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

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

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

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

Related Chapter Links • • • Distributed Computing (Chapter 3) Mobile Services (Chapter 4) 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 5

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 6

Ubiquitous computing: smart devices, environments and interaction 7 Ubiquitous computing: smart devices, environments and interaction 7

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 8

Ex: Communication Networks • Time order the following networks: – Internet (data), radio (audio), 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 9

Introduction • Ubiquitous applications need to access relevant remote external information and tasks, anywhere 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 10

Introduction Key design issues: • Should comms functions be largely transparent to services (network-oriented) 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 11

Introduction • Many general and introductory texts and descriptions about networking are specialised towards Introduction • Many general and introductory texts and descriptions about networking are specialised towards specific types of networks, e. g. , – ? ? ? – • An interpretation of Ubi. Com: – 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 12

Network Communication Functions Communication involves the following key functions: • Encoding and Modulation • 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 13

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

Digital Communication • Historically, audio / video content transmitted in analogue form although these 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 15

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

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 17

Types of Audio Networks • • PSTN Voice Networks Intelligent Networks (IN) IP Multimedia 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 18

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

Public Switched Telephone Network (PSTN) • PSTN orig. designed to support voice communication (not 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 20

Public Switched Telephone Network (PSTN) Home users • Single-line local loop to external local 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 21

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

PSTN • Core network orig. circuit switched not packet-switched networks • Designed to 1 PSTN • Core network orig. circuit switched not packet-switched networks • Designed to 1 st 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 23

PSTN • PSTNs were designed to be very resilient. • Circuit switching can enable PSTN • PSTNs were designed to be very resilient. • Circuit switching can enable a higher Qo. S 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 24

Intelligent Networks (IN) • Earliest digital telecommunication networks designed to support specific services, supported 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 25

Intelligent Networks (IN) • Supports independent component-based services in general purpose computer nodes rather 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 26

IP Multimedia Subsystems (IMS) • Active development in new IN services has declined in 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 27

IMS • A key challenge is application-layer control (signalling) protocol for controlling voice/video session, 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 28

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

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

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

Telecoms WWAN • Wireless Wide-Area Networks (WWAN)support anywhere access for mobile or cell phone 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 1 G analogue and 2 G 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 32

Telecoms WWAN • WWAN differ primarily on the way they are designed to share 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 33

Telecoms WWAN • WWAN transmitters or base stations have a limited range – • 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 34

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

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

DAB • For digital radio, the Eureka 147 Digital Audio Broadcast (DAB) standard is 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 (MP 2) codec for audio broadcasting while personal players use the MP 3 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 37

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 38

Internet • • • Early Internet (1960 s) was based upon several innovations. Shift Internet • • • Early Internet (1960 s) was based upon several innovations. Shift from batch to time-shared computers. Shift from P 2 P 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 39

Network Protocols • Types of data and control packets are defined in a network 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 40

Network Protocols • Types of packet to data packets called control packets, • • 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 41

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

Addressing • Before communication can occur between network elements, e. g. , computers, they 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 43

Address Space Size • IPv 4 supports 32 bit (about 4. 3 billion) addresses. Address Space Size • IPv 4 supports 32 bit (about 4. 3 billion) addresses. • IPv 6 supports 128 bit addresses Ubiquitous computing: smart devices, environments and interaction 44

Routing and Internetworking • Multiple paths may be available • • Data may be 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 45

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

Routing and Internetworking • Routers examine the addresses of data packets to decide – 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 47

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 48

Wireless Data Networks • • Wireless LANs (WLANs) / Wi. Fi Wi. MAX Blue. Wireless Data Networks • • Wireless LANs (WLANs) / Wi. Fi Wi. MAX Blue. Tooth Zig. Bee Infra. Red (IR) Ultra Wide Band (UWB) Satellite and Microwave Ubiquitous computing: smart devices, environments and interaction 49

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

Wireless Data Networks • Wide variety of wireless networks exist. • Networks vary according Wireless Data Networks • Wide variety of wireless networks exist. • Networks vary according to ? : Ubiquitous computing: smart devices, environments and interaction 51

Wireless Data Networks: examples • Most global, wide area and local area wireless networks Wireless Data Networks: examples • Most global, wide area and local area wireless networks are infrastructure dependent and use fixed transmitters, – • Ad Hoc Wireless Network the transmitters and routers are dynamic –. • Mobile wireless networks can vary by the range they cover. Ubiquitous computing: smart devices, environments and interaction 52

Wireless Data Networks • Range depends upon ? – • Generally, the higher the Wireless Data Networks • Range depends upon ? – • Generally, the higher the frequency …… Ubiquitous computing: smart devices, environments and interaction 53

Wireless Data Networks • Spatial Efficiency (SE ) • Power efficiency metric: • Spatial Wireless Data Networks • Spatial Efficiency (SE ) • Power efficiency metric: • Spatial and power efficiency Ubiquitous computing: smart devices, environments and interaction 54

Wireless Data Networks: bandwidth allocation • Proliferation of new wireless services • -> concern Wireless Data Networks: bandwidth allocation • Proliferation of new wireless services • -> concern over how to (re)allocate scarce radio frequency ( • New to techniques allow flexible & efficient spectrum use? Ubiquitous computing: smart devices, environments and interaction 55

Wireless Data Networks: Software Radio • Software Radio moves the radio functionality from hardware Wireless Data Networks: Software Radio • Software Radio moves the radio functionality from hardware into software • Software radio alters trad. radio design in 3 main ways. How? Ubiquitous computing: smart devices, environments and interaction 56

Wireless LANs (WLANs) • Ubiquitous computing: smart devices, environments and interaction 57 Wireless LANs (WLANs) • Ubiquitous computing: smart devices, environments and interaction 57

Wi. MAX • Wi. MAX, the Worldwide Interoperability for Microwave Access, from the Wi. Wi. MAX • Wi. MAX, the Worldwide Interoperability for Microwave Access, from the Wi. MAX Forum , is proposed as wireless wide-area broadband access technology, based upon the IEEE 802. 16 standard • Etc. Ubiquitous computing: smart devices, environments and interaction 58

Bluetooth • Bluetooth standard for short-range wireless communication over about 1 -100 M • Bluetooth • Bluetooth standard for short-range wireless communication over about 1 -100 M • Bluetooth applications include both local communication and increasingly local control. • Unlike IR, Bluetooth does not require a line of sight between the transmitter and receiver. • Current Bluetooth devices and applications include: ? Ubiquitous computing: smart devices, environments and interaction 59

Bluetooth versus WLAN • ? ? ? Ubiquitous computing: smart devices, environments and interaction Bluetooth versus WLAN • ? ? ? Ubiquitous computing: smart devices, environments and interaction 60

Zig. Bee • Zig. Bee is a specification for a suite of communication protocols Zig. Bee • Zig. Bee is a specification for a suite of communication protocols from the Zig. Bee alliance formed in 2002 • Uses small, low-power digital radios based on the IEEE 802. 15. 4 standard for Wireless Personal Area Networks (WPAN) • etc Ubiquitous computing: smart devices, environments and interaction 61

Zig. Bee versus Bluetooth • ? ? ? . Ubiquitous computing: smart devices, environments Zig. Bee versus Bluetooth • ? ? ? . Ubiquitous computing: smart devices, environments and interaction 62

Infrared (IR) • Infrared (IR): a short-range low bandwidth data communication – …. . Infrared (IR) • Infrared (IR): a short-range low bandwidth data communication – …. . Ubiquitous computing: smart devices, environments and interaction 63

Ultra-Wideband (UWB) • Transmits information at data rates exceeding 100 M bits / s, Ultra-Wideband (UWB) • Transmits information at data rates exceeding 100 M bits / s, spread over a large bandwidth (>500 MHz), in the 3. 1– 10. 6 GHz frequency range at a low power range, over short distances. • Provide an efficient use of scarce radio bandwidth while enabling both high data rate wireless connectivity • Uses: – Short-range: BANs, PANs and within buildings – Longer-range, low data rate applications: radar, collision obstacle avoidance, precision altimetry & imaging systems Ubiquitous computing: smart devices, environments and interaction 64

Satellite and Microwave Comms • Geostationary satellites use simpler antennae design and configuration & Satellite and Microwave Comms • Geostationary satellites use simpler antennae design and configuration & small No. of satellites can be interlinked to provide global coverage. • Satellite design issues? Ubiquitous computing: smart devices, environments and interaction 65

Internetworking WLANs • Benefits to internet wireless networks: ? • • WLAN can access Internetworking WLANs • Benefits to internet wireless networks: ? • • WLAN can access Internet for mobile computer, Ubiquitous computing: smart devices, environments and interaction 66

Internetworking WLANs • Mobile phone use faster? Cheaper? WLAN at hot spots – requires Internetworking WLANs • Mobile phone use faster? Cheaper? WLAN at hot spots – requires OS support pipelines across heterogeneous networks. • Generic Access Network (GAN), also known as Unlicensed Mobile Access (UMA), is a telecommunication system allowing seamless roaming and handover between local area networks and wide area networks using dual-mode mobile phones. • Femtocells, small cellular access points which provide enhanced coverage & converged voice, data and video services such as IPTV Ubiquitous computing: smart devices, environments and interaction 67

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 68

Universal Content Networks / Network Convergence • Services delivered over common network • Audio Universal Content Networks / Network Convergence • Services delivered over common network • Audio and Video (AV) broadcast Content Based Networks (CBN) have different drivers compared to Telecoms and networks. • Telecoms networks are developed to support duplex or two -way, one-to-one communication, global interoperability • Internet developed (initially) to support asynchronous communication. Ubiquitous computing: smart devices, environments and interaction 69

Audio and Video (AV) broadcast Content Based Networks (CBN) • Digital AV CBN designed Audio and Video (AV) broadcast Content Based Networks (CBN) • Digital AV CBN designed to transmits streamed audio & video – …. • Broadcast networks are designed more for: – …… Ubiquitous computing: smart devices, environments and interaction 70

Audio and Video (AV) broadcast Content Based Networks (CBN) • AV CBN oriented to Audio and Video (AV) broadcast Content Based Networks (CBN) • AV CBN oriented to for a regional rather than global customer base. • Video content is richer and it is more likely to be tailored to a specific region in terms of language and culture. • Receivers have limited control over live broadcasts • Video synchronisation with audio (& metadata) is complex Ubiquitous computing: smart devices, environments and interaction 71

Internet and Common Codecs • Internet focussed most on alphanumeric data transmission • support Internet and Common Codecs • Internet focussed most on alphanumeric data transmission • support for managing reliable and unreliable data streams, mainly for paired senders and receiver. • support for scalable AV content streamed broadcasts over Internet still maturing • Adoption of compatible standards for the triple-play (audio, video and alphanumeric data) will facilitate their integration. Ubiquitous computing: smart devices, environments and interaction 72

PSDN: IP and UDP • UDP ( User Datagram Protocol) used to support mutlicast PSDN: IP and UDP • UDP ( User Datagram Protocol) used to support mutlicast –. • Unreliable transport protocols, e. g. , UDP can be used to transmit media streams. • Depending on the protocol and the extent of the loss, receivers may be able to recover the data using Ubiquitous computing: smart devices, environments and interaction 73

Streaming Media over IP networks • Protocols designed to stream media over IP networks. Streaming Media over IP networks • Protocols designed to stream media over IP networks. • RTP and RTCP built on top of unreliable UDP • RTSP built on top of reliable TCP Ubiquitous computing: smart devices, environments and interaction 74

Combined Voice and Data networks: ADSL • In residential & SME buildings, single external Combined Voice and Data networks: ADSL • In residential & SME buildings, single external comms line is used to access multiple services, e. g. , voice, text, video, • ADSL is replacing use of older ISDN, dial-up modems • There are different types of access device or modem, e. g. , Ubiquitous computing: smart devices, environments and interaction 75

Ubiquitous computing: smart devices, environments and interaction 76 Ubiquitous computing: smart devices, environments and interaction 76

Voice over IP (Vo. IP) • Use of IP network, to In transmitting voice Voice over IP (Vo. IP) • Use of IP network, to In transmitting voice as data packets & interleave text data and voice over same network • Requirements / – • Delays can be caused by ? – Ubiquitous computing: smart devices, environments and interaction 77

Combined Audio-Video and Data Content Distribution Networks • Traditionally, the three different types of Combined Audio-Video and Data Content Distribution Networks • Traditionally, the three different types of conventional networks for broadcasting audio-video entertainment content are: – VHF TV – Satellite TV – Cable TV. Ubiquitous computing: smart devices, environments and interaction 78

Integrating Analogue Video and Text: Teletext • Analogue television broadcast signal can be augmented Integrating Analogue Video and Text: Teletext • Analogue television broadcast signal can be augmented with text data by embedding this data in the Vertical Blanking Interval or VBI part of the television signal. • In EU: called Teletext data transmission; closed-captioning in USA • …. Ubiquitous computing: smart devices, environments and interaction 79

Digital Video Broadcasting (DVB) • • • DVB replacing analogue video broadcasting Multiple standards Digital Video Broadcasting (DVB) • • • DVB replacing analogue video broadcasting Multiple standards for digital video broadcasting. DVB system is the most widely used DVB is modelled like TCP/IP at an abstract level • • All data is transmitted as MPEG-2 transport streams. Ubiquitous computing: smart devices, environments and interaction 80

Multimedia Broadcast networks • Triple-play networks, e. g. , Web documents Vo. IP, video Multimedia Broadcast networks • Triple-play networks, e. g. , Web documents Vo. IP, video streaming. • Quad-play networks: triple-play + mobile phone • Need to multiplex heterogeneous packets from multiple applications which have different sensitivities to time delays and jitter. Several ways to this in IPv 4 networks? • • IPv 6 has more inbuilt support for this. Ubiquitous computing: smart devices, environments and interaction 81

Multiplexing heterogeneous packets from multiple applications (IPv 4) • MPLS • • Differentiated Services Multiplexing heterogeneous packets from multiple applications (IPv 4) • MPLS • • Differentiated Services (Diffserv) • • Resource Reservation Protocol (RSVP) Ubiquitous computing: smart devices, environments and interaction 82

On-demand, Interactive and Distributed Content In contrast, Video-On-demand (Vo. D) Benefits? Ubiquitous computing: smart On-demand, Interactive and Distributed Content In contrast, Video-On-demand (Vo. D) Benefits? Ubiquitous computing: smart devices, environments and interaction 83

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 84

Pervasive Networks: Types Already covered some examples of pervasive networks • Mobile Telecoms Networks Pervasive Networks: Types Already covered some examples of pervasive networks • Mobile Telecoms Networks such as GSM, UTMS • Wireless data networks: Wi. Fi, Bluetooth, Zigbee etc In addition will cover • Power Line Communication (PLC) • Personal Area Networks (PAN) • Body Area Networks (BAN) • Mobile Users Networks Ubiquitous computing: smart devices, environments and interaction 85

Pervasive Telecoms Networks Ubiquitous computing: smart devices, environments and interaction 86 Pervasive Telecoms Networks Ubiquitous computing: smart devices, environments and interaction 86

Pervasive Wireless Networks Challenges • • • Signal Transmission Overlapping Networks Power Consumption & Pervasive Wireless Networks Challenges • • • Signal Transmission Overlapping Networks Power Consumption & Transmission Efficiency Soft Boundaries & Access Control Interference Ubiquitous computing: smart devices, environments and interaction 87

Power Line Communication (PLC) • An alternative to ubiquitously access data and A-V content. Power Line Communication (PLC) • An alternative to ubiquitously access data and A-V content. • Wherever there is an electricity PL connection, same network that conducts electricity to deliver energy • PL can be used modulate electricity as a signal and can be used as a channel to communicate data/AV content. • PLC describes a range of systems for using electricity distribution wires for simultaneous distribution of data. Ubiquitous computing: smart devices, environments and interaction 88

Wireless Personal Area Networks (WPAN) • Specified by the IEEE P 802. 15 working Wireless Personal Area Networks (WPAN) • Specified by the IEEE P 802. 15 working group • PAN is normally confined to a person or object typically <10 M in all directions and envelops two or more objects or persons whether stationary or in motion. • Could WLAN standard be used for PANs? – • Bluetooth, Zigbee and IR can be used to implement a PAN. Ubiquitous computing: smart devices, environments and interaction 89

Wireless Personal Area Networks (WPAN) Typical WPAN applications include ? ? Ubiquitous computing: smart Wireless Personal Area Networks (WPAN) Typical WPAN applications include ? ? Ubiquitous computing: smart devices, environments and interaction 90

Body Area Network or BAN • Consists of a set of mobile and compact Body Area Network or BAN • Consists of a set of mobile and compact intercommunicating sensors that are either wearable or implanted into the human body. • A typical BAN application can monitor vital body parameters and movements – E. g. , monitor EEG, ECG, and EMG signals • Data Management? – Either to store them in some device on the body for later upload analysis – To periodically transmit data in real-time via some external network interface Ubiquitous computing: smart devices, environments and interaction 91

BAN • Can Bluetooth or Zig. Bee be used for BAN? Ubiquitous computing: smart BAN • Can Bluetooth or Zig. Bee be used for BAN? Ubiquitous computing: smart devices, environments and interaction 92

BAN • Electronic devices can be connected as part of near field BANs to BAN • Electronic devices can be connected as part of near field BANs to exchange digital information by capacitively coupling picoamp currents through the body (Zimmerman). • Low-frequency carrier, less than one megahertz, was used. Why? – • Zimmerman demonstrated a near-field BAN system to support business processes Ubiquitous computing: smart devices, environments and interaction 93

Inter-BAN Application Ubiquitous computing: smart devices, environments and interaction 94 Inter-BAN Application Ubiquitous computing: smart devices, environments and interaction 94

Mobile Users Networks • Not all network access by mobile users, applications and devices Mobile Users Networks • Not all network access by mobile users, applications and devices need be via wireless networks and vice versa • Wireless access devices can be static and mobile users can move in between wired or wireless hotspots such as in Internet cafes. • Mobility vs. portability network support. Ubiquitous computing: smart devices, environments and interaction 95

Mobile User Networks: Design Issues • Design issues include? • We can also classify Mobile User Networks: Design Issues • Design issues include? • We can also classify mobile network support in terms of ? – • Advantage of mobile user support at the network level of the network protocol stack means that mobility, at least to some extent, is transparent to applications. Ubiquitous computing: smart devices, environments and interaction 96

Concepts: Mobile vs. Wireless Services Ubiquitous computing: smart devices, environments and interaction 97 Concepts: Mobile vs. Wireless Services Ubiquitous computing: smart devices, environments and interaction 97

Mobile Addresses • Network location or address for a mobile user needs to be Mobile Addresses • Network location or address for a mobile user needs to be determined in order for a user to receive data. • It is easier to send (somewhere) as the user just has to locate the nearest access network base station. • There are two basic approaches to mobile user addressing: – ? ? . Ubiquitous computing: smart devices, environments and interaction 98

Message Routing for Mobile Users Different types of routing for mobile users can be Message Routing for Mobile Users Different types of routing for mobile users can be classified along 2 dimensions: • Fixed versus variable routes • Single versus multi-path routes Ubiquitous computing: smart devices, environments and interaction 99

Message Routing for Mobile Users: single path route • Example of single path route Message Routing for Mobile Users: single path route • Example of single path route is Mobile IP consisting of Mobile Node, Home agent and foreign agent • Mobile IP performs three main functions: – Discovery: . – Registration – Tunnelling Ubiquitous computing: smart devices, environments and interaction 100

Message Routing for Mobile Users: single path route Mobile IP performs three main functions: Message Routing for Mobile Users: single path route Mobile IP performs three main functions: • Discovery • • Registration • Tunnelling: Ubiquitous computing: smart devices, environments and interaction 101

Multi-Path Routing in Mobile Ad hoc Networks (MANETs) • In contrast to fixed computer Multi-Path Routing in Mobile Ad hoc Networks (MANETs) • In contrast to fixed computer networks, ad hoc networks: – use connections established for duration of 1 session – require no base station or fixed router. • Ad hoc networks that support mobile nodes are called Mobile Ad hoc Networks (MANETs) • Rather than used dedicated router nodes, each node is willing to forward data for other nodes, and so the determination of which nodes forward data is made dynamically based on the network connectivity, hence the name ad hoc Ubiquitous computing: smart devices, environments and interaction 102

MANETs • Instead, devices discover others within range to form a network for those MANETs • Instead, devices discover others within range to form a network for those computers. • Devices may search for target nodes that are out of range by flooding the network with broadcasts that are forwarded by each node. • Connections can be made over multiple nodes (multi-hop ad hoc network). • Routing protocols then provide stable connections even if nodes are moving around. Ubiquitous computing: smart devices, environments and interaction 103

MANETs Applications: • in situations where a useful network infrastructure is not already in MANETs Applications: • in situations where a useful network infrastructure is not already in place – E. g. , in natural disaster • in armed conflict situations • Wireless multiplayer gaming – E. g. , Sony's Play. Station and the Nintendo Dsi and Wii game consoles Ubiquitous computing: smart devices, environments and interaction 104

MANET Ubiquitous computing: smart devices, environments and interaction 105 MANET Ubiquitous computing: smart devices, environments and interaction 105

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 106

Network Design Issues • Network Access Control • Controlling Network Access: Firewalls, NATs and Network Design Issues • Network Access Control • Controlling Network Access: Firewalls, NATs and VPNs • Group Communication: Transmissions for Multiple Receivers • Internetworking Heterogeneous Networks • Separating Management and Control from Usage • Ubiquitous versus Localised Access • Global Use: Low-cost Access Networks for Rural Use Ubiquitous computing: smart devices, environments and interaction 107

Network Access Control: Mobile Phone • Different networks use a range of access control Network Access Control: Mobile Phone • Different networks use a range of access control techniques to: – handle network resource allocation problems – allow multiple users to access network media with limited capacity. • TDMA: • CDMA: Ubiquitous computing: smart devices, environments and interaction 108

Network Access Control: WLAN • WLANs often based on sharing freq. between several active Network Access Control: WLAN • WLANs often based on sharing freq. between several active users. • Many simultaneous users may cause packet collisions -> waste channel bandwidth • Difficulty to detect some (hidden) nodes -> design to avoid packet collisions. • WLANs typically use a MACA type transmission protocol. Ubiquitous computing: smart devices, environments and interaction 109

Network Access Control: LAN • A further option is to use CSMA/CD Ubiquitous computing: Network Access Control: LAN • A further option is to use CSMA/CD Ubiquitous computing: smart devices, environments and interaction 110

Network Access Control: LAN • Token-based systems control access to local networks using special Network Access Control: LAN • Token-based systems control access to local networks using special control messages, tokens, which continuously circulate throughout a system, – e. g. , structured as a token ring topology. • … Ubiquitous computing: smart devices, environments and interaction 111

Controlling Network Access: Firewalls, NATs and VPNs • Many ICT resources connected to the Controlling Network Access: Firewalls, NATs and VPNs • Many ICT resources connected to the Internet are protected to control access to specific resources by specific users or to a closed user group. • If access is not restricted what happens? Ubiquitous computing: smart devices, environments and interaction 112

Controlling Network Access: Firewalls, NATs and VPNs How to protect access to local networks? Controlling Network Access: Firewalls, NATs and VPNs How to protect access to local networks? Ubiquitous computing: smart devices, environments and interaction 113

Controlling Network Access: Firewalls Routes versus Firewalls • A router / special purpose computer Controlling Network Access: Firewalls Routes versus Firewalls • A router / special purpose computer that …. – • Firewalls designed according to which level of network they work: – Ubiquitous computing: smart devices, environments and interaction 114

Controlling Network Access: Firewalls Packet-level firewalls • … • Application level firewalls • Ubiquitous Controlling Network Access: Firewalls Packet-level firewalls • … • Application level firewalls • Ubiquitous computing: smart devices, environments and interaction 115

Controlling Network Access: NAT • Network Address Translation (NAT) • Firewalls Ubiquitous computing: smart Controlling Network Access: NAT • Network Address Translation (NAT) • Firewalls Ubiquitous computing: smart devices, environments and interaction 116

Controlling Network Access: NAT • . Ubiquitous computing: smart devices, environments and interaction 117 Controlling Network Access: NAT • . Ubiquitous computing: smart devices, environments and interaction 117

Controlling Network Access: VPN • Useful to restrict the use of resources on remote Controlling Network Access: VPN • Useful to restrict the use of resources on remote networks to specific users that are accessed over a public Internet. • Common technique to achieve this is a VPN • . Ubiquitous computing: smart devices, environments and interaction 118

Controlling Network Access: VPN • Users normally authenticate themselves at VPN client or access Controlling Network Access: VPN • Users normally authenticate themselves at VPN client or access device to gain access to remote resources via VPN: • Several types of VPN / Service – ? ? Ubiquitous computing: smart devices, environments and interaction 119

Controlling Network Access: VPN Persistence of messaging • Proxy host • Bastion host Network Controlling Network Access: VPN Persistence of messaging • Proxy host • Bastion host Network Interfaces Available • ? ? ? Ubiquitous computing: smart devices, environments and interaction 120

Multicasts: Transmissions for Multiple Receivers • Sending the same message from a single source Multicasts: Transmissions for Multiple Receivers • Sending the same message from a single source to a defined group of multiple receivers, multicast communication or group communication is useful. Why? – • Hardware vs. software support Ubiquitous computing: smart devices, environments and interaction 121

Multicasts: Transmissions for Multiple Receivers • To avoid the overhead in managing large groups, Multicasts: Transmissions for Multiple Receivers • To avoid the overhead in managing large groups, groups can be split into hierarchies – • Messages can be tagged with sequenced identifiers to indicate ordering. • Acknowledgements can be used to support more reliable group communications. Ubiquitous computing: smart devices, environments and interaction 122

Multicasts: Transmissions for Multiple Receivers • Group membership may or may not be visible Multicasts: Transmissions for Multiple Receivers • Group membership may or may not be visible to the members depending upon the design. – ? ? ? Ubiquitous computing: smart devices, environments and interaction 123

Low-cost Access Networks for Rural Use: VSAT Very Small Aperture Terminal (VSAT): • . Low-cost Access Networks for Rural Use: VSAT Very Small Aperture Terminal (VSAT): • . Ubiquitous computing: smart devices, environments and interaction 124

Ubiquitous versus Localised Access • Networks can be designed for local context-aware access: • Ubiquitous versus Localised Access • Networks can be designed for local context-aware access: • Used to tailor services for local needs. Ubiquitous computing: smart devices, environments and interaction 125

Ubiquitous versus Localised Access • Services can be restricted to local access because? – Ubiquitous versus Localised Access • Services can be restricted to local access because? – • Local services can also be designed to have access control Ubiquitous computing: smart devices, environments and interaction 126

Ubiquitous Access: WANs Ubiquitous computing: smart devices, environments and interaction 127 Ubiquitous Access: WANs Ubiquitous computing: smart devices, environments and interaction 127

Global Use: Low-cost Access Networks for Rural Use • In theory, wireless networks could Global Use: Low-cost Access Networks for Rural Use • In theory, wireless networks could be ubiquitous but in practice they aren’t in many regions. • Currently, the total worldwide Internet usage penetration was only about 18% but only about 4% in Africa (2007). • but 29% of the global population use GSM type mobile phone technology (2007), more if other types of mobile phone are also included. • People in some rural areas may not be able to pay much • Hence low-cost networks and access terminals are needed. Ubiquitous computing: smart devices, environments and interaction 128

Low-cost Access Networks for Rural Use • In rural areas, several low cost network Low-cost Access Networks for Rural Use • In rural areas, several low cost network access methods have been developed? – – Cor. DECT Print. Cast VSAT Mesh Network Ubiquitous computing: smart devices, environments and interaction 129

Low-cost Access Networks for Rural Use: VSAT Very Small Aperture Terminal (VSAT): • ? Low-cost Access Networks for Rural Use: VSAT Very Small Aperture Terminal (VSAT): • ? ? . Ubiquitous computing: smart devices, environments and interaction 130

Low-cost Access Networks for Rural Use: Cor. DECT system • Based on the DECT Low-cost Access Networks for Rural Use: Cor. DECT system • Based on the DECT standard which initially was designed for use with cordless telephones. • Uses MC-TDMA to performs both time and frequency division in order to accommodate multiple channels. • Typically operates over distances of up to 10 KM with data rates supporting data rates of 35 and 70 kbps. T • Conventional listen before you talk type MAC is problematic when used in low bandwidth transmission over several km Ubiquitous computing: smart devices, environments and interaction 131

Low-cost Access Networks for Rural Use: Print. Cast • Print. Cast system: leverage broadcast Low-cost Access Networks for Rural Use: Print. Cast • Print. Cast system: leverage broadcast TV as a service access network. • ……. Ubiquitous computing: smart devices, environments and interaction 132

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 133

Service-oriented Networks • • Internetworking Network-Dependent vs. Independent Services Separating Management and Control from Service-oriented Networks • • Internetworking Network-Dependent vs. Independent Services Separating Management and Control from Usage Service Orientation in Edge Network Ubiquitous computing: smart devices, environments and interaction 134

Internetworking Heterogeneous Networks • Ideally, universal access means – any type of data – Internetworking Heterogeneous Networks • Ideally, universal access means – any type of data – may be accessed simultaneously – anywhere over any kind of network • Historically, many separate types of communication network exist that are not interlinked. • Networks are heterogeneous in terms of the physical media that electromagnetic signals propagate through. – e. g. , signals may propagate through wired copper or optical fibre networks or through wireless or Over-The-Air, (OTA) networks. Ubiquitous computing: smart devices, environments and interaction 135

Internetworking Heterogeneous Networks • Different types of physical or links of the network have Internetworking Heterogeneous Networks • Different types of physical or links of the network have different signal capacities and have different signal attenuation and hence different requirements for signal amplification and repeaters. • Each type of physical media network, – e. g. , Ethernet, Point to Point Protocol (PPP) defines its own protocols to partition, structure data into packets for transmission. Ubiquitous computing: smart devices, environments and interaction 136

Inter-Network Architecture Ubiquitous computing: smart devices, environments and interaction 137 Inter-Network Architecture Ubiquitous computing: smart devices, environments and interaction 137

Separating Management and Control from Usage • Are different options for designing application use Separating Management and Control from Usage • Are different options for designing application use versus control and management of networks • Architectural model can separate concerns about: – media access, – control of the communication – management of the communication. Ubiquitous computing: smart devices, environments and interaction 138

Separating Management and Control from Usage • Management – … FCAPS functions. • Control Separating Management and Control from Usage • Management – … FCAPS functions. • Control • Application centric model Ubiquitous computing: smart devices, environments and interaction 139

Separating Management and Control from Usage Ubiquitous computing: smart devices, environments and interaction 140 Separating Management and Control from Usage Ubiquitous computing: smart devices, environments and interaction 140

Separating Management and Control from Usage • in-band signalling: • • out-of-band signalling Ubiquitous Separating Management and Control from Usage • in-band signalling: • • out-of-band signalling Ubiquitous computing: smart devices, environments and interaction 141

Separating Management and Control from Usage • In some systems, each major application uses Separating Management and Control from Usage • In some systems, each major application uses its own dedicated network, • Hence management is application (network) specific. • As multimedia content applications are becoming integrated into single networks, …. . Ubiquitous computing: smart devices, environments and interaction 142

Network Dependent Services • Traditionally, different application services were coupled to specific networks because Network Dependent Services • Traditionally, different application services were coupled to specific networks because different applications need different levels of support for: – – – Data transmission functions, such as latency, sequencing, performance and reliability, channel sharing, data control security. Ubiquitous computing: smart devices, environments and interaction 143

Network Independent Services • Simpler to design networks to support 1 specific set of Network Independent Services • Simpler to design networks to support 1 specific set of application requirements rather than to support multiple applications. Why? • Disadvantages? – Ubiquitous computing: smart devices, environments and interaction 144

Service-Oriented Networks Focus was on network oriented models • To use a service, users Service-Oriented Networks Focus was on network oriented models • To use a service, users must subscribe to a particular network and service configuration on the network, – e. g. , voice calls via a telecoms network and audio-video content via an audio-video wireless broadcast network. Focus has now shifted to service- oriented models • Focus is on core networks that support multiple services • Services are coupled less to specific networks • Services can be available across heterogeneous networks Ubiquitous computing: smart devices, environments and interaction 145

Paradigm Shift from Network-Oriented to Service Orientated Architectures Ubiquitous computing: smart devices, environments and Paradigm Shift from Network-Oriented to Service Orientated Architectures Ubiquitous computing: smart devices, environments and interaction 146

A Simple Network Topology • Simplest network topology is to have only one network A Simple Network Topology • Simplest network topology is to have only one network – E. g. , analogue VHF radio network from transmitter to receiver • Next simplest network topology is to partition network into 2 parts: – Access network or edge network – Core network Ubiquitous computing: smart devices, environments and interaction 147

Service-Orientation: in Edge Network Important design decision is whether or not to put the Service-Orientation: in Edge Network Important design decision is whether or not to put the complexity or intelligence for service specific communication: • into the core network, – e. g. , PSTN • Or in the edge network • Or in both – e. g. , IP networks. Ubiquitous computing: smart devices, environments and interaction 148

Service-Orientation: in Edge Network • Motivation for end-to-end or edge-based complexity? • A main Service-Orientation: in Edge Network • Motivation for end-to-end or edge-based complexity? • A main argument is that “functions placed at low levels of system may be redundant or of little value when compared with cost of providing them at that low level. ” • This implies that networks that are simple and neutral as possible should be used Ubiquitous computing: smart devices, environments and interaction 149

Service-Orientation: in Edge Network • Widespread adoption of IP in the core network has Service-Orientation: in Edge Network • Widespread adoption of IP in the core network has given the Internet a nearly universal interoperability – allows all end users to access Internet applications and content on a non discriminatory basis. • IP provide a network neutrality vision for comms & content delivery worlds in which every end user can obtain access to every available application and piece of information is quite compelling. • However, it has led to some content providers resisting more open access to the edge network as they will lose market share. Ubiquitous computing: smart devices, environments and interaction 150

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 151

Service-Oriented Networks 2 This part gives an overview of network paradigms that support some Service-Oriented Networks 2 This part gives an overview of network paradigms that support some more flexible messaging • Content-based Networks (CN) • Programmable Networks • Overlay Networks • Mesh Networks • Cooperative Networks Ubiquitous computing: smart devices, environments and interaction 152

Content-based Networks (CN) • CN is a network in which the flow of messages Content-based Networks (CN) • CN is a network in which the flow of messages through the network is driven by the content of the messages, rather than by linking specific senders to specific receivers. • With this communication pattern, receivers subscribe to the types of content that are of interest to them without regard to any specific source (unless that is one of the selection criteria). • Senders simply publish information without addressing it to any specific destination. Ubiquitous computing: smart devices, environments and interaction 153

Programmable Networks • Typically, service providers do not have access to the router, in Programmable Networks • Typically, service providers do not have access to the router, in order to optimise network use for different applications. – e. g. , router control environments algorithms & router states, • This makes the deployment of new network services, which could be far more flexible than proprietary control systems, impossible due to the closed nature of network nodes. Ubiquitous computing: smart devices, environments and interaction 154

Programmable Networks • Programmable networks allow some of the network elements to be reprogrammed Programmable Networks • Programmable networks allow some of the network elements to be reprogrammed dynamically –. • Disadvantages? –. Ubiquitous computing: smart devices, environments and interaction 155

Programmable Networks • 2 two main initiatives to establish programmable networks: – DARAPA’s Active Programmable Networks • 2 two main initiatives to establish programmable networks: – DARAPA’s Active Networks (AN) program – Open Signalling (Opensig) community. • Difference in focus between these two? Ubiquitous computing: smart devices, environments and interaction 156

Overlay Network • An overlay network is a virtual network built on top of Overlay Network • An overlay network is a virtual network built on top of a physical network that provides a (virtual) infrastructure to one or more applications. • It handles the forwarding and handling of application data in ways that can differ from or in competition with the basic underlying physical network such as the Internet or PSTN. • It can be operated in an organised and coherent way by third parties, which may include collections of end-users. Ubiquitous computing: smart devices, environments and interaction 157

Overlay Network Motivation for Overlay networks • ? ? Ubiquitous computing: smart devices, environments Overlay Network Motivation for Overlay networks • ? ? Ubiquitous computing: smart devices, environments and interaction 158

Overlay Network • Another issue is that different applications may need different levels of Overlay Network • Another issue is that different applications may need different levels of reliability, performance and latency and security and access control. – • Application specific overlay networks can be incrementally deployed on end-hosts running an overlay protocol, – Ubiquitous computing: smart devices, environments and interaction 159

Mesh Networks • In a full mesh network topology, every network node is connected Mesh Networks • In a full mesh network topology, every network node is connected using point-to-point connections to every other one. Cons? – connecting every node to every other node is costly to wire and costly power wise to transmit to each other. • Hence, in practice, mesh networks are usually partial mesh networks, in which each node is not connected to every other node. • Partial mesh networks tend to combine ring and star based network topologies. Ubiquitous computing: smart devices, environments and interaction 160

Full Mesh Ubiquitous computing: smart devices, environments and interaction 161 Full Mesh Ubiquitous computing: smart devices, environments and interaction 161

Partial Mesh Ubiquitous computing: smart devices, environments and interaction 162 Partial Mesh Ubiquitous computing: smart devices, environments and interaction 162

Wireless Mesh Networks (WMNs) • Are partial mesh, ad hoc, networks that can significantly Wireless Mesh Networks (WMNs) • Are partial mesh, ad hoc, networks that can significantly improve the performance, at a lower cost and at a lower power output compared to other types of WLAN – • WMN is lower power because it uses a set of lower power multi-hop transmissions rather than needing a single more powerful transmission to base-station. • WNM may be a suitable solution in rural areas where conventional base-station wireless type network support or DSL support maybe patchy. • However, each WMN receiver is now more complex and more costly as it must also act as a relay. Ubiquitous computing: smart devices, environments and interaction 163

Wireless Mesh Networks (WMNs) • Instead of using a sophisticated and costly, centralised base Wireless Mesh Networks (WMNs) • Instead of using a sophisticated and costly, centralised base stations, each wireless receiver in a WMN can act as a relay point or node for other receivers within range • -> WMN acts as a kind of cooperative network for its users. • WMNs can be used to ? ? –. Ubiquitous computing: smart devices, environments and interaction 164

Wireless Mesh Networks (WMNs) • In WMNs, each node operates not only as a Wireless Mesh Networks (WMNs) • In WMNs, each node operates not only as a host but also as a router (mesh–clients), forwarding packets on behalf of other nodes that may not be within direct wireless transmission range of their destinations • In addition, dedicated mesh routers which contain additional routing capabilities and bridging and gateway function to other networks. • WMN can also dynamically self-organise and self-configure mesh connectivity to support ad hoc multi-hop networking. Ubiquitous computing: smart devices, environments and interaction 165

Wireless Mesh Network (WMN) Ubiquitous computing: smart devices, environments and interaction 166 Wireless Mesh Network (WMN) Ubiquitous computing: smart devices, environments and interaction 166

Cooperative Networks • Some network access devices cannot access multiple networks in order to Cooperative Networks • Some network access devices cannot access multiple networks in order to communicate, they just have access to 1 network connection • Some other network access devices have inbuilt support to heterogeneous network access, – e. g • Each of these networks must be used in isolation they do not interoperate. Ubiquitous computing: smart devices, environments and interaction 167

Cooperative Networks • Multiple types of the same type of physical and network layer Cooperative Networks • Multiple types of the same type of physical and network layer may exist – because multiple independent users and providers may offer overlapping wireless networks within the same vicinity but yet again these do not interoperate. • These overlap and the coincidence of multiple overlapping networks will increase as more networks get installed but yet again these networks do no interoperate. Ubiquitous computing: smart devices, environments and interaction 168

Cooperative Networks • Cooperative communication is designed to enable singleantenna mobile access devices to Cooperative Networks • Cooperative communication is designed to enable singleantenna mobile access devices to reap some of the benefits of being Multiple Input Multiple Outputs (MIMO) systems • A specific problem that cooperative communication can solve at the physical media layer concerns signal fading – because thermal noise, shadowing due to fixed obstacles and due to signal attenuation can vary significantly over the course of a given transmission. • Transmitting independent copies of the signal that will face independent fading generates diversity and can effectively combat the deleterious effects of fading through combining these multiple signals. Ubiquitous computing: smart devices, environments and interaction 169

Chapter 11: Overview The slides for this chapter are also expanded and split into Chapter 11: 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 170

Summary & Revision For each chapter • See book web-site for chapter summaries, references, Summary & Revision For each chapter • See book web-site for chapter summaries, references, resources etc. • Identify new terms & concepts • Apply new terms and concepts: define, use in old and new situations & problems • Debate problems, challenges and solutions • See Chapter exercises on web-site Ubiquitous computing: smart devices, environments and interaction 171

Exercises: Define New Concepts • Client-server, etc Ubiquitous computing: smart devices, environments and interaction Exercises: Define New Concepts • Client-server, etc Ubiquitous computing: smart devices, environments and interaction 172

Exercise: Applying New Concepts • What is the difference between client-server and P 2 Exercise: Applying New Concepts • What is the difference between client-server and P 2 P model? Ubiquitous computing: smart devices, environments and interaction 173