Glossary

10 BaseT An IEEE standard (802.3) for operating 10 Mbps Ethernet networks (LANs) with twisted pair cabling and a wiring hub.

Ad-Hoc Mode A client setting that provides independent peer-to-peer connectivity in a wireless LAN. ZoomAir Wireless LAN cards provide an "instant" Ad-Hoc network with all the required drivers and setup utilities. An alternative set-up is where PCs communicate with each other through an AP. See AP and Infrastructure Mode.

AP (Access Point). A hardware device, or software used in conjunction with a computer, that serves as a communications "hub" for wireless clients and provides a connection to a wired LAN. An AP can double the range of wireless clients and provide enhanced security. ZoomAir's software-based AP is an inexpensive alternative to dedicated hardware APs.

Application software A software program running on top of the operating system (Windows, UNIX, Mac) that has been created to perform a specific task for a user. Examples include word processing software like Word/Word Perfect, spreadsheets like Excel or Lotus 123, home finance packages like Quicken, etc.

Client Any computer connected to a network that requests services (files, print capability) from another member of the network.

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance): 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.

CSMA/CD (Carrier Sense Multiple Access/Collision Detection). The LAN access method used in Ethernet. When a device wants to gain access to the network, it checks to see if the network is free. If it is not, it waits a random amount of time before retrying. If the network is free and two devices access the line at exactly the same time, their signals collide. When the collision is detected, they both back off and each wait a random amount of time before retrying.

DOCSIS Data Over Cable Service Interface Specification. The governing body, which certifies cable modem vendors, is called CableLabs®. The DOCSIS standard and close derivatives are also being adopted in other countries around the world. Currently, CableLabs is certifying DOCSIS revision 1.0 cable modems.

DSSS and FHSS Wireless LAN products are available in three different technologies -- direct-sequencing spread-spectrum (DSSS), frequency-hopping spread-spectrum (FHSS) and infrared. DSSS and FHSS are spread-spectrum techniques that operate over the radio airwaves in the unlicensed ISM band (industrial, scientific, and medical). DSSS uses a radio transmitter to spread data packets over a fixed range of the frequency band. FHSS uses a technique by which the signal transmitted hops among several frequencies at a specific rate and sequence as a way of avoiding interference. ZoomAir incorporates DSSS.

Ethernet The most widely used LAN access method, which is defined by the IEEE 802.3 standard. Ethernet is normally a shared media LAN meaning all devices on the network segment share total bandwidth. Ethernet networks operate at 10Mbps using CSMA/CD to run over 10-BaseT cables.

FDM (Frequency Division Multiplexing). A technology that transmits multiple signals simultaneously over a single transmission path, such as a cable or wireless system. Each signal travels within its own unique frequency range. HomeLAN uses this to ensure compatibility between the different services sharing the same telephone wire, specifically voice, xDSL and the home network. Each service has a frequency spectrum that is different from the others to eliminate interference.

Gateway A network point that acts as an entrance to another network.

HomePNA (Home Phoneline Networking Alliance). An association of industry-leading companies working together to help ensure adoption of a single, unified phoneline networking industry standard and rapidly bring to market a range of interoperable home networking solutions. HomeLAN complies with the HomePNA standards and is a member of the organization.

Hz (Frequency) (Hertz). 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 0.551.6 MHz, the FM broadcast radio frequency band is 88108 MHz, and wireless 802.11 LANs operate at 2.4 GHz.

IEEE (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. HomePNA uses the IEEE standard (802.3 CSMA/CD) to enable the sharing of the telephone wiring with other devices on the home network. ZoomAir wireless network cards support IEEE 802.11.

IEEE 802.11 IEEE 802.xx is a set of specifications for LANs from The Institute of Electrical and Electronic 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.

IEEE 802.11b High Rate A revision of 802.11 standard that provides much higher data rates up to 11Mbps, while maintaining the 802.11 protocol.

Infrastructure Mode A client setting providing connectivity to an AP. As compared to Ad-Hoc Mode where 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.

IP The Internet Protocol (IP) is a method or protocol by which data is sent from one computer to another on a network, i.e. the Internet. Each computer on the Internet has at least one address that uniquely identifies it from all other computers on the Internet. When you send or receive data (for example, an e-mail note or a Web page), the message gets divided into little chunks called packets. Each of these packets contains both the sender's Internet address and the receiver's address. Any packet is sent first to a gateway computer that understands a small part of the Internet. The gateway computer reads the destination address and forwards the packet to an adjacent gateway that in turn reads the destination address and so forth across the Internet until one gateway recognizes the packet as belonging to a computer within its immediate neighborhood or domain. That gateway then forwards the packet directly to the computer whose address is specified. Because the data is divided into a number of packets, each packet can, if necessary, be sent by a different route across the Internet. A packet is treated as an independent unit of data so packets can arrive at their destination in a different order than they were sent in. Another protocol, the Transmission Control Protocol, (TCP) then reassembles the packets in the right order.

IP Address An IP address is a 32-bit number that identifies each sender or receiver of information that is sent across the Internet. An IP address has two parts: the 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.

ISO Network Model: The International Standards Organization (ISO) has developed a network model 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:

1. Physical
2. Data Link
3. Network
4. Transport
5. Session
6. Presentation
7. 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.

ISP (Internet Service Provider). An organization that provides access to the Internet. Small ISPs provide service via modem and ISDN while the larger ones also offer private line hookups (T1, fractional T1, etc.). The major online services such as America Online and CompuServe provide Internet access but are still known as "online services", not ISPs. They offer the members only content, forums and services in addition to Internet access.

LAN (Local Area Network). A communications network that serves users within a defined geographical area. The benefits include the sharing of Internet access, files and equipment like printers and storage devices. Special network cabling (10 BaseT) is often used to connect the PCs together. Zoom/HomeLAN uses existing telephone wiring and ZoomAir uses wireless communications, in a home or office, to network all PCs together so there is no need to run an extra set of cables.

MAC (Medium Access Control): In a WLAN network card, the MAC is radio controller protocol. It corresponds to the ISO Network Model's level 2 Data Link layer. The IEEE 802.11 standard specifies the MAC protocol for medium sharing, packets formats and addressing, and error detection.

NAT (Network Address Translation) The translation of an Internet Protocol address (IP address) used within one network to a different IP address known within another network. One network is designated the internal network and the other is the external. The internal network then appears as one entity to the outside world. In the case of HomeLAN, the NAT capability of the Internet sharing software allows the sharing of one Internet connection among all the PCs connected to the home network.

PHY (Physical Layer): The PHY is 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.

PCI A local bus standard for connecting peripherals to a personal computer. Within a computer, the bus is the transmission path on which signals and data transfers occur between the CPU, system memory, and attached devices such as a HomeLAN card, sound card, or CD-ROM drive.

Roaming Moving seamlessly from one AP coverage area to another with no loss in connectivity is a standard feature with ZoomAir networking.

SSID (Service Set ID). SSID is a group name shared by every member of a ZoomAir wireless network. Only client PCs with the same SSID are allowed to establish a connection.

TCP (Transmission Control Protocol) 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.

WECA (Wireless Ethernet Compatibility Alliance) WECA's mission is to certify interoperability of IEEE 802.11b High Rate wireless networking products and to promote that standard for the enterprise, small business, and the home. WECA will grant a seal of interoperability to vendors upon successful completion of prescribed test suites.

WEP (Wired Equivalent Privacy). WEP data encryption is defined by the 802.11 standard to prevent (i) access to the network by "intruders" using similar wireless LAN equipment and (ii) capture of wireless LAN traffic through eavesdropping. In addition to the security provided by SSID, ZoomAir incorporates WEP, allowing the administrator to define a set of respective "Keys" for each wireless network user based on a "Key String" passed through the WEP encryption algorithm. Access is denied by anyone who does not have an assigned key.

WAN (Wide Area Network). A wide area network connects local area networks together. Typical WAN interfaces include plain old telephone (POT) lines, digital subscriber lines (DSL), ISDN, T1/T3, and cable.

Wi-Fi™ (The Standard for Wireless Fidelity). The Wi-Fi™ brand name represented in a consumer friendly logo will serve as the awarded "seal of approval" for those WECA member products that have successfully completed the prescribed interoperability testing. Customers from enterprises to consumers can be assured that products bearing this logo will work together.