03/09/2003Helsinki University of Technology1 Overview of Thesis Topic Presented By: Zhao Xuetao

03/09/2003Helsinki University of Technology2 Contents SIP protocol Real-time services Presence Other tasks

03/09/2003Helsinki University of Technology3 SIP Protocol Overview of the protocols in multimedia sessions SIP Services, Components and Operations Implementation building blocks

03/09/2003Helsinki University of Technology4 Protocols Session Initiation Protocol – for signaling Reservation Protocol – for reserving network resources Real-Time protocol – Transporting real-time data and providing QoS feedback Real-Time Streaming protocol – for controlling delivery of streaming media Session Advertising Protocol – advertising multimedia sessions via multicast Session Description Protocol – to describe multimedia sessions

03/09/2003Helsinki University of Technology5 Session Initiation Protocol Application layer protocol for creating, modifying and terminating multimedia sessions Supports unicast, mesh and multicast conferences, and combination of these modes Similar to HTTP, Client-Server protocol, and text- based Provides reliability without assuming anything about the lower layer transport protocols

03/09/2003Helsinki University of Technology6 Components User Agents User Agent Client User Agent Server Network Servers Registration Servers Proxy Servers Stateful Proxy Server Stateless Proxy Servers Redirect Servers

03/09/2003Helsinki University of Technology7 Parser Sip messages are sent as text (Unicode characters) The Sip message grammar is given in the augmented BNF-form (RFC 2543) Syntax tree builder (JTBGJ) Parser Generator (Javacc)

03/09/2003Helsinki University of Technology8 Protocol Building blocks User Agent A Registration Server User Agent B Proxy Server Location Server B’s current location Registration Server

03/09/2003Helsinki University of Technology9 Real-time Services Real-time services situation in Ad Hoc networks Implementation of audio/video services

03/09/2003Helsinki University of Technology10 Real-time Services Challenges in Ad Hoc networks Ad hoc networks pose a great challenge to audio/video transport. The main problems are: 1.Frequently changing topology makes the established link likely broken, which may cause interruption, pause, or jerkiness in the received signal. 2. Other factors that influence quality include radom packet loss caused by wireless channel errors and small capacity of a wireless network.

03/09/2003Helsinki University of Technology11 Real-time services Video transport typically requires strict bandwidth and delay guarantees. However it is very hard to maintain end-to-end route which is both stable and has adequate bandwidth in Ad Hoc netwoks. Furthermore, compressed video is susceptible to transmission errors.

03/09/2003Helsinki University of Technology12 Real-time Services Include voice session in SIP client 1) Integrate RAT (Robust Audio Tool) that contains RTP/RTCP stack. 2) Develop a testing and validation use case for audio sessions. Collect audio measurements for performance analysis of audio sessions in Ad Hoc networks. 3) Propose a new transport protocol based on performance analysis. Implementation of video session???

03/09/2003Helsinki University of Technology13 Presence What is presence? Why do we use SIP as presence protocol? How it works to achieve presence infomation? Future task

03/09/2003Helsinki University of Technology14 What is presence? Presence known as presence infomation, conveys the ability and willingness of a user to communicate across a set of devices.

03/09/2003Helsinki University of Technology15 SIP as presence protocol SIP is a best choice as a presence protocol because actually presence information is already in SIP location services as registrations

03/09/2003Helsinki University of Technology16 How it works? SIP could contact the server that contains registration state for a user when any user requests the presence information. The registration state is a key component of user presence, SIP networks can route SUBSCRIBE requests to the same server. Thus global connectivity for presence subscriptions and notifications is established through reuse of SIP networks.

03/09/2003Helsinki University of Technology17 Future Task Include Presence with location information. This will consist of using SIP client for implementing a local presence server with databases containing presence information of neighbour Ad Hoc nodes.

03/09/2003Helsinki University of Technology18 Other Tasks Include other services in SIP client 1. Include Chat and conferencing service. This will consist of using SIP client for implementing chat server that includes databases for storing group information for initiating a chat or conference in Ad Hoc networks. 2. Performance testing of multimedia services in Ad Hoc networks (audio/video and presence). Based on the performance tests you would propose some solutions for enhancing the QoS for multimedia services.