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Overview of Thesis Topic

Presented By:Zhao Xuetao

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Contents SIP protocol Real-time services Presence Other tasks

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SIP Protocol

Overview of the protocols in multimedia sessions

SIP Services, Components and Operations

Implementation building blocks

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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

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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

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Components User Agents

User Agent Client User Agent Server

Network Servers Registration Servers Proxy Servers

Stateful Proxy Server Stateless Proxy Servers

Redirect Servers

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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)

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Protocol Building blocks

User Agent A

RegistrationServer

User Agent BProxy Server

Location Server

B’s current location

RegistrationServer

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Real-time Services Real-time services situation in Ad Hoc

networks Implementation of audio/video services

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Real-time Services Challenges in Ad Hoc networksAd 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.

  

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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.

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Real-time Services Include voice session in SIP client1) 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???

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Presence What is presence? Why do we use SIP as presence protocol? How it works to achieve presence

infomation? Future task

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What is presence? Presence known as presence infomation, conveys the

ability and willingness of a user to communicate across a set of devices.

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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

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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.

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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.

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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.