Emerging Wireless Networks Anand Balachandran http wwwcse ucsd

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

Outline n n n n Introduction Wireless Internet today Some history Access technologies and Standards Radio access technologies Going up the protocol stack Future of Ubiquitous Wireless Internet 05/18/01 Multimedia Systems

The New mobile mantra n Anywhere n n Anytime n n between any number of persons anywhere in the world Any device n n day or night Anyone n n home, office, car, mall, top of Mt. Everest Pager, cell phone, pocket computer, wireless watch, sensor badges, earrings Any service n multi-media (voice, video, data) 05/18/01 Multimedia Systems

What is the Wireless Internet? n n Wireless access to WWW services and content – no, not quite! Wireless Internet n n n Access Technologies Architecture Protocols Devices Heterogeneous blend of standards bodies, companies and industry forums 05/18/01 Multimedia Systems

Wireless Internet (contd. ) n n n n Advances in Integrated Circuits Displays Embedded Operating Systems Lightweight portable devices (form factor) Radio Access technologies Wireless networking protocols Services and software technologies 05/18/01 Multimedia Systems

Wireless Internet at 75 mph 05/18/01 Multimedia Systems

How it all Started n First wireless line of sight communications n n First radio transmission n n Demonstrated by Marconi in 1895 First wireless voice communication n n Early pioneers used smoke signals, mirrors, flares, semaphores Between NYC and SFO in 1915 First public mobile telephone service n 05/18/01 Introduced in 25 US cities in 1946 (very inefficient) Multimedia Systems

Frequency Spectrum Continuum 05/18/01 Multimedia Systems

Cellular Family Tree n First Generation introduced by AT&T in 1983 n Analog cellular telephony n n AMPS FDMA Divided the frequency band into 30 channels 2 G introduced in 1987 in Europe n n Digital cellular services at data rates upto 14. 4 Kbps Three primary wireless standards n n 05/18/01 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

Air Interface Standards 05/18/01 Multimedia Systems

Cellular Family Tree – 2. 5 G n 2. 5 G (Here and Now) n n In support of faster wireless data services HSCSD (High Speed Circuit-switched Data) n n GPRS (Generalized Packet Radio Service) n n Extension to GSM – 57. 6 Kbps Another extension to GSM – 100 Kbps Cellular Subscriber growth n n n 05/18/01 Currently ~300 million worldwide Heterogeneous standards Dual mode or Multimode phones Multimedia Systems

Cellular family tree – 3 G n 3 G (some time this year – we hope) n n ITU IMT-2000 Project Will transmit at n n Multiple proposals (US, Europe and Japan) n n 144 Kbps for fast moving vehicular users 384 Kbps for slow moving pedestrian users 2 Mbps for fixed location W-CDMA cdma 2000 UMTS The move is toward fast Internet access – so 4 G aims at an all-IP solution 05/18/01 Multimedia Systems

Packet Radio – History n First packet radio network, Hawaii, 1971 n n Better media access protocols n n Transmitted voice and data Channel access control was done through aloha Precursor for today’s 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!! 05/18/01 Multimedia Systems

Speed and Environment 05/18/01 Multimedia Systems

Major Challenges in Wireless n Limited Resources n n Limited Bandwidth n n 2 -10 Mbps in the LAN, wired is 100 Mbps Higher error rates n n n Scarce and expensive spectrum (FCC-regulated) Can be as poor as 10^-2!! Wired BER at 10^-12 Limited Power n 05/18/01 Short battery life – transmission and sensing are power-guzzling Multimedia Systems

Major Challenges in Wireless n Highly fluctuating channel conditions n n n 05/18/01 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

Multipath Propagation 05/18/01 Multimedia Systems

And finally… n User mobility n n 05/18/01 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

Network Layer Issues n Routing and Inter-domain Mobility Management – Mobile IP 05/18/01 Multimedia Systems

Transport Layer Issues n n TCP is custom-designed for the wired Internet But when you have a wireless last-hop Key: Packet loss is not due to congestion n Channel errors n User handoffs n TCP source scales back thinking there is a congestion (congestion control kicks in) n Solutions: n n 05/18/01 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

Application layer Issues n Intelligent Adaptation to help Multimedia data n Images – hierarchical coding n n Video – layered encoding n n 05/18/01 Progressive JPEG, Alternative 1, Alternative 2 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

So where are we? n Promise of Wireless LANs – anywhere, anytime access at almost any place n n 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) 05/18/01 Multimedia Systems

Can you do better than 4 G? n Of course! n n n 05/18/01 50 X difference in data rates 4 G will not work as well indoors Cannot provide desirable form factor and variety of applications – other than Web and email Multimedia Systems

Some challenges User authentication, access control and mobility management 05/18/01 Multimedia Systems

Some challenges User authentication, access control and mobility management Need mechanisms to authenticate unknown users 05/18/01 Multimedia Systems

Some challenges User authentication, access control and mobility management Need to protect network from malicious users 05/18/01 Multimedia Systems

Some challenges User authentication, access control and mobility management Need mechanisms to manage host configuration as users roam between the two networks 05/18/01 Multimedia Systems

A Public Wireless Network Internet Wireless Subnet Local Services 05/18/01 Multimedia Systems

Public Network Architecture Global Authenticator Internet Local Services 05/18/01 Authorizer Gateway Verifier Gateway Multimedia Systems Wireless Subnet

Client Connects to Local Portal Global Authenticator Internet Local Services 05/18/01 Authorizer Gateway Verifier Gateway Multimedia Systems Wireless Subnet

Client Authenticates with Global Authenticator Internet Local Services 05/18/01 Authorizer Gateway Verifier Gateway Multimedia Systems Wireless Subnet

Global Authenticator Responds Global Authenticator Internet Local Services 05/18/01 Authorizer Gateway Verifier Gateway Multimedia Systems Wireless Subnet

Authorizer Generates Session Key Policy Global Authenticator Internet Local Services 05/18/01 Authorizer Gateway Verifier Gateway Multimedia Systems Wireless Subnet

Client Gains Access Via Verifier Global Authenticator Internet Local Services 05/18/01 Authorizer Gateway Verifier Gateway Multimedia Systems Wireless Subnet

Service Models n Model 1: Free access to local resources n n Does not require authentication but needs a valid IP address Allow access to the Intranet n n e. g. Mall portal, splash screens, indoor navigation service, Starbucks coffee ordering etc. Model 2: Authenticate and pay n n n 05/18/01 Allow access to the Internet Allow applications like location-based buddy list, spontaneous sales that are based on profiles etc. Differentiated charging Multimedia Systems

A very viable model n n n 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) 05/18/01 Multimedia Systems

Unsolved Issues n Quality of Service n n n Power Conservation and control n n Energy-efficient channel access protocols Anonymity n n Resource reservation and efficient bandwidth allocation Providing differentiated services with guarantees Keep user identity hidden (zero knowledge algorithms) Secure location tracking 05/18/01 Multimedia Systems

There’s lot more info and lot less time n n 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 (Wow. Mom, Momuc) 05/18/01 Multimedia Systems