Wireless Standards Flashcards
Wireless Standards
802.11 - Wi-Fi
-managed by the IEEE LAN/MAN
many updates over time( check with IEEE for the latest)
Wi-Fi Alliance handles interoperability testing
802.11a
Original 802.11 wireless standards (Oct. 99) not common today
Operates in the 5 GHz range
- or other frequencies with special licensing
54 Megabits per second
smaller range than 802.11b
(high frequency is absorbed by objects in the way (Warehouses - due to open space)
802.11b
Original 802.11 wireless standards (Oct. 99)not common today
operates in the 2.4 GHz range
11 megabits per second
better range than 802.11a
-less absorption problems (office due to many object in the room)
more frequency conflict with…
- Baby monitors, cordless phones, microwave ovens, Bluetooth
802.11g
upgrade to 802.11b released on June 2003
operates up to 2.4 GHz range
52 megabits per second (802.11a similar)
backwards compatible with 802.11b
suffering the same 2
4 GHz frequency conflict problems as 802.11
802.11n (Wi-Fi 4)
update to 802.11(g)(b)(a) Oct.09
Operates at 5 GHz and/or 2.4 GHz
=40 MHz channel widths
600 Megabits per second
=40 MHz mode and 4 antennas
802.11n uses MIMO
- Multiple-input multiple-output
- Multiple transmit and receive antennas
What is MIMO? (MU-MIMO)
devices can transfer much more information simultaneously between the end station and the access point
MI-MIMO - (Multiple User - Multiple-input multiple-output) Multiple users could be communicating over multiple input and multiple output simultaneously
802.11ac (Wi-Fi 5)
Approved Jan.2014
Operates in the 5 GHz band
- Less crowded, more frequencies ( up to 160 MHz channel bandwidth)
Increased channel bonding
- Larger bandwidth usage
Denser signaling modulation
- Faster data transfers
Eight MU-MIMI downlink Streams
- Twice as many streams as 802.11n
- Nearly 7 gigabits per second
802.11ax (Wi-Fi 6)
Approved in Feb.2021
Operates at 5 GHz and/or 2.4 GHz
-20, 40, 80, and 160 MHz channel widths
1201 Megabit per second per channel
- Small increase in throughput
-Eight bi-directional MU-MIMO streams
OFDMA - Orthogonal Frequency-Davison Multiple Access
- Works similar to cellular communication
- Improves high-density installations
Antennas
Wireless access point in a house with a stock antennas
- Range of 40 - 50 meters
Try connecting two buildings located miles from each other
- Fixed directional antennas and increased signal strength
Outdoors
- Minimal signal absorption or bounce
Directional antennas (IE - Yagi Antenna)
- Focused, Point to point connection
Rules and Regulations
Wireless regulations are complex refer to country’s regulatory agency
Frequency use
- Unlicensed 2.4 GHz or 5 GHz frequencies
- Additional frequencies may available
- Additional licensing may be required
Outdoor Antenna installation is not trivial
- Get an expert, be safe
RFID (Radio-Frequency Identification)
It’s everywhere
- Access Badges
- Inventory/Assembly line tracking
- Pet/Animal identification
- Anything that needs to be tracked
Radar Technology
- Radio energy transmitted to the tag
- RF powers the tag, ID is transmitted back
- Bidirectional communication
- Some tag formats can be active/Powered (where the RFID tags have a power source)
