2. Emerging Broadband Wireless Standards IEEE 802.15 - Bluetooth WAN MAN LAN PAN IEEE 802.11n- Wireless LAN IEEE 802.16d Hybrid MAC/ MIMO OFDMA/ MIMO HSDPA/ HSUPA Super 3G 802.16e OFDM/ MIMO MC-CDMA OFDMA–VSF SC-WRF

3. The Electromagnetic Spectrum Human Voice Piano Radio Television Cellular Phone Microwave XRays Gamma Rays Frequency Spectrum HzKHzMegaHzGigaHzTeraHz Light Spectrum InfraredVisibleUltraviolet

4. Agenda What is a Wireless LAN (WLAN) WLAN technology overview Components of a WLAN WLAN specifications IEEE 802.11 Nortel Networks WLAN Product Overview

5. What is a Wireless Local Area Network (“WLAN”)? Over the air method of communicating with other wireless clients as well as wired network resources such as e-mail, file servers, databases, printers, intranets, and the Internet. A WLAN is a fully functional, high speed network connection without cables. All the advantages of a wired LAN connection are available without being tethered to a wire.

6. Spread Spectrum RF Radios Spread Spectrum RF Radios 2.4 Ghz frequency range ISM band (Industrial Science Medical) 2.4 Ghz frequency range ISM band (Industrial Science Medical) Wireless Standards (Interoperability) Wireless Standards (Interoperability) IEEE 802.11 IEEE 802.11 RF Coverage Area RF Coverage Area Max supported Distances Max supported Distances Maximum support speed Maximum support speed Wireless client Roaming capabilities Wireless client Roaming capabilities Load Balancing capabilities Load Balancing capabilities Security Security Network Protocol Independent Network Protocol Independent Scalability Scalability

7. Wireless Access Point (“AP”) Wireless Hub/Bridge functionality Connection point for multiple wireless clients Bridges wireless NICS traffic to wired Ethernet Serves as a gateway to the wired Ethernet backbone Connects to wired infrastructure via 10BaseT or 10Base2 data port

8. WLAN Access Points Act as wireless shared media hub Create separate independent WLAN segments Separate wireless traffic from wired traffic Support overlapping coverage area to reduce contention and load balancing

9. AP Contention Reduction & Load Balancing Multiple Overlapped APs for high density areas – Clients dynamically choose which AP to connect to based on AP load and signal strength – Increased system capacity and throughput – Aggregate system bandwidth up to 10 Mb/s

10. WLAN Cellular Architecture Access Points create zones of wireless coverage called cells Multiple Access Points can be deployed to provide large contiguous coverage areas Coverage areas do not have to be contiguous Deploy Access Point where coverage is desired Coverage area not limited by range of single AP

11. Dead Zone WLAN Client Roaming Unlimited Range – Network connection is maintained as users move about the building/campus (from one AP coverage area to another) – Handoff is automatic and seamless to user – DHCP for “cross IP segment” roaming

12. WLAN Performance Most Ethernet (10Mbps) clients share bandwidth with large numbers of users Real-world performance - most shared Ethernet clients realize throughput below 1 Mbps WLAN Performance similar to WAN performance WLAN performance exceeds performance of remote access solutions used by most remote users

13. What is Spread Spectrum? The term spread spectrum describes a modulation technique used to spread a transmitted signal over a frequency wider than the minimum bandwidth required to send the signal. Spread spectrum signals are wide band and noise-like making them very difficult to intercept or jam. During World War II the military used spread spectrum technology for “Secret” military communications and radar counter measures. Now Spread Spectrum technology is being exploited for commercial and industrial purposes.

14. Spread Spectrum Radio Types Direct Sequence Spread Spectrum - Signal spread over a broad transmission range Frequency Hopping Spread Spectrum - Signal jumps to a different 1 MHz channel at a predetermined interval

15. Direct Sequence Spread Spectrum (DSSS) Signal is spread using an 11-bit “chipping code” - Low power spread signal uses more spectrum but causes less interference - “Processing gain” provides noise rejection and security Continuous transmission = highest performance Provides migration path to future higher speed (11Mbps) data rate

16. DSSS Chipping Code Spreading Factor Original data stream is multiplied by a 11-bit chipping code (spreading factor) Result or coded data stream is now transmitted over a wide range in the ISM band

17. DSSS Interference Immunity & Security

18. DSSS Scalability

19. Frequency Hopping Spread Spectrum (FHSS) Radios transmit and receive short bursts of data on one frequency for a short period of time Signals change frequency (Hop) to another frequency automatically

20. FHSS Channel Hopping ISM band carved into 78 separate 1 MHz channels Signal moves from one frequency to another every 10th of a second Choice of channels based on a pseudo-random hopping algorithm

21. FHSS Interference Immunity & Security Susceptibility to interference significantly reduced since transmission frequency is constantly shifting; interference can effectively be avoided Constant frequency shifting makes signal very difficult to intercept or jam

22. FHSS Scalability Numerous Access Points can be placed in a coverage area Each AP uses one of the available “78” 1 MHz channels Multiple transmissions can occur simultaneously; each AP uses a different channel 10, 20, or even more overlapping Access Points can be deployed to support dense wireless user areas Overlapping Access Points provide capability to support larger loads As the wireless client population expands in particular areas, more Access Points can be add to support growth

23. Wireless Networking Standards

24. WLAN Specifications IEEE 802.11 Standardization effort started in 1989 Addresses three different wireless technologies – Direct Sequence Spread Spectrum – Frequency Hopping Spread Spectrum – Infrared The standard defines PHY and MAC layer specifications Initial 802.11 standard was ratified June 1997 Institute of Electrical & Electronics Engineering – The authority in networking standards – 802.3 Ethernet, 802.5 Token Ring, etc. 802.11 is a complete specification that provides full network functionality including multi-vendor roaming and true multi- vendor interoperability

25. What is IEEE 802.11 Specification? IEEE 802.11 is a wireless LAN standard developed by the Institute of Electrical and Electronic Engineering committee. The standard specifies an over the air interface between wireless clients and Access Points; it also addresses communication between other wireless clients. The Physical and Media Access Layers (Layers 1 & 2) of the Open Systems Interconnection (OSI) Model are defined by the standard. DSSS & FHSS are two WLAN physical characteristics defined by IEEE 802.11. Both are radio-based technologies that operate in the ISM band. Radios in this band do not require end user licenses. Most importantly the standard makes interoperability between wireless devices from different manufacturers possible.

26. IEEE 802.11 WLAN Standard Media Access Control (MAC Layer) – Similar to 802.3 Ethernet – CSMA/CA vs. CSMA/CD Physical (PHY layer) – Defines 3 alternatives – Diffuse Infra-Red – DS radios – FH radios – DS & FH operate in the 2.4 GHz frequency range

27. IEEE 802.11 MAC Layer Assures fair and controlled access to the media Carrier Sense Multiple Access/Collision Avoidance – Collision minimizing protocol – Provides reliable communication via virtual collision detection and enhanced error detection Defines security provisions (WEP) w/ RSA’s RC4 encryption Specifies the operation of power management Interfaces to the LLC through network drivers – NDIS3 driver for WIN95, 98 and NT 4.0

28. CSMA/CA Like Ethernet’s CSMA/CD arbitrates access to a shared medium More efficient method of controlling access to the physical meduim Collision Avoidance (CA) provides superior contention management

29. CSMA/CA Media Access Process

30. Separate virtual WLAN segments via different system SSIDs (Service Set IDs) –e.g. PCs with SSID=BNet will not associate with AP with SSID = ANet even if closer to ANet AP. WLAN Security

31. WLAN Application Options Infrastructure wireless clients use AP as gateway to resources on wired network Ad Hoc – multiple PCs communicate directly with each other - no AP needed!

32. Ad Hoc Mode Applications – Spontaneous and/or collaborative workgroups – Small/branch offices sharing resources – Deployment of a LAN where cabling is not readily available – Remote control of another PC – Field demonstrations – Multiple PCs in home