## 7 Classification of Mobile Sink based Data Collection Schemes
### Controlled Sink Mobility-Based Schemes
\begin{table}
\begin{tabular}{l l l l l l l l} \hline Date & & & & & & & & & \\ Collection & & & & & & & & \\ Collection & & & & & & & & \\ Status & & & & & & & & \\ Status & & & & & & & & \\ \hline \multirow{2}{*}{[45]} & Visiting only a set of cluster-heads & Multiple & Wait-and-Upload & Homogenous & Triggering updates only & & & \\  & & & & nodes deployment & when sink arrives at any & Medium & Balancing network \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & lifetime and latency \\ \hline \multirow{2}{*}{[12]} & Discrete mobility pattern & Single & Wait-and-Upload & Homogenous & Not specified & Low & Balancing energy consumption \\  & & & & & nodes deployment & & and delivery latency \\ \hline MSRP & Movement towards energy & & Single & Wait-and-Upload & Homogenous & Not specified & Medium & Prolonging network lifetime \\  & & & & & & & \\  & & & & & nodes deployment & & \\ \hline \multirow{2}{*}{[49]} & Movement towards energy rich areas or event source & One static sink and multiple sub-sinks & One static sink & & Heterogeneous & Bounded by area covered & & \\  & & & & & nodes deployment & by each mobile sub-sink & Low & Improving network lifetime \\  & & & & & & & while delivering real-time data \\ \hline GMRE & Discrete mobility pattern & Single & Periodic \& & Homogenous & Imposing a minimum pause & Low & Prolonging network lifetime \\  & & & & & & & \\  & & & & & & interval at each sojourn point & Low & and delay bound delivery \\ \hline AVRP & Constant speed & Multiple & Proactive & Homogenous & Bounded by Voronoi scope & & \\  & & & & & nodes deployment & of each mobile sink & Medium & Improving data \\  & & & & & & & delivery performance \\ \hline \multirow{2}{*}{[51]} & Following a computed trajectory covering all sensor nodes & Single & Wait-and-Upload & Homogenous & Not specified & Medium & Reducing Data Delivery Latency \\  & & & & & nodes deployment & & \\ \hline \multirow{2}{*}{[56]} & Reducing within cluster boundary & Multiple & Proactive & Heterogeneous & & & \\  & & & & nodes deployment & & \\ \hline NADC & Motion along a computed trajectory & Single & Query-Driven and Wait-and-Upload & Homogenous & Not specified & Low & Improving network lifetime \\  & & & & Wait-and-Upload & nodes deployment & & \\ \hline \multirow{2}{*}{
\begin{tabular}{l} MobileRoute \\ [13] \\ \end{tabular} } & Discrete mobility pattern & Single & Proactive & Homogenous & & & \\  & & & & nodes deployment & & \\ \hline \multirow{2}{*}{[60]} & Discrete mobility pattern & Single & Periodic and & Homogenous & & & \\  & & & & & nodes deployment & \\ \hline \end{tabular}
\end{table} 
Table 3: Summary of controlled sink mobility based data collection schemes. The aforementioned controlled sink mobility-based data collection schemes are summarized in Table 3. It illustrates each scheme in terms of any constraints it imposes on sink mobility, the number of sinks involved for data collection, data reporting mode (proactive, reactive, query-driven, periodic, or wait-and-upload), network architecture, network overhead control mechanism, and an estimate of network control overhead, together with the main goal(s).