## 7 Simulation and Results  
In this section we discuss the simulations and their results. Table 1 explains simulation setup and the environment that we utilized to conduct the simulations.  
Different kind of routing schemes that we refer in this section are as:  
_Definition 8: All wireless routing_ refers to the traditional WSN routing scheme that includes only the wireless media to communicate between source to the sink.  
_Definition 9: Hotline assisted routing_ refers to the reliable routing approach that we suggested where the source to the sink communication is assisted by the high speed hotline links between the gateways.  
_Definition 10: Signature Based Routing (SBR)_ is the enhanced hotline based routing that reduces the overall latency between the source to the sink communication.  
_Definition 11: Multipath AODV Signal Intensity Metric (maodv-sim)[14]_ is the routing scheme used for the comparison with our results.  
In hotline assisted simulation scenarios the nodes are deployed in clusters as explained in Section 3. The cluster head act as a gateway and all the communication to and from the cluster takes place through the gateway. All the gateways are connected via Ethernet cable. Multiple sources send data to a sink to emulate bursty traffic.  
In the all-wireless scenarios we have kept the same network topology and node deployment; however there were no gateways or Ethernet connections.  
The factors that are used to measure the reliability of a WSN are 1) Packet Success Ratio and 2) end-to-end Delay.  
_Definition 12_: The _Packet Success Ratio_ is defined as the ratio between the total number of packets sent by the sender to the total number of packets successfully received by the destination/sink.  
\begin{table}
\begin{tabular}{|c|c|} \hline Simulation Environment & Qualnet 4.5 \\ \hline Routing Protocol & AODV* \\ \hline Inter-Gateway Routing & OSPF \\ \hline Intra-Cluster Communication & Wireless (802.15.4) \\ \hline Inter-Cluster Communication & Wired (Ethernet) \\ \hline Number of Nodes & 20, 40, 60, 80 \\ \hline Total Terrain Area & 1500m \(\times\) 1500m \\ \hline Simulation Time & 60 seconds \\ \hline Total Runs & 20 \\ \hline \end{tabular}  
* In order to make AODV work efficiently in WSN environment we slightly modified its route discovery mechanism in our simulation. For example route discovery area has been partitioned and influx of extra control messages into the network has been monitored and controlled.  
\end{table}
Table 1: Simulation setup.  
**Definition 13**: _end-to-end delay_ is defined as the time taken for a packet to reach from the source to the destination/sink.  
If the packets are being dropped frequently, that network will be considered unreliable. In some mission critical applications like military and healthcare immediate communication is required, therefore end-to-end Delay is also considered to be one of the important criterions for measuring the reliability.  
We have divided the simulation discussion into three parts. Part A discusses the effect on reliability with respect to varying number of hops from source to the sink, Part B talks about the effect on reliability with respect to varying node density in a specific area and in Part C we compare SBR with all wireless routing and hotline assisted routing in terms of Average end-to-end delay.