2.4 Wireless Networks Flashcards
Wireless standards
Wireless standards (802.11)
Managed by IEEE standard committee
Updated many times over years
Devices should have wifi trademark, that shows it is operable with 802.11 network and has been tested
802.11A
Original
- introduced in october 1999
Operates in 5 ghz frequency range
54 mbit/s
- smaller range then 802.11b because operates on 5ghz frequency
- higher frequencies absorbed by objects in the way
Standard not commonly seen today
802.11B
Introduced also in october 1999
- operates on 2.4ghz range
11 mbit/s
Better range then 802.11a (lower ghz means less collision with regular objects so less absorption problems)
But more devices use same frequency so you get collision there
- ex: baby monitor/microwave
802.11G
Upgrade to 802.11b
- June 2003
- same frequency (2.4 ghz)
54 mbit/s
Backwards compatible (compatible with older standards)
Same frequency issue (other electronic devices using same frequency)
802.11N
Update to all 3 previous standards
- October 2009
- operates a 5ghz and or 2.4ghz
- 40 Mhz channel widths
600 mbit/s
Uses MIMO to achieve speed (throughput)
- multiple-input multiple output
- uses multiple transmission and Recieving antennas on same frequency to do this
802.11AC
Latest version
Update of 802.11N
January 2014
- operates on 5ghz band
- —less crowded frequency
6.8 max gbit/s
Increases channel bonding?
Changed signal modulation (denser)
Mimo improved
- multi user mimo (mu-mimo) streams (8)
- twice as many as previous standard
802.11 technologies
Frequencies
-2.4 or 5 or both
Channels
- group of frequencies within the ghZ range (split into megaherts/smaller blocks)
Bandwidth
- amount of frequency in use
- Ranges of blocks could span 20mhz, 40mhz, 80 Mhz or 160mgz
802.11 channel bandwidths
- 11a - 20 mhz channel badwidth
- 11b - 22 mhz channel badwidth
- 11g - 20 mhz channel badwidth
802.11n - 20 mhz or 40mhz channel badwidth (2 continuous 20mhz channels bonded)
In 2.4 Ghz, limited frequencies so 40m mhz channel uses most of the available bandwidth
- 11c
- 80 Mhz required (runs in 5 ghz, more frequencies available)
- 160 mhz optional (bonded or non bonded channels)
RFID
Radio frequency identification
Small tags we can put into anything we want to track
- Access badges
- pet/animal identification
Uses Radar tech
- Radio energy transmitted to tag
- energy powers tag amd ID is transmitted back
NFC builds on this, and makes communication 2 way
Zigbee
Aka IEEE 802.15.4 PAN
Internet of things wireless standard
Open standard
Alternative to wifiand Bluetooth
Pros
- longer distance than Bluetooth
- less power consumption than wifi
Mesh network: All zigbee devices can communicate through each other. No centralized device
Uses ISM band: industrial, scientific and medical
Operates on 900 Mhz and 2.4 ghz frequencies in USA
Z-wave
Proprietary home automation networking
IoT
- used for lights, locks, garage doors
Wireless mesh network
Uses ISM band
Runs in 900 Mhz frequency in US
No conflict with 802.11
Cellular networks 2G
Physical land is separated into cells, with antennas placed at the edge of these cells and the antenna covers that “cell” with its certain frequency
Started with…
2G networks - split into 2 sections
- GSM: global system for communication
- CDMA: code division multiple access
Built with voice communication and mod - basically so you can make phone calls
- poor data support
3G network
Introduced 1998
Upgraded data connectivity
Improved speeds
Several megabits p/s
Increased bandwidth allows for new functionality
- GPS
- Mobile television
- Video on demand
- Video conferencing
4G and LTE
LTE: Long term evolution
- 4g technology
- based on GSM and EDGE (enhanced data rates for GSM Evolution)
- supports download rates of 150 Mbit/s
LTE advanced (LTE-A)
- improvements made to LTE doubled speeds
- 300 mbit/s
5G
Worldwide launch 2020
- able to use higher frequencies
- which adds more available frequencies
- improvement in data transmission
