Study of Reliable Data Communication in Wireless Sensor Networks.

the technology of wireless sensor networks (WSNs) is in the vanguard of the investigation of the computer networks and could be the next technologic market of a huge sum of money. An advance in mote technology is "mesh of network" special software that lets each device wake up during a fraction of a second when events occur and data has to be sent and forwarded to neighbors. Sensor networks are designed to carry out a group of tasks about information processing like detection, search or classification. Applications of these networks have a wide range. An example of such an application is sensors with RFID readers mounted on them to read tag information from the objects in a factory warehouse. Here, the tag information recorded by the RFID reader is a critical piece of information, which may not be available at a later point of time and hence has to be reliably transported to the sink. We study the various issues and analyze the design choices proposed in literature in addressing the challenge of sensors-to-sink reliable data communication in such applications. A cross layer based protocol with MAC layer retransmissions and NACK (Negative Acknowledgment) based rerouting of data packets is developed to overcome link failures and provide reliability. The protocol is implemented on TinyOS and the performance of NACK based rerouting protocol in terms of percentage successful message reception is compared with NACK based retransmission protocol by running simulations on TOSSIM. The NACK based rerouting protocol provides greater reliability under different metrics like varying network size, network traffic and percentage of failed links in the network. [ABSTRACT FROM AUTHOR]