Broadband for all - an alternative vision - Communications Committee Contents


APPENDIX 5: GLOSSARY


4G Fourth Generation Mobile systems—intended to provide significantly faster data rates than previous generation systems for both upload and download.
Access network The "final mile" connections linking the backhaul network to the end user's premises.
Active Device An electronic device used to receive and send data; normally connecting two or more passive links.
ADSL Asymmetric Digital Subscriber Line—a broadband technology using the copper phone network. It provides higher download speed at the expense of upload speed, hence 'asymmetric.'
ALA Active Line Access—an open industry-led standard for providing Virtual Unbundled Local Access (VULA) together with technical standards for the operations, maintenance and administration (OMA) interface between an internet service provider (ISP) and an infrastructure provider.
Backhaul The part of the broadband network, which constitutes the intermediate link between the backbone, core network and the access network.
Bandwidth The channel capacity (speed) of a data link (measured in bits per second) or the width of a band of frequencies (measured in Hz).
BDUK Broadband Delivery UK—the unit within the Department for Culture, Media and Sport responsible for managing the Government's funding programme.
Bit The smallest unit of information on the internet—a bit can take one of two values. Communication speeds are measured in bits per second.
Bitstream access Access to the level of the network that communicates a stream of bits without reference to the information it represents (see bit).
Cabinet A street cabinet has a connection to the exchange and individual connections to each of the premises it serves. In the telephone network it served primarily as a junction box with copper connections in both directions. With Fibre to the Cabinet (FTTC) its function is changed as the connection to the exchange is replaced by fibre and it houses active electronic equipment. With Fibre to the Premises (FTTP) it again becomes passive and houses optical splices (in the case of a point-to-point network) or splitters (in the case of a point-to-multipoint network).
Contention ratio Where traffic from many users travels over a single link, the contention ratio is the ratio of the potential maximum demand to the actual bandwidth: in simple terms, the number of users sharing a single link. The higher the contention ratio, the greater the number of users that may be trying to use the actual bandwidth at any one time and, therefore, the lower the effective bandwidth offered, especially at times of peak demand.
Cable connection

or

Coaxial cable connection

A cable connection normally refers to an access link using coaxial cable. Coaxial cables use copper to carry electromagnetic waves, but they can carry higher frequencies than ordinary copper cable—and so higher data rates—over longer distances.
Copper connection A copper connection normally refers to an access link using legacy copper phone lines.
Dark fibre Unlit fibre with no active equipment connected. Dark fibre may be leased from the owner to be lit by the lessee.
Duct Underground pipe or conduit used to house (fibre, copper or coax) cables of a broadband network.
DSL   Digital Subscriber Line—a family of technologies that provide broadband connectivity by transmitting digital data over the wires of a local telephone network, utilising high frequencies that are not used by a voice telephone call. See also ADSL, VDSL.
DSLAM Digital Subscriber Line Access Multiplexer—an electronic device, typically located in the exchange or cabinet, that connects multiple customer digital subscriber lines (DSL) to a high-speed digital communications channel.
Exchange In this report 'exchange' normally refers to a telephone exchange now used as a node of the broadband network in which key pieces of active infrastructure are installed and exchange of data traffic takes place. This should be distinguished from what is usually meant by an 'internet exchange,' which instead refers to a node at a higher level of the architecture at which communications providers exchange traffic between their networks.
FTTC Fibre to the Cabinet, sometimes known as Fibre To The Copper. The fibre is terminated in a street cabinet some distance away from the customer premises, with the final connection being copper (in fibre to the cabinet networks) or coaxial cable (in the cable network).
FTTP Fibre to the Premises (homes and businesses), which reaches the end user premises with fibre.
Full unbundling Physical unbundling grants access to the end-consumer access line and allows the competitor's own transmission systems to directly transmit over it.
GEA Generic Ethernet Access—a proprietary BT product providing Virtual Unbundled Local Access (VULA).
Gbps Gigabit or 230 bits per second, a unit of throughput or bandwidth.
GPON Gigabit Passive Optical Network—a variety of Passive Optical Network (see PON).
Internet The internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite.
IP Intellectual Property or Internet Protocol.
IPTV Internet Protocol Television—television services delivered over the internet.
ISP Internet Service Provider.
Killer app A use to which a connection to the internet can be put which requires a certain level of broadband capacity to function, and which puts the case for wider or universal access to enhanced capacity broadband beyond all question.
Latency The round-trip time between two nodes, measured as the time for a 'ping' to be answered.
Lit fibre Fibre connected to active equipment that shines an optical signal down the fibre to communicate data.
Local loop Another name for the copper pair between the exchange and the premises.
Local Loop Unbundling (LLU) Local Loop Unbundling (see unbundling).
Mbps Megabits (220 bits) per second, a unit of throughput or bandwidth, commonly referred to as 'speed'.
NGA Next Generation Access—also known as next generation broadband, or superfast broadband.
Ofcom The Office for Communications—the UK's regulatory authority for, inter alia, telecommunications.
Open access Open access refers to a horizontally layered network architecture and business model that, by allowing competing providers direct access to the lower layers of the network infrastructure, enables competition in the provision of higher-layer services.
Point-to-point Point-to-Point—an access network where each end-user has a dedicated passive link to the backhaul node.
PIA Physical Infrastructure Access—A remedy imposed by Ofcom on Openreach, obliging Openreach to provide as a product access to its ducts and poles.
Point-to-multipoint A network topology that has dedicated individual customer lines to an intermediate passive node (e.g. street cabinet) where these lines are aggregated onto a shared line. Aggregation could be either passive (with splitters such as in a PON architecture) or active (as with FTTC, where each cabinet houses a DSLAM).
PON Passive Optical Network—a point-to-multipoint network including a passive 'splitter' so that many end-users share a single fibre.
PSB Public Service Broadcaster.
SLU Sub-Loop Unbundling.
SME Small and Medium-sized Enterprises.
SMP Significant Market Power.
Spectrum In the context of communications, 'spectrum' refers to a band, or range, of frequencies in the electromagnet spectrum (see bandwidth).
Trunk Part of the core network which provides a major link carrying data from many different users.
Unbundling The regulatory process of requiring an incumbent operator to allow other providers to provide services using its infrastructure (see open access).
USO Universal Service Obligation.
VDSL Very-high-bit-rate Digital Subscriber Line (see DSL).
VULA Virtual Unbundled Local Access—a set of regulatory requirements imposed by Ofcom.
Wayleave The right to make and use a connection running over the property of another.


 
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