A detailed explanation regarding the entire work process is depicted in this section. In the proposed scheme, both primary user (PU) and secondary user (SU) are clustered initially based on the graph theory process. After that, the in each cluster, formation of Robust spatial Gabriel Graph takes place at which the neighbouring nodes are predicted by estimating the weighted end-to-end delay approach. Once the multi path decision making condition is satisfied, the route path is established, and the communication takes place based on QoS constraint. The flow of the entire process is given in figure provided below:
A. System model or Model initialization
In the system initialization, two scenarios viz., Secondary user’s (SUs) and Primary Users (PUs) were taken into consideration. For instance, the wireless microphones, Pus, cellular phones, or TVs are the considered at which the amount of wireless spectrum is licensed. On the contrary, the SUs is signified for those that are devoid of wireless spectrum pre-assigned. Moreover, the SUs equipped with the cognitive radio might transmit its own packets individually by the opportunities that seize once the primary user does not employ wireless spectrum that are licensed. From this approach, the wireless spectrum that are available to SUs are being separated as several channels, all having an unchanging frequency bandwidth number.
B. Construction of graph that are equivalent to network and the formation of cluster
The suggested technique undergoes two major steps termed construction of graph and the formation of cluster. At first, a graph is being built corresponding to the network, then the graph clusters are carried out for attaining the optimal range of cluster head. Therefore, the process of clustering is being initiated by means of presented Robust spatial Gabriel graph (RS-GG) approach depending on the objective functions that are designed newly which comprises of several parameters like connectivity, link failure, mobility, power, and the distance. The presented technique estimates the optimized power level so as to attain secured level of network connectivity while the nodes moving randomly. The network in turn adapts the graph for acquiring the secured network that is categorized as clusters by this presented approach. Each cluster’s cluster head is then selected with the utilization of fitness function computed depending on the left-over power of battery, mobility, connectivity, squared distance, and lifetime of link with respect to neighboring nodes. The node clustering is carried by means of RS-Gabriel graph for sustaining the optimal level of energy and power. The RS-GG in turn exploits the rigid clusters for offering the communication or transmission between sensor nodes and the base station. in this RS-GG, sensor node that are connected to cluster are considered as a member for that particular cluster all through the lifetime of network. The major reason for using this rigid cluster is to reduce the overhead energy consumption needed at each round of transmission for creating new clusters and is regarded as a general constrain for several WSN routing protocols. This RS-GG protocol operation comprises of two major steps like steady-state phase and set-up phase. In the set-up phase, the rigid clusters are being produced by the election of initial CH thereby resolving each sensor node’s remaining cluster membership and thus selecting the early relay node. By means of steady-state phase each CH starts to accumulate the information from their own cluster individually for the transmission to base station BS either directly or indirectly by relay nodes.
C. Formation of Robust spatial Gabriel Graph
The Gabriel Graph (GG) is regarded as the set of vertices in the plane at which the edges among two node exists in case if the other node is not coinciding with the edges among the two nodes. Each node in turn constructs the GG in the cluster wise manner for reducing the transmission power. The node in each clusters constructs the GG so as to assure network connectivity with reduced energy and transmission cost. In this, the links were formed to attain a reduced graph. Therefore, the graph is formed by taking the consideration of shorter path link instead of huge links. The multiple links were removed by this graph and the network connectivity is attained by this GG for each cluster. The power computation of the constructed graph is expressed as follows:
![](data:image/png;base64,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)
Here, T is represented as source node and Z as the destination node, and R is the distance among two nodes, ω signifies the channel loss component and the power is computed. Thus, the power needed for transmission depends on the distance among the source and destination nodes.
The formation of robust Gabriel graph is carried out from the clusters formed. In the cluster, prediction of each node and neighboring node is made by the reception of reply message at which the end-to-end delay with their weight is estimated by means of weighted end-to-end delay approach. The formed edge among the nodes is being checked. In case, the edges are formed, then the connectivity among nodes are established or else the connectivity is being discarded. Once the selection of optimal clusters is made, the GG is built in the corresponding cluster. Each node will then update and list out their neighboring nodes once the RS-GG is formed and thereby handles the connectivity and adjusts transmission of power. The power of nodes may drain out due to huge transmission, this drains out the behavior of node and at last it becomes a dead node. Therefore, the nodes that are having high power are taken for clustering purpose. The Gabriel Graph formed or constructed is regarded as the set of vertices in the plane at which the edges among two node exists in case if the other node is not coinciding with the edges among the two nodes. The construction of GG is made by each node of the cluster so as to mitigate the transmission power. This formed GG guarantees the connectivity of network with less transmission power with reduced rate of energy cost. Each node in turn constructs the GG in the cluster wise manner for reducing the transmission power. The node in each clusters constructs the GG so as to assure network connectivity with reduced energy and transmission cost. In this, the links were formed to attain a reduced graph. Therefore, the graph is being formed through considering shorter link in place of larger links meant for reducing the nodes transmission power. This procedure eradicates multiple links, which might result in disconnected graph and this could be eradicated by using this RS-GG for each cluster thereby maintaining the network connectivity.
Once the node receives RREQ, which is the destination of RREQ the node then adds/updates the entry of their respective routing table information which thus creates the Route Reply (RREP). The RREP is then telecasted to the basis of node; i.e., the expected path delay (EPD) field is set back to zero. The successive nodes that accept RREP keep on updating their route table information as per the conditions specified. The field of EPD’s RREP is being incremented by their equipped probable delay through node and then the RREP is forwarded after that the hop of source node’s direction is being recognized in the reverse-path manner at the process of route discovery and is based on the EPD. As a consequence, the node then checks their RREP table and thus forwards RREP to the hop by means of lesser EPD rate. Once the consecutive route reply is attained from different last hop, RREP is produced for each distinctive adjacent hop. Also, each middle node is responsible for promoting each destination and each source progression number that is carried for disjoints of node’s path that are guaranteeing. The Route Reply will be redundant if there is no availability of reverse path, which is besides due to the condition that the node is at the active path participation for a similar source destination pair. Once the source reaches the whole RREPs from the destination, the maximum of three paths employs the path by means of the lowest EPD value and keep others as backup routes in the state that the substantial path is failed for some purpose.
RERR (Route Error message)
The route maintenance is the extension and is attained by means of packet route error (RERR). Once the intermediate node recognizes the link or node failure as their hello message, mobility, and so on are undetected and thus produces the packet RERR. The RERR packet thus broadcasts over the entire nodes that have the path in course of failed link thereby invalidating the entire nodes with the entire accessible paths alongside it comprises of the link-based paths that are unsuccessful. If the RERR packet is supposed to reach the source, the tranquil source is in need of destination enabled paths, and in such case, it switches to the next available path at the source node. Once the whole paths are not legal a tranquil source requirement of the path is needed for the analogous destination, the source in turn starts the fresh process of route discovery.
Prediction of neighbor node by Weighed end to end delay approach
The trusted neighbor node identification is made by means of weighted end-to-end delay approach. The delay based on number of hops and packets to be sent were affected during transmission since the source and destination keeps on changing the topology according to the length of hop with respect to time and speed. The path length is directly proportional to ethe end-to-end delay of the packet. This e-2-e delay also gets increased once the length of packet increases. The packet delay and length have the strong bonding at which the path weightage length among each node from source is estimated along with the computation of shortest path. The weighted node is the one having limited short distance and lack of breakage in link with less traffic load and is regraded as the authentic node. The packets can be sent directly to the destination node after the reception of node information. In this process, the energy is also saved along with time. That particular weighted node is responsible for broadcasting the information or message in the network at regular basis. Upon receiving the information’s, each node updates their own routing table. The focus node changes their locally maintained neighbor table as per the information received from the neighbor node. From this updation of information in routing table, the lifetime relation and the approximate bandwidth of the neighbor node is computed. Once the best optimal and shortest path is found having less traffic load, the data is sent straight from the source to destination node.
D. Maintaining the connectivity
The link breakage probability belongs to the established path and is being monitored by means of established signal strength from the next hop node in real-time. Once the probability of link interruption is set ahead of threshold, the source node then switches and notifies the alternating path for maintaining the process of transmission. So as to keep the traffic load increment ahead in the network, the system in turn employs the HELLO packets periodically for intellectual stability of the link. In this process of link monitoring, the relative distance among the nodes is employed for the estimation of possibilities of link discontinuity. The relative distance among the nodes is then estimated from the HELLO packet’s signal strength. The node never needs the comparative distance of whole adjacent nodes for reducing the computational overhead, moreover it requires simply the distance from next-hop of the node.
![](data:image/png;base64,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)
Here,
and un is the destination node. If the sn+1 value is better than the range of communication, the node then sends the packet of information to the source node instantly. In this, probability of link failure and monitoring are carried effectively which signifies the falsehood and truthfulness degrees proportions.