Introduction Technology Organizations Pros and
Cons FAQs Resources
Resources
Research
General
DARPA Information Technology Office
Lawrence
Berkeley National Laboratory
Interoperability
Lab, University of New Hampshire
Center for Wireless Integrated Microsystems
(WIMS), University of Michigan
Wireless Information Network Laboratory
(WINLAB), Rutgers University
Institute
for Systems Research, University
of Maryland
USC
Information Sciences Institute
Wireless LAN Related
University
of New Hampshire InterOperability Labs: Wireless Tutorial
Wireless LANs
Security White Paper
WLANA:
Introduction to Wireless LANs
Computer Networking - Wireless Networks
PaloWireless:
Wireless BookshopEverything
about Wireless LANs
HiperLAN Related
HiperLAN2
- The Broadband Radio Transmission Technology Operating in the 5GHz Frequency
Band
ETSI BRAN (BROADBAND RADIO
ACCESS NETWORKS)
PaloWireless:
HiperLAN2 Resource Center
OFDM Related
Publications
Professional Communication, IEEE
Transactions on
Wireless Personal
Communications
Shows
Wireless Systems Design Conference and
Expo 2002
Web
Directories
.
Glossary
Access Point (AP)
A WLAN
transceiver that operates either as a bridge in a peer-to-peer connection or as
a connector between the wired and wireless segments of the network.
Ad Hoc Network
A network made
up of exclusively of wireless nodes (with no APs) operating in peer-to-peer
configuration (see below).
Bandwidth
The frequency
allocation used by a signal in order for it to be transferred over a given
medium. Bandwidth is calculated in Hz (Hertz), KHz, or GHz.
BSS
Basic Service
Set. A basic configuration of a wireless LAN prescribed by the IEEE 802.11
standard, comprising an AP and at least one wireless node. All communications
to and from the wireless node flow through the AP.
BOM
Bill of
Material(s), a reference to the list of components on a board. The total BOM
cost of a board is a critical factor in designing a board.
CSMA/CA (Carrier Sense Multiple Access with
Collision Avoidance)
CSMA/CA is the
access medium prescribed by IEEE 802.11 aiming to minimize collisions caused by
simultaneous transmissions on the network. It imposes on the wireless node a
"listen" phase that precedes the frame transmission in order to make
sure the medium is free. Upon obtaining the frame, the receiving node transmits
back an acknowledge packet (ACK) that ensures data integrity. Failure to
receive an ACK packet will cause the transmitting node to wait until it detects
a "quiet" medium and retransmit the frame.
CSMA/CD (Carrier Sense Multiple Access with
Collision Detection)
Unlike
CSMA/CA, CSMA/CD (Ethernet's access medium) can actively detect collisions,
causing both transmitting nodes to hold back and retransmit their frame only after
a randomly chosen period of "silence".
DFS
Dynamic
Frequency Selection. A feature enabling AP's to perform interference measurements
and choose the least intrusive and noisy frequency available. DFS enables
efficient frequency spectrum management and enhances the wireless network's
immunity to interference. It is mandated by the HiperLAN2 standard and expected
to be incorporated in IEEE 802.11a following the completion of the work being
done by the IEEE 802.11 Task Group "h" (TGh).
DSSS
Direct
Sequence Spread Spectrum. One of two modulation schemes prescribed by the IEEE
802.11 standard group for wireless transmission, and the transmission method
employed by IEEE 802.11b. DSSS combines the data signal with a higher data rate
bit sequence, called a chipping code, to improve noise resistance and data
integrity.
Dual Mode
Due to
802.11b's increasing deployments , smooth transition to higher bands and higher
bandwidth capabilities have become a major issue among OEMs and end-users.
Low-cost dual mode NICs and APs incorporate both 2.4 and 5 GHz radios, and provide
seamless compatibility to existing 802.11b 2.4 GHz networks. This simplifies
the upgrade process to the 5 GHz band, by lowering its cost and protecting
investments in wireless technologies.
ESS
Extended Service
Set. A more complex configuration prescribed by the IEEE 802.11 standards,
comprising multiple BSS's connected either by wired or wireless means.
Ethernet
The IEEE 802.3
networking standard, Ethernet is the most common form of networking in
corporate environments, and has become the de-facto standard for wired
networking. Initially providing coaxial connectivity of up to 10 Mbps, Ethernet
in its most advanced configuration (Gigabit Ethernet) offers LAN links of up to
1000 Mbps.
ETSI
European
Telecommunications Standards Institute, an Non Profit Organization whose
mission is formulating and promulgating telecommunication standards in Europe.
ETSI's headquarters are located in France, and since its inception in 1988 it
has amassed 789 members, including national telecom companies and the
industry’s leading conglomerates.
FHSS
Frequency
Hopping Spread Spectrum. One of two modulation schemes prescribed by the IEEE
802.11 standards group. FHSS modulates the data signal by switching, or
hopping, frequencies using a coordinated and prearranged
"pseudo-random" pattern. Following a recent FCC ruling, a second
generation of FHSS modulation, dubbed WBFH, will improve on the relatively low
data rates of up to 2 Mbps currently offered by FHSS. FHSS LAN's make up for
poor data throughput with robust, reliable and fairly long ranged connectivity.
Fixed Network
A wired data
network with stationary nodes or PCs.
GHz
Giga-Hertz (or
billions of cycles per second) - a measurement unit for frequency.
HiperLAN
HIgh
PErformance Radio LAN. Generic title for a series of ETSI standards designed to
provide high-speed wireless connectivity within a LAN or between LANs (fixed
wireless access). HiperLAN1 was designed to provide 24 Mbps connections in the
5GHz frequency band, but hasn't been commercialized as yet. HiperLAN2 is touted
as the leading European standard for wireless LAN's operating in the 5GHz
range, offering 54 Mbps data rates and incorporating enhanced Security, QoS,
DFS and other features.
HiperLAN2
ETSI's 5GHz
standard; It shares IEEE 802.11a's modulation scheme (OFDM) and data rates (up
to 54 Mbps), but adds to the IEEEE 802.11a specification several important
features such as embedded QoS, DFS and TPC, and unlike IEEE 802.11a, it is
based on an ATM (connection oriented) model. HiperLAN2 has developed a strong
following in Europe.
IEEE
Institute of
Electrical and Electronic Engineers. A non-profit association set on promoting electrical
and IT knowledge. Since its inception in 1884, it has grown to become a leader
in the production of professional literature and technical standards.
IEEE 802.11
One of the best-known
wireless networking standard, it was conceived by a working group of the
Standards Association, an IEEE organ. It is also the generic, or umbrella,
title for a group of standards including IEEE 802.11a and IEEE 802.11b as well
as enhancements to both of them.
IEEE 802.11a
An IEEE
wireless Ethernet standard that operates in the 5GHz frequency range and uses
OFDM as its modulation scheme. IEEE 802.11a wireless LAN's can achieve nominal
data rates of up to 54 Mbps.
IEEE 802.11b
An IEEE
wireless Ethernet standard that operates in the 2.4GHz frequency range and uses
DSSS as its modulation scheme. IEEE 802.11b wireless LAN's are promoted by an
industry interest group called WECA, and are often identified as Wi-Fi
products. IEEE 802.11b achieves nominal data rates of up to 11 Mbps.
ISI
Inter-Symbol
Interference, a form of interference due to radio signal echoes interfering
with the original signal. ISI can reduce the effective data rate of wireless
LAN transceivers.
Kbps
Kilobits per
second, or thousands of bits per second. A unit measuring data rate.
LAN
Local Area
Network. A communications network shared by several computers and peripherals
within a given area. LANs benefit the users by enabling the sharing of
applications, files and peripherals. LAN connectivity would normally require
special cabling and network interface cards (NIC's).
MAC
Medium Access
Control. A networking protocol layer that handles transmission requests,
authentication and other overheads in local area networking.
Mbps
Mega-bits per
second, or millions of bits per second. Mbps has become the most commonly used
data rate unit.
MMAC
Multimedia
Mobile Access Communications. A Japanese promotion council designing wireless networking
recommendations for multimedia mobile access.
Multimedia
A combination
of data types, such as text, audio, video, still images etc.
NIC
Network Interface
Card. Generic name for adapter cards that serve as an interface between
computers and networks.
Node (Wireless)
Technical term
for a computer (or any other data terminal) connected to a wireless LAN using a
NIC
OEM
Original
Equipment Manufacturer
OFDM
Orthogonal
Frequency Division Multiplexing. A multi-carrier modulation scheme that is
based on splitting the signal over numerous narrowband channels
("carriers"), which are subsequently modulated and transmitted on
selective frequencies. OFDM is currently used for high definition digital audio
and video broadcasting, power line communications and wireless LANs. The
physical layer protocol (PHY) of both IEEE 802.11a and HiperLAN2 employ OFDM.
PAN
Personal Area
Network. Boosted by the promotion of Bluetooth, PANs are very short-range
(<10m) data networks that enable lower data rate connectivity between PCs
and peripherals, or between consumer electronics products.
Peer-to-Peer
P-t-P
configurations are typical to ad hoc networks. They involve at least two
wireless nodes setting up an independent network (as long as they're in communicating
distance from each other).
PHY
Physical layer
protocol. The lowest layer in the networking model. In wireless networking, it
defines the used signal modulation and RF transmission methods.
Roaming
The ability of
a wireless node to keep continuous connectivity to the network while moving
from one physical location to another, served by a different Access Point.
QoS
Quality of Service.
A feature that prioritizes and guarantees bandwidth for selected applications
to achieve optimal service performance. Real time applications, such as
streaming video and audio, are intolerant of latency or delay and as a result
QoS is an essential feature for wireless multimedia transmission.
Range
Transmitting
distance of a signal by a wireless node. Maximum range is the optimal effective
distance achieved by a wireless node under perfect conditions. The more relevant
term would be nominal range that refers to effective distance under normal,
everyday conditions.
RF
Radio
frequency. Describes an electric current that, when supplied to an antenna,
gives rise to an electromagnetic field that propagates through space. This
field is sometimes called a "radio wave".
Sensitivity
The
measurement of the weakest signal a receiver can receive and still demodulate
with an acceptable bit error rate.
TPC
Transmit Power
Control. A feature that enables wireless network elements (both APs and mobile
users) to dynamically switch between several transmission power levels in the
data transmission process, preserving battery life and decreasing interference
with adjacent wireless systems.
WAN
Wide Area
Network, a term typically used to describe networks that cover substantial
geographical areas.
WECA
Wireless
Ethernet Compatibility Alliance. An industry interest group formed by market
leaders in the interest of certifying standards compatibility and
interoperability of IEEE 802.11b products from different manufacturers.
Products are tested according to a given matrix, and consequently awarded a
"Wi-Fi" seal of approval.
WEP
Wired
Equivalent Privacy. Since wireless LANs are more susceptible to security
breaches IEEE 802.11 prescribes a security scheme based on a 40-bit strong key
encryption. Currently, proprietary solutions offer 128-bit encryptions, and a
forthcoming standard (dubbed IEEE 802.1x) will support authentication schemes
and stronger encryptions. Note: two main security breach scenarios exist -
unauthorized access to the network, and "sniffing" or eavesdropping
on a wireless LAN.
Wireless Bridge
Bridges
connect either wired or wireless networks with a physical gap between them.
Wireless bridges normally offer point-to-point or point-to-multipoint
connectivity for up to (approximately) 15 miles.
Wired Network
A fixed
network with wires to each specific node to carry data.
Wireless Network
A network in which
data is transmitted without wires, increasing mobility of the user and their
access to data.
WLAN
Wireless Local
Area Network or "wireless LAN". Currently, WLANs serve as extensions
to wired Ethernet, while emerging, high bandwidth WLAN standards, such as IEEE
802.11a and HiperLAN2, offer Ethernet-like data rates enabling users to replace
wired Ethernet altogether.
WLANA
The Wireless
LAN Association is a non-profit trade association that promotes the use of
wireless LANs by exposing end users to wireless LAN applications, product
availability, etc.