2.4 - 802.11 Wireless Standards Flashcards
1
Q
Wireless Standards
A
• Wireless networking (802.11) • Managed by the IEEE LAN/MAN Standards Committee (IEEE 802) • Many updates over time • Check with IEEE for the latest • The Wi-Fi trademark • Wi-Fi Alliance handles interoperability testing
2
Q
802.11a
A
• One of the original 802.11 wireless standards • October 1999 • Operates in the 5 GHz range • 54 megabits per second (Mbit/s) • Smaller range than 802.11b • Higher frequency is absorbed by objects in the way • Many rules-of-thumb calculate 1/3rd the range of 802.11b or 802.11g
3
Q
802.11b
A
• Also an original 802.11 standard - October 1999 • Operates in the 2.4 GHz range • 11 megabits per second (Mbit/s) • Better range than 802.11a • Less absorption problems • More frequency conflict • Baby monitors, cordless phones, microwave ovens, Bluetooth
4
Q
802.11g
A
An “upgrade” to 802.11b - June 2003
• Operates in the 2.4 GHz range
• 54 megabits per second (Mbit/s)
• Same as 802.11a (but a little bit less throughput)
• Backwards-compatible with 802.11b
• Same frequency conflict problems as 802.11b
5
Q
802.11n
A
- The update to 802.11g, 802.11b, and 802.11a
- October 2009
- Operates at 5 GHz and/or 2.4 GHz
- 40 MHz channel widths
- 600 megabits per second (Mbit/s)
- 40 MHz mode and 4 antennas
- 802.11n uses MIMO
- Multiple-input multiple-output
- Multiple transmit and receive antennas
6
Q
802.11 technologies
A
- Frequency
- 2.4 GHz or 5 GHz (and sometimes both)
- Channels
- Groups of frequencies, numbered by the IEEE
- Non-overlapping channels would be necessary
- Bandwidth
- Amount of frequency in use
- 20 MHz, 40 MHz, 80 MHz, 160 MHz
7
Q
802.11 channel bandwidths
A
• 802.11a - 20 MHz • 802.11b - 22 MHz • 802.11g - 20 MHz • 802.11n • 20 MHz or 40 MHz (two contiguous 20 MHz bonded channels) • In 2.4 GHz, a 40 MHz channel uses much of the available bandwidth • 802.11ac • 40 MHz for 802.11n stations • 80 MHz required for 802.11ac stations • 160 MHz optional (contiguous channels or noncontiguous bonded channels)
8
Q
Bluetooth
A
- High speed communication over short distances
- PAN (Personal Area Network)
- Connects our mobile devices
- Smartphones
- Tethering and file transfers
- Headsets and headphones
- Health monitors
- Automobile and phone integration
- Smartwatches
- External speakers
9
Q
Near field communication (NFC)
A
- Two-way wireless communication
- Builds on RFID, which is mostly one-way
- Payment systems
- Major credit cards
- Online wallets
- Bootstrap for other wireless
- NFC helps with Bluetooth pairing
- Access token, identity “card”
- Short range with encryption support
10
Q
RFID (Radio - frequency identification
A
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
11
Q
Zigbee
A
- Internet of Things networking
- Open standard - IEEE 802.15.4 PAN
- Alternative to WiFi and Bluetooth
- Longer distances than Bluetooth
- Less power consumption than WiFi
- Mesh network of all Zigbee devices in your home
- Light switch communicates to light bulbs
- Tell Amazon Echo to lock the door
- Uses the ISM band
- Industrial, Scientific, and Medical
- 900 MHz and 2.4 GHz frequencies in the US
12
Q
Z-Wave
A
• Proprietary home automation networking • Internet of Things (IoT) • Control lights, locks, garage doors, etc. • Wireless mesh networking • Nodes can hop through other nodes on the way to the destination • Uses the ISM band • Industrial, Scientific, and Medical • 900 MHz frequencies in the US • No conflicts with 802.11 IEEE Channel # 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 20 MHz 40 MHz 80 MHz 160 MHz
