Effect of Decentralized Clustering Algorithm and Hamming Coding on WSN Lifetime and Throughput
Nora A. Ali, Hany M. ElSayed, Magdy S. El-Soudani, Hassanein Hamed Amer, Ramez Daou · InTech eBooks · 2012
Cutting Edge Research in New Technologies 260 surroundings and sends the sensed data to the NM node) till network failure.Using this algorithm increased the lifetime by approximately 5% compared to the first algorithm.In this chapter, the network is divided into clusters and all the nodes inside each cluster will act as CHs once with a different number of cycles.The optimum number of clusters is obtained taking into account that the algorithm is decentralized, i.e., some nodes cannot reach the sink because their initial energy is too low.Also, the effect of clustering on networks covering large areas and on the applications that do not need data aggregation is examined.On the other hand, in some important applications such as industrial applications and critical applications such as medical applications (Tavares et al., 2008), lifetime is not the only important factor; receiving all sensor data correctly at the sink might be more important to prevent taking wrong decisions (Margi et al., 2009).But, this is very difficult in noisy environments.Hence Error Correcting Codes (ECC) must be used to improve data integrity (Schmidt et al., 2009).ECC can have an adverse effect on network lifetime due to the processing energy consumed for encoding and decoding.Therefore, in this work, the Hamming code will be introduced as an example of ECC due to its wide use in sensor networks (Karyonen & Pomalaza-Ráez, 2004;Sadeghi et al., 2006).It will be compared to the Cyclic Redundancy Check (CRC) as an example of a very widely used error detecting technique (Nguyen, 2005).In CRC, the error is only detected and the correction is done by retransmitting data.In contrast, in the Hamming code, the error can be detected and corrected without retransmission.The processing energy for coding will be investigated based on hardware implementations of encoding/decoding circuits.Moreover, a metric that represents a compromise between the lifetime and the amount of correct received data (throughput) will be introduced.The effect of using NM as a repeater is examined to improve network performance.Finally, the effect of using coding in case of fixed data length is investigated.In this research, network lifetime is defined as the time to the first node failure due to battery outage (Botros et al., 2009;Sadeghi et al., 2006).This chapter is organized as follows.Section 2 describes the decentralized algorithm, the optimum number of clusters using this algorithm and the effect of clustering on networks covering large areas and on the applications that do not need data aggregation.Section 3, describes coding in sensor networks and the processing energy for coding for both Hamming code and CRC.Section 4 describes the simulation results.Section 5 describes the fixed data length scheme and its simulation results.Finally, section 6 concludes the chapter.