1. Wireless LAN

2. Wireless?
A wireless LAN or WLAN is a wireless local area network that uses radio waves as its carrier.
The last link with the users is wireless, to give a network connection to all users in a building or campus.
The backbone network usually uses cables

3. Common Topologies The wireless LAN connects to a wired LAN
There is a need of an access point that bridges wireless LAN traffic into the wired LAN.
The access point (AP) can also act as a repeater for wireless nodes, effectively doubling the maximum possible distance between nodes.

4. Major Factors
There are four major factors to consider before implementing a wireless network:
High availability
Scalability
Manageability
Open architecture

5. 802.11 WLAN technologies IEEE 802.11 standards and rates
IEEE (1997) 1 Mbps and 2 Mbps (2.4 GHz band )
IEEE b (1999) 11 Mbps (2.4 GHz band) = Wi-Fi
IEEE a (1999) 6, 9, 12, 18, 24, 36, 48, 54 Mbps (5 GHz band)
IEEE g ( ) up to 54 Mbps (2.4 GHz) backward compatible to b
IEEE networks work on license free industrial, science, medicine (ISM) bands:
26 MHz
83.5 MHz
200 MHz
255 MHz
f/MHz
EIRP power
in Finland
200 mW
indoors only
100 mW
1 W

6. Building in Wireless LANs
Wireless LANs are an “addictive” technology
Strong commitment to Wireless LANs by technology heavy-weights
Cisco, IBM, Intel, Microsoft
Embedded market is growing
Laptop PC’s with “wireless inside”
PDA’s are next
The WLAN market is expanding from Industry-Specific Applications, to Universities, Homes, & Offices
Professional installers and technicians will be in demand

7. “Business-Class”vs Consumer WLAN
Industry has segmented: consumer vs. business
Cisco offers only “business- class” products:
Security
Upgradeability
Network management
Advanced features
Choice of antennas
Highest throughput
Scalability

8. Benefits of WLANs

9. WiFi

10. Unlicensed Frequency Bands

11. Wireless Data Networks
50 Mbps
Spread Spectrum Wireless LANs
10 Mbps
Infrared Wireless LANs
2 Mbps
1 Mbps
Data Rates
2.5 GHz Service
Broadband PCS
56 Kbps
Circuit and Packet Data
Cellular, CDPD, Mobitex, DataTac
19.6 Kbps
Narrow Band Wireless LANs
9.6 Kbps
Narrowband PCS
Satellite
Local
Wide
Coverage Area

12. Wireless Technologies
WAN
(Wide Area Network)
MAN
(Metropolitan Area Network)
LAN
(Local Area Network)
PAN
(Personal Area Network)
PAN
LAN
MAN
WAN
Bluetooth
Peer-to-Peer
Device-to-Device
Short
<1 Mbps
802.11a, 11b, 11g
HiperLAN2
Enterprise Networks
Medium
2–54+ Mbps
802.11
MMDS, LMDS
Fixed, Last
Mile Access
Medium–Long
22+ Mbps
GSM, GPRS,
CDMA, 2.5–3G
PDAs, Mobile
Phones, Cellular
Access
Long
10–384 Kbps
Standards
Speed
Range
Applications

13. The IEEE 802.11 and supporting LAN Standards
Logical Link Control (LLC)
OSI Layer 2
(data link)
IEEE 802.3
Carrier
Sense
IEEE 802.4
Token
Bus
IEEE 802.5
Token
Ring
IEEE
Wireless
MAC
PHY
OSI Layer 1
(physical) a b g
ring
bus
star

14. 802.11 LAN architecture wireless host communicates with base station
Internet
wireless host communicates with base station
base station = access point (AP)
Basic Service Set (BSS) (aka “cell”) in infrastructure mode contains:
wireless hosts
access point (AP): base station
ad hoc mode: hosts only AP
hub, switch
or router AP
BSS 1
BSS 2

15. Figure 14.1 Basic service sets (BSSs)

16. Figure 14.2 Extended service sets (ESSs)

17. IEEE 802.11 Architecture Network LLC MAC FHSS DSSS IR
IEEE defines the physical (PHY), logical link (LLC) and media access control (MAC) layers for a wireless local area network
networks can work as
basic service set (BSS)
extended service set (ESS)
BSS can also be used in ad-hoc networking
Network
LLC
802.11
MAC
FHSS
PHY
DSSS IR
LLC: Logical Link Control Layer
MAC: Medium Access Control Layer
PHY: Physical Layer
FHSS: Frequency hopping SS
DSSS: Direct sequence SS
SS: Spread spectrum
IR: Infrared light
BSS: Basic Service Set
ESS: Extended Service Set
AP: Access Point
DS: Distribution System
DS,
ESS
ad-hoc network

18. BSS and ESS
Basic (independent) service set (BSS)
Extended service set (ESS)
In ESS multiple access points connected by access points and a distribution system as Ethernet
BSSs partially overlap
Physically disjoint BSSs
Physically collocated BSSs (several antennas)

19. Icons

20. Icons

21. Icons

22. Wireless Technologies

23. In Building WLAN

24. Site to Site WLAN

25. Radio Signal Interference

26. Installation and Site Design Issues—Bridging

27. Installation and Site Design Issues—WLAN

28. WLAN Evolution: 2000–Present
Warehousing
Retail
Healthcare
Education
Businesses
Home
Radio
Network
Speed
860 Kbps
900 MHz
1 and 2 Mbps
2.4 GHz
Proprietary
1 and 2 Mbps
11 Mbps
54 Mbps
Standards-based
2.4 GHz
5 GHz
IEEE Begins Drafting
Ratified
802.11a,b Ratified
802.11g Drafted
1986
1988
1990
1992
1994
1996
1998
2000
2002

29. Wi-Fi™ Wi-Fi™ Alliance Wi-Fi’s™ Mission Wireless Fidelity Alliance
170+ members
Over 350 products certified
Wi-Fi’s™ Mission
Certify interoperability of WLAN products (802.11)
Wi-Fi™ is the “stamp of approval”
Promote Wi-Fi™ as the global standard

30. WLAN Devices In-building Infrastructure
1200 Series (802.11a and b)
1100 Series (802.11b)
350 Series (802.11b) not shown
Bridging
350 Series (802.11b)
BR350
WGB350
1400 Series (802.11a)

31. WLAN Devices Antenna 2.4GHz 5 GHz Antennas Clients
350 Series (802.11b)
5 GHz client adapter (802.11a)
Workgroup bridge (802.11b)

32. Antennas 2.4 GHz 5 GHz Indoor and Outdoor WLAN and Bridging Outdoor

33. Cable and Accessories

34. 802.11-Enabled Phones A cordless phone for the workplace
Cisco 7920 Wireless VoIP phone

35. Beyond Laptops: Other 802.11-Enabled Devices
HP iPAQ 5450 PDA
Epson Printer
PDA’s
Phones
Printers
Projectors
Tablet PC’s
Security Cameras
Barcode scanners
Custom devices for vertical markets:
Healthcare
Manufacturing
Retail
Restaurants
Compaq Tablet PC
SpectraLink Phone
HHP Barcode Scanner
Sharp M25X Projector

36. WLAN Markets

37. Wireless LAN Security: Lessons
“War Driving”
Hacking into WEP
Lessons:
Security must be turned on (part of the installation process)
Employees will install WLAN equipment on their own (compromises security of your entire network)
WEP keys can be easily broken (businesses need better security)

38. Reliability and Connectivity

39. Health Issues

40. IEEE 802.11 Standards Activities
802.11a: 5GHz, 54Mbps
802.11b: 2.4GHz, 11Mbps
802.11d: Multiple regulatory domains
802.11e: Quality of Service (QoS)
802.11f: Inter-Access Point Protocol (IAPP)
802.11g: 2.4GHz, 54Mbps
802.11h: Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC)
802.11i: Security
802.11j: Japan 5GHz Channels ( GHz)
802.11k: Measurement

41. WLAN Speeds & Frequencies
802.11g
2.4 GHz – OFDM/CCK
54 Mbps
802.11a
5 GHz – OFDM
54 Mbps
802.11b
2.4 GHz – CCK
11 Mbps
Proprietary
IEEE a/b Ratified
Jan’99
Jan’00
Jan’01
Jan’02
Jan’03
Jan’04

42. Summary Identify characteristics of Cisco Aironet 802.11a products.
Identify characteristics of Cisco Aironet b products.