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NGN Marketing wireless_industry glossary
Please use this online resource glossary to find a complete description and use of any product or term listed.

Wireless Industry Terms

  A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z
(click on word to show/hide definition)

1000Base-T

1 Gb/s (1000 Mbps) networking standard (Gigabit Ethernet) over copper wire (IEEE Std. 802.3ab). The standard defines 1 Gb/s data transfer over distances of up to 100 meters using four pairs of CAT-5 balanced copper cabling and a 5-level coding scheme.

100BASE-T

Fast Ethernet (IEEE 802.3u), a networking standard that supports data transfer rates up to 100 Mbps (100 megabits per second). 100BASE-T is based on the older Ethernet standard. Like Ethernet, 100BASE-T is based on the CSMA/CD LAN access method. There are several different cabling schemes that can be used with 100BASE-T, including: 100BASE-TX: two pairs of high-quality twisted-pair wires 100BASE-T4: four pairs of normal-quality twisted-pair wires 100BASE-FX: fiber optic cables.

10BASE-T

The interpretation of the Ethernet (IEEE 802.3) standard for Local Area Networks (LANs), where "T" means Twisted Pair Cable with maximum lengths of 100 meters. The transmission rate for 10Base-T system is 10 Mbps.

A

Access Point

A wireless LAN transceiver that acts as a center point and bridges between wireless and wired networks.

Ad Hoc Network

A wireless network composed only of stations without access points.

Antenna

That part of a transmitting or receiving system which is designed to radiate or to receive electromagnetic waves. An antenna can also be viewed as a transitional structure (transducer) between free-space and a transmission line (such as a coaxial line). An important property of an antenna is the ability to focus and shape the radiated power in space e.g.: it enhances the power in some wanted directions and suppresses the power in other directions.

Antenna Polarization

"In a specified direction from an antenna and at a point in its far field, is the polarization of the (locally) plane wave which is used to represent the radiated wave at that point". "At any point in the far-field of an antenna the radiated wave can be represented by a plane wave whose electric field strength is the same as that of the wave and whose direction of propagation is in the radial direction from the antenna. As the radial distance approaches infinity, the radius of curvature of the radiated wave's phase front also approaches infinity and thus in any specified direction the wave appears locally a plane wave". In practice, polarization of the radiated energy varies with the direction from the center of the antenna so that different parts of the pattern and different side lobes sometimes have different polarization. The polarization of a radiated wave can be linear or elliptical (with circular being a special case).

Asymmetric

Asymmetric networks support more bandwidth in one direction than the other. Asymmetric DSL offers more bandwidth for customer downloads at the cost of less bandwidth for uploads.

Authentication

A feature used to reduce fraud by confirming the identity of a phone to the wireless network.

Bandwidth

Specifies the amount of the frequency spectrum that is usable for data transfer. It identifies the maximum data rate that a signal can attain on the medium without encountering significant loss of power.

B

Beamwidth

The angle of signal coverage provided by a radio. Beamwidth may by decreased by a directional antenna to increase gain.

Bluetooth

Bluetooth is a specification for the use of low-power radio communications to wirelessly link phones, computers and other network devices over short distances.

Boot Protocol (BOOTP)

The protocol used for the static assignment of IP addresses to devices on the network.

Bridge

A device used to connect LANs by forwarding packets across connections at the Media Access Control (MAC) layer.

Broadband

The term broadband refers to any type of transmission technique that carries several data channels over a common wire. DSL service, for example, combines separate voice and data channels over a single telephone line.

Broadband Router

A broadband router combines the features of a traditional network switch, a firewall, and a DHCP server. Broadband routers are designed for convenience in setting up home networks, particularly for homes with high-speed cable modem or DSL Internet service.

Broadband Wireless Access

Broadband wireless access is a technology aimed at providing wireless access to data networks, with high data rates. According to the 802.16-2004 standard, broadband means 'having instantaneous bandwidth greater than around 1 MHz and supporting data rates greater than about 1.5 Mbit/s'. From the point of view of connectivity, broadband wireless access is equivalent to broadband wired access, such as ADSL or cable modems.

Wireless Internet Service Providers (WISP) are usually found in rural areas where cable or DSL is not available. A common case scenario is that a WISP will get large connection such as a T1 or DS3 and deliver it to a high point in the area such as a high rise or water tower. Then the consumers will mount a small dish to the roof of their home or office and point it towards the high area. Line of sight is usually necessary for wireless access to work.

C

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)

Wireless LAN media access method as specified by the IEEE 802.11 specification.

Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

Ethernet media access method as specified by the IEEE 802.3 specification.

CAT-5, Category 5 Cable

Category 5 cable, commonly known as Cat 5, is an unshielded twisted pair type cable designed for high signal integrity. The actual standard defines specific electrical properties of the wire, but it is most commonly known as being rated for its Ethernet capability of 100 Mbit/s.

Cat-6, Category 6 Cable

Cat 6 - Category - 6, (ANSI/TIA/EIA-568-B.2-1) A cable standard for Gigabit Ethernet and other interconnect that is backward compatible with Category 5 cable, Cat-5e and Cat-3. Cat-6 features more stringent specifications for crosstalk and system noise. The cable standard is suitable for 10BASE-T / 100BASE-TX and 1000BASE-T (Gigabit Ethernet) connections.

The cable contains four twisted copper wire pairs, just like earlier copper cable standards, although each twisted pair is made up of slightly larger 23 gauge copper wire as apposed to Cat 5's 24 gauge wire. When used as a patch cable, Cat-6 is normally terminated in RJ-45 electrical connectors. If components of the various cable standards are intermixed, the performance of the signal path will be limited to that of the lowest category. The distance without losing data is 220m.

CAT-7, Category 7 cable

Category 7 cable (CAT7), (ISO/IEC 11801:2002 category 7/class F), is a cable standard for Ultra Fast Ethernet and other interconnect technologies that can be made to be backwards compatible with traditional CAT5 and CAT6 Ethernet cable. CAT7 features even more stringent specifications for crosstalk and system noise then CAT6. To achieve this, shielding has been added for individual wire pairs and the cable as a whole.

The CAT7 cable standard has been created to allow 10-gigabit Ethernet over 100 m of copper cabling. The cable contains four twisted copper wire pairs, just like the earlier standards. CAT7 can be terminated in RJ-45 compatible GG45 electrical connectors which incorporate the RJ-45 standard, and a new type of connection to enable a smoother migration to the new standard. When combined with GG-45 connectors, CAT7 cable is rated for transmission frequencies of up to 600 MHz.

CDMA (Code Division Multiple Access)

A digital communication technology used by some carriers to provide PCS service. Also known as IS-95A or cdmaOne. Other technologies used are TDMA and GSM.

Coaxial Cable

Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, and usually surrounded by a final insulating layer.

The cable is designed to carry a high-frequency or broadband signal, as in a high-frequency transmission line. Sometimes DC power (called bias) is added to the signal to supply the equipment at the other end, as in direct broadcast satellite receivers. Because the electromagnetic field carrying the signal exists (ideally) only in the space between the inner and outer conductors, it cannot interfere with or suffer interference from external electromagnetic fields.

Complementary Code Keying (CCK)

Modulation technique used by IEEE 802.11-compliant wireless LANs for transmission at 5.5 and 11Mbps.

CPE Antenna (Customer Premises Equipment)

Customer Premises Equipment antenna is directional antenna which points to an Access Point (Base Station).

D

dBd

A ratio of decibels to half wave dipole antenna, that is commonly used to measure antenna gain. (0 dBd = 2.15 dBi).

dBi

A ratio of decibels to an isotropic antenna that is commonly used to measure antenna gain. The greater the dBi value, the higher the gain and, as such, the more acute the angle of coverage.

Differential Binary Phase Shift Keying (DBPSK)

Modulation technique used by IEEE 802.11-compliant wireless LANs for transmission at 1Mbps.

Differential Quadrature Phase Shift Keying (DQPSK)

Modulation technique used by IEEE 802.11-compliant wireless LANs for transmission at 2Mbps.

Dipole

A type of low gain (2.2 dBi) antenna consisting of two (often internal) elements.

Direct Sequence Spread Spectrum (DSSS)

A type of spread spectrum radio transmission that spreads its signal continuously over a wide frequency band.

Directional Antenna

An antenna that concentrates transmission power into a direction thereby increasing coverage distance at the expense of coverage angle. Directional antenna types include yagi, patch and parabolic dish.

Diversity Antennas

An intelligent system of two antennas that continually senses incoming radio signals and automatically selects the antenna best positioned to receive it.

Dynamic Host Configuration Protocol (DHCP)

A protocol available with many operating systems that automatically issues IP addresses within a specified range to devices on a network. The device retains the assigned address for a specific administrator-defined period.

E

E-Plane

E-plane: For a linearly polarized antenna, the plane containing the electric field vector and the direction of maximum radiation. The electric field or "E" plane determines the polarization or orientation of the radio wave. For a vertically-polarized antenna, the E-plane usually coincides with the vertical/elevation plane. For a horizontally-polarized antenna, the E-Plane usually concided with the horizontal/azimuth plane.

Ethernet

The predominant wired LAN technology standardized in the IEEE 802.3 specification.

F

Federal Communications Commission (FCC)

Independent United States government agency, created, directed, and empowered by Congressional statute.

The FCC was established by the Communications Act of 1934 as the successor to the Federal Radio Commission and is charged with regulating all non-Federal Government use of the radio spectrum (including radio and television broadcasting), and all interstate telecommunications (wire, satellite and cable) as well as all international communications that originate or terminate in the United States. The FCC took over wire communication regulation from the Interstate Commerce Commission. The FCC's jurisdiction covers the 50 states, the District of Columbia, and U.S. possessions.

Firewall

A firewall protects a computer network from unauthorized access. Network firewalls may be hardware devices, software programs, or a combination of the two.

Frequency Hopping Spread Spectrum (FHSS)

A type of spread spectrum radio transmission in which the transmitter and receiver hop in synchronization from one frequency to another according to a prearranged pattern.

Fresnel Effect

A phenomenon related to line of sight whereby an object that does not obstruct the visual line of sight obstructs the line of transmission for radio frequencies.

Front-to-Back Ratio (F/B Ratio)

Of an antenna, the gain in a specified direction, i.e., azimuth, usually that of maximum gain, compared to the gain in a direction 180° from the specified azimuth. dB

G

Gain

A method of increasing the transmission distance of a radio by the concentration its signal in a single direction, typically through the use of a directional antenna. Gain does not increase a radio's signal strength, but simply redirects it. Therefore, as gain increases, the decrease in angle of coverage is inversely proportional.

Gateway

A gateway is an internetworking system, a system that joins two networks together.

General Packet Radio Service (GPRS)

Mobile data service available to users of GSM mobile phones. It is often described as "2.5G", that is, a technology between the second (2G) and third (3G) generations of mobile telephony. It provides moderate speed data transfer, by using unused TDMA channels in the GSM network. Originally there was some thought to extend GPRS to cover other standards, but instead those networks are being converted to use the GSM standard, so that is the only kind of network where GPRS is in use. GPRS is integrated into GSM standards releases starting with Release 97 and onwards. First it was standardised by ETSI but now that effort has been handed onto the 3GPP.

Gigahertz (GHz)

One billion cycles per second. A unit of measure for frequency.

Global System for Mobile Communications (GSM)

One of the most popular standard for mobile phones in the world. GSM phones are used by over a billion people across more than 200 countries. The ubiquity of the GSM standard makes international roaming very common between mobile phone operators which enables phone users to access their services in many other parts of the world as well as their own country. GSM differs significantly from its predecessors in that both signalling and speech channels are digital, which means that it is seen as a second generation (2G) mobile phone system. This fact has also meant that data communication was built into the system from very early on. GSM is an open standard which is currently developed by the 3GPP.

From the point of view of the consumer, the key advantage of GSM systems has been higher digital voice quality and low cost alternatives to making calls such as text messaging. The advantage for network operators has been the ability to deploy equipment from different vendors because the open standard allows easy inter-operability. Also, the standards have allowed network operators to offer roaming services which mean subscribers can use their phone all over the world.

GSM retained backward-compatibility with the original GSM phones as the GSM standard continued to develop, for example packet data capabilities were added in the Release '97 version of the standard, by means of GPRS. Higher speed data transmission have also been introduced with EDGE in the Release '99 version of the standard.

H

H.323

H.323 is a protocol standard for multimedia communications. H.323 was designed to support real-time transfer of audio and video data over packet networks like IP.

Hertz (Hz)

Cycles per second. A unit of measure for frequency.

Hidden Node

A station on a wireless LAN that attempts to transmit data to another station but, due to its location relative to the others, cannot sense that there is a third station simultaneously communicating with the intended recipient. Lost message and multiple retries is the result.

Hotspot

A hotspot is any location where Wi-Fi network access is made publicly available. Technically speaking, hotspots consist of one or several wireless access points installed inside buildngs and/or adjoining outdoor areas.

H-Plane

For a linearly polarized antenna, the plane containing the magnetic field vector and the direction of maximum radiation. The magnetic field or "H" plane lies at a right angle to the "E" plane. For a vertically-polarized antenna, the H-plane usually coincides with the horizontal/azimuth plane. For a horizontally-polarized antenna, the H-plane usually coincides with the vertical/elevation plane.

I

IEEE 802.11 Standard

The IEEE standard that specifies a carrier sense media access control and physical layer specifications for 1 and 2 megabit per second wireless LANs.

IEEE 802.11a Standard)

802.11a, which has just started to ship, is much faster than 802.11b, with a 54Mbps maximum data rate (actually increased to 72Mbps or 108Mbps in a non-standard double-speed mode depending on the chipset vendor and component manufacturer). 802.11a (and its recently announced interoperability standard called Wi-Fi5) operates in the 5GHz frequency range and allows eight simultaneous channels. One big advantage to 802.11a is that it isn't subject to interference from Bluetooth or any of the other 2.4GHz frequency denizens. One big disadvantage is that it is not directly compatible with 802.11b, and requires new bridging products that can support both types of networks--although if you don't mind spending the money for access points for both 11a and 11b, you can plug them into hubs or better yet, switches on your network and they'll work just fine. Other clear disadvantages are that 802.11a is only available in half the bandwidth in Japan (for a maximum of four channels), and it isn't approved for use in Europe, where HiperLAN2 is the standard. Another IEEE group, 802.11h, is working on technologies that will tweak 802.11a to work around some of the 5GHz channels used by military in Europe. Like 802.11b, 802.11a has no provisions to optimize voice or multimedia content.

IEEE 802.11b Standard

The IEEE standard that specifies a carrier sense media access control and physical layer specifications for 5.5 and 11 megabit per second wireless LANs.

Today 802.11b is the clear winner in business wireless networking. Operating in the 2.4GHz frequency range, 802.11b (aka Wi-Fi) has a nominal maximum data rate of 11Mbps, with the potential of three simultaneous channels. 802.11b has a great advantage in that it is accepted worldwide. One of the more significant disadvantages of 802.11b is that the frequency band is crowded, and subject to interference from other networking technologies, microwave ovens, 2.4GHz cordless phones (a huge market), and Bluetooth. There are drawbacks to 802.11b, including lack of interoperability with voice devices, and no QoS provisions for multimedia content. Interference and other limitations aside, 802.11b is the clear leader in business and institutional wireless networking and is gaining share for home applications as well.

IEEE 802.11d Standard

IEEE 802.11d is supplementary to the Media Access Control (MAC) layer in 802.11 to promote worldwide use of 802.11 WLANs. It will allow access points to communicate information on the permissible radio channels with acceptable power levels for user devices. The 802.11 standards cannot legally operate in some countries; the purpose of 11d is to add features and restrictions to allow WLANs to operate within the rules of these countries. Comments: In countries where the physical layer radio requirements are different from those in North America, the use of WLANs is lagging behind. Equipment manufacturers do not want to produce a wide variety of country-specific products and users that travel do not want a bag full of country-specific WLAN PC cards. The outcome will be country-specific firmware solutions.

IEEE 802.11e Standard

802.11e is an enhancement to the 802.11 wireless LAN specification that will include quality of service (QoS) features, including the prioritization of data, voice, and video transmissions. 802.11e enhances the 802.11 MAC layer with a coordinated Time Division Multiple Access (TDMA) construct and adds error-correcting mechanisms for delay-sensitive applications such as voice and video.

IEEE 802.11g Standard

The IEEE 802.11g wireless Ethernet standard was adopted for wireless local area networks (WLANs) operating up to 54 megabits per second (Mbps) in the 2.4 gigahertz (GHz) band. The 802.11g draft standard utilizes existing elements from the original complimentary code keying (CCK)-orthogonal frequency division multiplexing (ODFM) and Packet Binary Convolutional Code (PBCC)-22 proposals. Each of these proposals called for true 802.11a OFDM operation in the 2.4 GHz band as an optional mode to the primary proposed modulation, either CCK-OFDM or PBCC-22. The 802.11g draft standard makes OFDM the mandatory technology, offering 802.11a data rates in the 2.4 GHz band, requires mandatory implementation of 802.11b modes and offers optional modes of CCK-OFDM and PBCC-22. This balanced compromise offers a much clearer bridge between 802.11a and 802.11b, plus is a straightforward means to develop true multi-mode WLAN products.

The obvious advantage of 802.11g is that it maintains compatibility with 802.11b (and 802.11b's worldwide acceptance) and also offers faster data rates comparable with 802.11a (at least on paper, since working silicon isn't available). The number of channels available, however, is not increased, since channels are a function of bandwidth, not radio signal modulation - and on that score, 802.11a wins with its eight channels, compared to the three channels available with either 802.11b or 802.11g. Another disadvantage of 802.11g is that the 2.4GHz frequency will get even more crowded. 802.11g also gives up roughly one year to 802.11a--products for the latter are already beginning to reach the market, although many products (those based on chipsets from companies other than Atheros) won't be out until mid year. Companies that want faster performance now may not have any choice but to upgrade to, or augment existing networks with 802.11a, which could make it harder for 802.11g to succeed.

IEEE 802.11h Standard

Description: This standard is supplementary to the MAC layer to comply with European regulations for 5GHz WLANs. European radio regulations for the 5GHz band require products to have transmission power control (TPC) and dynamic frequency selection (DFS). TPC limits the transmitted power to the minimum needed to reach the furthest user. DFS selects the radio channel at the access point to minimize interference with other systems, particularly radar.

Comments: Completion of 11h will provide better acceptability within Europe for IEEE-compliant 5GHz WLAN products. A fast-dwindling group will continue to support the alternative HyperLAN standard defined by ETSI. Although European countries such as the Netherlands and the United Kingdom are likely to allow the use of 5GHz LANs with TPC and DFS well before 11h is completed, pan-European approval of 11h is not expected until the second half of 2003, possibly longer.

When: The standard is expected to be finalized by the second half of 2002. Products will be available in the first half of 2003 (firmware implementation), with high availability in the second half of 2003 (0.7 probability).

IEEE 802.11i Standard

Description: Supplementary to the MAC layer to improve security. It will apply to 802.11 physical standards a, b and g. It provides an alternative to Wired Equivalent Privacy (WEP) with new encryption methods and authentication procedures. IEEE 802.1x forms a key part of 802.11i.

Comments: Security is a major weakness of WLANs. Vendors have not improved matters by shipping products without setting default security features. In addition, the WEP algorithm weaknesses have been exposed. The 11i specification is part of a set of security features that should address and overcome these issues by the end of 2002. Solutions will start with firmware upgrades using the Temporal Key Integrity Protocol (TKIP), followed by new silicon with AES (an iterated block cipher) and TKIP backwards compatibility.

When: Finalization of the TKIP protocol standard is expected in the first half of 2002. Firmware will be available in the second half of 2002 (0.8 probability). New silicon with an AES cipher is expected by the second half of 2003 (0.7 probability).

IEEE 802.16 Standard

IEEE 802.16 addresses the "first-mile/last-mile" connection in wireless metropolitan area networks. It focuses on the efficient use of bandwidth between 10 and 66 GHz and defines a medium access control (MAC) layer that supports multiple physical layer specifications customized for the frequency band of use.

IEEE 802.3 Standard

The IEEE standard that specifies carrier sense media access control and physical layer specifications for Ethernet LANs.

Institute of Electrical and Electronic Engineers (IEEE)

A professional society serving electrical engineers through its publications, conferences, and standards development activities. The body responsible for the Ethernet 802.3 and wireless LAN 802.11 specifications.

Isotropic

An antenna (or a theoretic construct of an antenna) that radiates its signal 360 degrees both vertically and horizontally - a perfect sphere.

L

LAN

A local area network (LAN) is a computer network covering a local area, like a home, office or small group of buildings such as a college.

Last Mile

The telecommunications technology that connects the customer's home directly to the Internet or telephone provider.

Light-Emitting Diode (LED)

A light-emitting diode (LED) is a semiconductor device that emits incoherent narrow-spectrum light when electrically biased in the forward direction. This effect is a form of electroluminescence. The color of the emitted light depends on the chemical composition of the semiconducting material used, and can be near-ultraviolet, visible or infrared. Nick Holonyak Jr. (born 1928) of the General Electric Company developed the first practical visible-spectrum LED in 1962.

Line of Sight

An unobstructed straight line between two transmitting devices. Line of sight is typically required for long-range directional radio transmission. Due to the curvature of the earth, the line of sight for devices not mounted on towers is limited to 16 miles (26km).

LLC (Logical Link Control)

According to the IEEE 802 family of standards, Logical Link Control (LLC) is the upper sublayer of the OSI data link layer. The LLC is the same for the various physical media (such as Ethernet, token ring, WLAN).
The LLC sublayer is primarily concerned with:

  • multiplexing protocols transmitted over the MAC layer (when transmitting) and demultiplexing them (when receiving)
  • optionally providing flow control, and detection and retransmission of dropped packets, if requested

M

MAC (Media Access Control) Layer

The Media Access Control (MAC) sublayer is the part of the OSI network model data link layer that determines who is allowed to access the physical media at any one time. It acts as an interface between the Logical Link Control sublayer and the network physical layer.
The MAC sublayer is primarily concerned with

  • recognizing where frames begin and end in the bit-stream received from the physical layer (when receiving)
  • delimiting the frames (when sending), i.e. inserting information (e.g. some extra bits) into or among the frames being sent so that the receiver(s) are able to recognise the beginning and end of the frames
  • detection of transmission errors by means of e.g. inserting a checksum into every frame sent and recalculating and comparing them on the receiver side
  • inserting the source and destination MAC addresses into every frame transmitted
  • filtering out the frames intended for the station by verifying the destination address in the received frames
  • the control of access to the physical transmission medium (i.e. which of the stations attached to the wire or frequency range has the right to transmit?)

Management Information Base (MIB)

A collection of network operational information residing in a virtual store that may be accessed, typically through an SNMP-compliant system, for analysis.

Megahertz (MHz)

One million cycles per second. A unit of measure for frequency.

Mesh Networking

Mesh networking is a way to route data, voice and instructions between nodes. It allows for continuous connections and reconfiguration around blocked paths by "hopping" from node to node until a connection can be established.

Mesh networks are self-healing: the network can still operate even when a node breaks down or a connection goes bad. As a result, a very reliable network is formed. This concept is applicable to wireless networks, wired networks, and software interaction.

A mesh network is a networking technique which allows inexpensive peer network nodes to supply back haul services to other nodes in the same network. It effectively extends a network by sharing access to higher cost network infrastructure.

Mesh networks differ from other networks in that the component parts can all connect to each other.

Modem

A modem, abbriviation for modulator and demodulator, is a device that modulates an analog carrier signal (sound) to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data.

Modulation

Any of several techniques for combining user information with a transmitter's carrier signal.

Multipath

Multipath is the composition of a primary signal plus duplicate or echoed images caused by reflections of signals off objects between the transmitter and receiver. The receiver "hears" the primary signal sent directly from the transmission facility, but it also sees secondary signals that are bounced off nearby objects. These bounced signals will arrive at the receiver later than the incident signal. Because of this misalignment, the "out-of-phase" signals will cause intersymbol interference or distortion of the received signal. Although most of the multipath is caused by bounces of tall objects, multipath can also occur from bounces on low objects such as lakes and pavements.

O

OFDM

Orthogonal Frequency Division Multiplexing, an FDM modulation technique for transmitting large amounts of digital data over a radio wave. OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver. OFDM reduces the amount of crosstalk in signal transmissions. 802.11a WLAN, 802.16 and WiMAX technologies use OFDM.

Omni-Directional Antenna

An antenna that provides a 360 degree transmission pattern. These types of antennas are used when coverage in all directions is required.

P

P2P

P2P technically stands for "peer-to-peer." A peer-to-peer architecture allows hardware or software to function on a network without the need for central servers.

Packet

A basic message unit for communication across a network. A packet usually includes routing information, data, and (sometimes) error detection information.

Parabolic

A concave or dish-shaped object. Often refers to dish antennas. Peer-to-Peer Network: A network design in which each computer shares and uses devices on an equal basis.

Physical Layer (PHY)

Provides for the transmission of data through a communications channel by defining the electrical, mechanical and procedural specifications for IEEE 802 local area networks. Protocol: Rules for communicating, particularly for the format and transmission of data.

R

Radiation Pattern

The Radiation (Antenna) Pattern is a graphical representation in three dimensions of the radiation of the antenna as a function of angular direction. Antenna radiation performance is usually measured and recorded in two orthogonal principal planes (such as E-Plane and H-plane or vertical and horizontal planes). The pattern is usually plotted either in polar or rectangular coordinates. The pattern of most WLAN antennas contains a main lobe and several minor lobes, termed side lobes. A side lobe occurring in space in the direction opposite to the main lobe is called back lobe.

Radio Frequency (RF)

A generic term for radio-based technology.

RADIUS (Remote Authentication Dial In User Service)

RADIUS (Remote Authentication Dial In User Service) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. It is intended to work in both local and roaming situations.

When you connect to an ISP using a modem, DSL, cable or wireless connection, you must enter your username and password. This information is passed to a Network Access Server (NAS) device over the Point-to-Point Protocol (PPP), then to a RADIUS server over the RADIUS protocol. The RADIUS server checks that the information is correct using authentication schemes like PAP, CHAP or EAP. If accepted, the server will then authorize access to the ISP system and select an IP address, L2TP parameters, etc.

The RADIUS server will also be notified when the session starts and stops, so that the user can be billed accordingly; or the data can be used for statistical purposes.

Range

A linear measure of the distance that a transmitter can send a signal.

Receiver Sensitivity

A measurement of the weakest signal a receiver can receive and still correctly translate it into data.

Reverse Polarity TNC (RP-TNC)

A connector type unique to Aironet radios and antennas. Part 15.203 of the FCC rules covering spread-spectrum devices limits the types of antennas that may be used with transmission equipment. In compliance with this rule, Aironet, like all other wireless LAN providers, equips its radios and antennas with a unique connector to prevent attachment of non-approved antennas to radios.

RJ-45

RJ-45 is a physical interface often used for terminating twisted pair type cables. It has eight "pins" or electrical connections per connector.

Roaming

A feature of some access points that allow users to move through a facility while maintaining unbroken connection to the LAN.

Rogue Access Point

A rogue access point is a wireless access point that has been installed on a secure company network without explicit authorization from a local network management. Rogue access points can pose a security threat to large organizations with many employees, because anyone with access to the premises can ignorantly or maliciously install an inexpensive wireless router that can potentially allow access to a secure network to unauthorized parties. To prevent the installation of rogue access points, large organizations sometimes even install wireless intrusion detection systems to monitor the radio spectrum for unauthorized access points.

RoHS

The Restriction of Hazardous Substances Directive (RoHS) 2002/95/EC was adopted in February 2003 by the European Union. The RoHS directive took effect on July 1, 2006, but is not a law; it is simply a directive. This directive restricts the use of six hazardous materials in the manufacture of various types of electronic and electrical equipment. It is closely linked with the Waste Electrical and Electronic Equipment Directive (WEEE) 2002/96/EC which sets collection, recycling and recovery targets for electrical goods and is part of a legislative initiative to solve the problem of huge amounts of toxic e-waste.

Router

A router is a computer networking device that forwards data packets toward their destinations through a process known as routing. Routing occurs at layer 3 (Network layer) of the OSI seven-layer model.

S

Side lobe level (SLL)

The ratio, in decibels (dB), of the amplitude at the peak of the main lobe to the amplitude at the peak of a side lobe.

Simple Network Management Protocol (SNMP)

The network management protocol that defines the transfer of LAN operational data between Management Information Bases (MIBs).

Spread Spectrum

A radio transmission technology that "spreads" the user information over a much wider bandwidth than otherwise required in order to gain benefits such as improved interference tolerance and unlicensed operation.

Switch

A network switch is a small device that joins multiple computers together at a low-level network protocol layer.

T

Transmit Power Control

Transmit Power Control is a technical mechanism used within some networking devices in order to prevent too much unwanted interference between different wireless networks (e.g. the owner's network and the neigbour's network).

The network devices supporting this feature are Wireless LAN devices in the 5GHz band compliant to the IEEE 802.11a. The idea of the mechanism is to reduce automatically the used transmission output power when other networks are within range. Reduced power means reduced interference problems. The power level of a single device can be reduced by 6dB which should result in an accumulated power level reduction (the sum of radiated power of all devices currently transmitting) of at least 3dB (which is half of the power).

V

V.34 Modem Protocol

The communication protocol from ITU for 28.8 kbps modems. Also known as V.Fast.

V.90 Modem Protocol

V.90 is an ITU-T recommendation for a modem, allowing 56 kbit/s download and 33.6 kbit/s upload. It was developed between March 1998 and February 1999. It is also known as V.Last as it was anticipated to be the last standard to be developed.

V.92 Modem Protocol

V.92 is an ITU-T modem standard allowing near 56 kbit/s download and 48 kbit/s upload rates first presented in August 1999. It is intended to succeed the V.90 standards. With V.92 PCM is used for both the upstream and downstream connections; previously 56K modems only used PCM for downstream data.

VoIP (Voice Over IP)

VoIP is a technology that allows telephone calls to be made over computer networks like the Internet. VoIP converts analog voice signals into digital data packets and supports real-time, two-way transmission of conversations using Internet Protocol.

VPN

A VPN utilizes public networks to conduct private data communications. Most VPN implementations use the Internet as the public infrastructure and a variety of specialized protocols to support private communications through the Internet.

W

WEP

WEP WEP (Wired Equivalent Privacy) is an optional IEEE 802.11 feature used to provide data confidentiality that is equivalent to the confidentiality of a wired LAN that does not employ crypto techniques to enhance privacy. WEP will only make the wireless LAN link in a system as secure as the wired link. As specified in the standard, WEP uses the RC4 algorithm with a 40-bit key. When WEP is enabled, each station (clients and Access Points) has a key. The key is used to scramble the data before it is transmitted through the airwaves. If a station receives a packet that is not scrambled with the appropriate key, the packet will be discarded and never delivered to the host. WEP will be available for the Aironet 3500, 4500, 4800, BR500 and BR100 Series products as a firmware upgrade. WEP will be released in phases. The first release will require the keys to be manually entered into each adapter, Bridge and AP. Improved key management and other features will be included in future releases. Key Features and Benefits Customers who are concerned about security can use WEP as a basis to build a comprehensive security system and be assured that the wireless link is not compromising the security of the network. Aironet can support longer keys—up to 128 bits—for customers who require security measures above and beyond what the standard specifies. In this mode, the product does not comply with the standard but the resulting system is more secure. Aironet’s WEP implementation is in the hardware, so there is minimal performance impact when WEP is used. Competition No other competitors will have better hardware support for WEP. Some competitors will do WEP encryption in their software, but the performance penalty for this type of implementation can be severe. Some competitors may have better management of keys and may also implement enhanced authentication. Future releases of Aironet’s WEP will include these improvements.

Wi-Fi

Wi-Fi is the industry name for wireless LAN (WLAN) communication technology related to the IEEE 802.11 family of wireless networking standards.

WiMAX

WiMAX is Worldwide Interoperability for Microwave Access, is a certification mark for products that pass conformity and interoperability tests for the IEEE 802.16 standards. IEEE 802.16 is working group number 16 of IEEE 802, specialising in point-to-multipoint broadband wireless access.

Wired Equivalent Privacy (WEP)

Optional security mechanism defined within the 802.11 standard designed to make the link integrity of the wireless medium equal to that of a cable.

Wireless Distribution System (WDS)

A Wireless Distribution System is a system that enables the interconnection of access points wirelessly.

It is described in IEEE 802.11. An access point can be either a main, relay or remote base station. A main base station is typically connected to the wired Ethernet. A relay base station relays data between remote base stations, wireless clients or other relay stations to either a main or another relay main station. A remote base station accepts connections from wireless clients and passes them to relay or main stations.

All base stations in a Wireless Distribution System must be configured to use the same radio channel, and share WEP keys if that is used. They can be configured to different service set identifiers.

WDS may also be referred to as repeater mode because it appears to bridge and accept wireless clients at the same time (unlike traditional bridging).

WDS may be incompatible between different products (even occasionally from the same vendor) as it is not certified by the Wi-Fi Alliance.

Notice that this WDS is different from the WDS implementation by Cisco, which stands for Wireless Domain Services.

Wireless Local Loop (WLL)

Wireless local loop (WLL), also called radio in the loop (RITL) or fixed-radio access (FRA) or fixed-wireless access (FWA), is the use of a wireless communications link as the "last mile" connection for delivering plain old telephone service (POTS) to telecommunications customers.

WISP

A WISP offers public wireless network services. WISPs typically install Wi-Fi wireless hotspots in airports, hotels and other public businessplaces.

WLAN (Wireless Local Area Network)

A WLAN provides wireless network communication over short distances using radio or infrared signals instead of traditional network cabling.

WPA

WPA, or Wi-Fi Protected Access, is a security technology for wireless networks. WPA improves on the authentication and encryption features of WEP (Wired Equivalent Privacy).