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Wireless Technology Glossary
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An IEEE standard (802.3) for operating 10 Mbps
Ethernet networks (LANs) with twisted pair cabling and a wiring hub.
802.11, or IEEE 802.11, is a type of radio
technology used for wireless local area networks (WLANs). 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 organization that develops standards for hundreds
of electronic and electrical technologies. The organization 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.
Wi-Fi , 802.11, is composed of several standards
operating in different radio frequencies: 802.11b is a standard for wireless
LANs operating in the 2.4 GHz spectrum with a bandwidth of 11 Mbps; 802.11a is a
different standard for wireless LANs, and pertains to systems operating in the 5
GHz frequency range with a bandwidth of 54 Mbps. Another standard, 802.11g, is
for WLANS operating in the 2.4 GHz frequency but with a bandwidth of 54 Mbps.
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.
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.
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.
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, firewalls, security, etc.
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.
An application or utility program that is designed
to do a very specific and limited task.
A computer program that is designed to do a general
task. For example, word processing, payroll, Internet browsers and graphic
design programs would all be considered applications.
The central part of a large network that links two
or more subnetworks 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.
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 PCs 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.
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—Bps. 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).
A technology specification for linking portable
computers, personal digital assistants (PDAs) 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.
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.
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.
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.
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 Wi-Fi gateway.
Any computer connected to a network that requests
services (files, print capability) from another member of the network.
Clients are end users. Wi-Fi 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
Wi-Fi radios. Client devices usually communicate with hub devices like access
points and gateways.
A network node characteristic for proactively
detecting that it can transmit a signal without risking a collision.
A special cable used for networking two computers
without the use of a hub. Crossover cables may also be required for connecting a
cable or DSL modem to a wireless gateway or access point. Instead of the signals
transferring in parallel paths from one set of plugs to another, the signals
"crossover." If an eight-wire cable was being used, for instance, the signal
would start on pin one at one end of the cable and end up on pin eight at the
other end. They "cross-over" from one side to the other.
CSMA/CA is the principle medium access method
employed by IEEE 802.11 WLANs. It is a "listen before talk": method of
minimizing (but not eliminating) collisions caused by simultaneous transmission
by multiple radios. IEEE 802.11 states collision avoidance method rather than
collision detection must be used, because the standard employs half duplex
radios—radios capable of transmission or reception—but not both simultaneously.
Unlike conventional wired Ethernet nodes, a WLAN station cannot detect a
collision while transmitting. If a collision occurs, the transmitting station
will not receive an ACKnowledge packet from the intended receive station. For
this reason, ACK packets have a higher priority than all other network traffic.
After completion of a data transmission, the receive station will begin
transmission of the ACK packet before any other node can begin transmitting a
new data packet. All other stations must wait a longer pseudo randomized period
of time before transmitting. If an ACK packet is not received, the transmitting
station will wait for a subsequent opportunity to retry transmission.
A method of managing traffic and reducing noise on
an Ethernet network. A network device transmits data after detecting that a
channel is available. However, if two devices transmit data simultaneously, the
sending devices detect a collision and retransmit after a random time delay.
Modules that convert AC power to DC. Depending on
manufacturer and product, these modules can range from typical "wall wart"
transformers that plug into a wall socket and provide DC power via a tiny plug
to larger, enterprise-level Power Over Ethernet systems that inject DC power
into the Ethernet cables connecting access points.
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.
A communication connection via the standard
telephone network, or Plain Old Telephone Service (POTS).
A type of antenna system that uses two antennas to
maximize reception and transmission quality and reduce interference.
A program that translates URLs 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.
Various technology protocols for high-speed data,
voice and video transmission over ordinary twisted-pair copper POTS (Plain Old
Telephone Service) telephone wires.
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.
A term that is often applied to large corporations
and businesses. The enterprise market can incorporate office buildings,
manufacturing plants, warehouses and R&D facilities, as well as large colleges
and universities.
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.
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.
A system that secures a network and prevents access
by unauthorized users. Firewalls can be software, hardware or a combination of
both. Firewalls can prevent unrestricted access into a network, as well as
restrict data from flowing out of a network.
A high-speed serial bus system, FireWire is the IEEE
1394 standard for input/output technology that connects multimedia and storage
peripherals to a PC. FireWire (Apple), 1394 (Linux) and iLink (Sony) are
different names for products that perform the same function. FireWire can
provide a bandwidth of about 400 Mbps.
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, firewalls, various levels of security,
etc.
A place where you can access Wi-Fi service. This can
be for free or for a fee. HotSpots can be inside a coffeeshop, airport lounge,
train station, convention center, 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.
A multiport device used to connect PCs 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 multigigabyte 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.
The international unit for measuring frequency,
equivalent to the older unit of cycles per second. One megahertz (MHz) is one
million hertz. One gigahertz (GHz) is one billion hertz. The standard US
electrical power frequency is 60 Hz, the AM broadcast radio frequency band is
535—1605 kHz, the FM broadcast radio frequency band is 88—108 MHz, and wireless
802.11b LANs operate at 2.4 GHz.
The term used to describe any operation, program or
device that transfers data to or from a computer.
Institute of Electrical and Electronics Engineers,
New York, www.ieee.org. A membership organization that includes engineers,
scientists and students in electronics and allied fields. It has more than
300,000 members and is involved with setting standards for computers and
communications.
A set of specifications for LANs from The Institute
of Electrical and Electronics Engineers (IEEE). Most wired networks conform to
802.3, the specification for CSMA/CD based Ethernet networks or 802.5, the
specification for token ring networks. 802.11 defines the standard for wireless
LANs encompassing three incompatible (non-interoperable) technologies: Frequency
Hopping Spread Spectrum (FHSS), Direct Sequence Spread Spectrum (DSSS) and
Infrared. WECA’s focus is on 802.11b, an 11 Mbps high-rate DSSS standard for
wireless networks.
Sony’s term for IEEE1394 technology that provides a
bandwdith of about 400 Mbps. Many people also refer to this high-speed
communication technology using Apple’s original term, FireWire. Regardless of
what it is called, it is the same. New versions of 1394 that will greatly
increase the bandwidth.
A client setting providing connectivity to an AP. As
compared to Ad-Hoc mode, whereby PCs 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 neighborhood, but
also provides communication with the wired network. See Ad-Hoc and AP.
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 customized web browsing,
touch-screen navigation, e-mail services, entertainment and personal information
management applications. An Internet appliance can be Wi-Fi enabled or it can be
connected via a cable to the local network.
A set of rules used to send and receive messages at
the Internet address level.
Technology that supports voice, data and video
transmission via IP-based LANs, WANs, and the Internet. This includes VoIP
(Voice over IP).
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.
IPX, short for Internetwork Packet Exchange, a
networking protocol used by the Novell NetWare operating systems. Like UDP/IP,
IPX is a datagram protocol used for connectionless communications. Higher-level
protocols, such as SPX and NCP, are used for additional error recovery services.
Sequenced Packet Exchange, SPX, a transport layer protocol (layer 4 of the OSI
Model) used in Novell Netware networks. The SPX layer sits on top of the IPX
layer (layer 3) and provides connection-oriented services between two nodes on
the network. SPX is used primarily by client/server applications. Whereas the
IPX protocol is similar to IP, SPX is similar to TCP. Together, therefore,
IPX-SPX provides connection services similar to TCP/IP.
A type of internal computer bus that allows the
addition of card-based components like modems and network adapters. ISA has been
replaced by PCI and is not very common anymore.
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.
A network model developed by the International
Standards Organization (ISO) that consists of seven different levels, or layers.
By standardizing these layers, and the interfaces in between, different portions
of a given protocol can be modified or changed as technologies advance or
systems requirements are altered. The seven layers are:
-
Physical -
Data Link
-
Network
-
Transport
-
Session
-
Presentation
-
Application
The IEEE 802.11 Standard encompasses the physical
layer (PHY) and the lower portion of the data link layer. The lower portion of
the data link layer is often referred to as the Medium Access Controller (MAC)
sublayer.
A special software application that allows all PCs
on a network access to the Internet simultaneously through a single connection
and Internet Service Provider (ISP) account.
A system of connecting PCs and other devices within
the same physical proximity for sharing resources such as an Internet
connections, printers, files and drives. When Wi-Fi is used to connect the
devices, the system is known as a wireless LAN or WLAN.
Every wireless 802.11 device has its own specific
MAC address hard-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.
Assigning a PC to a shared drive or printer port on
a network.
A salesperson or a "road warrior" who travels
frequently and requires the ability to regularly access his or her corporate
networks, via the Internet, to post and retrieve files and data and to send and
receive e-mail.
A network capability that enables a houseful of
computers to dynamically share a single incoming IP address from a dial-up,
cable or xDSL connection. NAT takes the single incoming IP address and creates
new IP address for each client computer on the network.
Identifies the wireless network for all the shared
components. During the installation process for most wireless networks, you need
to enter the network name or SSID. Different network names are used when setting
up your individual computer, wired network or workgroup.
A type of PC adapter card that either works without
wires (Wi-Fi) or attaches to a network cable to provide two-way communication
between the computer and network devices such as a hub or switch. Most office
wired NICs operate at 10 Mbps (Ethernet), 100 Mbps (Fast Ethernet) or 10/100
Mbps dual speed. High-speed Gigabit and 10 Gigabit NIC cards are also available.
See 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, PDAs and laptops. PC Card peripherals include Wi-Fi
cards, memory cards, modems, NICs, hard drives, etc.
A high-performance I/O computer bus used internally
on most computers. Other bus types include ISA and AGP. PCIs and other computer
buses enable the addition of internal cards that provide services and features
not supported by the motherboard or other connectors.
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.
Smaller than laptop computers but with many of the
same computing and communication capabilities, PDAs range greatly in size,
complexity and functionality. PDAs can provide wireless connectivity via
embedded Wi-Fi Card radios, slide-in PC Card radios, or Compact Flash Wi-Fi
radios.
A wireless or wired computer network that has no
server or central hub or router. All the networked PCs 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.
The lowest layer within the OSI Network Model. It
deals primarily with transmission of the raw bit stream over the PHYsical
transport medium. In the case of wireless LANs, the transport medium is free
space. The PHY defines parameters such as data rates, modulation method,
signaling parameters, transmitter/receiver synchronization, etc. Within an
actual radio implementation, the PHY corresponds to the radio front end and
baseband signal processing sections.
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.
Standard analog telephone service.
Used in larger companies and organizations 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.
How far will your wireless network stretch? Most
Wi-Fi systems will provide a range of a hundred feet or more. Depending on the
environment and the type of antenna used, Wi-Fi signals can have a range of up
to mile.
A wireless device that connects multiple PCs,
peripherals and the Internet on a home network. Most Wi-Fi residential gateways
provide DHCP and NAT as well.
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.
Moving seamlessly from one AP coverage area to
another with no loss in connectivity.
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.
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.
A computer that provides its resources to other
computers and devices on a network. These include print servers, Internet
servers and data servers. A server can also be combined with a hub or router.
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.
A term generally used to describe an office or
business with ten or fewer computers and/or employees.
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.
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
Found in larger networks, these smaller networks are
used to simplify addressing between numerous computers. Subnets 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.
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.
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.
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 (subnets) within an organization or worldwide.
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.
Voice transmission using Internet Protocol to create
digital packets distributed over the Internet. VoIP can be less expensive than
voice transmission using standard analog packets over POTS (Plain Old Telephone
Service).
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.
A communication system of connecting PCs and other
computing devices across a large local, regional, national or international
geographic area. Also used to distinguish between phone-based data networks and
Wi-Fi. Phone networks are considered WANs and Wi-Fi networks are considered
Wireless Local Area Networks (WLANs).
Basic wireless security provided by Wi-Fi. 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.
Also referred to as LAN. A type of local-area
network that uses high-frequency radio waves rather than wires to communicate
between nodes.
Information is provided from the
www.wifialliance.org website.
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