Hexagonal wireless sensor network refers to a network topology where a subset of nodes have six peer neighbors. These nodes form a backbone for multi-hop communications. In a previous work, we proposed the use of hexagonal topology in wireless sensor networks and discussed its properties in relation to real-time (bounded latency) multi-hop communications in large-scale deployments. In that work, we did not consider the problem of hexagonal topology formation in practice -which is the subject of this research. In this paper, we present a decentralized algorithm that forms the hexagonal topology backbone in an arbitrary but sufficiently dense network deployment. We implemented a prototype of our algorithm in NesC for TinyOS based platforms. We present data from field tests of our implementation, collected using a deployment of fifty wireless sensor nodes.

Abstract:In the context of WLAN (Wireless Local Area Network) and WPAN (Wireless Personal Area Network) systems for High Data Rate (HDR) wireless communications, the unlicensed frequency band available in the millimeter wave region has become more and more attractive. Currently focus is on use of OFDM system to cater for increased data rate of wireless medium with good performance. Diversity techniques play an important role in achieving higher performance level for limited power wireless systems. Wavelet analysis has some strong advantages over Fourier analysis, as it allows a time-frequency domain operation, allowing optimal resolution and flexibility. Wavelets have been satisfactorily used in almost all the fields of wireless communication systems including OFDM which is a strong candidate for next generation of wireless system. This paper proposes a DWT-OFDM Diversity to achieve better performance in terms of SNR and bit error rate (BER) for TSV model based channel at 60 GHz. The performances of different discrete wavelets for channels defined by IEEE 802.15.4a are analyzed. The results indicate better BER performance in case of lower order wavelet.

Now a day's innovations in production of mobile computers and smart phones, sensors and sensor networks in connection with next generation mobile networks opened great opportunities for researchers and developers of various systems and application in the field of Smart Cities. Some typical applications including garbage monitoring, Humidity built-in sensors, water supply monitoring street light monitoring, and air pollution monitoring etc. require a smart gateway to provide high data rate, end-to-end connectivity is required with higher bandwidth. This paper proposes a novel model for Smart city concept using the IoT which has important benefits.