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58 Cards in this Set
- Front
- Back
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NOTES from SATURN
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or SAUCER 8
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WLAN=
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wireless LAN and can use microwaves or sat uplinks but uses RF every day.
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FCC controls the whole mess
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from 9k to 300 gigs .
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1. Am
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=535 to 1605 kHz
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2. Infrared=
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300 gig to 300,000 gig
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3. 2.4 gig
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is most cordless and lans
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4. 5 gig
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is better
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5. ITU to blame
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4 stds for wi-fi world wide
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Wi-fi layer
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Data Link and Physical Layer
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Signal
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Problems
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1. Reflection
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= bounce back
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2. Diffraction
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= signal separation but continues
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3. Scattering =
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gets tore up bad
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All of the above
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= multipath which is good and bad.
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Three ways to broadcast signals
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in Wi-Fi these are
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1. Narrow Band =
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1 Freq. or at most a VERY small group of Freqs.
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2. Broad Band =
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“Wide Group of Freqs” = more thru put than #1
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3. Spread Spectrum (Freq-Hopping)
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= spread thru out a band or the wireless spectrum. Started in WW2 and is very secure.
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Frequency Hopping
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has two partsFrequency Hopping Spread Spectrum (FHSS)= hops several freqs synchronously in a way known only to TX and RX
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Direct Sequence Spread Spectrum (DSSS) =
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shotgun approach data sent all at once over a whole freq band caught at other end and stuffed in a sock.
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802.11 Wireless Standards
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Standard
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802.11 b=2.4 gig
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11Mbps
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802.11a =5 gig
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54 Mbps
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802.11g=2.4 Gig+ 5Gig
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54 Mbps real is 20-25 Mbps
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The 2 TYPES of WIRELESS
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COMMO are
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1. Fixed
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well duh
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2. Mobile
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More Duh but roaming means you’re still connected double duh
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AD HOC TOPO
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All stations can talk to each other when they want no access point used in this Topo.
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802.11 =
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B.A.G.N or Bagn
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802.11 b is DSSS
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direct-sequence spread spectrum
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Over the entire 2.4 band and makes,
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it into 22 Meg channels.
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IDEALLY 11 MBPS T-P
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but really 5 Mbps normally
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802.11a 5 gig band=
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max t-p of 54 Mbps but real is between 11 and 18 Mbps
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HIGHER Frequency signals
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require more power and a shorter range in this case 20 meters 66 ft.
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802.11g 2.4 gig
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works really well with 802.11b 802.11g ideal is 54 Mbps.
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802.11n
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hopefully rated in 2009 may go to 600Mbps works with BAG either 2.4 or 5 gig
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Wlans=
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access points or points makes it an infrastructure Topo.
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Site survey =
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tape measure prints and a hub and a laptop yep.
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FUBARS
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Major Screwups
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SSid Mismatch = not on auto =
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wi-fi Ip equivalent wrong +case sensitive Incorrect encryption = no match coding + password
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Ie3 Mismatch =
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check p.call
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Freq mismatch
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gotta say something
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Antenna in the wrong place
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move it
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Efi or RFI
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Interference
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802.11 Internet Access =
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hotspots or subscription service if not free.
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802.16 WIMAX +
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World Wide Interoperability for Microwave Access
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802.16e
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2005 better Qos and data
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Wimax in cities
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can be used without anything but a card.
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Satellite
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Internet Access
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Geo=
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Geosynchronous earth orbit
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Leo =
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low earth orbit
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Meo=
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medium earth orbit
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SAT
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FREQS
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L- Band ----
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1.5-2.7 Ghz
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S- Band----
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2.7 3.5 GHz
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C- Band ----
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3.4 -6.7 Ghz
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Ku- Band ----
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12—18 Ghz
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Ka- Band ----
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18-40 GHz
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