UbiCom Book Slides

1. UbiCom Book Slides Chapter 11 Ubiquitous Communication Stefan Poslad http://www.eecs.qmul.ac.uk/people/stefan/ubicom Ubiquitous computing: smart devices, environments and interaction

2. Chapter 11: Overview Chapter 11 focuses on: • Internal system properties: distributed • External interaction with ICT environment Ubiquitous computing: smart devices, environments and interaction

3. 5 Main Properties for UbiCom Systems Ubiquitous computing: smart devices, environments and interaction

4. UbiCom System Model Focussing on Interaction in Virtual Computing Environments Ubiquitous computing: smart devices, environments and interaction

5. Related Chapter Links • Distributed Computing (Chapter 3) • Mobile Services (Chapter 4) • Intelligent Interaction (Chapter 9) • Mobile Distributed Systems (Chapter 4) • Management of Distributed Systems (Chapter 12) Ubiquitous computing: smart devices, environments and interaction

6. Chapter11: Overview The slides for this chapter are also expanded and split into several parts • Part A: Introduction • Part B: Audio Networks • Part C: Data networks: Fixed • Part D: Data networks: Wireless • Part E: Video & Multi-Content Access Networks • Part F: Ubiquitous Networks: PLC, PAN, BAN, Mobile • Part G: Network Access Control • Part H: Service-Oriented Networks 1 • Part I: Service-Oriented Networks 2 Ubiquitous computing: smart devices, environments and interaction

7. Ubiquitous computing: smart devices, environments and interaction

8. Chapter11: Overview The slides for this chapter are also expanded and split into several parts • Part A: Introduction  • Part B: Audio Networks • Part C: Data networks: Fixed • Part D: Data networks: Wireless • Part E: Video & Multi-Content Access Networks • Part F: Ubiquitous Networks: PLC, PAN, BAN, Mobile • Part G: Network Access Control • Part H: Service-Oriented Networks 1 • Part I: Service-Oriented Networks 2 Ubiquitous computing: smart devices, environments and interaction

9. Ex: Communication Networks • Time order the following networks: • Internet (data), radio (audio), television, telephone • Which became established first for mass-use: when & why? Ubiquitous computing: smart devices, environments and interaction

10. Introduction • Ubiquitous applications need to access relevant remote external information and tasks, anywhere and anytime. • Different applications require different combinations of network functions and services, e.g., data streaming, minimal jitter, specific media access control etc. • Different networks support different sets of communication functions in different ways. Ubiquitous computing: smart devices, environments and interaction

11. Introduction Key design issues: • Should comms functions be largely transparent to services (network-oriented) versus should comms be exposed via some interfaces & configured / controlled by services (service-oriented). • Should networked services be accessible from anywhere versus selectively accessing networked services, e.g., some services may be limited to a locality? Ubiquitous computing: smart devices, environments and interaction

12. Introduction • Many general and introductory texts and descriptions about networking are specialised towards specific types of networks, e.g., • ??? • An interpretation of UbiCom: • Ubiquitous Communication • Any content on any network, anytime, anywhere • Hence, complete range of different media networks is treated holistically here Ubiquitous computing: smart devices, environments and interaction

13. Network Communication Functions Communication involves the following key functions: • Encoding and Modulation • Signal Distribution • Channel sharing and efficiency: • Medium Access Control (MAC) • Logical Link Control (LLC • Error checking and correction: • Data Transfer Control • buffered vs. unbuffered. • Asynchronous vs. synchronous • Data Routing • Message security • Metadata: • Transcoding. Ubiquitous computing: smart devices, environments and interaction

14. Network Communication Functions • Explain all these in detail in next slides Ubiquitous computing: smart devices, environments and interaction

15. Digital Communication • Historically, audio / video content transmitted in analogue form although these transmissions • Gradually being replaced by digital signal modulation of analog. • Signals as digital standards become established • N.B. Strictly speaking, all physical transmissions of signals are analogue, however, the modulation of signals may convey digital information. Ubiquitous computing: smart devices, environments and interaction

16. Benefits of Digital Communication • Benefits for using digital transmissions? Ubiquitous computing: smart devices, environments and interaction

17. Chapter11: Overview The slides for this chapter are also expanded and split into several parts • Part A: Introduction • Part B: Audio Networks  • Part C: Data networks: Fixed • Part D: Data networks: Wireless • Part E: Video & Multi-Content Access Networks • Part F: Ubiquitous Networks: PLC, PAN, BAN, Mobile • Part G: Network Access Control • Part H: Service-Oriented Networks 1 • Part I: Service-Oriented Networks 2 Ubiquitous computing: smart devices, environments and interaction

18. Types of Audio Networks • PSTN Voice Networks • Intelligent Networks (IN) • IP Multimedia Subsystems (IMS) • ADLS Broadband • Telecoms WWAN • Telecoms WLAN: DECT • Audio Broadcast (Radio Entertainment) Networks Ubiquitous computing: smart devices, environments and interaction

19. Audio Networks • 1st type of pervasive communications network Two basic types: • Audio unicast networks (PSTN) • Audio broadcast (radio) networks Ubiquitous computing: smart devices, environments and interaction

20. Public Switched Telephone Network (PSTN) • PSTN orig. designed to support voice communication (not data, video) • Analogue -> digital transmissions • Still use separate networks for voice & data although convergence of voice, data and audio-video progressing • Phones (fixed & mobile) act as PSTN access devices Ubiquitous computing: smart devices, environments and interaction

21. Public Switched Telephone Network (PSTN) Home users • Single-line local loop to external local switching station Work users • Phones connect to a private circuit switched network or Private Branch Exchange (PBX) to access external networks. • etc. Ubiquitous computing: smart devices, environments and interaction

22. PSTN Ubiquitous computing: smart devices, environments and interaction

23. PSTN • Core network orig. circuit switched not packet-switched networks • Designed to 1st set up dedicated circuit of links between switching offices • Circuit switching used in Telecoms networks used hierarchy ~5 levels Ubiquitous computing: smart devices, environments and interaction

24. PSTN • PSTNs were designed to be very resilient. • Circuit switching can enable a higher QoS per call but at the expense of non-optimal use of the channel, • Interleaved multiple data streams  throughput • E.g., • Later digital telecoms networks Ubiquitous computing: smart devices, environments and interaction

25. Intelligent Networks (IN) • Earliest digital telecommunication networks designed to support specific services, supported using specialised logic contained in specialised switching network elements. • New features / services have to be added and implemented directly in core switch systems -> very long development times for new services • -> Intelligent Networks (IN) network service model, Ubiquitous computing: smart devices, environments and interaction

26. Intelligent Networks (IN) • Supports independent component-based services in general purpose computer nodes rather in special switching nodes. • Enables service providers to drive new services rather than network providers • able to use these to form flexible overlay networks • such as toll free calls, e.g., “0800” numbers. Ubiquitous computing: smart devices, environments and interaction

27. IP Multimedia Subsystems (IMS) • Active development in new IN services has declined in recent years • Focus on development of telecom services & APIs rather than on developing new telecom network protocols. • Although, there seems to be a clear move to IP based networks, in shorter term, hybrid IN and Internet service architectures for mobile users are being proposed such as IP Multimedia Subsystems (IMS). Ubiquitous computing: smart devices, environments and interaction

28. IMS • A key challenge is application-layer control (signalling) protocol for controlling voice/video session, multimedia conference, messaging and Presence over IP. • Control can be performed using the IETF SIP (Session Initiation Protocol) replacing ITU’s earlier H.323 protocol. • Basic entities in a typical SIP system involve? Ubiquitous computing: smart devices, environments and interaction

29. IMS • SIP can use 3 different types of MCU: • full mesh, • mixer • multicast. Ubiquitous computing: smart devices, environments and interaction

30. Asynchronous Digital Subscriber Line (ADSL) Broadband • ADSL  transmission capability over existing physical • e.g., copper-wire PSTN type, access networks. • Audio telephony use ~ 3 kHz bandwidth but typical line transmits usable signals up to approximately 1MHz. • High-frequency signals however face more transmission challenges such as .. Ubiquitous computing: smart devices, environments and interaction

31. Telecoms: ADSL Ubiquitous computing: smart devices, environments and interaction

32. Telecoms WWAN • Wireless Wide-Area Networks (WWAN)support anywhere access for mobile or cell phone users, • WWAN differ w.r.t: • Geographic region • on the Generation (G) of the wireless network such as 1G analogue and 2G digital. • These differ primarily on the way they are designed to share access to the wireless network amongst different users. Ubiquitous computing: smart devices, environments and interaction

33. Telecoms WWAN • WWAN differ primarily on the way they are designed to share access to wireless network amongst different users. • Global System for Mobile Communications (GSM) • Code Division Multiple Access (CDMA) • Networks can interoperate via gateways … Ubiquitous computing: smart devices, environments and interaction

34. Telecoms WWAN • WWAN transmitters or base stations have a limited range • When a user moves between cells, What happens? Ubiquitous computing: smart devices, environments and interaction

35. WLAN: DECT (Digital Enhanced Cordless Telecommunications) • Deployed > 100 countries worldwide • Access control : • Frequencies: Ubiquitous computing: smart devices, environments and interaction

36. Audio Broadcast (Radio Entertainment) Networks • Several benefits in using audio broadcasting or radio? Ubiquitous computing: smart devices, environments and interaction

37. DAB • For digital radio, the Eureka 147 Digital Audio Broadcast (DAB) standard is most commonly used and is coordinated by the World DMB Forum. • DAB uses the MPEG-1 Audio Layer 2 audio (MP2) codec for audio broadcasting while personal players use the MP3 codec. • Original objectives of DAB were to ? • DAB+ standard with a better and more efficient transmission codec has been proposed. Ubiquitous computing: smart devices, environments and interaction

38. Chapter11: Overview The slides for this chapter are also expanded and split into several parts • Part A: Introduction • Part B: Audio Networks • Part C: Data networks: Fixed  • Part D: Data networks: Wireless • Part E: Video & Multi-Content Access Networks • Part F: Ubiquitous Networks: PLC, PAN, BAN, Mobile • Part G: Network Access Control • Part H: Service-Oriented Networks 1 • Part I: Service-Oriented Networks 2 Ubiquitous computing: smart devices, environments and interaction

39. Internet Early Internet (1960s) was based upon several innovations. • Shift from batch to time-shared computers. • Shift from P2P topology • Shift from analogue to digital communication • Support for high capacity and resilient network paths • Large data was split into fixed size data packets • Shift from circuit switched to packet-switched data model Ubiquitous computing: smart devices, environments and interaction

40. Network Protocols • Types of data and control packets are defined in a network communication protocol • Data packet size: • Data segmentation. • . Ubiquitous computing: smart devices, environments and interaction

41. Network Protocols • Types of packet to data packets called control packets, • Each data packet is labelled with the address • Enables packets from multiple messages to be multiplexed to use the same part of the network. Ubiquitous computing: smart devices, environments and interaction

42. Data Packet Protocols Ubiquitous computing: smart devices, environments and interaction

43. Addressing • Before communication can occur between network elements, e.g., computers, they need to be allocated network addresses. • Explain …. Ubiquitous computing: smart devices, environments and interaction

44. Address Space Size • IPv4 supports 32 bit (about 4.3 billion) addresses. • IPv6 supports 128 bit addresses Ubiquitous computing: smart devices, environments and interaction

45. Routing and Internetworking • Multiple paths may be available • Data may be too large to be transmitted • Normally performed at the network level without applications being aware of this. Ubiquitous computing: smart devices, environments and interaction

46. Packet-switched Routing Ubiquitous computing: smart devices, environments and interaction

47. Routing and Internetworking • Routers examine the addresses of data packets to decide • ???? • Routers communicate with each other using specialised routing protocols • ?? • Dynamic routing ? • Use of multiple routes ? Ubiquitous computing: smart devices, environments and interaction

48. Chapter11: Overview The slides for this chapter are also expanded and split into several parts • Part A: Introduction • Part B: Audio Networks • Part C: Data networks: Fixed • Part D: Data networks: Wireless  • Part E: Video & Multi-Content Access Networks • Part F: Ubiquitous Networks: PLC, PAN, BAN, Mobile • Part G: Network Access Control • Part H: Service-Oriented Networks 1 • Part I: Service-Oriented Networks 2 Ubiquitous computing: smart devices, environments and interaction

49. Wireless Data Networks • Wireless LANs (WLANs) / WiFi • WiMAX • BlueTooth • ZigBee • InfraRed (IR) • Ultra Wide Band (UWB) • Satellite and Microwave Ubiquitous computing: smart devices, environments and interaction

50. Wireless Data Networks Benefits for using wireless networks: • Anywhere • Mobility: • Less disruptive • Adaptivity Ubiquitous computing: smart devices, environments and interaction