## 4 Classification of Routing Protocols
### Postural-Movement-Based Routing Protocols
#### 4.4.7 Comparative Study of Postural-Movement-Based Routing Protocols  
Due to the movements of human body, the links among the sensor nodes often face disconnection problems. Different researchers have tried to solve this problem, which are discussed above. In Table 4 the aforementioned postural movement based routing protocols for WBSNs are compared with other state-of-the-art schemes in terms of delay, packet delivery ratio and energy consumption.  
OBSFR [21] has increased the pocket delivery ratio and decreased the average delay as compared to the PROPHET [69] and Relative LOCation based Forwarding (RLOCF), but still there is a unique packet loss due to the partition packet saturation. However, OBSFR [21] has high energy consumption and can only be applied to networks with a few nodes due to the list of IDs in each packet. The performance of PRPLC [22] is better in terms of packet delivery ratio and end-to-end delay as compared to generic probabilistic routing protocol PROPHET [69] but still it has high end-to-end packet delay and low packet delivery ratio as compared to the on-body store and flood routing (OBSFR) [21]. DVRPLC [23] reduces the average delay and enhances the packet delivery ratio as compared to PRPLC [22] and PROPHET [69]. However, OBSFR [21] performs better in terms of average delay and packet delivery ratio as compared DVRPLC [23]. Furthermore, DVRPLC having high packet hop count resulting in longer routes as compared to PRPLC [22].  
The opportunistic protocol [20] has half of the energy consumption for the relay node, and same energy consumption for the sensor node as compared to that multi-hop communication as discussed in [70], _i.e._, the overall energy consumption is in between the single-hop and multi-hop communication. However, the individual energy level of the sensor node is not considered. Furthermore, with the increase in the number of sensor nodes will increase the traffic load on the relay  
\begin{table}
\begin{tabular}{l l c c c c c} \hline \hline \multirow{2}{*}{**Protocol**} & \multicolumn{6}{c}{**Characteristics**} \\ \cline{2-7}  & **Goal** & **Mobility** & **Metrics** & **Avg. Delay** & **PDR** & **Energy Cons.** \\ \hline OBSFR & To decrease end-to-end & & & & & \\ (2009) & delay and hop-count & Yes & Link Quality & 1.88 s & 83–92\% & High \\ PRPLC & To reduce end-to-end & & & & & \\ (2009) & delay & & & & & \\ DVRPLC & To reduce end-to-end & & & & & \\ (2010) & delay & & & & & & \\ Opportunistic & To increase the life time of & & & & & \\ (2011) & the network & & & & & \\ ETPA & To reduce the temperature & & & & & \\ rise \& energy consumption & & & & & \\ PSR & To provide reliability and & & & & & \\ (2012) & security & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Postural-movement-based routing protocols.  
node. As compared to PRPLC [22], ETPA [66] shows an efficient performance in terms of the temperature rise, while packet delivery ratio and packet delay almost remain the same. However, the average packet hop is slightly higher than PRPLC. PSR [67] framework is suitable for wireless body sensor networks having a few number of sensor nodes because of the huge overhead of the link quality matrix.  
By comparing the postural-movement-based routing protocols in terms of packet delivery delay, packet delivery ratio and energy efficiency, we conclude the following: among the aforementioned postural-movement-based routing protocols for WBSNs, OBSFR [21] performs better to reduce the packet delivery delay. In terms of packet delivery ratio, ETPA [66] achieves highest packet delivery ratio compared to others. Finally, opportunistic postural movement based routing protocol [20] has lowest energy consumption among all.