Optimal transmission power of wireless sensors for real-time systems in ship area networks

Ship area networks (SANs) have lately attracted attention in order to guarantee the safety of sea travelers and marine transportation. The wireless sensor network (WSN) is one of the most important components of SAN because crew members must know any damage or malfunction of parts of ships promptly. The safety systems are mostly real-time applications, thus delay is the most important QoS requirement in SAN. Meanwhile, energy consumption is also a traditionally important metric in WSN. Therefore, the goal of this paper is to find the minimum possible transmission power of each sensor node on the condition that it can meet delay constraint. Assuming the uniformly distributed sensor nodes, the proposed method firstly suggests the way to compute the average per-hop advancement with a single transmission. The difference from the actual simulation is less than 1% although it uses only nodal density information. Based on this per-hop advancement, the minimum possible transmission power is calculated, which can guarantee delay QoS for the predetermined ratio of connections in WSNs. The error-prone channel is also considered since packet transmission may frequently fail due to many equipments and ship body made of steel.