Investigation of transport layer protocols for wireless haptic communication system

Recently, the study of real-world haptics has been actively researched. In order to transmit tactile sensation to a remote place, it is necessary to utilize a network. In Internet, as a factor which affects the hard real-time property and transfer reliability of communication. There are communication delays, packet losses and sequential number changes. In conventional studies, the communication delay is mainly dealt with and UDP (User Datagram Protocol) is used as transfer protocol, because the real-time property is valued in haptic communication. However, because the UDP does not check the state of receiving side, using the protocol is not actually allowed in some communication lines. In this case, TCP (Transmission Control Protocol) is used as transfer protocol; however, the TCP decreases the real time property of data transmission in return for checking the communication states. The real-time property of communication methods with TCP is able to be improved by invalidating the Nagle algorithm of the protocol. In this research, communication using UDP, TCP and TCP which the Nagle algorithm invalidation are evaluated from the viewpoint of haptic communication system. The experimental results are useful in choosing the appropriate transfer protocol for haptic communication.