head Election technique for Load balancing (EDCEL) is proposed. The main criterion of the algorithm, dispersal of cluster-heads, is achieved by increasing the Euclidian distance between cluster-heads.... 

In this paper, we study the secrecy throughput in a massive Multiple-Input-Multiple-Output (MIMO) full-duplex wireless powered communication network (WPCN). The network consists of a massive MIMO base station (BS) and two groups of single- antenna sensor nodes which harvest energy from the BS. The first group, referred to as information transmitters (ITs), use the harvested energy to transmit information back to the BS; the second group, referred to as energy receivers (ERs), use the harvested energy for non- transmission related operations. We consider a two-slot protocol. In the first time slot, all nodes harvest energy from the BS. In the second slot, ITs transmit information to the BS,...