1. INTRODUCTION To Wireless Networks

2. Wireless Comes of Age Guglielmo Marconi invented the wireless telegraph in 1896Guglielmo Marconi invented the wireless telegraph in 1896 –Communication by encoding alphanumeric characters in analog signal –Sent telegraphic signals across the Atlantic Ocean Communications satellites launched in 1960sCommunications satellites launched in 1960s Advances in wireless technologyAdvances in wireless technology –Radio, television, mobile telephone, communication satellites More recentlyMore recently –Broadband wireless networking, cellular technology

3. Broadband Wireless Technology Higher data rates obtainable with broadband wireless technologyHigher data rates obtainable with broadband wireless technology –Graphics, video, audio Shares same advantages of all wireless services: convenience and reduced costShares same advantages of all wireless services: convenience and reduced cost –Service can be deployed faster than fixed service –No cost of cable plant –Service is mobile, deployed almost anywhere

4. Limitations and Difficulties of Wireless Technologies Wireless is convenient and less expensiveWireless is convenient and less expensive Limitations and political and technical difficulties inhibit wireless technologiesLimitations and political and technical difficulties inhibit wireless technologies Lack of an industry-wide standardLack of an industry-wide standard Device limitationsDevice limitations –E.g., small LCD on a mobile telephone can only displaying a few lines of text –E.g., browsers of most mobile wireless devices use wireless markup language (WML) instead of HTML

5. A Wireless Network Definition: A Group of interconnected nodes that exchange information and share resources through a wireless transmission medium

6. TYPES OF WIRELESS NETWORKS Wireless PANWireless PAN Wireless LANWireless LAN Wireless BroadbandWireless Broadband Wireless WAN (satellite, Microwave,..etc)Wireless WAN (satellite, Microwave,..etc) Cellular NetworksCellular Networks

7. Characteristics of Wireless WANs Covers large geographical areasCovers large geographical areas Circuits provided by a common carrierCircuits provided by a common carrier Consists of interconnected switching nodesConsists of interconnected switching nodes Traditional WANs provide modest capacityTraditional WANs provide modest capacity –64000 bps common –Business subscribers using T-1 service – 1.544 Mbps common Higher-speed Wireless W AN s use satellite, and 10s of Mbps commonHigher-speed Wireless W AN s use satellite, and 10s of Mbps common

8. Characteristics of Wireless LANs Like WAN, Wireless LAN interconnects a variety of devices and provides a means for information exchange among themLike WAN, Wireless LAN interconnects a variety of devices and provides a means for information exchange among them Traditional Wireless LANsTraditional Wireless LANs –Provide data rates of 1 to 20 Mbps High-speed Wireless LANSHigh-speed Wireless LANS –Provide data rates of 100 Mbps Standards for Wireless LANS is WI-FIStandards for Wireless LANS is WI-FI

9. Characteristics of Wireless LANs Used to be a network with high prices, low data rates, occupational safety concerns, and licensing requirementsUsed to be a network with high prices, low data rates, occupational safety concerns, and licensing requirements Problems have been addressed and popularity of wireless LANs has grown rapidlyProblems have been addressed and popularity of wireless LANs has grown rapidly

10. Differences between Wireless LANs and WANs Scope of a LAN is smallerScope of a LAN is smaller –LAN interconnects devices within a single building or cluster of buildings LAN usually owned by organization that owns the attached devicesLAN usually owned by organization that owns the attached devices –For WANs, most of network assets are not owned by same organization Internal data rate of LAN is much greaterInternal data rate of LAN is much greater

11. The Need for Wireless MANs Traditional point-to-point and switched network techniques used in WANs are inadequate for growing needs of organizationsTraditional point-to-point and switched network techniques used in WANs are inadequate for growing needs of organizations Need for high capacity and low costs over large areaNeed for high capacity and low costs over large area MAN provides:MAN provides: –Service to customers in metropolitan areas –Required capacity –Lower cost and greater efficiency than equivalent service from telephone company Standards for Wireless MANS is WI-MAXStandards for Wireless MANS is WI-MAX

12. Wireless Standards PAN, LAN and MAN standards were defined by IEEE and Industrial forumsPAN, LAN and MAN standards were defined by IEEE and Industrial forums A LAN standard define media, coding scheme, frame form at, MAC protocol and other data link layer protocols :A LAN standard define media, coding scheme, frame form at, MAC protocol and other data link layer protocols : Examples of standards :Examples of standards : –Wireless PAN: Bluetooth, IEEE 802.15 –Wireless LAN : IEEE 802.11 (a,b, g ) –Broadband Wireless Networks : IEEE 803.16

13. Wireless LAN Configurations A wireless LAN uses wireless transmission medium in a local Area in :A wireless LAN uses wireless transmission medium in a local Area in : –Single Cell Configuration - Multi-cell Configuration –Infrastructure Wireless LAN –- Add Hoc LAN

14. Single Cell Wireless LAN Configuration

15. Multi-Cell Wireless LAN Configuration

16. Infrastructure Wireless LAN

17. Add Hoc LAN

18. Factors To Consider: For Wireless LAN Same as any LANSame as any LAN –High capacity, short distances, full connectivity, broadcast capability Throughput: efficient use wireless mediumThroughput: efficient use wireless medium Number of nodes:Hundreds of nodes across multiple cellsNumber of nodes:Hundreds of nodes across multiple cells Connection to backbone LAN: Use control modules to connect to both types of LANsConnection to backbone LAN: Use control modules to connect to both types of LANs Service area: 100 to 300 mService area: 100 to 300 m Low power consumption:Need long battery life on mobile stationsLow power consumption:Need long battery life on mobile stations –Mustn't require nodes to monitor access points or frequent handshakes Transmission robustness and security:Interference prone and easily eavesdroppedTransmission robustness and security:Interference prone and easily eavesdropped

19. Factors To Consider: For Wireless LAN Collocated network operation:Two or more wireless LANs in same areaCollocated network operation:Two or more wireless LANs in same area License-free operationLicense-free operation Handoff/roaming: Move from one cell to anotherHandoff/roaming: Move from one cell to another Dynamic configuration: Addition, deletion, and relocation of end systems without disruption to usersDynamic configuration: Addition, deletion, and relocation of end systems without disruption to users

20. Wireless LAN Applications LAN ExtensionLAN Extension Cross-Building InterconnectCross-Building Interconnect Nomadic AccessNomadic Access Ad Hoc NetworkingAd Hoc Networking

21. Applications - LAN Extension Saves installation of LAN cablingSaves installation of LAN cabling Eases relocation and other modifications to network structureEases relocation and other modifications to network structure Wireless LAN to replace wired LANs has not happenedWireless LAN to replace wired LANs has not happened In some environments, role for the wireless LANIn some environments, role for the wireless LAN –Buildings with large open areas Manufacturing plants, stock exchange trading floors, warehousesManufacturing plants, stock exchange trading floors, warehouses Historical buildingsHistorical buildings Small offices where wired LANs not economicalSmall offices where wired LANs not economical May also have wired LANMay also have wired LAN –Servers and stationary workstations

22. Applications – Cross-Building Interconnect Connect LANs in nearby buildingsConnect LANs in nearby buildings Point-to-point wireless linkPoint-to-point wireless link Connect bridges or routersConnect bridges or routers Not a LAN per seNot a LAN per se –Usual to include this application under heading of wireless LAN

23. Applications - Nomadic Access Link between LAN hub and mobile data terminalLink between LAN hub and mobile data terminal –Laptop or notepad computer –Enable employee returning from trip to transfer data from portable computer to server Also useful in extended environment such as campus or cluster of buildingsAlso useful in extended environment such as campus or cluster of buildings –Users move around with portable computers –May wish access to servers on wired LAN

24. Applications – Ad Hoc Networking Peer-to-peer networkPeer-to-peer network Set up temporarily to meet some immediate needSet up temporarily to meet some immediate need E.g. group of employees, each with laptop or palmtop, in business or classroom meetingE.g. group of employees, each with laptop or palmtop, in business or classroom meeting Network for duration of meetingNetwork for duration of meeting