**2.2.3 FSR protocol (Fisheye State Routing)**

252 Real-Time Systems, Architecture, Scheduling, and Application

This protocol is based on the BELLMANFORD routing idea, with a series of improvements [Bagad V. S and Dhotre, 2009]. Each mobile base maintains a routing table that includes all accessible destinations, the number of hops necessary for reaching that destination and the sequence of the digits appropriate to that destination. This sequence of digits is used to distinguish new routes from old routes and to determine the creation of a ring. In DSDV, stations send their routing tables alternatively to their direct neighbors [Maan. F and Mazhar. N., 2011]. Tables are updated generally in two perfect updating and incremental updating methods. Any route updating package increases information about routing. This protocol performs periodic updates, but also generates a supplementary traffic that adds to

This protocol is based on the DSDV routing algorithm. Mobile nodes are collected inside packets, and a cluster head is selected. A gateway node is a node in a communication interval between two or more cluster heads. In a dynamic network, the idea of a cluster head can decrease the efficiency resulting from the frequency of selecting cluster heads. Thus, CGSR uses an algorithm to change the last cluster or LCC. [Murthy S and Aceves J. J,

In LCC, a change in cluster head is made when changes are made in the network. In this state, the origin sends the packet to its cluster head; the cluster head sends this packet to the gateway node to which it and the node which is located in the route of destination are connected. The gateway sends the packet to another cluster head and this action continues until the cluster head receives the destination node of packet. Finally, the destination cluster head sends the packet to the destination node [Boukerche. A et al, 2011]. Figure 4 indicates

**2.2.1 DSDV (Dynamic Destination-Sequence Distance – Vector routing protocol)** 

**2.2.2 CGSR Protocol (Cluster head Gateway Switch Routing protocol)** 

the real data traffic. [Bamis. A et al, 2007].

an example of a CGSR routing plan.

Fig. 4. Example of CGSR routing from node 1 to node 12

1996].

In an FSR, an updating message does not include information about all of the nodes. Instead, it exchanges information with the adjacent nodes with a higher frequency more than it does with farther nodes, leading to a decrease in the size of the updating message [Pei. G et al, 2000]. Thus, each node has accurate information about its neighbours, and the details and accuracy of the information decrease when the distance between two nodes increases. Figure 5 defines the area of a fisheye for a central node that has been indicated in red [Boukerche. A et al, 2011].

Fig. 5. Accuracy of information in FSR protocol

The central node should know more detail about the nodes that are located inside the white circle. FSR is suitable for massive networks, because in this method, overload is controlled [Liu. Y et al, 2004].
