MEDHA - 2012 Proceedings published by International Journal of Computer Applications® (IJCA) 35 A Survey of Reliable Transport Layer Protocols for Wireless Sensor Network Abhijeet G. Bagadi MITCOE, Pune Sambhaji Sarode MITCOE, Pune Jagdish W. Bakal Shivajirao S. Jondhale college of Engineering, Dombivali, Mumbai ABSTRACT Wide research in the field of Wireless sensor network (WSN) made it applicable into various domain of organization, health, home appliances and many more. WSN has various issues in transporting data from one node to another. Reliability is considered to be one of the important requirements of WSN. Reliability concerns with the loss of data, retransmission of data, connection of links, energy consumption etc. So reliable transmissions of data from source to destination either node- node or node-sink is a challenging task. To meet Quality of service (QoS), congestion free and reliability is mandatory. Some protocols consider congestion in the network only while some consider reliability only and some consider both congestion and reliability in the network. In this survey we considered various reliable transport protocols for WSN in which few consider congestion control too. Keywords Wireless sensor network, Reliable transport protocol 1. INTRODUCTION Wireless sensor networks (WSNs) have gained worldwide attention in recent years, particularly with the proliferation in Micro- Electro-Mechanical Systems (MEMS) technology which has facilitated the development of smart sensors. These sensors are small, with limited processing and computing resources, and they are inexpensive compared to traditional sensors. These sensor nodes can sense, measure, and gather information from the environment and, based on some local decision process, they can transmit the sensed data to the user. Transmission can be done through wired or wireless connection. WSNs have great potential for many applications such as military target tracking and surveillance, natural disaster relief, biomedical health monitoring, and hazardous environment exploration and seismic sensing. In military target tracking and surveillance, a WSN can assist in intrusion detection and identification. Specific examples include spatially-correlated and coordinated troop and tank movements. With natural disasters, sensor nodes can sense and detect the environment to forecast disasters before they occur. In biomedical applications, surgical implants of sensors can help monitor a patient’s health. For seismic sensing, ad hoc deployment of sensors along the volcanic area can detect the development of earthquakes and eruptions. Wired connections are lot more reliable than wireless but also possess some drawbacks. For example deploying wired connections in volcanoes monitoring, lake monitoring or battle field monitoring is quite difficult or not possible. Hence wireless technology is used for transmission. Wired data is less susceptible to error than WSN since congestion is the only issue in wired data transmission while in WSN various factors participate in transmission that eventually degrades the performance of network. Some factors are environment interface, node failure and many more. High bit rate enhance the reliability too. Different types of data flows into network streaming, one packet data etc. Different applications require different level of guarantee for data transport for instance reporting of events, distribution of queries to sensor nodes and managing states in tracking application demands guaranteed delivery. 2. ASSUMPTION AND RELEVENT TERMS In network architecture of transport layer protocols include sensors (slaves) and actors (masters). Why two types of node are used here? It is to separate sensing and decision taking task among the nodes. There are two types of nodes namely sensor and actor. Sensor detects and monitors physical phenomenon while actor gather data and eventually take decision with some delay bound. As discussed in previous section sensors have very less memory as well as low processing power so it is welfare to divide the task among sensors and actors. Actually sensors detect, monitor a network field. This physical phenomenon is eventually transmitted to actors to which some neighboring sensor nodes are attached with. This is called as sensor-actor communication. Now actors will gather data, process them and collectively take decision. Communication among actors is called as actor-actor communication. All actors are attached to each other by an ad hoc communication channel. Sink node is master of all node where ultimately all data will be stored. 3. SURVEY OF RELIABLE TRANSPORT LAYER PROTOCOLS In [1] i.e. Real time and reliable transport (RT)2 achieves reliability and timely event detection with minimum possible energy consumption and no congestion. (RT)2 has to deal with sensor-actor and actor- actor transport reliabilities. In sensor- actor, densely deployed sensors are correlated with both spatial and time. Thus, the sensor–actor transport paradigm requires a collective event transport reliability notion rather than the traditional end-to-end reliability notions. Since actor- actor communication is ad hoc, incorporates adaptive rate-based transmission control and (SACK)-based reliability mechanism to achieve 100% packet reliability in the required ad hoc communication. Moreover for (RT) 2 real time event transport actor has to take decision with some delay bound i.e. event- action delay bound, . This delay has to greater than or equal to sum of transport delay, processing delay and action delays.