1. N ETWORKING WIRELESS MEDIA

2. COMMON NETWORK CABLES The connection between the source and destination may either be direct or indirect, and may span multiple media types. Copper Media Optical Media Wireless Media

3. WIRELESS FREQUENCY Wireless APs operate at: 2.4 GHz 5 GHz 2 GHZ! That’s the same as my microwave oven, isn’t that dangerous? Answer: No. Electromagnetic waves happen naturally. Light is an electromagnetic wave It is not the frequency, but the wattage, the power. Any electromagnetic wave can be dangerous with too much power. A 25 watt light bulb is safe, but it wouldn’t be safe at 250,000 watts Wireless access points generate signals at 1/10 th of a watt. Like all electromagnetic waves, the signal does not fade in a linear manner, but inversely as the square of the distance.

4. Rick Graziani graziani@cabrillo.edu 4

5. INVERSE SQUARE LAW Double the distance of the wireless link, we receive only ¼ of the original power. Triple the distance of the wireless link, we receive only 1/9 the original power. Move 5 times the distance, signal decreases by 1/25. Point A 2 times the distance ¼ the power of Point A 1020304050100 3 times the distance 1/9 the power of Point A 5 times the distance 1/25 the power of Point A 10 times the distance 1/100 the power of A

6. PUTTING IT IN SOME PERSPECTIVE Measurements from an antenna transmitting 100mW at 1 inch Remember a milliwatt is 1/1,000 th of a Watt Microwave oven typically operates at 1,000 watts in a confined space. 1” 100 mW 1/10 th watt 2” 25 mW 1/40 th watt 4” 6.25 mW 1/166 th watt 8” 1.56 mW 1/1000 th watt 16” 0.39 mW 4/10,000 th watt 32” 0.097 mW 1/10,000 th watt 64” (5.3 ft) 0.024 mW 2/100,000 th watt 128” (10.6 ft) 0.006 mW 6/1,000,000 th watt 256” (21.3 ft)0.0015 mW 15/10,000,000 th watt Light bulbs would also be dangerous the were 10,000 to 1,000,000,000,000 stronger. A 250,000 watt up to a 250,000,000,000,000 watt light bulb would also be dangerous.

10. WIRELESS 802.11 Wireless N provides better speeds (bandwidth) and better range by utilizing multiple antennas. Backwards compatible with 802.11 b and g. n

11. 802.11n

12. WIRELESS 802.11 ac o More reliable o Better Speed o Better Range o Steady Connection o Ideal for video steaming or gaming

13. WIRELESS 802.11 ac Key advantages of 802.11ac over 802.11n: o Gigabit speed wireless with approximately 3 times the performance of 802.11n o Better performance at any range with fewer dead spots o More reliable connections for media streaming with beam-forming o More Wi-Fi bandwidth on your mobile o Only utilizes the 5 GHz Band, which is less prone to interference o Backward compatible to 802.11 a & n, which also use the 5 GHz band Next Generation Gigabit Wi-Fi