WiFi Wireless Ethernet Adapter User Guide ASR-102, ACR-201

Hidden Node The situation where two or more radios in a multiple-radio network

fail to detect the RF signals from each other. For example, in a 3-radio network,

radio 2 and 3 both have good link to radio 1. Radio 2 and 3, however, are

isolated from each other by, say, a metal wall. Radio 2 therefore is a “hidden

node” to radio 3, and vice versa. Since an 802.11 network relies on the

CSMA/CA protocol to control network access, hidden nodes break down the

Carrier Sensing mechanism of controlling medium access because two or more

radios cannot sense the carrier from each other.

IEEE 802.11 The 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 standards ensure interoperability

between systems of the same type.

Infrastructure Network A wireless network centered about 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.

IP Internet Protocol. The standard protocol within TCP/IP that defines the basic

unit of information passed across an Internet connection by breaking down data

messages into packets, routing and transporting the packets over network

connections, then reassembling the packets at their destination. IP corresponds

to the network layer in the ISO/OSI model.

IP Address An IP address is a 32-bit number that identifies each sender or

receiver of information 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.

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.).

LAN Local Area Network. A communication network that serves users within a

defined geographical area. The benefits include the sharing of Internet access,

files, and equipment, such as printers and storage devices. Special network

cabling (10BaseT) is often used to connect the PCs together.

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.