Buffering_Slotted_ALOHA protocol for underwater acoustic sensor networks based on the slot status

Abstract

The high throughput, the time saving, and the lower energy consumption are fundamental issues that draw in the consideration of the Underwater Wireless Sensor Networks (UWSNs) field specialists. Medium Access Control (MAC) protocols in UWSNs are significant methods used for increasing the network lifetime and decreasing the consumption rate of energy. ALOHA Protocol that is a class of random-access MAC protocols is considered as the precept of all the complex designs of MAC protocol such as multi-channel networks. This paper proposes a new protocol for handling the previously mentioned issues called a Buffering_Slotted_ALOHA protocol. The main idea of this protocol is based on dividing the network into small parts called closed clusters to reduce the movement of nodes from one cluster to another. Each closed cluster in the network contains some small clusters with a specific number of nodes to reduce the traffic in the network and to avoid the collision and then reduce the transmission time to the least value. In this protocol, the uw-sink node interacts with a small number of nodes and that is a one of the benefits of using a small cluster. Each node in the small cluster has two choices to send its packets, either to the uw-sink or to the uw-main sink depending on the slot status. Moreover, each node has a buffer that holds the transmitted packets until getting their acknowledgment. This buffer has a large capacity to store a lot of packets. Checking the status of the slot before the transmission is a significant point in our protocol to speed the transmission process. The simulation results of this new protocol proved a good performance related to the throughput rate, the average delay, the energy consumption, and the number of dropped nodes in comparison with the other three most common slotted protocols: Slotted ALOHA, Slotted carrier sense ALOHA protocol (Slotted-CS-ALOHA), and time-saving ALOHA protocol with slotted carrier sense (ST-Slotted-CS-ALOHA protocol). Also, the results proved that the higher the density of the network, the higher the performance of our protocol.