Multi-path routing in RPL for supporting bandwidth hungry applications

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.