Abstract:
In Wireless Sensor Network (WSN), nodes have to share the medium for data transmission.
Therefore, Medium Access Control (MAC) protocol has been developed
to provide collision free access through this common channel. Standard MAC protocols
for WSNs can be categorized into synchronous, asynchronous and hybrid.
Synchronous MAC protocols, specify the duration of wake-up and sleep time to
reduce the unnecessary communication time and energy wasted in idle listening.
One major drawback of these protocols is that they are highly dependent on clock
synchronization. On the other hand, asynchronous MAC protocols are found to
be more energy e cient compared to synchronous MAC protocols as they remove
the system overhead required for synchronization. However, asynchronous MAC
protocols inherently introduce high latency, especially in multi hop communication
scenarios. Another drawback is that nodes may severely su er from `hidden node
problem' due to the lack of synchronization. In this thesis, a multi-radio multichannel
based X-MAC protocol (MX-MAC) with the objective of eliminating hidden
node problem of existing asynchronous MAC protocol, as well as reducing average
packet delay is proposed. For multi-radio WSNs, each node is equipped with two or
more radio interfaces where one radio is dedicated to control channel and the rests to
data channel. Both the separate interfaces can be remain active and can send control
information and data simultaneously. To address the hidden terminal problem,
multi channel enables a receiver to send a preamble with next receiver ID on the
control channel to notify its neighbors that an ongoing reception is in progress and
alert intended next hop neighbor to wake up on time as well as to forward received
data to next hop without sending any additional preamble. In consequence of this
process, packet collisions are reduced and the network throughput is increased. In
order to carry out the performance analysis, analytical models of the existing XMAC/
CA, ZeroMAC, MCAS-MAC as well as the proposed MX-MAC protocols are
developed. Based on these models, di erent performance metrics of the proposed
MX-MAC protocol are compared with those of the existing asynchronous MAC protocols.
Analytical results show that the proposed protocol can signi cantly improve
the throughput as well as can reduce average packet delay.
