Suleiman Almasri

A survey on wireless sensor networks for smart grid

The traditional power grid in many countries suffers from high maintenance costs and scalability issues along with the huge expense of building new power stations, and lack of efficient system monitoring that could increase the overall performance by acting proactively in preventing potential failures. To address these problems, a next-generation electric power system, called the smart grid (SG), has been proposed as an evolutionary system for power generation, transmission, and distribution. To this end, the SGs utilize renewable energy generation, smart meters and modern sensing and communication technologies for effective power system management, and hence, succeeding in addressing many of the requirements of a modern power grid system while significantly increase its performance. Recently, wireless sensor networks (WSNs) have been recognized as a promising technology to achieve seamless, energy efficient, reliable, and low-cost remote monitoring and control in SG applications. In these systems, the required information can be provided to electric utilities by wireless sensor systems to enable them to achieve high system efficiency. The real-time information gathered from these sensors can be analyzed to diagnose problems early and serve as a basis for taking remedial action. In this paper, first WSN-based SG applications have been explored along with their technical challenges. Then, design challenges and protocol objectives have been discussed for WSN-based SG applications. After exploring applications and design challenges, communication protocols for WSN-based SG applications have been explained in detail. Here, our goal is to elaborate on the role of WSNs for smart grid applications and to provide an overview of the most recent advances in MAC and routing protocols for WSNs in this timely and exciting field.

A routing framework for energy harvesting wireless nanosensor networks in the Terahertz Band

Wireless NanoSensor Networks (WNSNs) will allow novel intelligent nanomaterial-based sensors, or nanosensors, to detect new types of events at the nanoscale in a distributed fashion over extended areas. Two main characteristics are expected to guide the design of WNSNs architectures and protocols, namely, their Terahertz Band wireless communication and their nanoscale energy harvesting process. In this paper, a routing framework for WNSNs is proposed to optimize the use of the harvested energy to guarantee the perpetual operation of the WNSN while, at the same time, increasing the overall network throughput. The proposed routing framework, which is based on a previously proposed medium access control protocol for the joint throughput and lifetime optimization in WNSNs, uses a hierarchical cluster-based architecture that offloads the network operation complexity from the individual nanosensors towards the cluster heads, or nano-controllers. This framework is based on the evaluation of the probability of saving energy through a multi-hop transmission, the tuning of the transmission power of each nanosensor for throughput and hop distance optimization, and the selection of the next hop nanosensor on the basis of their available energy and current load. The performance of this framework is also numerically evaluated in terms of energy, capacity, and delay, and compared to that of the single-hop communication for the same WNSN scenario. The results show how the energy per bit consumption and the achievable throughput can be jointly maximized by exploiting the peculiarities of this networking paradigm.

Joint physical and link layer error control analysis for nanonetworks in the Terahertz band

Nanonetworks consist of nano-sized communicating devices which are able to perform simple tasks at the nanoscale. The limited capabilities of individual nanomachines and the Terahertz (THz) band channel behavior lead to error-prone wireless links. In this paper, a cross-layer analysis of error-control strategies for nanonetworks in the THz band is presented. A mathematical framework is developed and used to analyze the tradeoffs between Bit Error Rate, Packet Error Rate, energy consumption and latency, for five different error-control strategies, namely, Automatic Repeat reQuest (ARQ), Forward Error Correction (FEC), two types of Error Prevention Codes (EPC) and a hybrid EPC. The cross-layer effects between the physical and the link layers as well as the impact of the nanomachine capabilities in both layers are taken into account. At the physical layer, nanomachines are considered to communicate by following a time-spread on-off keying modulation based on the transmission of femtosecond-long pulses. At the link layer, nanomachines are considered to access the channel in an uncoordinated fashion, by leveraging the possibility to interleave pulse-based transmissions from different nodes. Throughout the analysis, accurate path loss, noise and multi-user interference models, validated by means of electromagnetic simulation, are utilized. In addition, the energy consumption and latency introduced by a hardware implementation of each error control technique, as well as, the additional constraints imposed by the use of energy-harvesting mechanisms to power the nanomachines, are taken into account. The results show that, despite their simplicity, EPCs outperform traditional ARQ and FEC schemes, in terms of error correcting capabilities, which results in further energy savings and reduced latency.

Client-Server Based LBS Architecture: A Novel Positioning Module for Improved Positioning Performance

This work presents a new efficient positioning module that operates over client-server LBS architectures. The aim of the proposed module is to fulfil the position information requirements for LBS pedestrian applications by ensuring the availability of reliable, highly accurate and precise position solutions based on GPS single frequency L1 positioning service. The positioning module operates at both LBS architecture sides; the client mobile device, and the server positioning server. At the server side, the positioning module is responsible for correcting users location information based on WADGPS corrections. In addition, at the mobile side, the positioning module is continually in charge for monitoring the integrity and available of the position solutions as well as managing the communication with the server. The integrity monitoring was based on EGNOS integrity methods. A prototype of the proposed module was developed and used in experimental trials to evaluate the efficiency of the module in terms of the achieved positioning performance. The positioning module was capable of achieving a horizontal accuracy of less than 2 meters with a 95% confidence level with integrity improvement of more than 30% from existing GPS/EGNOS services.

Location-Based Services (LBS) in Micro-Scale Navigation: Shortcomings and Recommendations

Pedestrians LBS are accessible by hand-held devices and become a large field of energetic research since the recent developments in wireless communication, mobile technologies and positioning techniques. LBS applications provide services like finding the neighboring facility within a certain area such as the closest restaurants, hospital, or public telephone. With the increased demand for richer mobile services, LBS propose a promising add-on to the current services offered by network operators and third-party service providers such as multimedia contents. The performance of LBS systems is directly affected by each component forming its architecture. Firstly, the end-user mobile device is still experiencing a lack of enough storage, limitations in CPU capabilities and short battery lifetime. Secondly, the mobile wireless network is still having problems with the size of bandwidth, packet loss, congestions and delay. Additionally, in spite of the fact that GPS is the most accurate navigation system, there are still some issues in micro scale navigation, mainly availability and accuracy. Finally, LBS server which hosts geographical and users information is experiencing difficulties in managing the huge size of data which causes a long query processing time. This paper presents a technical investigation and analysis of the performance of each component of LBS system for pedestrian navigation, through conducting several experimental tests in different locations. The results of this investigation have pinpointed the weaknesses of the system in micro-scale environments. In addition, this paper proposes a group of solutions and recommendations for most of these shortcomings.

The Impact of Zoning Concept on Data-Flow Management within LBS System Components

Typical Location Based Services LBS system is compound of a mobile device with positioning capability connected to a LBS service provider via wireless network. Thus, the efficiency of LBS System depends on each sub-element composing its architecture. One of the most important factors affecting LBS efficiency is the volume of data streamed from the server to the client. This problem has emerged as a consequence of customer demands for richer services such as videos and high-quality pictures. Therefore this paper discusses the impacts of transmitting huge size of information and services on: the mobile devices, wireless networks and the data server. In addition, it introduces a mechanism to improve the data flow based on the zoning concept in which data is organised in individual databases and then streamed gradually according to the end users new location. The outcome of the evaluation of this mechanism has shown better utilisation of the mobile device resources memory and battery as well as reducing the network and server consumption time.

Evaluation of HSDPA (3.5G) mobile link quality

The modern and dynamic world has imposed pressure on technologies to match the speed at which the world is moving. Responding to the challenge, third generation (3G) technologies have introduced a new era of mobility not only for cellular phones but also for broadband services. With the rise of high bandwidth demand applications, a number of challenges emerge. This paper presents results obtained while testing the performance of the 3.5 G wireless broadband in a number of scenarios to reflect the end userspsila experience. The test evaluates high speed downlink packet access (HSDPA), a 3.5 G mobile technology, testing its link characteristics in different scenarios. During the test, four major link characteristics: latency, throughput, link stability and packet loss were tested. These are the characteristics that cause direct effects to the quality of service (QoS). The mobility features were also tested. The result shows that number of users highly affects QoS. To perform the test, the T-mobile of-the-shelf public available WebdasianpsilaWalk data card was used.

Reducing the energy consumption at the user equipment through multi-stream cross-carrier-aware discontinuous reception (DRX) in LTE-advanced systems

In order to minimize the amount of energy consumption at the user equipment (UE) level, the 3rd Generation Partnership Project (3GPP) presented in the Long Term Evolution (LTE) an approach called discontinuous reception (DRX). Nevertheless, existing models for the LTE DRX and their extension to scenarios that support carrier aggregation (CA) and multi-stream carrier aggregation (MSCA) have several drawbacks. In this paper, we utilize a semi-Markov Chain to model the operation of the LTE DRX and characterize its performance metrics. Then, we exploit the new features introduced in LTE Advanced (LTE-A) to develop a novel cross-carrier-aware DRX for scenarios that support CA and MSCA since the energy consumption in such scenarios can be significantly higher and existing techniques simply reapplied the traditional DRX scheme. We present a detailed examination of our DRX solution along with the analytical expressions of its performance metrics. The accuracy of our modeling approach for both the classical and our novel LTE DRX is validated through extensive simulations across a wide range of parameters. We evaluate the performance of our cross-carrier-aware DRX solution and show that it can significantly outperform the classical one, especially under a low tolerable delay. In addition, we also show the effects of implementation-dependent power levels on the performance of our cross-carrier-aware DRX.

Distributed Timely Throughput Optimal Scheduling for the Internet of Nano-Things

Nanotechnology is enabling the development of miniature devices able to perform simple tasks at the nanoscale. The interconnection of such nano-devices with traditional wireless networks and ultimately the Internet enables a new networking paradigm known as the Internet of Nano-Things (IoNT). Despite their promising applications, nano-devices have constrained power, energy, and computation capabilities along with very limited memory on board, which may only be able to hold one packet at once and, thus, requires packets to be delivered before certain hard deadlines. Toward this goal, a fully-distributed computation-light provably-correct scheduling/MAC protocol is introduced for bufferless nano-devices, which can maximize the network throughput, while achieving perpetual operation. More specifically, the proposed scheduling algorithm allows every nano-device to make optimal transmission decisions locally based on its incoming traffic rate, virtual debts, and channel sensing results. It is proven that the proposed algorithm is timely throughput optimal in the sense that it can guarantee reliable data delivery before deadlines as long as the incoming traffic rates are within the derived maximum network capacity region. This feature not only can lead to high network throughput for the IoNT, but also guarantees that the memory of each device is empty before the next packet arrives, thus addressing the fundamental challenge imposed by the extremely limited memory of nano-devices. In addition, the optimal deadline is derived, which guarantees that all the nano-devices can achieve perpetual communications by jointly considering the energy consumption of communications over the terahertz channel and energy harvesting based on piezoelectric nano-generators.

Zone-based update mechanism for Location Based Services (LBS)

In the past few years, there has been a rapid expansion of activities in location-based services (LBS) providing pedestrians with easy access to useful information whilst travelling from one place to another. LBS systems use the power of mobile networks to locate users and provide data and services based on their location. In view of the fact that such systems suffer from sending huge volume of information from the server to the user, this paper presents a new update mechanism which improves the performance of the service provided by LBS Systems. Such mechanism will reduce the usage of network bandwidth which will contribute in minimising the memory and power consumption of the userpsilas device (mobile smartphone, PDA... etc.).