Abstract:
IPv6 routing protocol for low-power and lossy networks (RPL) is one of the most interesting
research areas in the domain of wireless personal area networks (WPANs). RPL is the standard
IPv6 based protocol for routing over low power, lossy networks (LLNs) to allow the integration
of wireless sensor networks (WSNs) on the Internet. It is proposed for networks with
characteristics like small packet size, low bandwidth, low data rate and low power. RPL creates a
directed acyclic graph (DAG) of the network topology for routing. RPL defines different metrics
like hop count, energy consumption and throughput for defining object function in RPL that is
used for routing path selection. Since, RPL is a proposed underlying protocol for IPv6LoWPAN
therefore its objective function is optimized to select routes for low data rate applications.
However, RPL is increasingly used for internet of things (IoT) which can comprise of
heterogeneous networks and applications. One of the most promising applications of IoT is
surveillance using multimedia sensor networks. In surveillance application, the amount of sensed
data can be many folds as compared to scalar data. Also, low latency of information delivery is
critical in multimedia applications. RPL is proposed as a single path routing protocol and the
existing objective functions do not support creation of multiple routing paths between source and
destination. Multipath routing is an important strategy used in both sensor and ad-hoc network
for performance enhancement. Multipath routing can be used to achieve multi-fold objectives,
including higher reliability, increase in throughput, fault tolerance, congestion mitigation and
hole avoidance. The main idea of multi-path routing is to provide multiple paths for information
to reach the destination. In order to support high date rate and maximize network life time RPL
can be enhanced to support multipath routing in RPL. In existing literature, very little work is
done in the field of multipath routing in RPL. In this thesis, M-RPL a multi-path extension of
RPL is proposed that aims to provide temporary multipath routing during congestion over a path.
Congestion is primarily detected by a forwarding node by monitoring buffer size and is mitigated
by partially disjoint multipath routing. Detailed simulation analysis of M-RPL against RPL in
both grid and random topologies shows that using multi-path RPL can support high data rates.
