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Emerging Wireless Networks

Emerging Wireless Networks. Anand Balachandran http://www-cse.ucsd.edu/users/abalacha/. Outline. Introduction Wireless Internet today Some history Access technologies and Standards Radio access technologies Going up the protocol stack Future of Ubiquitous Wireless Internet.

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Emerging Wireless Networks

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  1. Emerging Wireless Networks Anand Balachandran http://www-cse.ucsd.edu/users/abalacha/

  2. Outline • Introduction • Wireless Internet today • Some history • Access technologies and Standards • Radio access technologies • Going up the protocol stack • Future of Ubiquitous Wireless Internet Multimedia Systems

  3. The New mobile mantra • Anywhere • home, office, car, mall, top of Mt. Everest • Anytime • day or night • Anyone • between any number of persons anywhere in the world • Any device • Pager, cell phone, pocket computer, wireless watch, sensor badges, earrings • Any service • multi-media (voice, video, data) Multimedia Systems

  4. What is the Wireless Internet? • Wireless access to WWW services and content – no, not quite! • Wireless Internet • Access Technologies • Architecture • Protocols • Devices • Heterogeneous blend of standards bodies, companies and industry forums Multimedia Systems

  5. Wireless Internet (contd.) • Advances in Integrated Circuits • Displays • Embedded Operating Systems • Lightweight portable devices (form factor) • Radio Access technologies • Wireless networking protocols • Services and software technologies Multimedia Systems

  6. Wireless Internet at 75 mph Multimedia Systems

  7. How it all Started • First wireless line of sight communications • Early pioneers used smoke signals, mirrors, flares, semaphores • First radio transmission • Demonstrated by Marconi in 1895 • First wireless voice communication • Between NYC and SFO in 1915 • First public mobile telephone service • Introduced in 25 US cities in 1946 (very inefficient) Multimedia Systems

  8. Frequency Spectrum Continuum Multimedia Systems

  9. Cellular Family Tree • First Generation introduced by AT&T in 1983 • Analog cellular telephony • AMPS • FDMA • Divided the frequency band into 30 channels • 2G introduced in 1987 in Europe • Digital cellular services at data rates upto 14.4 Kbps • Three primary wireless standards • TDMA (Time Division Multiple Access) • GSM (Global System for Mobile Communications) • CDMA (Code Division Multiple Access) • Cellular Digital Packet Data (CDPD) at 19.2 Kbps Multimedia Systems

  10. Air Interface Standards Multimedia Systems

  11. Cellular Family Tree – 2.5G • 2.5G (Here and Now) • In support of faster wireless data services • HSCSD (High Speed Circuit-switched Data) • Extension to GSM – 57.6 Kbps • GPRS (Generalized Packet Radio Service) • Another extension to GSM – 100 Kbps • Cellular Subscriber growth • Currently ~300 million worldwide • Heterogeneous standards • Dual mode or Multimode phones Multimedia Systems

  12. Cellular family tree – 3G • 3G (some time this year – we hope) • ITU IMT-2000 Project • Will transmit at • 144 Kbps for fast moving vehicular users • 384 Kbps for slow moving pedestrian users • 2 Mbps for fixed location • Multiple proposals (US, Europe and Japan) • W-CDMA • cdma2000 • UMTS • The move is toward fast Internet access – so 4G aims at an all-IP solution Multimedia Systems

  13. Packet Radio – History • First packet radio network, Hawaii, 1971 • Transmitted voice and data • Channel access control was done through aloha • Precursor for today’s protocols • Better media access protocols • Slotted aloha • Carrier sense multiple access (CSMA) • Number of problems with detection • Led to Wireless LAN standard (IEEE 802.11) in 1990 – based on CSMA/CA We will revisit wireless LANS!! Multimedia Systems

  14. Speed and Environment Multimedia Systems

  15. Major Challenges in Wireless • Limited Resources • Scarce and expensive spectrum (FCC-regulated) • Limited Bandwidth • 2-10 Mbps in the LAN, wired is 100 Mbps • Higher error rates • Can be as poor as 10^-2!! • Wired BER at 10^-12 • Limited Power • Short battery life – transmission and sensing are power-guzzling Multimedia Systems

  16. Major Challenges in Wireless • Highly fluctuating channel conditions • Multipath fading, noise, signal attenuation • Time-varying changes • Dependent on environmental conditions • Impose severe limitations on range, data rates and reliability of communications • - e.g. a radio for an indoor user at walking speeds will support much higher data rates than an outdoor user channel that operates in the shadow of tall buildings and where the user moves at high speeds Multimedia Systems

  17. Multipath Propagation Multimedia Systems

  18. And finally… • User mobility • Need to locate the user • Need to support routing to a moving user • Need to continuously track the change in the location and deliver data while the user is roaming • Need to manage the scarce resources in an fair and efficient manner while catering to varying user demands Multimedia Systems

  19. Network Layer Issues • Routing and Inter-domain Mobility Management – Mobile IP Multimedia Systems

  20. Transport Layer Issues • TCP is custom-designed for the wired Internet • But when you have a wireless last-hop Key: Packet loss is not due to congestion • Channel errors • User handoffs • TCP source scales back thinking there is a congestion (congestion control kicks in) • Solutions: • Split the connection and use 2 TCP connections; source to Base station, Base station to mobile • Rexmit at the link-layer, hide loss from sender Multimedia Systems

  21. Application layer Issues • Intelligent Adaptation to help Multimedia data • Images – hierarchical coding • Progressive JPEG, Alternative 1, Alternative 2 • Video – layered encoding • Base layer, enhancement layers in MPEG-2 • Selective transmission of I, P, B frames • Dynamic Rate Shaping – DCT coefficients • Trans-coding of images into different formats Multimedia Systems

  22. So where are we? • Promise of Wireless LANs – anywhere, anytime access at almost any place • High Bandwidth (11 Mbps today and expected to grow 10-fold in three year) • Provides accessibility at home, offices, and public places like sports arenas, airports, malls, university campuses, and hospitals • Can extend the network to most places where people are likely to spend their time • Need to extend connectivity beyond homes and offices to public places Solution: Public-area Wireless Networks (PAWNS) Multimedia Systems

  23. Can you do better than 4G? • Of course! • 50X difference in data rates • 4G will not work as well indoors • Cannot provide desirable form factor and variety of applications – other than Web and email Multimedia Systems

  24. Some challenges User authentication, access control and mobility management Multimedia Systems

  25. Some challenges User authentication, access control and mobility management Need mechanisms to authenticate unknown users Multimedia Systems

  26. Some challenges User authentication, access control and mobility management Need to protect network from malicious users Multimedia Systems

  27. Some challenges User authentication, access control and mobility management Need mechanisms to manage host configuration as users roam between the two networks Multimedia Systems

  28. A Public Wireless Network Internet Wireless Subnet Local Services Multimedia Systems

  29. Public Network Architecture AuthorizerGateway GlobalAuthenticator Internet VerifierGateway Wireless Subnet Local Services Multimedia Systems

  30. Client Connects to Local Portal AuthorizerGateway GlobalAuthenticator Internet VerifierGateway Wireless Subnet Local Services Multimedia Systems

  31. Client Authenticates withGlobal Authenticator AuthorizerGateway GlobalAuthenticator Internet VerifierGateway Wireless Subnet Local Services Multimedia Systems

  32. Global Authenticator Responds AuthorizerGateway GlobalAuthenticator Internet VerifierGateway Wireless Subnet Local Services Multimedia Systems

  33. Authorizer Generates Session Key Policy AuthorizerGateway GlobalAuthenticator Internet VerifierGateway Wireless Subnet Local Services Multimedia Systems

  34. Client Gains Access Via Verifier AuthorizerGateway GlobalAuthenticator Internet VerifierGateway Wireless Subnet Local Services Multimedia Systems

  35. Service Models • Model 1: Free access to local resources • Does not require authentication but needs a valid IP address • Allow access to the Intranet • e.g. Mall portal, splash screens, indoor navigation service, Starbucks coffee ordering etc. • Model 2: Authenticate and pay • Allow access to the Internet • Allow applications like location-based buddy list, spontaneous sales that are based on profiles etc. • Differentiated charging Multimedia Systems

  36. A very viable model • Information at the fingertips (end users win) • WLAN hardware sold (hardware vendors win) • Backbone network resources get used (ISP’s win) • Building attracts more people (store owners win) • Software sold (software vendors win) Multimedia Systems

  37. Unsolved Issues • Quality of Service • Resource reservation and efficient bandwidth allocation • Providing differentiated services with guarantees • Power Conservation and control • Energy-efficient channel access protocols • Anonymity • Keep user identity hidden (zero knowledge algorithms) • Secure location tracking Multimedia Systems

  38. There’s lot more info and lot less time • Exciting area to be in • You will define the future of networking (Oh! Well) • Read papers from ACM Mobicom, and Infocom • Several workshops on Mobile Multimedia (WowMom, Momuc) Multimedia Systems

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