Energy Balanced Localization-Free Cooperative Noise-Aware Routing Protocols for Underwater Wireless Sensor Networks  
[PERSON]  
1 Department of Electronics, Quaid-i-Azam University, Islamabad 45320, Pakistan; [EMAIL_ADDRESS] or [EMAIL_ADDRESS]  
[PERSON]  
2 Department of Electronics, University of Peshawar, Peshawar KPK 25120, Pakistan 2  
delivery to the water surface, because in these protocols, a source node delivers a packet through a single path. Also, while delivering packets from a sender to a destination, they do not consider the channel conditions. Therefore, packets transfer reliability is compromised. Several routing schemes exist in the literature that incorporate reliability in packets transfer through cooperative routing [16; 17; 18; 19]. In this type of routing, at least one relay sends a copy of the signal it receives from the sender to the destination. So, it tends to minimize adversely affected links by the harsh sea properties (noise, fading). However, these schemes are based on localization. In localization, the knowledge about the position of the coordinates of the nodes is required, which is challenging, as tides and currents in the sea change the positions of nodes regularly [20]. The authors in [21] propose a cooperative position-aware mobility pattern. In this protocol, the void zones are avoided by using multiple gliders. The gliders are capable of dynamic mobility pattern and they can also stay for a moment at sojourn positions in a specified time to collect the nodes' information. Moreover, two of the best gliders are selected by a source node that delivers data in a cooperative method. The packets' advancement to target destination is optimized at the cost of high consumed energy and latency, as the involvement of gliders. [PERSON] et al. in [22] propose a scheme in which a sender chooses two optimal relays based on their depth. The scheme is localization free and has high packets advancement towards target destination but suffers from high energy consumption due to redundant packets transfer. It also has a high delay due to using two relays instead of one. In [23], a cooperative with an opportunistic routing scheme is presented. A sender checks the relay nodes' set, by considering only depth knowledge The holding time logic is also used for each relay node to prevent data from collision. Moreover, an opportunistic routing technique is applied to choose an optimal node from the set of relays. The framework has a high packet delivery ratio (PDR) and consumes less energy. However, the forwarder set bears a high data load that results in an unbalanced consumption of energy. The authors in [24] propose a DEAC protocol for UWSNs. A sender chooses its relay node based on link condition, depth threshold, and residual energy. Furthermore, the packet is being forwarded in two methods. The first one is directly from a source to a destination and the second one is via the relays, which amplify and forward the data to the destination. The protocol achieves a good result for packet delivery ratio. However, for long network operation time, the performance is compromised in energy consumption. Another cooperative protocol known as SMIC is presented in [16]. In this protocol, each source selects the relay as per depth, link condition, and residual energy. The MSs proceed in the water and collect the information from each node. High PDR and improvement in consumed energy and packets drop are obtained. However, the delay is high when mobile sinks accumulate data from far nodes. To enhance the reliability in [13], the authors in [25] propose the adaptive cooperation. A source chooses the best relay only when the latter has the lowest depth and sufficient energy. The data are transmitted to the destination in cooperation mode. The destination node sends back the request when it receives the erroneous packets. The protocol achieves good performance in throughput. However, high energy nodes bear the most data burden. The authors in [26] present a region-based cooperative routing protocol.