| 释义 |
cell 1. In asynchronous transfer mode (ATM) and Switched Multimegabit Data Service (SMDS) networks, a small protocol data unit (PDU) comprising 53 octets.The ATM cell consists of a header of 5 octets and payload of 48 octets.The small cell size offers the advantage of effectively supporting any type of data, including voice, fax, text, image, video, and multimedia, whether compressed or uncompressed and whether real-time or non-real-time. The fixed cell size offers the advantage of predictability, unlike the variable-length frames associated with services such as X.25, frame relay, and Ethernet, or the variable-length packets associated with the Internet Protocol (IP).This level of predictability yields much improved access control and congestion control. See also ATM, compression, Ethernet, frame relay, header, IP, non-real-time, packet, payload, PDU, real-time, SMDS, and X.25. 2. In radio systems, a relatively small geographical area 74570c03.qxd 9/11/07 12:19 PM Page 91 |