A survey on energy efficient techniques in wireless sensor networks

International audienceThe myriad of potential applications supported by wireless sensor networks (WSNs) has generated much interest from the research community. Various applications range from small size low industrial monitoring to large scale energy constrained environmental monitoring. In all cases, an operational network is required to fulfill the application missions. In addition, energy consumption of nodes is a great challenge in order to maximize network lifetime. Unlike other networks, it can be hazardous, very expensive or even impossible to charge or replace exhausted batteries due to the hostile nature of environment. Researchers are invited to design energy efficient protocols while achieving the desired network operations. This paper focuses on different techniques to reduce the consumption of the limited energy budget of sensor nodes. After having identified the reasons of energy waste in WSNs, we classify energy efficient techniques into five classes, namely data reduction, control reduction, energy efficient routing, duty cycling and topology control. We then detail each of them, presenting subdivisions and giving many examples. We conclude by a recapitulative table

An Overview of Own Tracking Wireless Sensors with GSM-GPS Features

Wireless Sensors (WS) mobility and pause time have a major impact directly influencing the energy consumption. Lifetime of a WS Network (WSN) depends directly on the energy consumption, thus, the hardware and software components must be optimized for energy management. This study aims to combine a compact hardware architecture with a smart energy management efficiency in order to increase ratio Lifetime/Energy Consumption, to improve the operating time on a portable tracking system with GPS/GSM/GPRS features and own power. In this paper we present the evolution of own WS tracking architecture with GPS/GSM/GPRS features, basic criterion being the lifetime combined with low power consumption. Concern was focused on hardware and software areas: Large number of physical components led to reconsideration of hardware architecture, while for software, we focused on algorithms able to reduce the number of bits in transmitted data packets, which help to reduce energy consumption. The results and conclusions show that the goal was achieved

The design and evaluation of an opportunistic multicast routing protocol

This thesis aims to examine the efficiency of opportunistic multicast routing in Wireless Mesh Network (WMN). Specifically, an opportunistic multicast routing protocol has been developed in this work in order to gain better performance in WMNs compared to traditional multicast routing protocols. The number of transmissions in the network to deliver a packet from a source to group of destinations has been taken as measure for the performance of the protocol. Less number of transmissions in the network to deliver a packet to group of destinations is an indicator for a better performance. The work has been divided into two parts. In the first part, a proposal of the first version of opportunistic multicast routing protocol (OMRPv1) will be explained. By calculating the expected number of transmissions in the network, the efficiency of the protocol will be examined. OMRPv1 will be compared against a traditional protocol, non-opportunistic protocol, to confirm its better performance in the network. Then, a second version of our protocol will be introduced, OMRPv2, as a solution for some problems encountered in the first version. The comparison between OMRPv1 and OMRPv2 will show the better performance achieved with the newer version. In the second part, QualNet simulator will be used to simulate the protocol OMRPv2. In this part, not only the number of transmissions in the network will be considered, but also other metrics like end to end delay and delivery rate will be taken into account. The overhead of the protocol will be examined as well. Observation of the results from the simulation will lead to the third version of the protocol (OMRPv3). OMRPv3 will be simulated as well to show the improvement in the performance over the previous version OMRPv2. Finally, OMRPv3 will be compared to the best opportunistic multicast routing protocol in the literature, Beacon-less Geographic Routing for Multicast Applications (BRUMA). For that reason, BRUMA will be simulated in QualNet as well. For fair comparison, few modifications will be added to BRUMA. Then, the two protocols will be compared to each other using many metrics. Delivery rate, end to end delay, and number of transmissions in the network to serve the multicast groups are some of the metrics that will be used to compare the two protocols. Results show that our protocol, OMRPv3, outperforms BRUMA in many of these metrics

Optimizing Source Anonymity Of Wireless Sensor Networks Against Global Adversary Using Fake Packet Injections

Wireless Sensor Networks WSNs have been utilized for many applications such as tracking and monitoring of endangered species in a national park, soldiers in a battlefield, and many others, which require anonymity of the origin, known as the Source Location Privacy (SLP). The aim of SLP is to prevent unauthorized observers from tracing the source of a real event (an asset) by analyzing the traffic of the network. We develop the following six techniques to provide anonymity: Dummy Uniform Distribution (DUD), Dummy Adaptive Distribution (DAD), Controlled Dummy Adaptive Distribution (CAD), Exponential Dummy Adaptive Distribution (EDAD), Exponential Dummy Adaptive Distribution Plus One (EDADP1), and Exponential Dummy Adaptive Distribution Plus Two (EDADP2). Moreover, an enhanced version of the well-known FitProbRate technique is also developed. The purpose of these techniques is to overcome the anonymity problem against a global adversary model that has the capability of analyzing and monitoring the entire network. We perform an extensive verification of the proposed techniques via simulation, statistical, and visualization approaches. Three analytical models are developed to verify the performance of our techniques: A Visualization model is performed on the simulation data to confirm anonymity. A Neural Network model is developed to ensure that the introduced techniques preserve SLP. In addition, a Steganography model based on statistical empirical data is implemented to validate the anonymity of the proposed techniques. The Simulation demonstrates that the proposed techniques provide a reasonable delay, delivery ratio, and overhead of the real event's packets while keeping a high level of anonymity. Results show that the improved version of FitProbRate massively reduces the number of operations needed to detect the distribution type of a data sequence despite the number of intervals when compared to the original. A comprehensive comparison between EDADP1, EDADP2, and FitProbRate in terms of the average delay, anonymity level, average processing time, Anderson-Darling test, and polluted scenarios is conducted. Results show that all three techniques have a similar performance regarding the average delay and Anderson-Darling test. However, the proposed techniques outperform FitProbRate in terms of anonymity level, average processing time, and polluted scenarios. WSN applications that need privacy can select the suitable proposed technique based on the required level of anonymity with respect to delay, delivery ratio, and overhead

Interference analysis of and dynamic channel assignment algorithms in TD–CDMA/TDD systems

The radio frequency spectrum for commercial wireless communications has become an expensive commodity. Consequently, radio access techniques are required which enable the efficient exploitation of these resources. This, however, is a difficult task due to an increasing diversity of wireless services. Hence, in order to achieve acceptable spectrum efficiency a flexible air– interface is required. It has been demonstrated that code division multiple access (CDMA) provides flexibility by enabling efficient multi user access in a cellular environment. In addition, time division duplex (TDD) as compared to frequency division duplex (FDD) represents an appropriate method to cater for the asymmetric use of a duplex channel. However, the TDD technique is subject to additional interference mechanisms in particular if neighbouring cells require different rates of asymmetry. If TDD is combined with an interference limited multiple access technique such as CDMA, the additional interference mechanism represents an important issue. This issue poses the question of whether a CDMA/TDD air–interface can be used in a cellular environment. The problems are eased if a hybrid TDMA (time division multiple access) / CDMA interface (TD–CDMA) is used. The reason for this is that the TDMA component adds another degree of freedom which can be utilised to avoid interference. This, however, requires special channel assignment techniques. This thesis analyses cellular CDMA/TDD systems used in indoor environments. A key parameter investigated is the interference in such systems. In the interference analysis a special focus is placed on adjacent channel interference since the jamming entity and victim entity can be in close proximity. The interference analysis shows that co–location of BS’s using adjacent channels is not feasible for an adjacent channel protection factor that is less than 40 dB and frame synchronisation errors of more than 10%. Furthermore, it is demonstrated that ideal frame synchronisation does not necessarily yield the highest capacity. As a consequence, a new technique termed ’TS–opposing’ is introduced. This method is intended to enable a cellular TD–CDMA/TDD system to apply cell independent channel asymmetry. For this purpose, a centralised DCA is developed. It is found that this algorithm indeed enables neighbouring cells to adopt different rates of asymmetry without a significant capacity loss. Moreover, a decentralised DCA algorithm based on the TS–opposing principle is developed. In this context, a novel TS assignment concept is proposed which reduces the complexity associated with the TS–opposing technique. In addition, the TS assignment plan allows for full spatial coverage. It is shown that the capacity of a TD–CDMA/TDD interface can be greater than the capacity of an equivalent FDD interface. The performance of the decentralised DCA algorithm is limited by the interference in the uplink. Therefore, additional methods which assist in reducing the interference in the uplink are envisaged to further improve the performance of the decentralised DCA algorithm. The exploitation of the TS–opposing technique in two different ways demonstrates that this method can be used to improve the performance of a TD–CDMA/TDD system significantly