Sensing task handover for indoor clustered wireless sensor network

This paper presents the proposal of implementing sensing task handover initiation control for wireless sensor network deployed in indoor environment. The structure of the wireless sensor network is based on indoor clustering so that sensor nodes are grouped in different clusters according to room partitions. For such a network, a simple and efficient multi-node handover initiation control method is proposed for the decision of handover initiation by comparing the combined received signal strengths and the number of effective nodes between two neighbouring clusters. Experiments were conducted to test the possibility and evaluate the performance of the proposed method. The results show that sensing task handover is possible to happen at accurate time while crossing boundary between two clusters by applying the proposed method

Measurement arrangement for the estimation of path loss exponent in wireless sensor network

Path loss model is generally used to relate distance and signal strength in wireless applications. This has been widely implemented in ranging, localization, and location tracking systems. A range of extension models have been proposed to enhance the performance for various environments and applications. Nevertheless, path loss exponent remains its significance as the main factor in the model regardless of how the model is varied. Based on the nature as an exponent of the model, inaccurate path loss exponent amplifies the error if it is used to estimate distance from received signal strength. Therefore, measurement of accurate value for path loss exponent becomes very important as it directly influences the output of distance estimation. Researchers have been studying the methods of measuring accurate path loss exponent in various environments. Instead of emphasizing the calculation process, this paper focuses more on the allocation of transmitters and receivers, and the arrangement among them. From the results obtained from experiments, properly arranged transmitter and receiver nodes provides better estimation of the path loss exponent. Based on the results, this paper also proposes a suitable nodes arrangement scheme for path loss exponent estimation

Accuracy and stability analysis of path loss exponent measurement for localization in wireless sensor network

In wireless sensor network localization, path loss model is often used to provide a conversion between distance and received signal strength (RSS). Path loss exponent is one of the main environmental parameters for path loss model to characterize the rate of conversion. Therefore, the accuracy of path loss exponent directly influences the results of RSS-to-distance conversion. When the conversion requires distance estimation from RSS value, small error of measured path loss exponent could lead to large error of the conversion output. To improve the localization results, the approaches of measuring accurate parameters from different environments have become important. Different approaches provide different measurement stabilities, depending on the performance and robustness of the approach. This paper presents four calibration approaches to provide measurements of path loss exponent based on measurement arrangement and transmitter/receiver node’s allocation. These include one-line measurement, online-update spread locations measurement, online-update small-to big rectangular measurement, and online-update big-to-small rectangular measurement. The first two are general approaches, and the last two are our newly proposed approaches. Based on our research experiments, a comparison is presented among the four approaches in terms of accuracy and stability. The results show that both online-update rectangular measurements have better stability of measurements. For accuracy of measurement, online-update big-to-small rectangular measurement provides the best result after convergence

Measured radio wave behavior of a partially open drain in urban environment

This paper attempts to analyze the propagation characteristics of radio signal inside a partially open drain environment using an empirical approach. The proposed research topic concerns a unique situation in several Asian countries because the drainage systems in these countries differ notably from those in the US and Europe in that the former are partially open on the top while the latter are primarily below ground and covered. Measurement results are reported for one drain located on Sunway University campus at 2.4 and 5.8 GHz. The differences between the measurement results at the aforementioned two frequencies are discussed. These measurement results serve as a useful indicator as to how signal might behave differently in partially enclosed spaces, such as those where partially open drains exist, especially in an urban environment

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Clustering Techniques For Channel Equalisation Using Fuzzy And Minimal Radial Basis Function Networks

Digital communication over bandlimited channels often encounter the problem of intersymbol interference (ISI), which can degrade signal quality down to an unacceptable level. As such, a channel equaliser is usually used at the receiving end to mitigate the ISI. This thesis studies adaptive channel equalisation based on softcomputing techniques

Investigation of Embroidery Conductive Layer Dyed with Graphene and ZnO

Abstract -This paper presents a method to improve the conductivity of embroidered patch antenna by using graphene and zinc oxide (ZnO) nanopowder. By dispersion and immersion of graphene and ZnO, the embroidered conductive patch layers have been designed, fabricated and tested. Analysis of the effect of graphene and ZnO solution on patch resistance has been carried out. The measured results show that the conductivity performs better with ZnO dyed embroidered patch layer. In contrast, graphene improves the sheet resistance while ethanol solvent reacts with silver thread

Dragon-MAC: Securing Wireless Sensor Networks with Authenticated Encryption

Abstract. Sensor networks offer economically viable monitoring solutions for a wide variety of applications. In order to combat the security threats that sensor networks are exposed to, a cryptography protocol is implemented at sensor nodes for point-to-point encryption between nodes. Disclosure, disruption and deception threats can be defeated by authenticating data sources as well as encrypting data in transmission. Given that nodes have limited resources, symmetric cryptography that is proven to be efficient for low power devices is implemented. Data protection is integrated into a sensor’s packet by the means of symmetric encryption with the Dragon stream cipher and incorporating the newly designed Dragon-MAC Message Authentication Code. The proposed algorithm was designed to employ some of the data already computed by the underlying Dragon stream cipher for the purpose of minimizing the computational cost of the operations required by the MAC algorithm. In view that Dragon is a word based stream cipher with a fast key stream generation, it is very suitable for a constrained environment. Our protocol regarded the entity authentication and message authentication through the implementation of authenticated encryption scheme in Telos B wireless sensor nodes