Wireless routing Flashcards
802.11b WLAN routing protocol
- most widely deployed wireless standard
- operate at 2.4 ghz radio ban 11mps data rate
- has the ability to data-rate-shift while moving, and transmission by transmission basis
-means access point an support multiple clients at varying speeds
-uses CSMA?CA and Request to send, clear to send (RTS?CTS)
Has interference
802.11g
-backwards compatable with 802.11b
- 54mbps max data rate
- runs on 5 + 2.4 ghz range
can communicate on same network
uses module technique called OFDM- better performance at same rate
gets 70% of RF bandwidth
Wifi channels for 802.11g
11 configurable channels
- 1,6,11- non overlapping
- must be aware of channels when installing AP to not overlap channels
802.11a
-5ghz
can data rate shift
- 12 non-overlapping channels
immune to interferences eg microwave, Bluetooth
802.11h
5ghz
FCC added 11 channels
gained 23 non-overlapping channels
Dynamic frequency selection (DFS)
- monitors a device operating range for any radar signals allowed to operate in 5ghz proportions
- if dfc discovers radar signals it will either: abandon channel, mark it unavailable to prevent interference
Transmit power control (TPC)
- employed by the mobile phone industry
- can set client machine adapter + access point to cover various size ranges
Radio frequencies
go straight with signal
- if anything blocking hard to send signal
- can lose all or part of a signal
Reflection
the signal bounces off material that cant absorb the signal
objects can scatter signal
-
Wireless degredation
- factors that interfere with RF (Radio frequency)
what is fading?
signal weakening due to reflection
Attenuation
signal weakening due to distance
can correct with an extender
noise
interference from other devices
common due to unlicensed spectrum
wireless fidelity
devices communicate directly
- communication managed through wireless access points
-WAPS may interoperate to provide large seamless coverage
max distance 300 ft station with wap
max distance b/w waps 1000ft w/ antenna
Antenna types
omni directional
unidirectional