## 2 Related Studies
However, they did not provide a brief review nor a comparison of protocols in the literature. Figure 1: Statistics on the publication related to OR with ADCM in WSNs. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Papers** & **Survey Criteria** & **OR Protocols** & **ADCM Protocols** & **Partial Comparisons** & **Description** \\ \hline Ref. [18] 2015 & Routing objectives, approaches, optimization tools. & \(\surd\) & x & \(\surd\) & Provided a comparative analysis that can give a clear view of the main features of the protocols and their contributions \\ \hline Ref. [19] 2016 & Performance of OR in different types of wireless networks. & \(\surd\) & x & \(\surd\) & Evaluate the performance of opportunistic routing protocols in other communication networks \\ \hline Ref. [20] 2015 & Various sleep-wake scheduling schemes with routing. & \(\surd\) & x & \(\surd\) & Describes various scheduling schemes with routing and their performance in a wireless sensor network \\ \hline Ref. [21] 2015 & Candidate selection processes and coordination schemes in OR. & \(\surd\) & x & \(\surd\) & Focused on the issue of reducing retransmission in order to prevent unnecessary energy consumption \\ \hline Ref. [3] 2014 & Overall routing issues of WSN. & \(\surd\) & x & \(\surd\) & Focused on all WSN issues and discussed the contribution of the opportunistic routing protocol to these issues \\ \hline Ref. [22] 2009 & Underlying access techniques of MAC protocols. & x & \(\surd\) & \(\surd\) & Focused on the energy efficiency, latency and throughput factors of WSNs and discussed the open research issues \\ \hline Ref. [23] 2010 & Issues of WSN related to MAC protocols. & x & \(\surd\) & \(\surd\) & Explained the MAC protocol functionalities in order to solve the WSN issues and pointed out hardware factors of the protocols \\ \hline Ref. [24] 2013 & Time management and the sender and receiver waiting time in MAC. & x & \(\surd\) & x & Classified the protocols and explained the course of motivation that drove the evaluation of the protocols \\ \hline Ref. [25] 2014 & Energy consumption factors of WSN MAC. & x & \(\surd\) & x & Explained how sensor nodes communicate with each other using their mismatched duty cycles in each MAC protocol \\ \hline Ref. [24] 2015 & Mode of operation in synchronous and asynchronous MAC. & x & \(\surd\) & \(\surd\) & Examined the protocols’ performances considering a linear/chain-type WSN \\ \hline Ref. [27] 2017 & Throughput, efficiency, stability, fairness, low access delay, low transmission delay and low overhead. & x & \(\surd\) & \(\surd\) & Presented the study of various WSN-specific MAC protocols based on various design factors \\ \hline Our Survey & Unnecessary power consumption and load balancing factors of OR with ADCM in WSN & \(\surd\) & \(\surd\) & \(\surd\) & Based on load-balancing factors provided reviews on the evolution of ADCM and OR protocols and pointed out the issues while using both protocols together in WSN \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Previous survey related works at a glance. [PERSON] and [PERSON], 2015 [21], focused on the issue of reducing retransmission in order to prevent unnecessary energy consumption. Similar to [PERSON], 2015 [18], the paper by [PERSON] and [PERSON] [21] also described the main design blocks of opportunistic routing protocols. However, they divided the protocol into two main parts: (i) coordination method and (ii) candidate selection method. Since their main focus was on taking control over retransmission, they reviewed protocols on the basis of their candidate selection processes and coordination schemes. As we know, by structure, opportunistic routing protocols run their processes depending on the MAC protocol used by the node. In contrast, the authors did not specifically mention the underlying MAC mechanism of the reviewed OR protocols.