International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438 Volume 4 Issue 1, January 2015 www.ijsr.net Licensed Under Creative Commons Attribution CC BY QoS Routing Protocols in MANETs - A Review Shreekant Telang 1 , Megha Singh 2 1 RGPV University, Central India Institute of Technology, Indore - Dewas Bypass Road, Village- Arandiya, Indore (M.P.), India 2 HOD-CS, Central India Institute of Technology, RGPV University, Indore-Dewas Bypass Road, Village- Arandiya, Indore (M.P.), India Abstract: A Mobile Ad hoc Network (MANET) is an autonomous amalgamation of mobile nodes that form a dynamic network and communicating over wireless links. Owing to its unique abilities such as easy deployment and self-organizing capability, it has shown enormous potential in many applications. As MANETs popularity is increasing, their need to facilitate real time and multimedia applications is growing as well. Such applications have Quality of Service (QoS) requirements such as bandwidth, end-to-end delay, jitter and energy. Consequently, it is becoming very necessary for MANETs to have an efficient routing and QoS mechanism to facilitate these applications. There are several number of QoS routing protocols with distinguishing features that have been proposed recently. This paper presents a detailed overview of some of the QoS routing protocols along with their respective strengths and flaws. A comparative study of the QoS routing protocols is done and future prospects are also presented. Keywords: MANETs, QoS, Routing protocols, Ad-hoc networks. 1. Introduction A mobile ad hoc network (MANET) is a collection of randomly changing wireless devices (also called nodes) within a predefined area. Unlike in cell based networks, there is not any particular fixed base-stations for supporting routing and mobility management. The wireless nodes are equipped with individual wireless transmitter and receivers that facilitate communication with each other without using the help of wired base-stations. Since every transmitter have a fixed effective range, far away nodes communicate through multi hop paths with the help of using other nodes in the middle that serve as routers. These networks are especially suitable for run time emergent situations like warfare, natural calamities and other disasters where other infrastructure based networks are inefficient to operate. Routing is one of the primary problems for data transfer between several nodes in networks. Several routing protocols have been under study for wireless networks, such as Dynamic Source Routing protocol (DSR) [1], Ad hoc On- Demand Distance Vector (AODV) protocol [2], Temporally Ordered Routing Algorithm (TORA) [3] that establish and maintain routes on a particular network with maximum efficiency possible. These protocols are restricted in a sense that they do not consider quality of service of the routes that they generate. By QoS we mean that they have to provide guarantee to the end to end node delivery in a diverse situations. This particular characteristic is missing from the above mentioned protocols. A number of QoS routing protocols having distinguishing features are proposed in recent years. Most of QoS routing protocols are nothing but extensions of existing routing protocols, so they can be classified into two distinct categories: table-driven protocols (proactive) and on-demand protocols (reactive). In table driven protocols routing information is kept tall the time whether the nod is transmitting or not whereas in on demand protocols these information are not kept in advanced but are taken only when the node need to send data. In this research work, a few of the reactive QoS routing protocols have been studied which provide QoS using distinct approaches. The strengths and weaknesses of these QoS routing protocols have been discussed. Finally, a comparison of the routing protocols has been made to further facilitate research in this area. The rest of the paper is organized as follows. In section II, survey of some of the diverse QoS protocols has been discussed. In section III, a comprehensive comparison of the QoS routing protocols based on certain parameters and features has been completed. Finally, section IV contains the conclusion and future work for the research community. 2. QoS Routing Protocol of Survey A. Q-AOMDV C.Wu et al. [9] presented an ad hoc on-demand multipath routing (Q-AOMDV), which provides Quality of Service (QoS) support, in terms of bandwidth, hop count and end-to- end delay in mobile ad hoc networks (MANET). The protocol uses path preference probability that is calculated by using the parameters such as delays, bandwidth, and no of hops to select the path for transmitting the packet. For discovering the route for the message the node gives the ROUTE REQUEST (RREQ) message to the entire network. Because of the flooding of this packet, several duplicates reach the destination. The destination node then sends the RREP packets back to the source that gives the source information about the routing mechanism to be used for further communication. The RREQ message that is received contains the several QoS parameters discussed above. The performance of Q-AOMDV has been compared with AOMDV [10] by C. Wu et al. [9] and it performed much better than the existing AOMDV protocol for the metrics such as packet delivery ratio, normalized control overhead and end-to-end delay. This protocol has multi path capability which is providing way better data routing capability as compared to AOMDV. Paper ID: SUB15323 1022