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802 Standards Flashcards

(57 cards)

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1
Q

How many wifi channels are in the 2.4GHz range?

A

-14

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2
Q

HAM radio

A

licensed

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3
Q

International org that is responsible for coordinating worldwide communication standards and dividing the radio spectrum according to wavelength

A

ITU

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4
Q

WIFI uses

A

unlicensed band

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5
Q

WIFI channels in the 5GHz range do not

A

overlap

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6
Q

combines 2 or more adjacent channels to increase the bandwidth and allow for more data throughput;
Happens at all 3 frequencies- 2.4, 5, and 6GHz but mostly at the higher two;
Commonly used in 802.11n and newer;
5 and 6GHz can bond two, four, or eight contiguous 20MHz channels together for a max bandwidth of 160MHz;
2.4GHz requires two channels that are two channels apart (1 & 3, 5 & 7 etc). The max bandwidth allowed is 40 MHz

A

Channel bonding

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7
Q

Two types of channel interference:

A

co-channel & adjacent channel

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8
Q

two or more transmitters are operating on the same channel, causing interference and possible data loss

A

co-channel interference

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9
Q

two or more devices are using channels that are overlapping, causing interference and probable data loss;
For WIFI, this predominantly affects the 2.4GHz channels, because they have so much overlap

A

Adjacent Channel Interference

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10
Q

A technique that combines adjacent channels to increase the bandwidth for more data throughput is known as what?

A

channel bonding

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11
Q

non-overlapping channels in the 2.4GHz band

A

channel 1, 6, 11, 14

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12
Q

What 802.11 standards use 5GHz Radio Frequency? (4)

A

802.11a, 802.11n, 802.11ac, 802.11ax

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13
Q

both are spread spectrum signals, and operate in the 2.4GHz band. All 14 channels here are 22MHz wide

A

Frequency-Hopping spread spectrum (FHSS) & Direct Sequence Spread Spectrum (DSSS)

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14
Q

uses a predetermined set of frequencies within a channel, and rapidly switches between them;
Signals are harder to intercept;
Multiple can use the same channels;
highly resistant to interference at specific frequencies;
downside is that it is a narrow band, only capable of 1-2Mbits throughput

A

Frequency-Hopping spread spectrum (FHSS)

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15
Q

Uses a spreading sequence to make the transmitted signal wider than the information’s bandwidth;
Once received on the other end, a despreading process occurs and most interference is substantially reduced;
-Significantly reduced interference
-Allows for up to 11Mbits throughput

A

Direct Sequence Spread Spectrum (DSSS)

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16
Q

What modulation method is used for 802.11n? What frequency band?

A

2.4 GHz / 5 GHz

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17
Q

What modulation method is used for 802.11ac? What frequency band?

A

-2.4 GHz / 5 GHz

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18
Q

multiplexing type that takes signals from multiple different frequencies and turns them into a single signal

A

Frequency Division Multiplexing (FDM)

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19
Q

Divides the time frame into slots. Each slot is given for each message or piece of data to be sent

A

Time Division Multiplexing (TDM)

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20
Q

very similar to normal FDM, but the sub-carrier frequencies are chosen so that the other sub-carriers are orthogonal to each other;
used in WIFI, Cellular technologies, WiMAX, satellite, etc;
Optimize use of all available bandwidth;
eliminates interference;
easier/better channel bonding;
Maximize throughput with speeds up to 10Gbits;
20MHz wide and can be bonded up to max of 160MHz

A

Orthogonal/Orthogonal frequency-division multiplexing (OFDM)

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21
Q

signals are perpendicular to each other, which eliminates the interference that can happen with adjacent sub-channels

A

orthogonal

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22
Q

Process of using multiple antennas broadcasting at proper time to take advantage of constructive interference to boost signal strength;
Directional antennas do this by design, otherwise multiple omni-directional antennas would have to work in conjunction to accomplish this same thing;
Receiving device will monitor signal strength and report back to transmitting device the signal strength. Based on that the router will calculate if the receiver needs more or less power

A

beamforming

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23
Q

Uses channel bonding and beamforming, in conjunction with multiple antennas and receivers to maximize data transmission;
-802.11n and newer
-Up to 8 streams
-More efficient use of spectrum

Study These Flashcards
A

Multiple Input Multiple Output (MIMO)

24
Q

Wireless technique that uses multiple transmission and receiving antennas and up to 8 spatial streams to exploit multipath propagation for 1 specified user/device

25
Is just like MIMO but uses multiple transmitter sets to allow multiple, simultaneous transmissions on different channels. Allows more devices to be simultaneously connected. Requires more transmitters/receivers -Multiple User
Multiple Input Multiple Output (MU-MIMO)
26
Wireless technique that uses multiple, simultaneous transmissions on different channels to enable transmissions to several users at the same time
MU-MIMO
27
Which modulation technique uses a spreading sequence to make the transmitted signal wider than the information bandwidth?
Direct Sequence Spread Spectrum (DSSS)
28
Which modulation technique uses sub-carrier frequencies that are perpendicular to other sub-carrier frequencies?
Orthogonal
29
The process of using multiple antennas and constructive interference to boost signal strength is known as what?
Beamforming
30
What is the use of channel bonding along with multiple transmitters and receivers to maximize transmission called?
Multiple Input Multiple Output (MIMO)
31
sets the standards for all WIFI Devices & designed to work in tandem with 802.3 components but WIRELESSLY Components include: Clients, Access Point, Distribution Systems, Wireless Gateway
802.11
32
an end device that can connect to a wireless network Phone, Computer, Tablet, Game system, Fridge, Thermostat. Clients are known by Access Points by their ________
client; MAC address
33
a device that will connect many clients together; Essentially a wireless Hub- a device will connect to it and send it data, which will then be broadcasted out to the client the data was meant for; Also known as base stations
Access Point(AP)
34
Facilitates the connection between two or more AP’s by converting from 802.11 to 802.3 standards and back to the other side; Allows for a larger separation of AP’s than wireless can
Distribution System (DS)
35
a networking system that facilitates wireless coverage to be expanded by establishing wireless connections between several access points; Can’t send as far as a DS could Doesn’t require wires
Wireless Distribution System (WDS)
36
Router; Provides access outside the WLAN to another WLAN, LAN or to the internet(WAN); incorporate multiple devices in one- router, AP, firewall, or modem; Two types: Residential: provides wireless internet connection in a small setting such as home Enterprise: capable of handling many more clients with better equipment
Wireless gateway
37
WLAN topology components (4)
Clients, Access Point, Distribution Systems, Wireless Gateway
38
devices that connect to a wireless network
clients
39
What facilitates the wireless connection of multiple access points?
Wireless Distribution System
40
two types of wireless gateways
Residential and Enterprise
41
3 802.11 basic topologies:
Independent Basic Service Set (IBSS) Basic Service Set (BSS) Extended Service Set (ESS)
42
area around an AP that clients can communicate with the AP; have to be in range to stay connected; uplink limited
Basic Service Area(BSA)/Cell
43
MAC of the AP; Who will remember this is their network Ex: 00:15:5E:00:DC:F9
Basic Service Set Identifier(BSSID)
44
Human readable version of BSSID -not unique -made when the network is setup
Service Set Identifier(SSID)
45
the SSID of the entire ESS
Extended Service Set Identifier(ESSID)
46
contains two or more wireless devices directly connected to each other; -No central device or any access points, so faster than other types, but may have to wait to transmit -simplest type of 802.11 network -not many clients can connect -rarely used, cheaper
Independent Basic Service Set(IBSS)
47
An access point facilitates connections between two or more clients, creating a basic wireless network; -Can connect many clients to one access point -Cheap and easy setup/management -no outside connection just the one network
Basic Service Set(BSS)
48
two or more BSS’s that are joined through a DS; -upgraded as needed -cheaper than wired networks -DS replaced by a wireless gateway -All AP’s must use the same SSID to work properly
Extended Service Set(ESS)
49
The MAC of an access point is known as what?
Basic Service Set Identifier (BSSID)
50
An ad-hoc connection between devices is known as what?
Independent Basic Service Set (IBSS)
51
A network of devices connected by an access point is known as what?
Basic Service Area (BSA)
52
An ESS occurs when two or more BSS’s are connected through a what?
Distribution System (DS)
53
When you connect to the network you have to open a web browser and accept the user agreement or network access will not be allowed; Used in Hotels, airports, coffee shops, etc; user agreement has two main parts: acceptable use policy which entails what you can or cannot do while on their network & Authorization to monitor/record your data usage
Captive portal
54
Used to help businesses make money by 1)Recording your data to either market to you or sell your data 2) Require you to “login” or use a social media to login 3) Bandwidth Throttling- slowing of someones network connection speed so you pay to upgrade for more speed 4) keep you in their place of business spending money
Captive portals
55
The intentional slowing of someones network connection speed to try and make you pay to upgrade for more speed
Bandwidth Throttling
56
user agreement of freely giving them access to your data: Email, Social media accounts, room number, etc; specifically intercept, track and monitor your data which negates the security functions of HTTPS; If a Hacker has already infiltrated a captive portal network, they can do what they want to your connected device; VPN’s are no guarantee either as they take time to establish a connection
captive portals
57
What is a web page that requires user acknowledgment before public WiFi can be used?
captive portals

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