AOLSR: hybrid ad hoc routing protocol based on a modified Dijkstra's algorithm

Natarajan and Rajendran EURASIP Journal on Wireless Communications and Networking 2014, 2014:90 http://jwcn.eurasipjournals.com/content/2014/1/90 RESEARCH Open Access AOLSR: hybrid ad hoc routing protocol based on a modified Dijkstra's algorithm Dhanalakshmi Natarajan1* and Alli P Rajendran2 Abstract Mobile ad hoc networks (MANETs) are highly vulnerable to both link and node failures due to nodal mobility. The routing resilience against link and/or node failures needs to be enhanced to avoid the degradation of network performance. This can be achieved by multipath routing which uses multiple alternative paths to route the messages via multiple disjoint paths and result in increased bandwidth, fault-tolerance, and security. An optimized link state routing (OLSR) protocol is a proactive routing protocol. An advanced OLSR (AOLSR) protocol is proposed based on a modified Dijkstra's algorithm which enables routing in multiple paths of dense and sparse ne0074work topologies. The routing is based on the energy of nodes and links (implied from the lifetime) and the mobility of the nodes. It is a hybrid ad hoc routing protocol because it combines the proactive and reactive features. It is another form of source routing protocol which allows a sender of a data packet to partially or completely reveal the route the packets take through the network. Two cost functions are introduced to build link-disjoint or node-disjoint paths. Secondary functions, namely path recovery and loop discovery process are involved to manage the topology changes of the network. AOLSR protocol is analyzed and compared with the existing MANET routing protocols namely, dynamic source routing (DSR) and OLSR. Its performance is observed to be satisfactory in terms of average end-to-end delay, packet delivery ratio (PDR), average time in first-in-first-out (FIFO) queue, and throughput. Keywords: Dynamic source routing (DSR); Dijkstra's algorithm; Mobile ad hoc network (MANET); Packet delivery ratio (PDR); Optimized link state routing (OLSR); Quality of service (QoS) 1. Introduction Network connectivity is an important aspect of mobile technologies. An advantage in mobile ad hoc networks (MANETs) is that all the nodes can act as routers to forward the packets without any additional infrastructure. This is efficient due to its self-coordinated, self-maintained, and spontaneous nature. Data routing in such networks is a challenging task owing to the lifetime, scalability, and security issues. Several routing protocols have been designed for ad hoc networks. The link failures and node failures in ad hoc networks form a major problem due to the depleted node mobility or node power and might break down the path for routing. The routing resiliency can be enhanced by simultaneous routing of a message through multiple disjoint routes. This will ensure that the destination * Correspondence: 1 Department of Information Technology, NPR College of Engineering & Technology, Natham, Dindigul, Tamil Nadu 624003, India Full list of author information is available at the end of the article node will receive the message. Multipath routing protocols are advantageous especially in large and dense ad hoc networks. They solve the limitations in bandwidth and energy consumption. The primary goals of a multipath routing protocol are to balance the network load, decrease the intersection of nodes or connections among the parallel routes, enhance the quality of service (QoS), and ensure that reliable communication is provided, while the secondary goals are to decrease the delay, overhead, and increase the network lifetime. A link failure in one path should not affect other routes. The multiple paths utilized in this type of routing protocol can act as backup routes or additional routes for parallel data transmission. A hybrid ad hoc routing protocol is a combination of proactive and reactive routing protocols. A proactive routing protocol maintains a routing table (next hop information) for all potential destinations and so it is also known as table-driven routing protocol. A reactive routing protocol determines a route only on demand by © 2014 Natarajan and Rajendran; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. Natarajan and Rajendran EURASIP Journal on Wireless Communications and Networking 2014, 2014:90 http://jwcn.eurasipjournals.com/content/2014/1/90 inundating the network with route request (RREQ) packets and so it is also known as an on-demand routing protocol. An optimized link state routing (OLSR) protocol is a proactive routing protocol. An advanced OLSR (AOLSR) protocol is proposed based on a modified Dijkstra's algorithm which permits routing in multiple paths of dense and sparse network topologies. The routing is based on the energy of nodes and links (implied from the lifetime) and the mobility of the nodes. Energy factors are used to determine the multiple parallel and disjoint routes. AOLSR is a hybrid ad hoc routing protocol because it integrates the proactive and reactive characteristics. It is also a source routing protocol which permits the sender of a data packet to partially or completely reveal the route that the packets traverse through a network. This enables the discovery of all possible paths to a host. Two cost functions are introduced to construct link-disjoint or node-disjoint routes. Secondary functions namely, path recovery and loop discovery process are included to manage the topology changes of the network. The network topology varies frequently due to the movement of the mobile nodes and energy constraints. The remaining part of the paper is organized as follows: section 2 involves a brief description of the existing methods - dynamic source routing (DSR) and OLSR and the problems involved in them. Section 3 involves the works related to probable solutions for problems in DSR and OLSR in terms of routing overhead and QoS. Section 4 involves the description of the proposed method - advanced OLSR (AOLSR). Section 5 involves the performance evaluation and comparison of AOLSR and existing techniques based on DSR and OLSR. The paper is concluded in section 6. 2. Existing methods Two existing routing protocols for MANET are considered. One is the DSR which is a reactive routing protocol and another one is the OLSR protocol which is a proactive routing protocol. 2.1 Dynamic source routing protocol In DSR [1], the mobile nodes maintain the path caches that comprise the pre-known source routes. The elements of the path cache are updated as the new paths are discovered. This protocol consists of two functions namely, path discovery and path maintenance. When a packet is to be transmitted to a destination, the source node first determines whether its p (...truncated)