WiFi Glossary
802.11 standard
802.11, or ieEE 802.11, is a type of radio technology used for wireless local
area networks (WLAN's). It is a standard that has been developed by the ieEE
(Institute of Electrical and Electronic Engineers), http://standards.ieee.org.
The ieEE is an international organisation that develops standards for hundreds
of electronic and electrical technologies. The organisation uses a series
of numbers, like the Dewey Decimal system in libraries, to differentiate
between the various technology families.
The 802 subgroup (of the ieEE) develops standards for local and
wide area networks with the 802.11 section reviewing and creating
standards for wireless local area networks.
WiFi , 802.11, is composed of several standards operating in different
radio frequencies: 802.11b is a standard for wireless LAN's operating
in the 2.4 GHz spectrum with a bandwidth of 11 Mbps; 802.11a is a
different standard for wireless LAN's, and pertains to systems operating
in the 5 GHz frequency range with a bandwidth of 54 Mbps. Another
standard, 802.11g, is for WLAN's operating in the 2.4 GHz frequency
but with a bandwidth of 54 Mbps.
802.11a
An ieEE specification for wireless networking that operates in the 5 GHz frequency
range (5.725 GHz to 5.850 GHz) with a maximum 54 Mbps data transfer rate.
The 5 GHz frequency band is not as crowded as the 2.4 GHz frequency, because
the 802.11a specification offers more radio channels than the 802.11b. These
additional channels can help avoid radio and microwave interference.
802.11b
International standard for wireless networking that operates in the 2.4 GHz
frequency range (2.4 GHz to 2.4835 GHz) and provides a throughput of up to
11 Mbps. This is a very commonly used frequency. Microwave ovens, cordless
phones, medical and scientific equipment, as well as Bluetooth devices, all
work within the 2.4 GHz frequency band.
802.11g
Similar to 802.11b, but this standard provides a throughput of up to 54 Mbps.
It also operates in the 2.4 GHz frequency band but uses a different radio
technology in order to boost overall bandwidth.
Antenna Gain
Antenna don't increase the transmission power, but focus the signal more. So
instead of transmitting in every direction (including the sky and ground)
antenna focus the signal usually either more horizontally or in one particular
direction. This gain is measured in decibels.
Access point
A wireless LAN transceiver or "base station" that can connect a wired
LAN to one or many wireless devices. Access points can also bridge to each
other.
There are various types of access points and base stations used
in both wireless and wired networks. These include bridges, hubs,
switches, routers and gateways. The differences between them are
not always precise because certain capabilities associated with one,
can also be added to another. For example, a router can do bridging
and a hub may also be a switch. But they are all involved in making
sure data is transferred from one location to another.
A bridge connects devices that all use the same kind of protocol.
A router can connect networks that use differing protocols. It also
reads the addresses included in the packets and routes them to the
appropriate computer station, working with any other routers in the
network to choose the best path to send the packets on. A wireless
hub or access point adds a few capabilities, such as roaming and
provides a network connection to a variety of clients but, it does
not allocate bandwidth. A switch is a hub that has extra intelligence:
It can read the address of a packet and send it to the appropriate
computer station. A wireless gateway is an access point that provides
additional capabilities such as NAT routing, DHCP, firewall's, security,
etc.
Ad-Hoc mode
A client setting that provides independent peer-to-peer connectivity in a wireless
LAN. An alternative set-up is one where PCs communicate with each other through
an AP. See access point and Infrastructure mode.
Backbone
The central part of a large network that links two or more sub networks and
is the primary path for data transmission for a large business or corporation.
A network can have a wired backbone or a wireless backbone.
Bandwidth
The amount of transmission capacity that is available on a network at any point
in time. Available bandwidth depends on several variables such as the rate
of data transmission speed between networked devices, network overhead, number
of users and the type of device used to connect PC's to a network. It is
similar to a pipeline in that capacity, is determined by size; the wider
the pipe, the more water can flow through it; the more bandwidth a network
provides, the more data can flow through it. Standard 802.11b provides a
bandwidth of 11 Mbps; 802.11a and 802.11g provide a bandwidth of 54 Mbps.
Bits per second (bps)
A measure of data transmission speed over communication lines based on the
number of bits that can be sent or received per second. Bits per second—bps—is
often confused with bytes per second. While "bits" is a measure
of transmission speed, "bytes" is a measure of storage capability.
8 bits make a byte, so if a wireless network is operating at a bandwidth
of 11 megabits per second (11 Mbps or 11 Mbits/sec), it is sending data at
1.375 megabytes per second (1.375 MBps).
Bluetooth wireless technology
A technology specification for linking portable computers, personal digital
assistants (PDA's) and mobile phones for short-range transmission of voice
and data across a global radio frequency band, without the need for cables
or wires. Bluetooth is a frequency-hopping technology in the 2.4 GHz frequency
spectrum, with a range of 30 feet.
Bridge
A product that connects a local area network (LAN) to another local area network
that uses the same protocol (for example, wireless, Ethernet or token ring).
Wireless bridges are commonly used to link buildings in campuses.
Broadband
A comparatively fast Internet connection. Services such as ISDN, cable modem,
DSL and satellite are all considered broadband as compared to dial-up Internet
access. There is no official speed definition of broadband but services of
100Kbps and above are commonly thought of as broadband.
Bus adapter
A special adapter card that installs in a PC's PCI or ISA slot and enables
the use of PC Card radios in desktop computers. Some companies offer one
piece PCI or ISA Card radios that install directly into an open PC or ISA
slot.
Cable modem
A kind of converter used to connect a computer to a cable TV service that provides
Internet access. Most cable modems have an Ethernet out-cable that then attaches
to the user's WiFi gateway.
Client
Any computer connected to a network that requests services (files, print capability)
from another member of the network.
Client devices
Clients are end users. WiFi client devices include PC Cards that slide into
laptop computers, mini-PCI modules embedded in laptop computers and mobile
computing devices, as well as USB radios and PCI/ISA bus WiFi radios. Client
devices usually communicate with hub devices like access points and gateways.
DHCP
A utility that enables a server to dynamically assign IP addresses from a predefined
list and limit their time of use so that they can be reassigned. Without
DHCP, an IT Manager would have to manually enter in all the IP addresses
of all the computers on the network. When DHCP is used, whenever a computer
logs onto the network, it automatically gets an IP address assigned to it.
Dial-up
A communication connection via the standard telephone network or Plain Old
Telephone Service (POTS).
Diversity antenna
A type of antenna system that uses two antennas to maximise reception and transmission
quality and reduce interference.
DNS
A program that translates URL's to IP addresses by accessing a database maintained
on a collection of Internet servers. The program works behind the scenes
to facilitate surfing the Web with alpha versus numeric addresses. A DNS
server converts a name like mywebsite.com to a series of numbers like 107.22.55.26.
Every website has its own specific IP address on the Internet just like a
telephone number.
DSL
Various technology protocols for high-speed data, voice and video transmission
over ordinary twisted-pair copper POTS (Plain Old Telephone Service) telephone
wires.
Encryption key
An alphanumeric (letters and/or numbers) series that enables data to be encrypted
and then decrypted so it can be safely shared among members of a network.
WEP uses an encryption key that automatically encrypts outgoing wireless
data. On the receiving side, the same encryption key enables the computer
to automatically decrypt the information so it can be read.
ESSID
The identifying name of an 802.11 wireless network. When you specify your correct
ESSID in your client setup you ensure that you connect to your wireless network
rather than another network in range. (See SSID.) The ESSID can be called
by different terms, such as Network Name, Preferred Network, SSID or Wireless
LAN Service Area.
Ethernet
International standard networking technology for wired implementations. Basic
10BaseT networks offer a bandwidth of about 10 Mbps. Fast Ethernet (100 Mbps)
and Gigabit Ethernet (1000 Mbps) are becoming popular.
Firewall
A system that secures a network and prevents access by unauthorised users.
Firewall's can be software, hardware or a combination of both. Firewall's
can prevent unrestricted access into a network, as well as restrict data
from flowing out of a network.
Gateway
In the wireless world, a gateway is an access point with additional software
capabilities such as providing NAT and DHCP. Gateways may also provide VPN
support, roaming, firewall's, various levels of security, etc.
HotSpot
A place where you can access WiFi service. This can be for free or for a fee.
HotSpots can be inside a coffee shop, airport lounge, train station, convention
centre, hotel or any other public meeting area. Corporations and campuses
are also implementing HotSpots to provide wireless Internet access to their
visitors and guests. In some parts of the world HotSpots are known as CoolSpots.
Hub
A multiport device used to connect PC's to a network via Ethernet cabling or
via WiFi. Wired hubs can have numerous ports and can transmit data at speeds
ranging from 10 Mbps to multi-gigabyte speeds per second. A hub transmits
packets it receives to all the connected ports. A small wired hub may only
connect 4 computers; a large hub can connect 48 or more. Wireless hubs can
connect hundreds.
Infrastructure mode
A client setting providing connectivity to an AP. As compared to Ad-Hoc mode,
whereby PC's communicate directly with each other, clients set in Infrastructure
Mode, all pass data through a central AP. The AP not only mediates wireless
network traffic in the immediate neighbourhood but also provides communication
with the wired network. See Ad-Hoc and AP.
Internet appliance
A computer that is intended primarily for Internet access, is simple to set
up and usually does not support installation of third-party software. These
computers generally offer customised web browsing, touch-screen navigation,
e-mail services, entertainment and personal information management applications.
An Internet appliance can be WiFi enabled or it can be connected via a cable
to the local network.
IP
A set of rules used to send and receive messages at the Internet address level.
IP (Internet Protocol) telephony
Technology that supports voice, data and video transmission via IP-based LAN's,
WAN's and the Internet. This includes VoIP (Voice over Internet Protocol).
IP address
A 32-bit number that identifies each sender or receiver of information that
is sent across the Internet. An IP address has two parts; an identifier of
a particular network on the Internet and an identifier of the particular
device (which can be a server or a workstation) within that network.
ISDN
A type of broadband Internet connection that provides digital service from
the customer's premises to the dial-up telephone network. ISDN uses standard
POTS copper wiring to deliver voice, data or video.
ISS
A special software application that allows all PC's on a network access to
the Internet simultaneously, through a single connection and Internet Service
Provider (ISP) account.
LAN
A system of connecting PC's and other devices within the same physical proximity
for sharing resources such as an Internet connections, printers, files and
drives. When WiFi is used to connect the devices the system is known as a
wireless LAN or WLAN.
MAC
Every wireless 802.11 device has its own specific MAC address coded into it.
This unique identifier can be used to provide security for wireless networks.
When a network uses a MAC table, only the 802.11 radios that have had their
MAC addresses added to that network's MAC table will be able to get onto
the network.
Mapping
Assigning a PC to a shared drive or printer port on a network.
MeshBox (Hot Spot)
The MeshBox is a box about the size of a small video recorder. It has a number
of ports for connecting other devices and one or more on-board WiFi radios.
It is a multi-purpose device but its core function is creating wide area
wireless broadband. This means that each MeshBox communicates with other
MeshBoxes nearby and the internet signal is passed from one box to the next,
over the air, until it reaches the final destination.
'License free' wireless networking usually works at low power levels
and is considered a 'line of sight' technology. This normally limits
the range and usefulness in traditional operating environments. The
Red MeshBox overcomes these limitations by passing the data from
box to box in multiple low-power hops. The data can then travel further,
around obstructions and interference, taking the best possible route
to the final destination.
PC card
A removable, credit-card-sized memory or I/O device that fits into a Type 2
PCMCIA standard slot, PC Cards are used primarily in PCs, portable computers,
PDA's and laptops. PC Card peripherals include WiFi cards, memory cards,
modems, NIC's, hard drives, etc. (Definition: A network adapter supplies
the interface between a computer and a network connection)
PCI
A high-performance I/O computer bus used internally on most computers. Other
bus types include ISA and AGP. PCI's and other computer buses enable the
addition of internal cards that provide services and features not supported
by the motherboard or other connectors.
PCMCIA
Expansion cards now referred to as "PC Cards" were originally called "PCMCIA
Cards" because they met the standards created by the Personal Computer
Memory Card International Association.
PDA
Smaller than laptop computers but with many of the same computing and communication
capabilities, PDA's range greatly in size, complexity and functionality.
PDA's can provide wireless connectivity via embedded WiFi Card radios, slide-in
PC Card radios, or Compact Flash WiFi radios.
Peer-to-peer network (P2P)
A wireless or wired computer network that has no server or central hub or router.
All the networked PC's are equally able to act as a network server or client,
and each client computer can talk to all the other wireless computers without
having to go through an access point or hub. However, since there is no central
base station to monitor traffic or provide Internet access, the various signals
can collide with each other, reducing overall performance.
Plug and Play
A computer system feature that provides for automatic configuration of add-ons
and peripheral devices such as wireless PC Cards, printers, scanners and
multimedia devices.
Proxy server
Used in larger companies and organisations to improve network operations and
security, a proxy server is able to prevent direct communication between
two or more networks. The proxy server forwards allowable data requests to
remote servers and/or responds to data requests directly from stored remote
server data.
Range
Most WiFi systems will provide a range of a hundred feet or more. Depending
on the environment and the type of antenna used, WiFi signals can have a
range of up to mile.
Residential gateway
A wireless device that connects multiple PC's, peripherals and the Internet
on a home network. Most WiFi residential gateways provide DHCP and NAT as
well.
RJ-45
Standard connectors used in Ethernet networks. Even though they look very similar
to standard RJ-11 telephone connectors, RJ-45 connectors can have up to eight
wires, whereas telephone connectors have only four.
Roaming
Moving seamlessly from one AP coverage area to another with no loss in connectivity.
Router
A device that forwards data packets from one local area network (LAN) or wide
area network (WAN) to another. Based on routing tables and routing protocols,
routers can read the network address in each transmitted frame and make a
decision on how to send it via the most efficient route based on traffic
load, line costs, speed, bad connections, etc.
Satellite broadband
A wireless high-speed Internet connection provided by satellites. Some satellite
broadband connections are two-way, up and down. Others are one-way, with
the satellite providing a high-speed downlink and then using a dial-up telephone
connection or other land-based system for the uplink to the Internet.
Site survey
The process whereby a wireless network installer inspects a location prior
to putting in a wireless network. Site surveys are used to identify the radio
and client-use properties of a facility so that access points can be optimally
placed.
SSID
A 32-character unique identifier attached to the header of packets sent over
a WLAN that acts as a password when a mobile device tries to connect to the
BSS. (Also called ESSID.) The SSID differentiates one WLAN from another,
so all access points and all devices attempting to connect to a specific
WLAN must use the same SSID. A device will not be permitted to join the BSS
unless it can provide the unique SSID. Because an SSID can be sniffed in
plain text from a packet, it does not supply any security to the network.
An SSID is also referred to as a Network Name because essentially it is a
name that identifies a wireless network.
SSL
Commonly used encryption scheme used by many online retail and banking sites
to protect the financial integrity of transactions. When an SSL session begins,
the server sends its public key to the browser. The browser then sends a
randomly generated secret key back to the server in order to have a secret
key exchange for that session
Sub-network or Subnet
Found in larger networks, these smaller networks are used to simplify addressing
between numerous computers. Subnet's connect to the central network through
a router, hub or gateway. Each individual wireless LAN will probably use
the same subnet for all the local computers it talks to.
Switch
A type of hub that efficiently controls the way multiple devices use the same
network so that each can operate at optimal performance. A switch acts as
a networks traffic cop; rather than transmitting all the packets it receives
to all ports as a hub does, a switch transmits packets to only the receiving
port.
TCP
A protocol used along with the Internet Protocol (IP) to send data in the form
of individual units (called packets) between computers over the Internet.
While IP takes care of handling the actual delivery of the data, TCP takes
care of keeping track of the packets that a message is divided into for efficient
routing through the Internet. For example, when a web page is downloaded
from a web server, the TCP program layer in that server divides the file
into packets, numbers the packets, and then forwards them individually to
the IP program layer. Although each packet has the same destination IP address,
it may get routed differently through the network. At the other end, TCP
reassembles the individual packets and waits until they have all arrived
to forward them as a single file.
TCP/IP
The underlying technology behind the Internet and communications between computers
in a network. The first part, TCP, is the transport part, which matches the
size of the messages on either end and guarantees that the correct message
has been received. The IP part is the user's computer address on a network.
Every computer in a TCP/IP network has its own IP address that is either
dynamically assigned at startup or permanently assigned. All TCP/IP messages
contain the address of the destination network as well as the address of
the destination station. This enables TCP/IP messages to be transmitted to
multiple networks (subnet's) within an organisation or worldwide.
USB
A high-speed bidirectional serial connection between a PC and a peripheral
that transmits data at the rate of 12 megabits per second. The new USB 2.0
specification provides a data rate of up to 480 Mbps, compared to standard
USB at only 12 Mbps. 1394, FireWire and iLink all provide a bandwidth of
up to 400 Mbps.
VoIP (SIP)
Voice transmission using Internet Protocol to create digital packets distributed
over the Internet. VoIP can be less expensive than voice transmission using
standard analogue packets over POTS (Plain Old Telephone Service).
VPN
A type of technology designed to increase the security of information transferred
over the Internet. VPN can work with either wired or wireless networks, as
well as with dial-up connections over POTS. VPN creates a private encrypted
tunnel from the end user's computer, through the local wireless network,
through the Internet, all the way to the corporate servers and database.
WAN
A communication system of connecting PC's and other computing devices across
a large local, regional, national or international geographic area. Also
used to distinguish between phone based data networks and WiFi. Phone networks
are considered WAN's and WiFi networks are considered Wireless Local Area
Networks (WLAN's).
WEP
Basic wireless security provided by WiFi. In some instances, WEP may be all
a home or small-business user needs to protect wireless data. WEP is available
in 40-bit (also called 64-bit), or in 108-bit (also called 128-bit) encryption
modes. As 108-bit encryption provides a longer algorithm that takes longer
to decode, it can provide better security than basic 40-bit (64-bit) encryption.
WiFi
An interoperability certification for wireless local area network (LAN) products
based on the Institute of Electrical and Electronics Engineers (ieEE) 802.11
standard.
WLAN
Also referred to as LAN. A type of local-area network that uses high-frequency
radio waves rather than wires to communicate between nodes.
WMM
WiFi Multimedia. Features for WiFi networks that improve the user experience
for audio, video and voice applications.
|
