Wireless Networking

• 1.Presented By Mrs. Vasanthi Muniasamy M.Sc., M.Phil

2. INTRODUCTION Wireless network is an interconnection of many systemscapable of providing service to mobile users within a particular geographic region (country or continent) In wireless network, data are carried by electrical wave(e.g., radio wave) from one node to another. There is no physical cable/wire connecting onecomputer to another Components Base station Mobile Switching Center (MSC) PSTN (Public Telecommunication Switching Network) 3. Wired (Cabled) Network versus Wireless Network Advantages of Wireless Network over Wired (Cabled) Network Mobility: Users can roam around the network without being disconnected Installation speed and cost: Building wireless medium to large network isusually faster and cheaper than building wired (cabled) medium to large network because there is no need to pull cable through walls and ceilings Reach of network: Wireless network can be extended to places where wire/cable cannot reach Flexibility/scalability: New computers can be added easily without having to pull cable into the computers Disadvantages of Wireless Network compared to Wired Network Speed: In general, wireless network technology is slower than wired networktechnology Security: In general, wireless network is less secured than wired network 4. Basic Components of Wireless Network 5. Wireless Network Hardware Wireless NIC (e.g., wireless Ethernet NIC or Bluetooth NIC) must be installed in each computer Major functions of wireless NIC: Sender NIC: Take data from Layer 3 (Network Layer) Encapsulate the data into frame Load the frame to electrical wave Transmit the electrical wave Receiver NIC performs the reverse activities Wireless NIC comes in various forms (Eg., Expansion board, PCMCIA, USB, built-in) 6. Wireless Network Hardware Wireless Access Point (WAP/Access Point/AP/UniversalAccess Point/UAP) Central wiring device to connect wireless nodes towireless/wired network If a network uses WAP, all computers must communicate viathe WAP 7. Wireless Network Mode Ad-Hoc Mode (Peer-to-Peer Mode) Each wireless node can communicate directly with each of the other nodes in thenetwork (without Wireless Access Point) Mesh network topology IBSS (Independent Basic Service Set): a group of nodes communicating in ad-hoc mode Infrastructure Mode All wireless node communicate to one another via Wireless Access Point Star network topology BSS (Basic Service Set): a group of nodes communicating in infrastructure mode.An BSS has one wireless access point EBSS (Extended Basic Service Set): two or more BSS that can communicate to one another An EBSS contains two or more wireless access points 8. Ad-Hoc versus Infrastructure Mode Ad-Hoc ModeInfrastructure Mode(IBSS)(BSS) 9. Wireless Network Security Three basic wireless network security methods: SSID (Service Set Identification) MAC Address Filtering Encryption 10. Wireless network Speed Wireless network speed depends on: The wireless network technology standard The distance between sender and receiver, or between a nodeand a Wireless Access Point Interference from other wireless devices or electronic devices (e.g., wireless phone) The presence of solid object (especially metal object, electronic appliance) between the sender and receiver, or between a node and a Wireless Access Point 11. Wireless Network Range Wireless network range depends on: The wireless network technology standard Interference from other wireless devices or electronic devices The presence ofsolid object (especially metal object, electronicappliance) between the sender and receiver, or between a node and a Wireless Access Point To increase the wireless network range: Using signal booster Using Wireless Access Point (i.e., instead of using ad-hoc mode, useinfrastructure mode) Using MULTIPLE Wireless Access Points 12. Wireless Spectrum (1) Broadcast TV VHF: 54 to 88 MHz, 174 to 216 MHz UHF: 470 to 806 MHz30 MHz300 MHz3 GHzFM Radio 88 to 108 MHzDigital TV 54 to 88 MHz, 174 to 216 MHz, 470 to 806 MHz Wireless Environment and Wireless LANs 1330 GHz 13. Wireless Spectrum (2) 3G Broadband Wireless 746-794 MHz, 1.7-1.85 GHz, 2.5-2.7 GHz30 MHz300 MHz3 GHz30 GHzCellular Phone 800-900 MHz Personal Communication Service (PCS) 1.85-1.99 GHzWireless Environment and Wireless LANs 14 14. Wireless Spectrum (3) Wireless LAN (IEEE 802.11b/g) 2.4 GHz30 MHz300 MHz Bluetooth 2.45 GHzWireless Environment and Wireless LANs 15Wireless LAN (IEEE 802.11a) 5 GHz3 GHz30 GHzLocal Multipoint Distribution Services (LMDS) 27.5-31.3 GHz 15. Evolution of Mobile Wireless (1) Advance Mobile Phone Service (AMPS) FDMA 824-849 MHz (UL), 869-894 MHz (DL) U.S. (1983), So. America, Australia, ChinaEuropean Total Access Communication System (E-TACS) FDMA 872-905 MHz (UL), 917-950 MHz (DL) Deployed throughout EuropeWireless Environment and Wireless LANs 16 16. Evolution of Mobile Wireless (2) Global System for Mobile communications (GSM) TDMA Different frequency bands for cellular and PCS Developed in 1990, expected >1B subscriber by end of 2003IS-95 CDMA 800/1900 MHz Cellular/PCS U.S., Europe, AsiaWireless Environment and Wireless LANs 17 17. Evolution of Mobile Wireless (3) General Packet Radio Services (GPRS) Introduces packet switched data services for GSM Transmission rate up to 170 kbps Some support for QoSEnhanced Data rates for GSM Evolution (EDGE) Circuit-switched voice (at up to 43.5 kbps/slot) Packet-switched data (at up to 59.2 kbps/slot) Can achieve on the order of 475 kbps on the downlink, by combining multiple slots Wireless Environment and Wireless LANs 18 18. Evolution of Mobile Wireless (4) Universal Mobile Telecommunication Systems (UMTS) Wideband DS-CDMA Bandwidth-on-demand, up to 2 Mbps Supports handoff from GSM/GPRSIS2000 CDMA2000: Multicarrier DS-CDMA Bandwidth on demand (different flavors, up to a few Mbps) Supports handoff from/to IS-95Wireless Environment and Wireless LANs 19 19. Generations in Mobile Wireless Service First Generation (1G) Mobile voice services Second Generation (2G) Primarily voice, some low-speed data (circuit switched) Generation 2 (2.5G) Higher data rates than 2G A bridge (for GSM) to 3G Third Generation (3G) Seamless integration of voice and data High data rates, full support for packet switched data 20. Block Diagram of Cellular System 21. Development of Wireless Networks First Generation Wireless Networks Second Generation Wireless Networks Third Generation Wireless Networks Fixed Network transmission Hierarchy Traffic Routing in Wireless Networks Circuit Switching Packet Switching X.25 Protocol 22. First Generation Wireless NetworksMobile UserBase StationMSC 23. Second Generation Wireless Networks Employs digital modulation and advanced call processing capabilities Ex: GSM, TDMA ,CDMA, Cordless Phones. Dedicated control channel for voice, signal data. Provides paging and other data services. High data rate (N/W access.) Uses MAHO (Mobile Assisted Hand Off) where mobile units performs the following functions: reporting received power. scanning adjacent base station. data encoding and encryption. 24. Third Generation Wireless Networks Aim: to provide single set of standards that can meet wide range of applications and provide universal access thru out the world. Distinction between cordless and cellular phones disappear as personal handset provides access to voice, data and video services. It uses broadband integrated service digital N/W (ISDN) to provide internet for both fixed or mobile users. Provides reliable transfer of information. 25. Traffic Routing in Wireless Networks 1. 2. 3.Circuit Switching Packet Switching X.25 Protocol 26. Circuit Switching There are three phases in circuitswitching: Establish Transfer Disconnect The telephone message is sent inone go, it is not broken up. The message arrives in the same order that it was originally sent. 27. Packet Switching In packet-based networks, the messagegets broken into small data packets. These packets are sent out from the computer and they travel around the network seeking out the most efficient route to travel as circuits become available. This does not necessarily mean that they seek out the shortest route. Each packet may go a different route from the others. 28. Packet Switching HEADERUSER DATATRAILERPacket Data FormatFLAGADDRESS CONTROL FIELD FIELDINFORMATION FIELDFields in a Typical packet dataFRAME CHECK SEQUENCE FIELD