## 5 Conclusions  
Exponentially rising technologies and allied applications have always prompted the exploration of better systems. The underwater acoustic wireless sensor network (UWSN) has emerged as one of the most sought after research domains in communication systems to serve civil as well as defense purposes. However, encompassing exceedingly dynamic environment and channel conditions, it demands a more effective and optimal transmission model so as to enable reliable and QoS oriented communication. This paper presented multiple contributions targeted to enable an optimal channel model, transmission model and routing protocol for energy efficient, delay tolerant and QoS enriched UWSN communication. Realizing the need for a robust channel model with small scale as well as large scale deviations (fading conditions), at first, a novel computationally efficient statistical channel model was developed. Incorporating principle physical concepts of acoustic propagation as well as arbitrary topological variations, the proposed channel model was intended to derive an efficient and realistic channel model for acoustic communication. Unlike traditional channel models, consideration of the proposed statistical model can provide more accurate and real-time responses. In the next research phase, a robust systematic random linear network coding (RLNC) based transmission model will be developed. The simulation of the proposed systematic RLNC or SRLNC based UWSN routing protocol has exhibited better performance in terms of higher PDR and throughput, minimal delay and energy consumption. The performance with a dynamic and computationally efficient channel model  
Figure 11: Effect of number of nodes on the average delay.  
Figure 12: Effect of number of nodes on the energy consumption.  
exhibits that the proposed SRLNC based UWSN routing scheme can be significant for those cases where small scale fading (due to scattering and small wavelength deviation) as well as large scale fading (primarily due to node movement or dislocation) occur frequently. The proposed routing protocol with iterative buffer flush-based SRLNC strengthens it to be used for large scale UWSNs where QoS oriented mission critical data transmission and energy efficient communication is required. In the future, the enhancement scopes could allow the proposed channel model to enhance spatial correlation between acoustic paths. In addition, enriching SRLNC data compression and encoding/decoding can also be explored to make FEC more productive.  
Conceptualization, P.H.B. and G.H.L.; methodology P.H.B. and G.H.L.; software, G.M.; validation, N.Z.J. and F.F.; formal analysis, P.H.B.; investigation, G.H.L.; resources, G.M.; data curation, G.M.; writing--original draft preparation, P.H.B.; writing--review and editing, G.H.L.; visualization, G.M.; supervision, N.Z.J.; project administration, F.F.; funding acquisition, F.F. All authors have read and agreed to the published version of the manuscript.  
No financial support was received to perform the research work of this manuscript.  
Data Availability StatementData will be made available on demand.  
No potential conflict of interest was reported by the authors.