 that has been reflected or otherwise returned with sufficient magnitude and delay for it to be perceived as a wave distinct from that directly transmitted. echo cancellation A process that allows full-duplex transmission to occur over a single elec- trical path. It relies on frequency splitting to derive separate voice and data channels from one wire. This feature is necessary for voice transmission but often interferes with data transmission. Ecma International (formerly European Computer Manufacturers Association) A European standards organization that creates ICT and consumer electronics standards. e-commerce (electronic commerce) The secure exchange of funds, executed over a net- work, for goods and services exchanged between parties. EDFA (erbium-doped fiber amplifier) An optical amplifier. Erbium is injected into fiber, and as a light pulse passes through the erbium, it is amplified; thus, it does not have to be stopped and processed as an electrical signal. The introduction of EDFAs opened up the opportu- nity to make use of fiber-optic systems operating at 10Gbps. edge The network boundary between a customer and the core or central network. EDGE (Enhanced Data Rates for Global Evolution) An enhanced version of GPRS that combines digital TDMA and GSM to provide 48Kbps to 69.2Kbps per time slot on an aggregated basis, up to 384Kbps. edge caching edge caching A system in which Web content is duplicated on a machine close to the end user the first time the user requests the content. Subsequent requests for this content are satisfied from the nearby machine. This improves the speed and reliability of access because it avoids Internet backbone and its peering points. edge device A device that can pass packets between a legacy type of network such as an Ethernet network and an ATM network, using data link layer and network layer information. An edge device does not have responsibility for gathering network routing information but simply uses the routing information it finds in the network layer using the route 