Survey on Load balancing protocols in MANET S (mobile ad-hoc networks) Ramandeep Kaur 1, Gagandeep Singh 2, Sahil Vashist 3 1 M.tech Research Scholar, Department of Computer Science & Engineering, Chandigarh Engineering College, Landran(Mohali),Punjab, India 2 Asstt Professor, Department of Computer Science and Engineering, Chandigarh Engineering College, Landran(Mohali),Punjab, India Abstract In this paper we describe about mobile ad hoc networks(manet S) and the load balancing schemes used in manet s.a selfconfiguring, a MANET, is a network of mobile devices connected by wireless links. Devices in MANET are free to move in any direction and so they change their links to other devices frequently. The nodes that are more powerful in a mobile ad hoc network finish their assigned tasks as soon as possible and become idle much earlier than those which are less powerful and do their tasks slowly. If we split the efficiency of the nodes on multiple paths then the source to destination flow could be speed up. this scenario is called as load balancing and is used for improving the efficiency of the application. The basic utilization of such a scheme is to decrease the difference between overloaded and under loaded nodes, maximize the use of the network resources, minimize end-to-end delay and to minimize congestion. This scheme prevents the network to go in congestion state and avoid the resouces of congested node to be exhausted. Keywords : mobile ad-hoc networks, load balancing scheme, load balancing Routing Protocols. 1. INTRODUCTION 1. MANET S In mobile ad hoc networks nodes are free to move anywhere in any direction and also without any prior knowledge. In short manet s are synamic in nature The characteristics of manets are:- (a) Dynamic nature- the nodes in manets are free to move anywhere and at anytime (b) Increased packet loss- because of the unstable links and the transmission errors there are a large chances of packet loss. (c) Bandwidth is limited- because of the lower bandwidths the data rates are also low. 2. AD-HOC NETWORKS With no fixed routers in the ad-hoc networks the nodes are capable of movement and can be dynamically connected in any manner. The whole network is mobile and the individual nodes are free to move. The nodes in this network behave as routers which perform functions like discovering and maintaining routes to the other nodes in a network. 3. MANET APPLICATIONS Day to day life applications of manets are as follows (a) Military functions- manets are useful in automation of battlefields through sensor networks (b) Emergency operations- the services such as search and rescue operations, hospital services and disaster recovery etc are the emergency services served by manets. (c) Educational areas- virtual classroom setting, ad-hoc communication through lectures and meetings, online distance education and college campus etc are the examples of educational services provided by the manets (d) Home and entertainment services- muti user gaming facility, theme park setups, robotic parks etc are also applications of manets (e) E-Services- E-banking and E-commerce, that is business anytime and anywhere makes use of the manet networks.. 2. LOAD BALANCING SCHEMES In manets when a node is powerful and completes its work and becomes idle before a less powerful node,which is occupied all the time and consumes more energy. The data flow from source to destination could be effectively controlled and split on multiple paths between the nodes,this scheme is called as load balancing schemes. The difference between a overloaded and an under loaded node is effectively improved by the load balancing technique. It helps to improve the life Volume 3, Issue 5, May 2014 Page 88
of the nodes which is called as the network lifetime. The load balancing technique also helps to improve the end-to-end delay and also minimizes congestion as all the load that comes on the nodes are distributed to the nodes that remain idle at that time. PURPOSE OF LOAD BALANCING TECHNIQUE- The overall purpose of balancing the load from the source node to the destination load on a network is as follows:- (a) Firstly we select the non congested paths so as to distribute the load on the paths that remain idle. (b) The load balancing schemes ensure the efficiency and robustness. (c) It helps to reduce the end-to-end delay and the overflow that is the packet loss(in case a node gets over packets to deliver than it can deliver. (d) It also balances the energy consumption of the nodes in the network. (e) It also enhances the utilization of resources in the network (f) It helps to improve the overall performance of the network. (g) It helps to reduce collision by the distribution of load. 3. LOAD BALANCING SCHEME PROTOCOLS (a) DLAR PROTOCOL (dynamic load aware routing):- This protocol takes the intermediate nodes load as a metric for selection of the route and then it detects the status of the routes that are active to construct the paths when the nodes of the route have overloaded interface queue. The RRQ (route request ) packet is flooded to the discovery of the route from source. DLAR dynamically builds the route when in case there is no information about the destination node. It follows the backward learning that is it records the <source,destination> node and searches for the previous hop. The load information is attached to the RRQ packet. The destination now at this time waits for some time to learn about all possible routes. This protocol does not facilitate REQUEST REPLY to be send from that routes. In case the REQUEST REPLY is also send then the congestion will take place. DLAR does not allow congestion and so does not allow sending of REPLY via that route. When the active sessions occur the nodes piggyback their load information on the data packets. These data packets now have the information which the destination receives and so the destination comes to know whether the path is congested or not. In case the path is congested, a new and light path is constructed so that the data packet can be send safely over that route to the destination without congestion. (b) LARA PROTOCOL (load aware routing):- Traffic density is a parameter in LARA which is used for mobile ad-hoc networks load balancing. Traffic density is a degree of contention at the MAC layer. When the route is being set then at that time this metric is used to select the path which has minimum traffic density. Each node in LARA maintains the traffic queue latest estimation as a neighbourhood table. LARA BROADCASTS are of 2 types:- ROUTE REQUEST- In this the node attempts to discover the route to destination. HELLO PACKET BROADCASTING- it is explained below with the help of a flowchart. Important points about hello packet broadcasting:- 1. When a new packet comes from a new node the neighbourhood node updates the neighbourhood table. 2. In case a message is not received in some particular time then it is assumed that the node has lost its radio signal and updations are made in the neighbourhood table. Important terms used in LARA:- 1. Traffic Queue- in a period of time when the average of the interface queue length value is calculated then it is called traffic queue. Q t = N k=1 Q t / N 2. Traffic density- the node t has the traffic density as the sum of traffic queue (Q t ) plus the traffic queue of all neighbours. Volume 3, Issue 5, May 2014 Page 89
Q t = j N(t) Q j (c) D-LOAR PROTOCOL (delay aware on demand routing)- Two main things are a maor concern in DLOAR Hop count Total path delay DLOAR has the implementation of a new route selection in which the packet which is congested is dropped. DLOAR drops a packet in two situations:- The total node delay of node i is greater than that of node j When the total number of packets that are being queued at the interface queue of node i is more than the buffer size by 80% (d) SLAR PROTOCOL (simple load balancing ad-hoc routing)- This protocol has a few advantages over the others- Reduces the severe battery power consumption caused by forward packets Reduces overhead (e) WLAR PROTOCOL (weighted load balancing aware routing)- This protocol is defined for those networks which neither reflect congestion nor burst traffic. (f) LBAR PROTOCOL (load balancing ad-hoc routing)- The major concern here is packet transmission delay mostly. The purpose here is to find the most optimal path on which the packets are send so that there is least delay on the transmission. Degree of nodal activity- It represents the load on the metric node. The purpose is started only when one node has to communicate with the other node and the route is also unknown. There are two stages in this process:- Forward stage- it is started at the source node where a setup message is broadcasted to its neighbours. Setup message carries the cost from node 1 to the current node. The node which receives the setup message will send it to all its neighbours the same way and also update its cost which will be on nodal activity. All setup messages have route records to prevent looping. collects the setup messages within a predefined time for selecting the best cost path called route select waiting period. Backward stage- it starts from the last node when acknowledgement is send backwards to the source node on the best selected path which we call as the active path. The cost function is used to select the path from the node to destination which fulfils the goal. (g) DSR PROTOCOL (dynamic source routing)- It is the simplest and the most effectively used protocol for balancing load in mobile ad-hoc networks. It enable a network to be completely self organising and self configuring. It follows two processes- Route Discovery When a source node n wants to send the data to destination node d only then the route is to be discovered between source node n and destination node d. Route Maintenance In some cases it is possible that node n which is the source node while sending packets to the destination node d, the route does not work any longer on that context either some other route is followed or the route discovery is called again to select a route from source node n to destination node d. Maintenance is only used used on this route when node n is actually sending data to destination node d. ROUTE DISCOVERY- ROUTE REQUEST ROUTE REPLY Volume 3, Issue 5, May 2014 Page 90
ROUTE REQUEST- node a wants to send the data to node e but does not know the path. It has a unique identification number (id=4) It also contains address of each node through which the nodes are passed or forwarded. ROUTE REPLY- when the target (node e) receives the packet then it sends the signal back with the route information. It caches the route in the route cache and then the packets are send to destination. Volume 3, Issue 5, May 2014 Page 91
4. TABULAR COMPARISION OF PROTOCOLS PARAMETERS DLAR LARA D-LOAR LBAR WLAR SLAR Route criteria selection No. of packets in interface Traffic density Cost of path delay and hop count Degree of nodal activity Total traffic load Forwarding load Routing path Single path Single path Multipath Single path Multi path Single path Category Traffic size Traffic size Delay Traffic size Delay Traffic size Traditional used Neighboring considerations protocol load DSR DSR ADOV DSR ADOV ADOV + DSR No Yes No Yes No No Load decisions balancing Intermediate -node- Interface queue No Yes Yes No Yes No Advantages Routes are reconstructed dynamically in advance of congestion Uniformly distributes the load among all the nodes in the network, leading to better overall performance Increases packet delivery fraction and decreases end-to-end delay in a moderate network scenario in comparison to ADOV and LOAR protocols other Mainly indented for connectionless applications Avoid influencing of burst traffic Reduces message overhead 5. CONCLUSION In this paper we have discussed important issues on load balancing in mobile ad-hoc networks. The nodes which are heavily loaded and which consume high power and also cause congestion are of a major concern here. Here we have discussed about the protocols which are used to balance the load in mobile ad-hoc networks (MANET S). The load balancing protocols help to minimize the congestion and helps in full node utilization. The nodes that remain idle at a particular time while the others are communicating in a network are balanced here. These protocols in MANET S help to minimize end-to-end delay and maximize mobile nodes packet delivery ratio and throughput. REFERENCES [1] AELB: Adaptive and Efficient Load Balancing Schemes to Achieve Fair Routing in Mobile Ad hoc Networks (MANETs) by Shruti Sangwan, Nitin Goel, Ajay Jangra in ISSN: 2229-4333 (Print) ISSN : 0976-8491 (Online ) IJCSTVol. 2, Issue 3, September 2011. [2] S. J. Lee, M. Gerla, Dynamic Load Aware Routing in Ad Hoc Networks, Proc. ICC 2001, Helinski, Finland, June 2001, pp. 3206-3210. [3] V. Saigal, A. K. Nayak, S. K. Pradhan, and R. Mall, Load Balanced routing in mobile ad hoc networks, E lsevier Computer Communications 27(2004), pp. 295-305. [4] H. Hassanein, and A. Zhou, Load-aware destination-controlled routing for MANETs, Elsevier Computer Communications 26(2003), pp. 1551-1559. Volume 3, Issue 5, May 2014 Page 92
[5] K. Wu, J. Harms, Load Sensitive Routing for Mobile Ad Hoc Networks, Proc. IEEE ICCCN 01, Phoenix, AZ Oct. 2001, pp. 540-546. [6] A Distributed Load Balanced Routing Protocol for Real-Time Traffic in Mobile Adhoc Networks P. Sivakumar and K. Durai Swamy European Journal of Scientific Research ISSN 1450-216X Vol.53 No.4 (2011), pp.626-636 EuroJournals Publishing, Inc. 2011. [7] Node Centric Load Balancing Routing Protocol for Mobile Ad Hoc Networks Amjad Ali, Wang Huiqiang, IMACS 2012. Volume 3, Issue 5, May 2014 Page 93