## 7 Comparative Study  
Now we compare the above mentioned routing protocols according to their performance depending on different parameters. Table 1 shows the comparison. LEACH, TEEN, APTEEN and PEGASIS have similar features and their architectures are to some extent similar. They have fixed infrastructure. LEACH, TEEN, APTEEN are cluster based routing protocols, whereas PEGASIS is a chain-based protocol. The performance of APTEEN lies between TEEN and LEACH with respect to energy consumption and longevity of the network [9]. TEEN only transmits time-critical data, while APTEEN performs periodic data transmissions. In this respect APTEEN is also better than LEACH because APTEEN transmits data based on a threshold value whereas LEACH transmits data continuously. Again PEGASIS avoids the formation of clustering overhead of LEACH, but it requires dynamic topology adjustment since sensor energy is not tracked. PEGASIS introduces excessive delay for distant nodes on the chain. The single leader can become a bottleneck in PEGASIS. PEGASIS increases network lifetime two-fold compared to the LEACH protocol. In directed diffusion the base station sends queries to sensor nodes by the flooding technique but in SPIN the sensor nodes advertise the availability of data so that interested nodes can query that data. In Directed diffusion each node can communicate with its neighbors, so it does not need the total network information, but SPIN maintains a global network topology. SPIN halves the redundant data in comparison to flooding. Since SPIN cannot guarantee data delivery, it is not suitable for applications that need reliable data delivery. SPIN, directed diffusion and rumor routing use meta-data whereas the other protocols don't use it. Since they are flat routing protocols routes are formed in regions that have data for transmission, but for the others, as they are hierarchical routing methods they form clusters throughout the network. In case of hierarchical routing energy dissipation is uniform and it can't be controlled; but in the case of \begin{table}
\begin{tabular}{|l|l|l|l|l|l|l|l|l|l|} \hline
**Protocols** & \multirow{2}{*}{**Mobility**} & \multirow{2}{*}{**Power**} & \multirow{2}{*}{**Network**} & \multirow{2}{*}{**Scalability**} & \multirow{2}{*}{**Resource**} & \multirow{2}{*}{**Classification**} & \multirow{2}{*}{**Data**} & **Query** & **Multipath** \\  & & & **management** & & & & **awareness** & & **aggregation** & **based** & \\ \hline LEACH & Fixed BS & Maximum & Very good & Good & Yes & Clustering & No & No & No \\ \hline TEEN & Fixed BS & Maximum & Very good & Good & Yes & ReactiveClustering & Yes & No & No \\ \hline APTEEN & Fixed BS & Maximum & Very good & Good & Yes & Hybrid & Yes & No & No \\ PEGASIS & Fixed BS & Maximum & Very good & Good & Yes & ReactiveClustering & Yes & No & No \\ \hline SPIN & Supported & Limited & Good & Limited & Yes & Proactive/flat & Yes & Yes & Yes \\ \hline DD & Limited & Limited & Good & Limited & Yes & Proactive/flat & Yes & Yes & Yes \\ \hline RR & Very limited & Not support & Very good & Good & Yes & Hybrid/ flat & Yes & Yes & No \\ \hline GEAR & Limited & Limited & Good & Limited & Yes & Location & No & No & No \\ \hline GAF & Limited & Limited & Good & Limited & Yes & Location & No & No & No \\ \hline \end{tabular}
\end{table} 
Table 1: Comparison of different routing protocols. flat routing energy dissipation depends on the traffic pattern. For the previous case data aggregation is done by cluster heads but in the later case, nodes on multi-hop path aggregates incoming data from neighbours. GEAR limits the number of interests in Directed Diffusion by considering only a certain region rather than sending the interests to the whole network. GEAR thus complements Directed Diffusion and conserves more energy. According to simulation results [17], GAF performs at least as well as a normal _ad hoc_ routing protocol in terms of latency and packet loss and increases the lifetime of the network by saving energy.