Broadband Networks

1. Broadband Networks

2. Introduction • Me Dr Amelia Platt Communication Networks Research Group James Went 7.13 email amp@dmu.ac.uk

3. Introduction • What are Broadband Networks? • Networks which carry multiservice traffic • (Other terms are Integrated Networks or Multiservice Networks) • What is multiservice traffic? • Anything which can be encoded in bits • Audio e.g. Voice • Video e.g. HDTV pictures • Data e.g. File transfer • This includes multimedia (any combination of the three basic traffic types) and multicast applications

4. Introduction • Multiservice traffic have a wide diversity of characteristics • bit rate a few hundred bps (telemetry) to >100Mbps (HDTV) • Quality of Service (QoS) requirements • end-to-end delay & delay variation • cell loss rate • method of encoding • Constant Bit Rate (CBR) / Variable Bit Rate (VBR) • How does the network know what characteristics to expect from applications? • How does the network transport these diverse and sometimes conflicting traffic requirements?

5. Introduction • Constant Bit Rate traffic • Application generates bits at a uniform rate for the duration of the call • voice traffic in today’s telephone networks • 8000 samples / second@ 8 bits / sample - gives 64Kbps • television signals • Variable Bit Rate traffic • Application generates random, variable length bursts of bits (Sometimes referred to as bursty traffic)

6. Introduction • Applications can be CBR or VBR depending on how they are encoded • e.g. voice can be compressed and encoded in < 4Kbps • similarly HDTV can be compressed into < 20Mbps • Above gives the scale of the problem broadband networks must solve! • Application characteristics (particularly QoS requirements) is a recurring theme in the discussion of Broadband Networks!

7. Introduction • Evolution of Networks • WANs - circuit switched telephone networks • Packet switched networks evolved in response to the requirements of data • WANs - low bit rate packet switched data networks • LANs - high speed (10 Mbps) packet switched data networks

8. Introduction • MANs - Evolved in response to the need to interconnect LANs • Broadband WANs evolved to compete with and extend the services offered by MANs (ATM Networks). Now have the concept of a multi-service (integrated) network. • Broadband LANS evolved in response to the need to deliver multi-media traffic in a local environment.

9. Introduction • Technologies which made the evolution possible • Microelectronics - low cost, sophisticated hardware • Photonics - fibre optics - high bit rate with low bit error rate • Evolution of Computing environments - from centralised to distributed • Success of Broadband Networks • Deployment of fibre (or alternative) to home - gives network penetration • Enhanced Network Reliability - Customers must be able to rely on network • Development of new protocols - to deliver multimedia/multicast applications

10. Introduction • Expected Broadband Applications • Access to sophisticated databases • Entertainment video on demand - note that traditionally this is considered to be broadcast entertainment! (Expect big changes here within the next decade!) • Life like video conferencing • Anything not yet thought about • Hence the scene is set for this module

11. Introduction • Order of delivery of Various topics noted in syllabus • MANs - DQDB (802.6) • WANs • Frame Relay & ATM • Signalling & Intelligent Networks • LANS • 100VG AnyLAN (802.12) • 100BASET • Wireless LANs • Cellular Networks

12. Introduction • Tutorials • Lectures • Coursework • Implementation of distributed Q in DQDB • or • Written report on selected topics