Glossary of Terms: PRO/Wireless LAN Mini PCI Adapter User's Guide

Glossary

Numerical A B D E F I K M O P R S T U W

Numerical

802.11a: The 802.11a standard specifies a maximum data transfer rate of 54Mbps and an operating frequency of 5GHz. The 802.11a standard uses the Orthogonal Frequency Division Multiplexing (OFDM) transmission method. Additionally, the 802.11a standard supports 802.11 features such as WEP encryption for security.

802.11b: The 802.11b standard specifies a maximum data transfer rate of 11Mbps, an operating frequency of 2.4GHz, and WEP encryption for security. 802.11b networks are also referred to as Wi-Fi networks.

802.11x: A series of IEEE specifications for LANs: currently 802.11b, 802.11a, and 802.11g. Using any one of these extensions to the 802.11 standard permits wireless communication between a client and an access point or between two clients. 802.1x is based on the Extensible Authentication Protocol (EAP), the 802.1x standard is one of the IEEE standards for network authentication and key management. It establishes a framework that supports multiple authentication methods. This standard can be incorporated into any type of network to enhance its security.

A

Access Point: A device that serves as a communications hub for wireless clients and provides a connection to a wired LAN.

Advanced Encryption Standard (AES): A federal information-processing standard, supporting 128-, 192-, and 256-bit keys.

B

Basic Service Set Identifier (BSSID): A unique identifier for each wireless client on a wireless network. The BSSID is the Ethernet MAC address of each adapter on the network.

Bit Rate: The total number of bits (ones and zeros) per second that a network connection can support. Note that this bit rate will vary, under software control, with different signal path conditions.

Bluetooth: An incompatible, very short-range lower speed communications system (PAN), developed first in Europe as a “cable replacement” for printers and similar peripheral connections. Its usage has expanded to include cordless earphones and similar devices. It uses the 2.4 GHz ISM band, and “co-exists” with 802.11b. Here the term, “co-exist” means that not all researchers agree on the amount of mutual interference generated when both systems operate in the same location.

Broadcast SSID: Used to allow an access point to respond to clients on a wireless network by sending probes.

D

Data Rate (Information Rate): Not all bits carry user information. Each group (packet) of bits contains headers, trailers, echo control, destination information, and other data required by the transmission protocol. It is important to understand the difference between bit rate and data rate, since the overhead information may consume more than 40% of the total transmission. This difference is common to many such data systems, including Ethernet.

Direct-Sequence Spread Spectrum (DSSS) and Frequency-Hop Spread Spectrum (FHSS): Two incompatible technologies used in radio transmission.

Dynamic IP Address: An IP address that is automatically assigned to a client station in a TCP/IP network, typically by a DHCP server. Network devices that serve multiple users, such as servers and printers, are usually assigned static IP addresses.

E

Extensible Authentication Protocol (EAP): An IETF standard that establishes an authentication protocol for network access. Many authentication methods, including passwords, certificates, and smart cards, work within this framework.

EAP-TLS: A type of authentication method using the Extensible Authentication Protocol (EAP) and a security protocol called the Transport Layer Security (TLS). EAP-TLS uses certificates which use passwords. EAP-TLS authentication supports dynamic WEP key management.

EAP-TTLS: A type of authentication method using the Extensible Authentication Protocol (EAP) and Tunneled Transport Layer Security (TTLS). EAP-TTLS uses a combination of certificates and another method, such as passwords. It is more secure than MD5 authentication, which uses passwords, and less secure than EAP-TLS authentication, which exclusively uses certificates. EAP-TTLS authentication supports dynamic WEP key management.

Encryption: Scrambling data so that only the authorized recipient can read it. Usually a key is needed to decrypt the data.

Extended Service Set IDentifier (ESSID): A type of unique identifier applied to both the AP and the wireless PC Card that is attached to each packet. This allows the AP to recognize each wireless client and its traffic.

F

Firewall: A firewall is a set of related programs, located at a network gateway server, that protects the resources of a network from users from other networks.

Frequencies: Strike a piano key and you generate a tone. Pick up the tone with a microphone and your tone turns in to a “vibrating” or “cycling” electronic signal. The rate of vibration depends on the key struck. In electronics we refer to this rate of vibration as the number of “cycles per second.” The formal term for this value is Hertz. As we move up in rate, such as in the Broadcast Band, we can use Kilohertz (KHz) to represent 1,000 Hz, or Megahertz (MHz) to represent 1,000,000 Hz. Continuing much further upward, we finally reach 1,000,000,000 Hz, which we can fortunately shorten to a Gigahertz (GHz). These frequencies are the home of both 802.11a (5 GHz) and 802.11b (2.4 GHz).

I

Independent Basic Service Set Identifier (IBSSID): Used to identify a wireless network configured to allow each wireless client to communicate directly with each other without an access point.

Independent Network: A network that provides (usually temporarily) peer-to-peer connectivity without relying on a complete network infrastructure.

Infrastructure Network: A wireless network centered around an access point. In this environment, the access point not only provides communication with the wired network but also mediates wireless network traffic in the immediate neighborhood.

Institute of Electrical and Electronics Engineers (IEEE): An organization involved in setting computing and communications standards.

ISM Bands: A series of frequency bands, set aside by the FCC for Industrial, Scientific and Medical applications. Users of these bands operate equipment on a shared basis, meaning that they must expect, and accept interference from other legal users. Products manufactured for ISM Band use must be approved by the FCC, but the user does not have to be licensed. In addition to WLAN, ISM bands support cordless phones, microwave ovens, baby monitors, toys, ham radio transceivers, and other wireless services.

K

Kerberos: An authentication system enabling protected communication over an open network using a unique key called a ticket.

M

Media Access Control (MAC) Address: A hardwired address applied at the factory. It uniquely identifies network hardware, such as a wireless PC Card, on a LAN or WAN.

Microcell: A bounded physical space in which a number of wireless devices can communicate. Because it is possible to have overlapping cells as well as isolated cells, the boundaries of the cell are established by some rule or convention.

Microwave: Technically, the term describes any frequency above 1.0 GHz. Unfortunately the advertising industry has contorted this meaning considerably. In our discussion we will stick to the technical definition.

Multipath: The signal variation caused when radio signals take multiple paths from transmitter to receiver.

O

Orthogonal Frequency Division Multiplexing (OFDM): A modulation technique for transmitting large amounts of digital data over radio waves. 802.11a uses OFDM, as will 802.11g.

P

Peer-to-Peer Mode: A wireless network structure that allows wireless clients to communicate with each other without using an access point.

Personal Area Network (PAN): A personal area network, or PAN, is a networking scheme that enables computing devices such as PCs, laptop computers, handheld personal computers, printers and personal digital assistants (PDAs) to communicate with each other over short distances either with or without wires.

Preamble: A preliminary signal transmitted over a WLAN to control signal detection and clock synchronization.

R

Radio Frequency (RF) Terms (GHz, MHz, Hz): The international unit for measuring frequency is Hertz (Hz), which is equivalent to the older unit of cycles per second. One Mega-Hertz (MHz) is one million Hertz. One Giga-Hertz (GHz) is one billion Hertz. For reference: the standard US electrical power frequency is 60 Hz, the AM broadcast radio frequency band is 0.55 -1.6 MHz, the FM broadcast radio frequency band is 88-108 MHz, and microwave ovens typically operate at 2.45 GHz.

Range: The distance over which a given system can communicate.

RC4: An encryption algorithm designed at RSA Laboratories; specifically, a stream cipher of pseudo-random bytes that is used in WEP encryption.

Remote Authentication Dial-In User Service (RADIUS): An authentication and accounting system that verifies users' credentials and grants access to requested resources.

Roaming: Movement of a wireless node between two microcells. Roaming usually occurs in infrastructure networks built around multiple access points.

S

Service Set Identifier (SSID): Used to identify clients on a wireless network.

Shared key: An encryption key known only to the receiver and sender of data.

Site Survey: A process where you set up one transceiver in a fixed location, and then use another unit to plot the field strength of the first unit’s transmitted signal. By moving the transmitter around, and repeating the plots, you can develop a plan as to the best locations for access points. You will also identify dead zones and other areas in need of special attention. This can be a long, slow process, but it beats ripping up an unsatisfactory installation and starting over. These tests require special software commands. Refer to your manual for specific instructions. If you have a very large, or unusually complex installation situation, you might want to consider calling in professionals to do your survey. We are not permitted to suggest installer names, but you can check your yellow pages or similar sources for likely candidates.

Static IP Address: A permanent IP address that is assigned to a node in a TCP/IP network.

T

Transmission Control Protocol (TCP): A method (protocol) used with the IP (Internet Protocol) to send data in the form of message units between network devices over a LAN or WAN. The IP carries the delivery of the data (routing), and TCP keeps track of the individual units of data (called packets) that a message is divided into for delivery over the network.

Transmission Control Protocol/Internet Protocol (TCP/IP): The basic communication language or set of protocols for communications over a network (developed specifically for the Internet). TCP/IP defines a suite or group of protocols and not only TCP and IP.

Transceiver: A commonly used term that describes a combination transmitter and receiver. Both 802.11a and 802.11b devices would be properly described as data transceivers.

U

UNII Bands: Unlicensed National Information Infrastructure. In contrast to the ISM bands, these are a group of frequency bands set aside by the FCC for WLAN type communications only. Users must accept interference from other legal WLAN users, but the other sources of interference problems are, or legally should be, missing.

W

WEP64 and WEP128: Wired Equivalent Privacy, 64 bit and 128 bit (64 bit is sometimes referred to as 40 bit). This is a low-level encryption technique designed to give the user about the same amount of privacy that he would expect from a LAN. It is extremely important to understand that WEP is not some CIA-proof supercode! It performs as intended, giving the user a simple level of data security and protection from casual electronic eavesdropping. Use of the 128 bit option at all possible times is recommended. Remember that 802.11 devices transmit (broadcast) in all directions, and that it is possible, with very complex software, to copy and decode WEP transmissions. The task is not trivial, but it is possible. If your data is extremely sensitive, you should consider some form of secondary protection, such as strong passwords and an additional level of encryption. Suitable software packages are available from reputable suppliers. Although not intended by the original architects, WEP also helps prevents unauthorized access to your system by an outsider. Hackers have been known to access systems from outside a building, and to then to access the Web for a leisurely session, all at the system owner’s expense.

Wide Area Network (WAN): A wide area network (WAN) is a voice, data, or video network that provides connections from one or more computers or networks within a business to one or more computers or networks that are external to such business.

Wireless: A microwave transceiver system.

Wireless LAN (WLAN): Wireless LAN is a type of local-area network that uses high-frequency radio waves rather than wires to communicate between nodes. WLAN is a flexible data communication system used as an alternative to, or an extension of a wired LAN.

Wireless Node: A user computer with a wireless network interface card (adapter).

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