802.11 Flashcards
who is in charge of the standards and policies for certain electronic equipment?
The Institute of Electrical and Electronics Engineers (IEEE)
United Nations’ agency responsible for coordinating global use of the RF spectrum, satellite orbits, and international communications standards.
International Telecommunication Union (ITU)
In the United States, _____ regulates RF spectrum use and broadband services. The FCC separated the spectrum into licensed and unlicensed bands.
Federal Communications Commission (FCC)
Operators in licensed bands, however, must have a license because they are allowed to follow different rules, such as transmitting at higher powers.
FCC approved 802.11 on only channels 1-11 of the 2.4 GHz band and most of the 5 GHz UNII bands
Licensing
specifying Wi-Fi technologies at the Physical (PHY), and MAC sub layer of the Data-Link
Infrared at 1 Mbps data rates
Frequency-Hopping Spread-Spectrum (FHSS) at 1 Mbps and 2 Mbps data rates
Direct-Sequence Spread-Spectrum (DSSS)
2.4 GHz
first 802.11 standard aka 802.11 prime (1997)
wireless information is converted to a digital format in the form of bits
In higher order of modulation
used in in Wi-Fi 802.11ac, 4G, 5G cellular technologies, WiMAX, satellite, etc. OFDM utilizes the available bandwidth better and offers higher data transmission rate.
Orthogonal frequency-division multiplexing (OFDM)
means signals are multiplexed in a way that the peak of one signal occurs at the null of the other neighbor signals.
Orthogonal
process of combining one or more cellular modem connections into a single, faster virtual connection allowing the end user to utilize combined bandwidth.
Channel Bonding
uses multiple transmitters and receivers to transfer more data at the same time.
More antennas usually equate to higher speeds.
MIMO (Multiple Input Multiple Output)
an over-the-air interface between a wireless client and a base station or between two wireless clients.
802.11 Wireless Local Area Network (WLAN)
Access Point default mode
Master
client’s default mode
Managed
enables a client to communicate with another client without the need for an access point
Ad hoc
passively monitor RF signals
Monitor
allows access points to extend the range of another access point by helping relay traffic
Repeater
layer 2 routing, and helps any station act as a routing node
Mesh
access point connected to the main wired network
Root Mode
provides wireless connectivity between multiple wired networks
Bridge Mode
connectivity between a group of wired network stations
Workgroup Bridge Mode
re-broadcasts a signal
Repeater Mode
rich interconnection of communication networks made up of radio nodes
Mesh Mode
when a client device discovers wireless networks within range of a Wi-Fi adapter.
Scanner Mode
two kinds of wireless gateways
Residential and Enterprise
home router, and it provides a wireless internet connection in a small setting
Residential
for larger scale wireless local area networks (WLAN) such as offices.
Enterprise
allows a wireless network to expand using multiple access points without a traditional wired link between them.
Wireless Distribution System (WDS)
Independent Basic Service Set (IBSS), Basic Service Set (BSS) and Extended Service Set (ESS)
IEEE 802.11 supports three basic topologies for WLAN
ad-hoc mode or peer-to-peer mode refers to an office network in which there is no single node required to functions as a server.
IBSS
contains at least one access point connected to a wired network infrastructure and a set of wireless end stations.
BSS
has multiple overlapping BSSs (each BSS having at least one access point) connected by the means of a Distributed System.
ESS
usually a web page where the user of a public-access network is forced to interact with in order to gain access to their Wi-Fi.
Captive portals
requires a user to look/read over their acceptable user policy (AUP) page and agree to it before granting access.
Simple Captive Portal
may ask for a username and password before granting internet access to a user.
Complicated Captive Portal
How many modes of operation are there in a station?
6
