2.3-Wireless Network Standards

Question 1

Bluetooth

Answer 1

Uses the 2.4 GHz range – Unlicensed ISM
(Industrial, Scientific and Medical) band – Same as 802.11
Short-range
– Most consumer devices operate
to about 10 meters
– Industrial Bluetooth devices can communicate
over 100 meters

Question 2

802.11 technologies

Answer 2

• Frequency
  – 2.4 GHz or 5 GHz
  – And sometimes both
• Channels
  – Groups of frequencies, numbered by the IEEE
  – Non-overlapping channels would be ideal
• Regulations
  – Most countries have regulations to
  manage frequency use
  – Spectrum use, power output,
  interference requirements, etc.

Question 3

NFC (Near field communication)

Answer 3

• 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

Question 4

RFID (Radio-frequency identification)

Answer 4

• 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

Question 5

Long-range fixed wireless

Answer 5

• Wireless access point in a house with the stock antennas – You might get a range of 40 to 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
  – Focused, point-to-point connection
• Wireless regulations are complex
  – Refer to your country’s regulatory agency
• Frequency use
  – Unlicensed 2.4 GHz or 5 GHz frequencies
  – Additional frequencies may be available
  – Additional licensing may be required
• Signal strength
  – Indoor and outdoor power is usually regulated * Outdoor antenna installation is not trivial
  – Get an expert, be safe

Question 6

802.11ax (Wi-Fi 6)

Answer 6

• Approved in February 2021
  – The successor to 802.11ac/Wi-Fi 5
• Operates at 5 GHz and/or 2.4 GHz
  – 20, 40, 80, and 160 MHz channel widths
• 1,201 megabits per second per channel
  – A relatively small increase in throughput
  – Eight bi-directional MU-MIMO streams
• Orthogonal frequency-division multiple access (OFDMA)
  – Works similar to cellular communication
  – Improves high-density installations

Question 7

802.11ac (Wi-Fi 5)

Answer 7

• Approved in January 2014
  – Significant improvements over 802.11n
• 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-MIMO downlink streams
  – Twice as many streams as 802.11n
  – Nearly 7 gigabits per second

Question 8

802.11n (Wi-Fi 4)

Answer 8

• 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

Question 9

802.11g

Answer 9

• An “upgrade” to 802.11b - June 2003
• Operates in the 2.4 GHz range
• 54 megabits per second (Mbit/s) - Similar to 802.11a
• Backwards-compatible with 802.11b
• Same 2.4 GHz frequency conflict problems as 802.11b

Question 10

802.11b

Answer 10

• 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
• Not commonly seen today

Question 11

802.11a

Answer 11

• One of the original 802.11 wireless standards – October 1999
• Operates in the 5 GHz range
  – Or other frequencies with special licensing
• 54 megabits per second (Mbit/s)
• Smaller range than 802.11b
  – Higher frequency is absorbed by objects in the way
• Not commonly seen today

Question 12

Wireless standards

Answer 12

• 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