Acknowledgement. Abbreviated term for the return message in any signaling message exchange when a request or action requires confirmation of receipt or completion. Usually used to describe the confirmation of delivery/receipt of a message - could be coupled with a ""response"" which indicates the success or failure of the operation. A failed/error acknowledgement is termed a NACK or NAK, negative acknowledgement.

Association ID. This term is used in Wireless LAN 802.11 standards. When a station wishes to associate itself with an Access Point (AP), it sends an Association Request. The AP responds with an Association Response and assigns the station an AID. AID is a 16 bit field and is assigned in an arbitrary manner by the AP.

Amplitude Modulation. Amplitude modulation (AM) is one way of conveying information on a transmission line. Variations in the strength, or amplitude, of the signal are interpreted as data. Other common modulation methods are Frequency Modulation (FM) and Phase Modulation (PM). It is possible to use combinations of AM, PM and FM on a single transmission line.

American National Standards Institute. The United States primary nation standards body. ANSI represents the United States in international standards bodies such as the ISO.

Access Point. An AP is an integral component of the IEEE 802.11 wireless LAN architecture configuration known as the infrastructure mode. In this mode, the AP acts as a central coordinator for all the stations. All communications in the infrastructure mode go through the AP. Stations cannot directly communicate with each other in this mode and the AP relays traffic messages to stations. All communications between stations and any wired network such as the LAN, if present, go through the AP. The function of the AP is similar to a cellular network that employs a radio network to interface with mobiles. APs are not mobile and form part of the wired network.

Basic Service Set. The basic configuration of the 802.11 architecture is the Basic Service Set (BSS), which is a group of stations communicating with each other. There are two distinct configurations of BSSs that are possible in IEEE 802.11. One is the Ad-Hoc mode where stations are communicating with each other without central coordination. The other is the Infrastructure mode, where stations are centrally coordinated by the use of a special station known as the Access Point.

Base Transceiver Station. In a cellular network, the BTS is the radio-related equipment, typically mounted at the base of an antenna tower, serving a geographical area known as a 'cell'. It is responsible for providing the radio interface to the mobile nodes. The base station is connected to a base station controller (BSC). A BTS is sometimes called a BS.

Code Division Multiple Access. CDMA is multiple access technology in which a number of users transmit on the same spectrum simultaneously. Each user's transmission is identified by a digital code that is used at the receiver to identify transmission from the correct user and reject other user's transmission as noise. CDMA technology is used in mobile networks such as IS-95, cdma2000, and UMTS, as well as in short range technologies such as 802.11 wireless LANs.

The next step in the evolution of IS-95 CDMA networks.

Circuit Switched-Core Network. This provides all network functionality for the circuit switched network.

Carrier Sense Multiple Access. CSMA is a commonly employed mechanism in IEEE 802.3 Local Area Networks (LANs) and also in IEEE 802.11 Wireless LANs. It is a mechanism used to help nodes communicate when using a shared physical medium. This mechanism requires that each station "sense" the wireless medium before any transmission. Similar to checking for traffic before entering the highway, computers that have data to send, listen to or "sense" the shared physical medium before transmitting data packets.

Carrier Sense Multiple Access/Collision Avoidance. CSMA/CA technique is used in Wireless LANs (IEEE 802.11 family) as opposed to the CSMA/Collision Detection (CSMA/CD) technique used in IEEE 802.3 LANs. The CSMA mechanism requires that each station senses the wireless medium before any transmission. CSMA can be performed in the wireless medium without any issues just like it is done in the wired medium. However, Collision Detecion (CD) is not employed in IEEE 802.11 WLANs because detecting collisions is very difficult in the wireless medium. The solution in IEEE 802.11 WLAN is to use a Collision Avoidance (CA) mechanism, where collisions are evaded. This requires stations to send acknowledgements (ACKs) for each packet received and stations can contend for the channel after the ACKs have been sent out.

Carrier Sense Multiple Access/Collision Detection. CSMA/CD technique is used in IEEE 802.3 LANs. CSMA requires the nodes to sense the physical medium before transmitting. However, two nodes can simultaneously sense the physical medium is free and may both send packets at the same time. This may end up in a “Collision” of the packets. To solve this problem, computers “detect” that both computers have sent the data at the same time (i.e. they “sense” what they sent) and therefore will “collide” with each other. So, they will back off a random amount of time and restart the process of sending packets when the timer expires. This is known as Collision Detection used in conjunction with CSMA technique.

Clear To Send. A signal used in point-to-point communications indicating that the remote endpoint should begin transmitting data.