1. 24-July-2007 Wireless Networks

2. Wireless Technologies Bluetooth, ZigBee & Wireless USB short range communication between devices typically controlled by a single person. short range communication between devices typically controlled by a single person. WiFi, DECT, HIPERLAN WLAN. WiFi is the most widely implemented in this space. WLAN. WiFi is the most widely implemented in this space. UMTS over W-CDMA, UMTS-TDD, EVDO HSPA, WiMAX UMTS over W-CDMA, UMTS-TDD, EVDO HSPA, WiMAX Wide Area Wide Area

3. WiFi Base Standard 802.11 Utilises unlicensed spectrum 2.4 GHz ISM range 2.4 GHz ISM range 5 GHz UNII range 5 GHz UNII range Access technology

4. 802.11 (1997) 1 or 2 Mbps 2.4GHz Industrial, Scientific & Medical (ISM) band; or IR Frequency Hopping Spread Spectrum (FHSS) or Direct-Sequence Spread Spectrum (DSSS) CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)

5. DSSS Channel Frequencies Channel ID Freq. Hz) North America Europe**SpainFrance 12.412YesYes 22.417YesYes 32.422YesYes 42.427YesYes 52.432YesYes 62.437YesYes 72.442YesYes 82.447YesYes 92.452YesYes 102.457YesYesYesYes 112.462YesYesYesYes 122.467YesYes 132.472YesYes 142.484

6. DSSS Channel Centre Frequency +11MHz-11MHz+22MHz-22MHz ≥30 dB ≥50 dB

7. 7 89 10 1213 12 3 4 5 6 11 DSSS Channel Overlap

8. 802.11b Operates in the 2.4GHz ISM band Utilises HR-DSSS to provide speeds up to 11Mbps Rates are 1M, 2M, 5.5 M 11M

9. 802.11a (1999) Operates in 5GHz UNII bands Consumer equipment generally uses middle & low bands Consumer equipment generally uses middle & low bands 4 channels/band at 20m MHz spacing resulting in 8 non-overlapping channels Utilises OFDM to produce speeds up to 54Mbps UNII-1 (Low)UNII-2 (Mid)UNII-2 (High) 5.150GHz 5.250GHz 5.350GHz 5.725GHz 5.825GHz

10. OFDM Orthogonal Frequency Division Multiplexing Communications channels is made up of many sub-carriers in parallel Convolution coding used for error checking. Utilises Quadrature Amplitude Modulation (QAM )to achieve data rates of 24Mbps-54Mbps

11. 802.11g Operates in the 2.4 GHz ISM band Utilises OFDM and DSSS to provide speeds up to 54Mbps Thus 802.11g equipment can act as 802.11b equipment Thus 802.11g equipment can act as 802.11b equipment Presence of 802.11b equipment will reduce the throughput of an 802.11g WLAN Presence of 802.11b equipment will reduce the throughput of an 802.11g WLAN

12. Beyond 802.11g 802.11e - QoS extensions 802.11f - hand-off for roaming 802.11i – improved security 802.11s – Mesh Networks 802.11n - MIMO

13. Common Issues in WiFi Interference; other hotspots, other equipment in same band, microwave ovens. Near/Far Hidden Node Multipath

14. WiMAX Worldwide Interoperability for Microwave Access Fixed WiMAX 802.16-2004 ('802.16d') Mobile WiMAX 802.16e-2005 OFMD / SOFDMA As with DSL & WiFi more distance / interference = less throughput.

16. Wireless Mesh