摘要： With the rapid improvements in engineering technology, underwater communications have gained major interests from researchers with application areas from commercial to military water based communication systems. However, underwater wireless communication is challenging and difficult compared to wireless terrestrial as it can be easily interrupted due to interference from harsh underwater operation conditions, noise, limited bandwidth and power resources. Various researches in underwater acoustic, optical, and RF communications for secured and reliable underwater wireless network have been carried out. In this paper, an LED based optical wireless communications is proposed using a layered 2 Morse-code based encoding protocol for short distance underwater communication. The proposed system converts the data into a serial of dots and spaces before it is transmitted using the LED as a light source. At the receiver end, the system decodes sequences of on-off light sensed by the photo-diode into the data. The main contribution of this work is the design of a layer 2 signature-based encoding and decoding systems for short range wireless underwater optical communication protocol that can provide a higher data rates compared to traditional acoustic systems with significant lower power consumption and simpler computational complexity. The transmission protocol is evaluated in a dark room and in a water medium. The results have shown above 90% transmission success rate. The result also showed that different colors of the LED emission can affect the reliability of data transmission.