Animated Optical Glossary
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Half-Duplex...............HO TCMHO VCAT...............Hypertext Transfer Protocol (HTTP)
Half-DuplexHeadends Re-architected as Data Centers (HERD)High Density Bipolar 3 (HDB3)
HBAHeader Error Control (HEC)High-Bit-Rate Digital Subscriber Line (HDSL)
HDB3HECHigh-Definition Television (HDTV)
HDDHeterogeneous Network (HetNet)High-Speed Packet Access (HSPA)
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Data transmission over a circuit capable of transmitting in either direction, but not simultaneously. For Ethernet, the CSMA/CD method is a half-duplex protocol.


Acronym for: Horizontal direct drilling


The equipment in a cable system that receives the various program source signals, processes them, and retransmits them to subscribers.

Headends Re-architected as Data Centers (HERD)

Expands on the CORD initiative, re-architecting the way streaming video traffic is routed to take advantage of virtualization, caching and SDN in the headend.

Header Error Control (HEC)

A bit-error detection and correction mechanism used in data transmission and reception.


Acronym for:

1. Head error check

2. Header error control

Heterogeneous Network (HetNet)

Environment made of several transmission technologies, macrocell, microcell, smallcell, picocell, femptocell, DAS, RRH, etc.


Acronym for: Heterogeneous network


Acronym for: Home gateway

High Density Bipolar 3 (HDB3)

A digital-line coding technique used internationally to carry E1 signals over the local loop.

High-Bit-Rate Digital Subscriber Line (HDSL)

The earliest variation of DSL to be widely used. HDSL is applied for wideband digital transmission within corporate sites and between telephone companies and customers. The main characteristic of HDSL is that it is symmetrical; i.e., an equal amount of bandwidth is available in both directions. For this reason, the maximum data rate for HDSL is lower than for ADSL. HDSL can carry as much on a single wire of twisted-pair wire as can be carried on a T1 line in North America or an E1 line in Europe (2,320 kbit/s).

High-Definition Television (HDTV)

Any television system that provides a significant improvement in picture quality over existing television systems. Most HDTV systems offer more than 1000 scan lines, in a wider aspect ratio, with superior color and sound fidelity.

High-Speed Packet Access (HSPA)

An amalgamation of two mobile telephony protocols, high-speed downlink packet access (HSDPA) and high-speed uplink packet access (HSUPA), which extends and improves the performance of existing third generation mobile telecommunication networks utilizing the WCDMA protocols. 


Acronym for: High-performance parallel interface


Acronym for: Higher-order tandem connection monitoring