# DOW-PR DOlphin and Whale Pods Routing Protocol for Underwater Wireless Sensor Networks (UWSNs)
## 6 Performance Comparison and Analysis  
We evaluate DOW-PR against WDFAD-DBR and DBR in term of APD, energy tax, end-to-end delay, packets dropped number and alive nodes number for different ranges of \(PFN_{num}\) and \(SUP_{num}\). We defined the measurement sets (SET1, SET2, SET3) of three different ranges for \(PFN_{num}\) and \(SUP_{num}\) as shown in Tables 2 and 3, respectively. The simulation results for SET3 gives optimal results in comparison to the other two in terms of all metrics. Therefore, SET3 is found to be the best selection for simulation (refer to Figure 11).  
Figure 11: (**a**) PDR vs. number of nodes; (**b**) energy tax vs. number of nodes; (**c**) end-to-end delay vs. number of nodes; (**d**) APD vs. number of nodes. Comparison in Dolphin Pods using SET1, SET2, SET3.  
Performance Metrics:The proposed system will define a new metric called Alive Nodes Number (ANN) besides the common performance metrics, i.e., APD, End-to-End Delay (E2 ED), Energy Tax (ET) and PDR.
* _Alive Nodes Number (ANN)_: A node having enough energy that it can receive, process and forward the packet is called alive node. To categorize the alive nodes, the threshold \(E_{TH}\) is defined i.e., the minimum energy required for the node to receive \(E_{RCV}\), process \(E_{PROC}\) and forward \(E_{FOR}\)-Threshold energy may be defined mathematically as: \(E_{TH}>E_{RCV}+E_{PROC}+E_{FOR}\)
* _Packet Delivery Ratio (PDR)_: PDR is the ratio of the packets received by the sink to the total packets generated by the network. The packets may be received multiple times, so this redundant packet is considered to be a one distinct packet: \[PDR=\frac{Packets\;received}{Packet\;Sent}.\] (21)
* _End-To-End Delay (E2 ED)_: The E2 ED is defined as the average time taken for a packets transmission from the instant the source node started transmission to the instant it is delivered to the destination. E2 ED consists of transmission delay, propagation delay, processing time and holding time. Due to the multiple-sink nature of the network, a packet may be received by more than one sink, so the shortest time will be considered as end-to-end delay.
* _Energy Tax (ET)_: The energy tax is defined as the average energy expenditure per node when a packet is successfully delivered to its destination. It includes the energy for sending packet, receiving packet, computational energy, and the idle state energy shown in the equation below: \[Energy\;Tax=\frac{Etotal}{nodes\times packets},\] (22) where Etotal defined the total energy consumption, nodes define the total number of nodes in the network and packets define the total packets successfully received by the sink. The duplicate packet received by the sink is removed from the total number of packets because energy tax is the amount of energy per packet per node in the network.
* _Average Accumulated Propagation Distance (APD)_: APD is defined as the average accumulated distance of each hop of all the packets that are successfully delivered to the sinks. There is a multi-sink network environment in which more than one sink can receive a packet, so the shortest accumulated propagation distance is considered as a final accumulated propagation distance. The APD can be found by the following mathematical equation: \[APD=\frac{1}{n_{-}p}\sum_{j=1}^{n_{p}}\sum_{i=1}^{h}dist_{j},\] (23) where \(n_{p}\) is the number of packets, \(h\) is the hop number of packet from source node to sink and \(dist_{j}^{i}\) is the distance of the ith hop of the jth packet.