# Investigating Master-Slave Architecture for Underwater Wireless Sensor Network
## 2 Related Work
### Localization-Based Routing Protocols  
These protocols need the location information in two or three-dimensional distribution of the node for calculating the optimal routes for transmission of the data from the sender to receiver end of the network. Such information of coordinates is required for the calculation of the distance between the two nodes and routing trajectories of the routing protocols. The following protocols are classified into this category based on their parameters and the solutions they propose. * VBF: The Vector-Based Forwarding (VBF) [4] protocol uses a virtual pipe core in a virtual vector for data forwarding. The virtual vector extends from source to destination and chooses only the nodes lying in the pipe. The protocol uses redundant and different routes for stability in terms of node movement from source to destination. However, by choosing the forwarders within the pipe repeatedly, the energy usage is not optimized. Furthermore, the network lifetime is high due to imbalanced energy usage. * HH-VBF: To increase the efficiency of VBF, another protocol called Hop-by-Hop Vector-Based Forwarding (HH-VBF) has been proposed in [5]. In this protocol, every node generates a virtual pipe that changes the vector path by the node position. In contrast to VBF, energy consumption is balanced in this protocol. However, the HH virtual pipe approach creates significant contact overheads compared to VBF and lacks a mechanism to avoid the void space. * AHH-VBF: The Adaptive Hop-by-Hop Routing Protocol (AHH-VBF) [6] is another attempt to improve the VBF and HH-VBF protocols. It uses variable transmission ranges to save network resources. The transmission range of AHH-VBF varies by distance from the farthest carrier and improves the network lifetime due to the adjustment of the holding time. However, this protocol is limited to select the forwarder by ignoring any residual energy which results in replication packages and unbalanced energy usage. * ANU-AHH-VBF: In [7], the author suggests another location-based protocol called Avoiding Void Node with Adaptive Hop-by-Hop Vector-Based Forwarding (AVN-AHH-VBF) that uses a virtual routing pipeline with the configured radius for data analysis. In this protocol, when a node receives a packet, the distance from the forwarder is observed in the predefined range. The AVN-AHH-VBF uses the concept of holding time to reduce unwanted broadcasts. The PDR is improved because the packet collision is minimized. However, the performance concerning end-to-end delay is not improved. Therefore, by using residual energy, the technique could not achieve the balancing of energy consumption among nodes. * ESEVBF: In [8], the authors proposed Energy Scaled and Expanded Vector-Based Forwarding (ESEVBF) protocol to offset energy consumption. The selection is based on the residual energy of the forwarder nodes. It measures and increases the time difference of holding with the residual PFN energy. While lowering the end-to-end delay, the selection process achieves reduced packets' duplication and network energy consumption. The routing protocol demonstrates little changes in Packet Delivery Rate (PDR), as the forwarding node suppresses vast amounts of nodes with a slight variation in the residual energy, inside the potential forwarding region. If a communication void hole happens, VBF fails to react. * NEFP: The Novel Efficient Forwarding Protocol (NEFP) [9] is also a localization-based routing protocol. It has three main tasks, i.e., forwarding/routing zones to avoid unimportant forwarding using Markov chain to measure the forwarding probability of the packets in different network topologies and the calculation of holding time to avoid packet duplication and Collison. However, this protocol does not perform well in sparse conditions because of the less probability of finding the next forwarder in the forwarding zone. * TC-VBF: To address the issue of node's communication in sparse environment, the Topology Control VBF (TC-VBF) [10] was introduced.