number A B C D E F G H

Glossary : E

Collapse all | Expand all

collapse/expand E1
  • A data rate unit equivalent with 2.048 Mbps. Used outside North America and Japan, mainly in Europe. Larger data units: E2 (8.448 Mbps), E3 (34.368 Mbps).
    Compare with T1. Also see PDH.

collapse/expand EAP
  • Extensible Authentication Protocol. EAP provides transport for other authentication protocols. It is an extension to the PPP for use beyond dial-up connection.
    Also see PPP, PAP, and CHAP.

collapse/expand EDGE
  • Enhanced Data-rates for GSM and TDMA/146 Evolution. Packet switched data transmission over GSM or TDMA/136 network that can provide data rate of 384 kbps. EDGE is faster than GPRS, and it is a transition to 3G.
    Also see GPRS.

collapse/expand EGP
  • Exterior Gateway Protocol. A routing protocol that is used to interconnect autonomous systems on the Internet. EGP has been replaced by BGP.
    Also see BGP.

collapse/expand EIGRP
  • Enhanced Interior Gateway Routing Protocol. A proprietary protocol that was developed by Cisco, used to exchange routing information between routers within an autonomous system.

collapse/expand EHF
  • Extremely High Frequency. Frequency band in the range of 30 - 300 GHz, corresponding to wavelength from 10 mm - 1 mm. This microwave band is used in radio astronomy and satellite communications. EHF band is affected by atmospheric attenuation, caused by rain.

collapse/expand EIA
collapse/expand Electromagnetic
  • Electromagnetic wave is energy radiation that consists of electric and magnetic fields perpendicular to each other. Electromagnetic wave is produced by electric charge acceleration or magnetic field variation. In vacuum, electromagnetic wave travels at the speed of light (notation: c), that is 300,000 kilometers/second or 186,000 miles/second.

    Electromagnetic spectrum encompasses all types of electromagnetic radiation. In general, in the order from the lowest to the highest frequency or from the longest to the shortest wavelength, it can be classified to:
    - radio wave (ELF, SLF, ULF, VLF, LF, MF, HF, VHF, UHF, SHF, EHF)
    - microwave (SHF, EHF)
    - infrared light (300 GHz - 400 THz)
    - visible light (> 400 THz)
    - ultraviolet light
    - x-rays
    - gamma rays

    Electromagnetic radiation is described in two equations below:
    c = λf where c: the speed of light, λ: wavelength, f: frequency
    E = hf where E: photon energy, h: Planck's constant, f: frequency

    The first is for electromagnetic radiation as a wave, and the second as particles. EM is the shorthand of electromagnetic.

collapse/expand ELF
  • Extremely Low Frequency. Frequency band in the range of 3 - 30 Hz, corresponding to wavelength from 100,000 km to 10,000 km. EHF band overlaps audio frequencies. Because of its wavelengths, it's almost impossible to make antenna and transmitter that works at this band.

collapse/expand Encapsulation
  • A process of carrying upper layer protocol in a lower layer protocol by adding a lower layer specific header to the passing data.

collapse/expand Encryption
  • A conversion of a message into another format using an assigned key to hide the message from unauthorized access. The encrypted message can be converted back only by a receiver which has the corresponding key.
    Contrast with decryption.

collapse/expand EPON
  • Ethernet PON. A PON (Passive Optical Network) specification that was ratified by the IEEE in 2004, i.e. IEEE 802.3ah or Ethernet in the First Mile (EFM). EPON standard was created to address capacity limitation of DSL technology and targeted to provide high speed Internet access.
    EPON provides symmetric capacity both downstream and upstream at 1.25 Gbps before being split for distribution to customer premises. It supports spit ratio of 1:32 and fiber optic reach of up to 20 km. EPON uses Ethernet encapsulation for transporting traffic.
    Also see PON.

collapse/expand Ethernet
  • The established LAN standard that was first developed by XEROX in the late 1970, then promoted in 1980 by DEC, Intel, and XEROX (DIX). It specified CSMA/CD computer communication over coaxial cabling.  It was then adopted by IEEE as the basis for 802.3 LAN standard. While both the original version and the IEEE version of Ethernet use CSMA/CD, the IEEE 802.3 standard also extends the original Ethernet to cover the use of other media, i.e. twisted pair and fiber optic.
    Also see 802.3.

collapse/expand ETSI
collapse/expand EV-DO
  • Evolution Data Only (or Evolution Data Optimized). An enhancement to the 3G CDMA2000 network that is optimized for carrying data traffic. EV-DO Rel.0 which is already deployed by many 3G cellular operators provides peak forward link (from Base Station to user handset) data rate of 2.4 Mbps in a 1.25 MHz FDD channel and peak reverse link (from user handset to Base Station) data rate of 153 kbps. Real world download speed using EV-DO capable terminal is about 400 - 700 kbps.
    The coming EV-DO Revision A promises peak forward link data rate of 3.1 Mbps and peak reverse link rate of 1.8 Mbps. While 1xEV-DO Revision B (a.k.a. DO Multi-Carrier) is expected increase peak forward link (downlink) data rate up to 4.9 Mbps per 1.25 MHz-carrier. Using 3 carriers in a 5 MHz channel will give peak downlink data rate of 14.7 Mbps and peak uplink data rate of 5.4 Mbps.

collapse/expand EV-DV
  • Evolution Data and Voice. A.k.a. CDMA2000 Revision C. An enhancement to the 3G CDMA2000 that supports data and voice in the same RF carrier. EV-DV offers peak forward link data rate of 3.1 Mbps .

collapse/expand Evil Twin
  • A Wi-Fi hotspot, operated by a hacker, which tries to fool users to believe that it is a legitimate hotspot by mimicking a network name (SSID) and a login page of a legitimate hotspot provider. The hacker purpose is to steal the users' login details or other personal information. This type of hotspot is also called rogue hotspot.

collapse/expand Extranet
  • An extension of a private network. Extranet gives limited access to individuals or organizations to some of the private network resources. It is often built by a company to share information with its suppliers, partners, distributors, and customers.
    See picture.