1.6 Flashcards
What are 802.11a specifications:
- 5GHz
- 54 megabits/s
- smaller range than 802.11b
What are 802.11b specifications:
- 2.4 GHz
- 11 megabits/s
- better range than 802.11a
- more frequency conflict
What are 802.11g specifications:
- 2.4 GHz
- 54 megabits/s
- backwards-compatible with 802.11b
- Same frequency conflict problem as 802.11b
What are 802.11n specifications:
- 5GHz and/or 2.4 GHz
- 600 megabits/s
- uses MIMO (multiple-input multiple-output, multiple transmit and receive antennas)
What are 802.11ac specifications:
- 5 GHz
- Increased channel bonding
- denser signaling modulation
- Eight MU_MIMO streams (twice as 802.11n)
What are the 2G Networks types?
- GSM
2. CDMA
What does GSM stand for?
Global System for Mobile Communications
WHat does CDMA stand for?
Code Division Multiple Access
What is TDMA?
The original GSM used TDMA to multiplex calls.
What is a SIM card?
Subscriber Identity Module
What does LTE stand for?
Long Term Evolution ( a 4G technology) with a download rate of 150 Mbit/s
What is LTE-A?
LTE Advanced which supports download rate of 300 Mbit/s
What frequencies do 802.11 technologies use?
some use 2.4 GHz, some use 5 GHz and some use both.
What are channels?
Groups of frequencies, numbered by the IEEE, but non-overlapping channels would be necessary.
What is bandwidth?
Amount of frequency in use (like 20, 40, 80 or 160 MHz)
What does MU-MIMO stand for?
Multi User MINO
What does the MIMO depend on?
Number of antennas
How can you read the number of antennas?
(Antennas on the access point)x(antennas on the client):number of streams
2x2:2, 3x3:2, 4x4:4
What is Omnidirectional antennas?
Omni = all. One of the most common which distributes signal evenly on all sides.
What is advantage and disadvantage of Omnidirectional antennas?
Av: Good choice for most environments because it send signals in all directions.
Disadv: No ability to focus the signal and a different antenna will be required.
What is a directional antenna?
It’s an antenna which focuses the signal (sends and receives signal in a single direction) and is measured in dB
What are some examples of directional antennas?
- Yagi (Very directional and high gain)
2. Parabolic (Focus the signal to a single point)
What is a site survey?
A site survey is performed first by examining the blueprints or floor plan of the premises to understand the layout and to identify features that might produce radio frequency interference (RFI).
What is channel bonding?
802.11n can obtain more bandwidth with the option to use two adjacent 20 MHz channels as a single 40 MHz channel, referred to as channel bonding.
