## 6 Continuous Transmission of Packet Traffic  
UWSNs can be classified as either small-scale or large-scale networks. The numeral of sensor nodes and the deployment scope determine the network scale's size. For various network scales, however, different localization techniques are needed. Small-scale UWSNs generally employ a single-stage localization technique in which existing nodes do not facilitate the deployment of other sensor nodes. The sensor nodes located using the two-stage localization method for large-scale UWSNs  
Despite the many challenges in this area, many pertinent researchers optimize and investigate the localization approach based on UWSNs from various perspectives. As new studies on a localization algorithm based on UWSNs are consistently published, an analysis of the pertinent and best literature is required [58]. **Distance measurement**  
Depending on how differently distance is determined, the two categories of localization approaches are both range-free and range-based schemes. We introduce the two sub-classes' traditional and cutting-edge underwater localization techniques. We summarise and compare all the approaches mentioned above and highlight the benefits and drawbacks of specific algorithms [59]. **Range based Algorithms**  
The localization accuracy may be impacted by the partial loss of the wave signal intensity caused by the geometric dispersion and acoustic energy absorption by the propagation medium. This circumstance occurs during the process of underwater acoustic wave propagation. The authors developed a brand-new underwater acoustic localization technique based on energy (EB) for such conditions [60]. The algorithm's concept may be broken down into two phases. One method is to analyze the signal energy and strength of the target. The other involves determining a signal transmission model and the UWSN's design to predict the target's best placement. The outcomes of the numerical simulation demonstrate the particular reference value used by this approach for the localization of underwater nodes based on energy [61]. In [62], an iterative technique is described for an asynchronous target locating method based on the time difference of arrival (TDOA) for a heterogeneous underwater propagation \begin{table}
\begin{tabular}{p{14.2 pt} p{142.3 pt} p{142.3 pt} p{142.3 pt}} \hline \hline
**S.no** & **Area Focused** & **Findings** & **Metrics** \\ \hline \multirow{4}{*}{1} & Difficulties with UWSN routing and upcoming work & The speed of sound rises with rising ocean temperature and falls with falling ocean temperature; an increase in ocean temperature of 10C can bring the sound speed up to almost 4.0 m/s. & \multirow{4}{*}{as the temperature rises almost 4.0 m/s.} \\ \cline{1-1} \cline{3-4}  & Wireless Communication Prospects and Challenges for Underwater Sensor Networks & Temperature differences, surface noise, and the multi-path effect due to reflection and refraction all have an impact on auditory communication. & Communication’s effects \\ \hline \multirow{4}{*}{3} & An analysis of how temperature changes affect underwater wireless audio transmission & Temperature, depth, and salinity of the undersea environment all have an impact on sound speed. These elements cause changes in the sound speed in the water. & \multirow{4}{*}{varying the speed} \\ \cline{1-1} \cline{3-4}  & The underwater audio communication channel’s capacity might vary depending on the depth and temperature. & Larger temperatures and depths result in higher channel capacities and throughput rates when computing the acoustic channel capacity over short distances. & \multirow{4}{*}{expanding throughput} \\ \cline{1-1} \cline{3-4}  & Simulation of an underwater channel & The temperature at the sea’s surface is substantially higher than the temperature at the bottom. As depth, salinity, and temperature increase, so does the sound’s velocity. & \multirow{4}{*}{grows when the temperature rises} \\ \cline{1-1} \cline{3-4}  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Findings of propagation of UWSN. medium.