O¶
Objective C¶
An object-oriented language that adds Smalltalk-style messaging to C. It was Apple’s main language for macOS and iOS apps until Swift arrived.
See also: Swift, C Language.
Objectives¶
See Goals.
ODF¶
Optical Distribution Frame. A frame that terminates fibre cables and lets connections between them be made and changed with patch leads.
OFC¶
Optical Fibre Connector. A connector that joins optical fibres, aligning their cores so light passes with little loss. It is quicker to connect and disconnect than a splice. Common types include LC, SC and ST.
OFC.
See also: ODF.
Ofcom¶
Office of Communications. The UK regulator for broadcasting, telecoms, post and the radio spectrum, set up under the Communications Act 2003.
OFDMA¶
Orthogonal Frequency-Division Multiple Access. The multi-user form of OFDM, in which different users get different sets of closely spaced subcarriers at the same time. LTE downlinks, 5G and Wi-Fi 6 use it.
See also: SC-FDMA, COFDM, LTE (4G).
OO¶
Object-Oriented. A paradigm that organises software around objects, which bundle data with the code that acts on it. Most OO languages are class-based, with inheritance and polymorphism.
See also: Programming paradigm, Polymorphism, UML.
Operations Plan¶
A plan for running a system after deployment: roles, responsibilities, procedures and maintenance schedules.
See also: Deployment Plan, Maintenance Plan.
OPUS¶
Opus. An open, royalty-free audio codec, standardised by the IETF in RFC 6716. It combines the SILK speech coder with the CELT low-delay coder and adapts from narrowband speech to full-band music. It is the standard codec for WebRTC.
See also: SPEEX, Vorbis, Audio Codecs.
OS X¶
macOS. Apple’s operating system for Mac computers, released in 2001 as Mac OS X and renamed OS X and then macOS. It is a Unix system built on the Darwin kernel.
See also: Unix.
OSA-FC¶
Optical Spectrum Access Filter Connect. An Openreach service that gives a provider a managed fibre connection on which it runs its own optical equipment. It works like dark fibre, but Openreach monitors and repairs the link.
OSA-FC.
See also: Dark Fibre, EAD.
OSPF¶
Open Shortest Path First. A link-state interior gateway protocol: each router learns the whole topology of its area and calculates the shortest paths. Version 2 (RFC 2328) is for IPv4 and version 3 for IPv6.
OSS¶
Operations Support Systems. The systems a telecoms operator uses to run its network, such as inventory, provisioning, configuration, fault and performance management. They work with the business support systems (BSS).
OSS.
OTN¶
Optical Transport Network. The ITU-T G.709 standard for carrying client signals, such as Ethernet or SDH, over wavelengths. It adds framing, forward error correction and management to optical networks.
See also: SDH.
Out-of-order delivery¶
Packets arriving in a different order from the one in which they were sent, for example because they took different paths. TCP puts the data back in order; real-time protocols must cope with it.
Out-of-order delivery.
See also: TCP, Jitter buffer.
Overlap Dialling¶
Sending a dialled number in pieces as the caller enters it, rather than all at once, so that routing can begin before the number is complete. The far end waits for more digits until a timer runs out.