An efficient multichannel wireless sensor networks MAC protocol based on IEEE 802.11 distributed co-ordinated function.

This research aimed to create new knowledge and pioneer a path in the area relating to future trends in the WSN, by resolving some of the issues at the MAC layer in Wireless Sensor Networks. This work introduced a Multi-channel Distributed Coordinated Function (MC-DCF) which takes advantage of multi-channel assignment. The backoff algorithm of the IEEE 802.11 distributed coordination function (DCF) was modified to invoke channel switching, based on threshold criteria in order to improve the overall throughput for wireless sensor networks. This work commenced by surveying different protocols: contention-based MAC protocols, transport layer protocols, cross-layered design and multichannel multi-radio assignments. A number of existing protocols were analysed, each attempting to resolve one or more problems faced by the current layers. The 802.15.4 performed very poorly at high data rate and at long range. Therefore 802.15.4 is not suitable for sensor multimedia or surveillance system with streaming data for future multichannel multi-radio systems. A survey on 802.11 DCF - which was designed mainly for wireless networks –supports and confirm that it has a power saving mechanism which is used to synchronise nodes. However it uses a random back-off mechanism that cannot provide deterministic upper bounds on channel access delay and as such cannot support real-time traffic. The weaknesses identified by surveying this protocol form the backbone of this thesis The overall aim for this thesis was to introduce multichannel with single radio as a new paradigm for IEEE 802.11 Distributed Coordinated Function (DCF) in wireless sensor networks (WSNs) that is used in a wide range of applications, from military application, environmental monitoring, medical care, smart buildings and other industry and to extend WSNs with multimedia capability which sense for instance sounds or motion, video sensor which capture video events of interest. Traditionally WSNs do not need high data rate and throughput, since events are normally captured periodically. With the paradigm shift in technology, multimedia streaming has become more demanding than data sensing applications as such the need for high data rate protocol for WSN which is an emerging technology in this area. The IEEE 802.11 can support data rates up to 54Mbps and 802.11 DCF was designed specifically for use in wireless networks. This thesis focused on designing an algorithm that applied multichannel to IEEE 802.11 DCF back-off algorithm to reduce the waiting time of a node and increase throughput when attempting to access the medium. Data collection in WSN tends to suffer from heavy congestion especially nodes nearer to the sink node. Therefore, this thesis proposes a contention based MAC protocol to address this problem from the inspiration of the 802.11 DCF backoff algorithm resulting from a comparison of IEEE 802.11 and IEEE 802.15.4 for Future Green Multichannel Multi-radio Wireless Sensor Networks

A taxonomy and evaluation for developing 802.11‐based wireless mesh network testbeds

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92433/1/dac1299.pd

Channel Allocation in An Overlaid Mesh Network

In spite of recent advancement of Wireless Mesh Technology, a lot of research challenges remained to be solved to extract the full capacity of this modern technology. As 802.11a/b/g standards make available the use of multi radio multi channel in a wireless node, a lot of research activities are going on to efficiently allocate the channel of a Mesh Network to boost its overall performances. In this research, the prospect of dividing the total network area into two non-overlapping channels of a given Mesh Network is investigated and analyzed numerically. It is found that the throughput is doubled as well as the fairness improves considerably if we deploy two channels instead of single channel backbone. An extensive simulation study has been carried out to find the optimum coverage area between two channels. The study shows that at a particular point of allocation, the network gives the optimum response.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Dish networks: Protocols, strategies, analysis, and implementation

Ph.DDOCTOR OF PHILOSOPH

A study on stryi-icnos potatorum and pisum sativum as natural coagulants for meat food processing wastewater

Slow maintained load test is widely used by contractors in Malaysia to ensure the driven pile could accommodate the design load of the structure. Slow maintained load test is a test to determine load-settlement curve and pile capacity for a period of time using conventional load test. Conventional static pile load test equipment is large in size thus making it heavier and takes a long time to install. In addition, it consumes a lot of space which causes congestion at construction sites. Therefore, the objective of this thesis is to conduct a conventional load test by replacing the pile kentledge load with anchorage and reaction pile. Preparations of ten designs comprising six commercial designs were reviewed. In addition, four proposed designs were suggested for the setup. Final design was produced based on its safety factors and criteria referred via literature review. The test frame consists of reaction frame with four reaction helical pile with two helixes per reaction pile. The deformation shapes, safety factor, stress, and strain of the design and finite element of the model has been analysed with the use of SolidWorks and Pia.xis 30 software. SolidWorks software emphasizes on the model load-deflection relationship while Plaxis 30 ensures a correlation of reaction between pile uplift force and soil. Then, the model was tested on site to determine the relationship between physical load­deflection and pile-soil uplift force. The results of uplift force and displacement for numerical and physical test were nearly identical which increment of load­displacement graph pattern. The higher the uplift force, the higher the displacement obtained. In conclusion, the result obtained and the design may be considered as a guideline for future application of sustainable slow maintained pile load test

A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks

In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs