1.6 - Wireless technologies and configurations

Question 1

Describe 802.11a

Answer 1

Released after 802.11b, it had greater theoretical coverage area and greater throughput. But, the commercial development for 802.11b was already in motion, so 802.11a lost the race.

Question 2

Describe 802.11b

Answer 2

Implemented in 1999. Provides 22 separate channels in the 2.4 Ghz band. Up to 11 Mbps and up to 50 meters.

Question 3

Describe 802.11g

Answer 3

Also used 2.4 Ghz band, making it a reasonable upgrade from 802.11b. Increased throughput to 54 Mbps.

Question 4

Describe 802.11n

Answer 4

Ratified in 2009, allows for 600 Mbps throughput. Backwards compatible with a, b, and g.

Question 5

Describe 802.11ac

Answer 5

Provides well over 6 Gbps on the 5 Ghz frequency. Can handle multiple data streams, and are often dual-band (2.4 Ghz AND 5 Ghz).

Question 6

Describe 1G

Answer 6

Generation 1 of Cell technology. Used analog communication and were cumbersome and slow by today’s standards.

Question 7

Describe 2G

Answer 7

Generation 2 adopted digital transmission. Also supported media and text downloads at 240 Kbps. GSM was also introduced for voice data.

Question 8

Describe 3G

Answer 8

Generation 3 brought 384 Kbps and pack-switching.

Question 9

Describe 4G

Answer 9

Generation 4 provides up to 1 Gbps to a stationary or low speed (walking) device. IP based packet-switching for voice and data.

Question 10

Describe GSM

Answer 10

Global System for Mobile Communications. Uses TDMA (Time Division Multiple Access) to separate data into timeslots, allowing multiple users on the same channel. GSM requires a SIM card (Subscriber Identity Module).

Question 11

Describe CDMA

Answer 11

Code Division Multiple Access. Uses spread spectrum technology, the use of varying frequencies and intervals, as defined by the code, to send transmissions. Improves privacy as the transmitting and receiving devices must follow the same pattern.

Question 12

Elaborate on the 2.4 Ghz frequency.

Answer 12

Ranges from 2.4 to 2.4835 Ghz. Wi-Fi designates 11 channels each 22 Mhz wide. Overseas, 14 channels are defined.

Question 13

Elaborate on the 5 Ghz frequency.

Answer 13

Considerably less congested than 2.4 Ghz, often rivaling Ethernet in speed.

Question 14

What is channel bonding?

Answer 14

802.11n uses channel bonding to increase bandwidth by combining two adjacent 20 Mhz channels into one 40 Mhz channel.

Question 15

What is MIMO and MU-MIMO+?

Answer 15

Multiple Input - Multiple Output. Allows more than one antenna to be used on clients and access points, allowing devices to transmit and receive simultaneously.
Multiuser MIMO. Allows multiple client communications to be combined.

Question 16

What is unidirectional and omnidirectional?

Answer 16

Unidirectional antennas send in a specific direction, while omnidirectional antennas send in a 360 degree spread.

Question 17

What is a site survey?

Answer 17

Analyzing the Wi-Fi to determine the best AP placement of a WLAN and achieve the strongest signal-to-noise (S/N) ratio.