Wireless sensor networks are battery operated computing and sensing devices that collaborate to
achieve a common goal for a specific application. They are formed by a cluster of sensor nodes
where each sensor node is composed of a single chip with embedded memory (microprocessor), a
transceiver for transmission and reception (resulting in the most energy consumption), a sensor device
for event detection and a power source to keep the node alive. Due to the environmental nature
of their application, it is not feasible to change or charge the power source once a sensor node is deployed.
The main design objective in WSNs (Wireless Sensor Networks) is to define effective and
efficient strategies to conserve energy for the nodes in the network. With regard to the transceiver,
the highest consumer of energy in a sensor node, the factors contributing to energy consumption in
wireless sensor networks include idle listening, where nodes keep listening on the channel with no
data to receive; ovehearing, where nodes hears or intercept data that is meant for a different node;
and collision, which occurs at the sink node when it receives data from different nodes at the same
time. These factors all arise during transmission or reception of data in the Transceiver module in
wireless sensor networks.
A MAC (Medium Access Control) protocol is one of the techniques that enables successful operation
while minimizing the energy consumption in the network. Its task is to avoid collision,
reduce overhearing and to reduce idle listening by properly managing the state of each node in the
network. The aim, when designing a MAC protocol for WSNs is to achieve a balance amongst
minimum energy consumption, minimum latency, maximum fault-tolerance and providing QoS
(Quality of Service).
To carefully achieve this balance, this dissertation has proposed, designed, simulated and analyzed
a new cooperative MAC scheme with an overhearing avoidance technique with the aim of
minimizing energy consumption by attempting to minimize the overhearing in the WSN. The new
MAC protocol for WSNs supports the cooperative diversity and overhearing communications in
order to reduce the effects of energy consumption thus increase the network lifetime, providing improved
communication reliability and further mitigating the effects of multipath fading in WSNs.
The MAC scheme in this work focuses on cooperation with overhearing avoidance and reducing
transmissions in case of link failures in order to minimize energy consumption. The cooperative
MAC scheme presented herein uses the standard IEEE 802.15.4 scheme as its base physical
model. It introduces cooperation, overhearing avoidance, receiver based relay node selection and a Markov-based channel state estimation. The performance analysis of the developed Energy Efficient
Distributed Receiver based MAC (E2DRCMAC) protocol for WSNs shows an improvement
from the standard IEEE 802.15.4 MAC layer with regard to the energy consumption, throughput,
reliability of message delivery, bit error rates, system capacity, packet delay, packet error rates, and
packet delivery ratios. / M.Sc.Eng. University of KwaZulu-Natal, Durban 2013.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/11421 |
| Date | January 2013 |
| Creators | Gama, Sithembiso G. |
| Contributors | Walingo, Tom., Takawira, Fambirai. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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