# Interconnecting Haptic Interfaces with High Update Rates through the Internet +
## 1 Introduction  
This paper is an extended version of the paper, presented at IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB), 2017 [1]. It presents the existing transport protocols that could be used for transferring haptic streams with high update rates over the Internet. Simulation and emulation tests for transferring haptic streams over the Internet are undertaken. A thorough analysis of these results is presented.  
Real-time multi-sensory streams carry audio, video, haptics, and other sensory data [2]. Supermedia data obtain massive variety and volume. This increase of data deteriorates the network status of the Internet.  
Researchers [3; 4; 5; 6] try to determine the QoS of the network, in order to maximize the Quality of Experience (QoE) of the user [7] in a real-time internet haptic application. In order to maximize the QoE of the user in a haptic application, the update rate of the haptic stream should rather high, closeto 1 KHz. This high update rate should be supported by the QoS requirements of the network, in order to successfully transfer online the haptic feeling real-time. The network performance of the Internet is not stable. It is changing from one area to another and from one hour to another. The recent network conditions of the Internet might permit online real-time haptic applications to flourish. This paper investigates whether the Internet is capable of transferring real-time the haptic sense.  
In order to transfer haptic data through the Internet, specific transport protocols should be enforced. Several protocols have been developed for transferring haptic data. The most important are the Application Layer Protocol for Haptic Networking (ALPHAN) Protocol [8], the Smoothed--Synchronous Collaboration Transport Protocol (S-SCTP) [9], the Efficient Transport Protocol (ETP) [10, 11], the Interactive Real-time Protocol (IRTP) [12], the Real Time Application Level Protocol For Distributed Interactive Media protocol (RTP/I) [13] and the Real Time Network Protocol (RTNP) [14].  
Other protocols that are being widely used to transfer real-time multimedia data, such as UDP, RTP [15], Datagram Congestion Control Protocol (DCCP) [16] and Stream Control Transmission Protocol (SCTP) [17], should be tested for haptic data transferring as well. All the above protocols have been proposed for transferring real-time streams of voice and video, but they have not been tested for transferring the haptic sense. This research tries to investigate whether some of the above real-time protocols could be used for transferring real time the haptic sense. Taking into account the special features of each protocol, the authors will try to propose which protocol suits best for the real-time transfer of the haptic feeling.  
The rest of this paper is organized as follows. Section 2 outlines the most recent haptic applications. Section 3 depicts the network conditions that are met in the Internet today. Section 4 presents the simulation scenario that is used for the evaluation of transport protocols. Section 5 analyses the results of the simulation testing. Section 6 discusses the complements, differences and relevancies between simulation and real world experiments. Finally, Section 7 concludes the paper.