Adaptive TDMA Slot Assignment Using Request Aggregation in Wireless Sensor Networks

AbstractTDMA-based MAC protocols are considered an energy effcient solution to prolong wireless sensor network lifetime. However, their drawbacks such as complexity of slot assignment and schedule maintenance and adaptivity to varying traffc conditions are yet to be handled in an effcient way. In this paper we present On-demand Convergecast Scheduling based (OCS) MAC protocol. It is a centralized and adaptive multihop scheduling-based TDMA protocol which supports convergecast applications. OCS adopts a novel requests aggregation mechanism for adaptive slot assignment such that time slots are assigned on-demand to currently active sources as well as relays. The performance of OCS is compared to existing protocols based on simulations in ns-2. Results show that OCS outperforms protocols such as Z-MAC, S-MAC, and others in terms of delay, throughput and energy effciency

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Isu atau masalah rasuah menjadi topik utama sama ada di peringkat antarabangsa mahupun di peringkat dalam negara. Pertubuhan Bangsa- bangsa Bersatu menegaskan komitmen komuniti antarabangsa bertegas untuk mencegah dan mengawal rasuah melalui buku bertajuk United Nations Convention against Corruption. Hal yang sama berlaku di Malaysia. Melalui pernyataan visi oleh mantan Perdana Menteri Malaysia, Tun Dr. Mahathir bin Mohamed memberikan indikasi bahawa kerajaan Malaysia komited untuk mencapai aspirasi agar Malaysia dikenali kerana integriti dan bukannya rasuah. Justeru, tujuan penulisan bab ini adalah untuk membincangkan rasuah dari beberapa sudut termasuk perbincangan dari sudut agama Islam, faktor-faktor berlakunya gejala rasuah, dan usaha-usaha yang dijalankan di Malaysia untuk membanteras gejala rasuah. Perkara ini penting bagi mengenalpasti penjawat awam menanamkan keyakinan dalam melaksanakan tanggungjawab dengan menghindari diri daripada rasuah agar mereka sentiasa peka mengutamakan kepentingan awam

Wireless industrial monitoring and control networks: the journey so far and the road ahead

While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks

Balanced Multi-Channel Data Collection in Wireless Sensor Networks

Data collection is an essential task in Wireless Sensor Networks (WSNs). In data collection process, the sensor nodes transmit their readings to a common base station called Sink. To avoid a collision, it is necessary to use the appropriate scheduling algorithms for data transmission. On the other hand, multi-channel design is considered as a promising technique to reduce network interference and latency of data collection. This technique allows parallel transmissions on different frequency channels, thus time latency will be reduced. In this paper, we present a new scheduling method for multi-channel WSNs called Balanced Multi Channel Data Collection (Balanced MC-DC) Algorithm. The proposed protocol is based on using both Non-Overlapping Channels (NOC) and Partially Overlapping Channels (POC). It uses a new approach that optimizes the processes of tree construction, channel allocation, transmission scheduling and balancing simultaneously. Extensive simulations confirm the superiority of the proposed algorithm over the existing algorithms in wireless sensor networks

The Hybrid Algorithm for Data Collection over a Tree Topology in WSN

Wireless sensor networks have wide range of application such as analysis of traffic, monitoring of environmental, industrial process monitoring, technical systems, civilian and military application. Data collection is a basic function of wireless sensor networks (WSN) where sensor nodes determine attributes about a phenomenon of concern and transmits their readings to a common base station(sink node). In this paper, we use contention-free Time Division Multiple Access (TDMA) support scheduling protocols for such data collection applications over tree-based routing topology. We represent a data gathering techniques to get the growing capacity, routing protocol all along with algorithms planned for remote wireless sensor networks. This paper describes about the model of sensor networks which has been made workable by the junction of micro-electro-mechanical systems technologies, digital electronics and wireless communications. Firstly the sensing tasks and the potential sensor network applications are explored, and assessment of factors influencing the design of sensor networks is provided. In our propose work using data compression and packet merging techniques; or taking advantage of the correlation in the sensor readings. Consider continuous monitoring applications where perfect aggregation is achievable, i.e., every node is capable of aggregate the entire packets expected from its children as well as that generate by itself into a particular packet before transmit in the direction of its sink node or base station or parent node. Keyword: Aggregation, Data Converge-cast, Data fusion, Energy Efficiency, Routing and TDMA

Wireless communication protocol architectures for nanosensor networks

Thesis (M.S.) University of Alaska Fairbanks, 2004Recent developments in micro fabrication and nanotechnology will enable the inexpensive manufacturing of massive numbers of tiny computing elements with sensors. New programming paradigms are required to obtain organized and coherent behavior from the cooperation of large numbers of sensor nodes. The individual nodes are identical, randomly placed and unreliable. They communicate with a small local neighborhood via wireless broadcast. In such environments, where individual nodes have limited resources, aggregating the node into groups is useful for specialization, increased robustness, and efficient resource allocation. In this paper, an application-specific self-organization protocol stack is developed. The clustering process is divided into phases. The first phase is to know the neighbor nodes. The second phase is to set up the cluster and routing. A 'find maximum clique algorithm' is used to set up clusters. A back off method is used to set up the hop field and routing. Group leaders set up a TDMA schedule for steady state operation. This schedule ensures that there is no conflict among in the same cluster and between clusters. Direct-sequence spread spectrum (DS-SS) is used to avoid inter-group conflict. The limited power resource is a challenge in nanosensor networks. This paper uses two different ways to analyze energy consumed in nanosensor networks, energy cost field and bit flow method. Sensor node deployment, cluster size, and propagation condition effect are discussed in this paper by those two methods respectively

A Hybrid based Distributed Slot Scheduling Approach for WSN MAC

In Wireless Sensor Networks(WSNs), collision handling during transmission of data is an important challenge. MAC protocol plays a vital role in handling those collisions. Among different types of MAC protocols, schedule based MAC protocol is one where a valid schedule is prepared to handle the collision. The existing schedule based MAC protocols focus on preparing either a feasible schedule or an optimal schedule. In order to satisfy both feasibility as well as optimality feature, in this paper, we proposed a hybrid approach for slot scheduling that prepares a feasible schedule in a distributed manner and at the same time reduces the number of slots in the feasible schedule to achieve optimality. In this paper, we named this as Hybrid based Distributed Slot Scheduling (HDSS) approach. The proposed HDSS algorithm initially prepares a feasible schedule which is further tuned in quick time to prepare a valid schedule with a reduced number of slots. The reduction of the number of slots in the schedule improves the efficiency of data transmission in terms of latency. The simulation results show that the HDSS algorithm outperforms RD-TDMA with respect to both the number of slots allotted for a feasible schedule as well as the data transmission latency