Wireless Technology

Question 1

CSMA/CA

Answer 1

802.11 access method - Carrier Sense Multiple Access/Collision Avoidance - Tried to fix network collisions before they happen by activley listening and only transmitting when the channel is clear

Question 2

Wireless Frequencies

Answer 2

2.4 GHz, 5 GHz, & 6 GHz

Question 3

Gigahertz (GHz)

Answer 3

How many billions of times a full wave oscillates through a given point in a second - Wireless frequencies measured based on this

Question 4

Which frequencies carry more / less data?

Answer 4

Lower Frequencies carry less data, but they have stronger (farther) range and are less susceptible to interference from obstructions such as walls

Question 5

What is a Channel?

Answer 5

A frequency (i.e. 2.4 GHz) is broken down into “Channels” which are smaller portions or narrower bands of that frequency - Frequency = highway then Channels = lanes

Question 6

2.4 GHz Channel band width

Answer 6

20 MHz Bands with 14 max channels

Question 7

5 GHz Channel Band Width

Answer 7

20 MHz, 40 MHz, 80 MHz, or 160 MHz

Question 8

6 GHz Channel Band Width

Answer 8

20 MHz, 40 MHz, 80 MHz, or 160

Question 9

802.11a (Legacy)

Answer 9

first Wi-Fi standard - 54 Mbps speed in the 5 GHz band using orthogonal frequency division multiplexing (OFDM)

Question 10

802.11b (Legacy)

Answer 10

Second (Barely) Wi-Fi standard -11 Mbps speed in the 2.4 GHz range

Question 11

801.11g (Legacy)

Answer 11

Third Wi-Fi Standard - 54 Mbps in the 2.4 GHz range using orthogonal frequency division multiplexing (OFDM) or Direct-Sequence Spread Spectrum (DSSS); backward compatible with 802.11b due to both operating in the 2.4 GHz frequency range thus replacing 802.11b

Question 12

802.11n (Legacy)

Answer 12

Wi-Fi 4 - PHY rate of 600 Mbps but really about 300 - 450 Mbps; operated in both 5 GHz and 2.4 GHz range using orthogonal frequency division multiplexing (OFDM) or Direct-Sequence Spread Spectrum (DSSS); Backward compatible with 802.11b/g; Introduced MIMO and increased 40 MHz channels by combining two 20 MHz channels

Question 13

802.11ac

Answer 13

Wi-Fi 5 - 5 GHz with 6.9 Gbps using Orthogonal Frequency Division Multiplexing and 256 Quadrature Amplitude Modification (QAM)

Question 14

Beamforming

Answer 14

Introduced in 802.11ac, which allows for range increases by sending the wireless signal in the specific direction of the client, as opposed to broadcasting it omnidirectionally

Question 15

802.11ax

Answer 15

Wi-Fi 6 - PHY rate 9.6 Gbps using 2.4 GHz and 5 GHz range using orthogonal frequency division multiplexing access (OFDMA) & 1024 Quadrature Amplitude Modification (QAM); First to allow wireless access points and routers to connect to devices on multiple frequencies at one time

Question 16

Multi-Link Operation (MLO)

Answer 16

Introduced in Wi-Fi 7 - allows a single device to connect to the router across multiple frequencies simultaneously

Question 17

802.11be

Answer 17

Wi-Fi 7 - PHY 46 Gbps using 2.4, 5, and 6 GHz range

Question 18

Three non-overlapping channels in the 2.4 GHz Range

Answer 18

1, 6, & 11

Question 19

Wi-Fi 6e

Answer 19

802.11ax that introduced the 6 GHz Frequency range

Question 20

Multiple-input, Multiple-Output (MIMO)

Answer 20

Introduced by 802.11n (Wi-Fi 4) - allowed the use of mutliple antennas rather than a single antenna to communicate information

Question 21

Channel Bonding

Answer 21

Introduced by 802.11n (Wi-Fi 4) - combined two 20 MHz channels to create a single 40 MHz channel - thus increasing thoroughput

Also allowed the device to communicate simultaneously at 2.4GHz and 5 GHz and “bond” the data streams which also increased throughput

Question 22

Spatial streams

Answer 22

Multiple antennas and can send and receive data simultaneously on these different antennas, i.e. a single data transmission that’s sent using multiple antennas

Question 23

Frequency Hopping Spread Spectrum (FHSS)

Answer 23

A modulation technique that “Frequency hops”, or switches rapidly between frequencies

Question 24

Direct-Sequence Spread Spectrum (DSSS)

Answer 24

A modulation technique that takes the signal and spreads it out across the available band

Question 25

Orthogonal frequency division Multiplexing (OFDM)

Answer 25

A modulation technique that divides the signal into pieces and transmits it among multiple subcarriers

Question 26

Binary Phase Shift Keying (BPSK)

Answer 26

A modulation scheme that transmits one bit per symbol. Think of a symbol as representing data, either one bit or a group of bits, that's transmitted over a specific amount of time. Each symbol is marked by a unique combination of the wireless signal's phase and amplitude. BPSK is the simplest and uses the least amount of power among the three modulation schemes

Question 27

Quadrature Phase Shift Keying (QPSK)

Answer 27

A modulation scheme that transmits 2 bits per symbol by modifying the signal's phase

Question 28

Quadrature Amplitude Modification (QAM)

Answer 28

A modulation scheme that transmits multiple bits per symbol, giving it the highest data throughput. It is also the most sensitive to interference.