2.3 Wireless Networking Standards

Question 1

802.11a

Answer 1

OG .11 standard (1999)

Operates in 5 GHz range

54 mbit/s

Smaller range than .11b
-Higher frequency absorbed by objects in the way

Uncommon today

Question 2

802.11b

Answer 2

OG .11 standard (1999)

Operates in 2.4 GHz range

11 mbit/s

Better range than .11a
-less absorption issues

More frequency conflict
-baby monitors, microwave ovens, cordless phones, bluetooth

Uncommon today

Question 3

802.11g

Answer 3

Upgrade to 802.11b (2003)

Operates in 2.4 GHz range

54 mbit/s

Backwards compatible with 802.11b

Same 2.4 GHz frequency conflict problems as 802.11b

Question 4

802.11n (Wi-Fi 4)

Answer 4

2009

Operates at 5 GHz and/or 2.4 GHz

600 mbit/s

Uses MIMO
-multiple input/output
-multiple transmit + receive antennas

Question 5

802.11ac (Wi-Fi 5)

Answer 5

2014

Operates in 5 GHz band
-less crowded
-more frequencies

increased channel bonding, larger bandwidth usage

denser signaling modulation
-faster data transfers

8 MU-MIMO downlink streams
-twice as many streams as 802.11n
-nearly 7 gigabits/second

Question 6

802.11ax (Wi-Fi 6)

Answer 6

2021

Operates at 5 GHz and/or 2.4 GHz

1,201 megabits/second per channel
-small increase in throughput
-8 bidirectional MU-MIMO streams

OFDMA (orthogonal frequency division multiple access)
-works similar to cellular comm.
-improves high density installations

Question 7

Long-range fixed wireless

Answer 7

Wireless access point in a house with the stock antennas
-range of 40->50 meters

Try connecting two buildings located miles from each other
-fixed directional antennas
-increased signal strength

Outdoors
-minimal signal absorption/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 + outdoor power usually regulated

Outdoor antenna installation is not trivial
-get an expert, be safe

Question 8

RFID

Answer 8

Radio-frequency identification

Everywhere
-access badges
-pet IDs
-anything that needs to be tracked

Radar technology
-radio energy transmitted to tag
-powers tag and ID is transmitted back
-bidirectional communication

Question 9

NFC

Answer 9

Near field communication

Access token identity card

2 way wireless communication
-builds on RFID

Payments systems
-credit cards
-online wallets

Helps with bluetooth pairing

Question 10

802.11 technologies

Answer 10

Frequency
-2.4 or 5 GHz (sometimes both)

Channels
-Groups of frequencies (numbered by IEEE)
-Non-overlapping channels are ideal

Regulations
-Most countries have regulations to manage frequency use
-Spectrum use, power output, interference requirements, etc.

Question 11

Bluetooth

Answer 11

Removes wires

Uses 2.4 GHz range
-unlicensed ISM band
-same as 802.11

Short range
-Consumer devices = operate to about 10 meters
-Industrial devices = communicate over 100 meters