Improved transport service for remote sensing and control over wireless networks

Abstract

In a bilateral teleoperated system, the signal transmissions between the operator and the slave manipulators have different QoS requirements in comparison to traditional network traffic. Running teleoperated systems over wireless networks poses more challenges in comparison to wired networks. The media streams involved differentiate themselves from other media types in that they require both reliable and smooth delivery. Reliable delivery requires the transport service to have TCP style semantics. By being smooth, the transport service should be able to deliver the control and sensing data with bounded and reduced latency and its variation. For example, we have conducted numerous teleoperated experiments using our system. We have found in some of our applications that if the end-to-end latency variance becomes larger than 0.3 second, the operator has difficulty maintaining smooth control of the slave manipulator. However, our simulations show that using TCP, the end-to-end latency variance can be as much as 2.5 seconds in an ad hoc wireless network. This paper proposes an improved transport service for remote sensing and control (TRSC). The service reduces the end-to-end latency and latency variance (jitter) for real-time reliable media in mobile ad hoc networks by using forward error correction encoding and multiple network paths. Simulation using NS2 shows the approach performs well under different wireless scenarios