# FuGeF: A Resource Bound Secure Forwarding Protocol for Wireless Sensor Networks
## 4 The Proposed FuGeF Protocol
### Design Parameters in FuGeF  
In this section, we detail more on the parameters used in our proposed protocol.  
1. _Progressive distance (Pd)_: This is the Euclidean distance from the sending node to each candidate nodes within the broadcast range. It enables the sender to determine the position of a nodes within its range and their progress toward the destination (Unlike IDTD). This information also allows the sender to determine its link strength relative to the candidate nodes within its range.
2. _Connectivity cost (C)_: Modeled as a function of distance as shown in Equation (1), the connectivity cost denotes the loss in link/connection quality between the sending node and the forwarding candidates, due to the gap existing between the nodes. This gap determines the weak and good connection quality in the network. The larger the gap between the nodes, the weaker is the connection. \[C=\frac{1-Pd}{Radius}\] (1)The parameter is derived from Equation (2), which has been adopted from [PERSON] _et al._ in [30] as follows: \[Q=\frac{(Wp\times\frac{1-Pd}{Radius}+Wr\times rand())}{(Wp+Wr)}\] (2) where \(Wp\) is the weight of progress, \(Wp\) is the weight of randomness, \(Pd\) is the Progressive distance and Radius is the Range. The cost \(Q\) was also utilized in FuGeF, as it determines the distribution of nodes within the 60-degree sextant region. \(Q\) depends on both \(Wp\) and \(Wr\). The higher the value of \(Wp\), the more it enhances the few nodes with the most progressive distance value (leading to shorter routes to the destination) with the least traffic distribution and lower connectivity cost. On the other hand the higher the value of \(Wr\), the more distributed are the traffic to more nodes, leading to better load balance and higher connectivity cost [30]. Information regarding node's connectivity cost is useful towards enhancing node selection. In this paper, to obtain candidate nodes that have made significant progress with links that are good enough to prevent excessive packet loss when routing, we assumed \(Wp=Wr\).
3. _Remaining Energy (RE)_: Otherwise known as residual energy is considered as one of the most important parameters in WSN's technology because it determines the lifetime of a node in a network. Using the first order radio model [31], remaining energy of a node is calculated as \[RE=NodesInitialEnergy-(E_{Tx}+E_{Rx})\] (3) where \(E_{Tx}\) and \(E_{Rx}\) are the Transmit and Received Energy, respectively, which are calculated as follows: \[E_{Rx}=E_{elect}\times k\] (4) \[E_{Tx}=E_{Rx}+\epsilon_{amp}\times k\times d^{2}\] (5) where: \(\epsilon_{amp}\) and \(E_{elect}\) are Transmit amplifier and Electronics Energy, respectively. \(k\) and \(d\) are bit message communicated and distance between two nodes, respectively. In this paper, only transmit and received modes were utilized because they represent the main energy consuming modes in any communication process. A node with the highest remaining energy is deemed as the most reliable.  
These three locally generated parameters provide external information about a node in the network, each of them can be used (independently) to make forwarding decisions in the protocol. However, in this paper, all the parameters are simultaneously utilized for selecting a forwarding node based on reliability theory. The proposed parameters are processed using the FLS to enable selection of an appropriate node.