Nora A. Ali

Effect of node distributions on lifetime of Wireless Sensor Networks

Wireless Sensor Networks has recently become an attractive research topic due to the rapidly growing field of applications. This paper focuses on prolonging network lifetime by investigating different node deployments including both geometric and uniform. Geometric distributions resulted in a 35.6% increase in lifetime as opposed to random distributions. Furthermore, different sink locations were examined. The optimum sink location introduced a considerable lifetime elongation compared to the previously used location.

Effect of hamming coding on WSN lifetime and throughput

Wireless Sensor Networks has become an attractive field of research due to its wide range of applications. This paper focuses on improving network throughput without affecting the lifetime. It shows that the use of the Hamming code has a negligible effect on network lifetime irrespective of the SNR. In contrast, the CRC with retransmissions reduces the lifetime by 37.3% compared to the uncoded system. It is also proven that using the Hamming code increases system throughput when compared to the use of CRC. High-rate Hamming codes have a higher throughput than low-rate Hamming codes over network lifetime. Both AWGN and Rayleigh fading channels are considered. If the Network Master is used as a repeater, it is found that this generally increases network lifetime. Furthermore, at low SNR, system throughput in the case of high-rate Hamming codes is increased. The above results are shown both for fixed data and fixed frame schemes.

Monitoring electromagnetic pollution using Wireless Sensor Networks

Wireless Sensor Networks (WSN) has become an attractive field for research due to the increasing number of applications. This paper uses a WSN to monitor Electromagnetic Pollution and report any violations in power levels. An event-by-event simulator is developed to calculate network lifetime and study important factors affecting it. One of these factors is determining the energy threshold of the Network Master. Different node distributions are investigated. It is found that the 10×10 star results in a 77% increase in lifetime in comparison with the Homogeneous Density distribution.

Heterogeneous LTE/Wi-Fi architecture for ITS traffic control and infotainment

Intelligent Transportation Systems (ITS) make use of advanced technologies to enhance road safety and to improve traffic efficiency. In order to assist passengers to travel safely, efficiently and conveniently, several application requirements have to be met simultaneously. For this purpose, this paper proposes a heterogeneous LTE/Wi-Fi vehicular system that supports both infotainment and ITS traffic control data. A performance simulation-based study is conducted to validate the feasibility of the proposed system in an urban vehicular environment. The system performance is evaluated in terms of data loss, data rate, delay and jitter. The results indicate that the proposed system offers acceptable performance that meets the requirements of both infotainment and traffic control.

New hybrid frequency reuse method for packet loss minimization in LTE network

This paper investigates the problem of inter-cell interference (ICI) in Long Term Evolution (LTE) mobile systems, which is one of the main problems that causes loss of packets between the base station and the mobile station. Recently, different frequency reuse methods, such as soft and fractional frequency reuse, have been introduced in order to mitigate this type of interference. In this paper, minimizing the packet loss between the base station and the mobile station is the main concern. Soft Frequency Reuse (SFR), which is the most popular frequency reuse method, is examined and the amount of packet loss is measured. In order to reduce packet loss, a new hybrid frequency reuse method is implemented. In this method, each cell occupies the same bandwidth of the SFR, but the total system bandwidth is greater than in SFR. This will provide the new method with a lot of new sub-carriers from the neighboring cells to reduce the ICI which represents a big problem in many applications and causes a lot of packets loss. It is found that the new hybrid frequency reuse method has noticeable improvement in the amount of packet loss compared to SFR method in the different frequency bands. Traffic congestion management in Intelligent Transportation system (ITS) is one of the important applications that is affected by the packet loss due to the large amount of traffic that is exchanged between the base station and the mobile node. Therefore, it is used as a studied application for the proposed frequency reuse method and the improvement in the amount of packet loss reached 49.4% in some frequency bands using the new hybrid frequency reuse method.

Elongation of WSN lifetime using a centralised clustering technique

Wireless sensor networks (WSN) is one of the most important fields of research in recent years due to its wide range of applications. Lifetime elongation is the main concern in WSN. This paper focuses on improving the lifetime by using the clustering technique with a centralised algorithm. The optimum number of clusters that maximises the lifetime is obtained and the relation between clusters is investigated. The results prove that the independency of cluster head selection decisions improves the lifetime. Clustering is applied to networks covering large areas and the clustering efficiency is verified. Also, using clustering in applications that do not need data aggregation, is investigated.

Node Deployment and Mobile Sinks for Wireless Sensor Networks Lifetime Improvement

In the last two decades, and owing to advances in MEMS technologies, wireless communications and low-power electronics, the development of low-cost micro sensor nodes was possible. This enabled the deployment of Wireless Sensor Networks (WSN) comprising large numbers of nodes to monitor various physical phenomena in real-time. This can be of prime importance in several industrial, environmental, health, and military applications (Akyildiz et al., 2002; Tavares et al., 2008). A WSN may have up to hundreds or even thousands of sensor nodes densely deployed either inside or close to a monitored area. Nodes process data prior to transmission, to ensure acquisition of accurate and detailed information. Processed information is then passed on to a sink node, which transmits necessary data to some base station. Nodes may also be divided into clusters, with nodes in each cluster sending data to a particular sink node. Sensor nodes typically operate in an unattended environment, and are equipped with small, often irreplaceable batteries with limited power capacity. Thus a major consideration in WSN research is to ensure reliable transmission of data while prolonging network lifetime by making maximum use of the available energy in the nodes (Heinzelman et al., 2002). In this chapter, recent work by the authors in the area of WSN is presented with particular emphasis on maximizing the lifetime of the network. In Section 2, algorithms are described that build upon two well known WSN routing techniques, namely LEACH (Heinzelman et al., 2000) and LEACH-C (Heinzelman et al., 2002) to further optimize network lifetime through carefully planned selection of the sink nodes. Simulation results that illustrate the resulting improvement in network lifetime are presented. The position of sensor nodes need not be predetermined, which allows random deployment in inaccessible terrains. However, in some applications, the deployment of nodes at pre-specified positions is feasible. Taking advantage of this feature is thus considered to achieve further enhancement in network lifetime by considering the effect of various geometrical distributions of nodes and relative sink locations. Further reductions of the transmission energy requirements can be attained by making use of uncontrolled mobile sinks in addition to the distant fixed sinks. It is not possible to 16

Effect of Decentralized Clustering Algorithm and Hamming Coding on WSN Lifetime and Throughput

Wireless Sensor Networks (WSN) has become an interesting field of research because of its wide range of applications such as environmental monitoring, electromagnetic pollution monitoring, medical applications and industrial applications (Teo et al., 2007; Margi et al., 2009; Castelluccia et al., 2005; AbouElSeoud et al., 2010; Tavares et al., 2008). WSN consists of multi-functioning sensor nodes with limited power capacity, so prolonging the lifetime is essential and is one of the main concerns (Castelluccia et al., 2005; Schmidt et al., 2009; Karlsson et al., 2005). For this reason different routing protocols are obtained to increase network lifetime. The clustering routing protocol is one of the most commonly routing protocols because it is energy efficient (Heinzelman et al., 2000, 2002). In any clustering protocol, the network is divided into clusters where some nodes are responsible for others. These nodes are called cluster heads (CHs) or network masters (NMs). There are different algorithms and different methods of choosing the CHs. For example, LEACH (Heinzelman et al., 2000) used the randomized rotation to choose CH nodes. This randomized rotation allows some nodes to act as CHs and the others cannot. Therefore LEACH was improved to be LEACH-C (Heinzelman et al., 2002) that uses central algorithm to choose the CHs and allows only the nodes in the center of each cluster to act as CHs. Also two different algorithms of choosing the NMs are considered in (Botros et al., 2009). The network is considered as one cluster; therefore the CH node that is responsible for collecting data from other nodes is called NM. In the first algorithm, the sensor could become NM more than once for a fixed number of cycles. It was proven that this algorithm provided a lifetime longer than the lifetime obtained by LEACH and LEACH-C algorithms (Heinzelman et al., 2000, 2002). However, this algorithm has some residual energy after the network failure and this energy cannot be used anymore. Therefore, the second algorithm is obtained to improve the first one by allowing each sensor to become NM once with a different number of cycles and acts as an active node or ordinary node (that senses the

General expressions for downlink signal to interference and noise ratio in homogeneous and heterogeneous LTE-Advanced networks

Graphical abstract

WSN lifetime prolongation for deterministic distributions using a hierarchical routing protocol

Extending the lifetime of Wireless Sensor Networks is one important design goal when practically deploying them. The paper addresses the problem of choosing the optimum number of clusters in deterministically distributed nodes in a wireless sensor network in order to maximize its lifetime. Hierarchical routing protocol is used on some of the deterministic nodes distributions such as uniform, circular, hexagonal and star distribution, to show how to choose the optimal number of clusters. Compared to non-clustering case and arbitrary clustering, lifetime enhancement is noticed for all the examined distributions. The paper also shows that choosing the right cluster shape is one of the important factors that affect the network lifetime.