Time-division multiplexing (TDM) is a method of transmitting and receiving independent signals over a common signal path by means of synchronized switches at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern. It can be used when the bit rate of the transmission medium exceeds that of the signal to be transmitted. This form of signal multiplexing was developed in telecommunications for telegraphy systems in the late 19th century, but found its most common application in digital telephony in the second half of the 20th century.
TAT-14 was the 14th consortium transatlantic telecommunications cable system. In operation from 2001 to 2020, it used wavelength division multiplexing. The cable system was built from multiple pairs of fibres—one fibre in each pair was used for data carried in one direction and the other in the opposite direction. Although optical fibre can be used in both directions simultaneously, for reliability it is better not to require splitting equipment at the end of the individual fibre to separate transmit and receive signals—hence a fibre pair is used. TAT-14 used four pairs of fibres—two pairs as active and two as backup. Each fibre in each pair carried 16 wavelengths in one direction, and each wavelength carried up to an STM-256. The fibres were bundled into submarine cables connecting the United States and the European Union in a ring topology.
A metropolitan area network (MAN) is a computer network that interconnects users with computer resources in a geographic region of the size of a metropolitan area. The term MAN is applied to the interconnection of local area networks (LANs) in a city into a single larger network which may then also offer efficient connection to a wide area network. The term is also used to describe the interconnection of several LANs in a metropolitan area through the use of point-to-point connections between them.
A dark fibre or unlit fibre is an unused optical fibre, available for use in fibre-optic communication. Dark fibre may be leased from a network service provider.
A passive optical network (PON) is a fiber-optic telecommunications technology for delivering broadband network access to end-customers. Its architecture implements a point-to-multipoint topology in which a single optical fiber serves multiple endpoints by using unpowered (passive) fiber-optic splitters to divide the fiber bandwidth among the endpoints. Passive optical networks are often referred to as the last mile between an Internet service provider (ISP) and its customers. Many fiber ISPs prefer this technology.
An add-drop multiplexer (ADM) is an important element of an optical fiber network. A multiplexer combines, or multiplexes, several lower-bandwidth streams of data into a single beam of light. An add-drop multiplexer also has the capability to add one or more lower-bandwidth signals to an existing high-bandwidth data stream, and at the same time can extract or drop other low-bandwidth signals, removing them from the stream and redirecting them to some other network path. This is used as a local "on-ramp" and "off-ramp" to the high-speed network.
In fiber optics, a reconfigurable optical add-drop multiplexer (ROADM) is a form of optical add-drop multiplexer that adds the ability to remotely switch traffic from a wavelength-division multiplexing (WDM) system at the wavelength layer. This is achieved through the use of a wavelength selective switching module. This allows individual or multiple wavelengths carrying data channels to be added and/or dropped from a transport fiber without the need to convert the signals on all of the WDM channels to electronic signals and back again to optical signals.
Phonoscope Communications is a broadband and communications provider with corporate headquarters in Houston, Texas. The company's infrastructure spans eight counties and reaches distant locations such as Baytown, Galveston, Freeport, Magnolia, Richmond-Rosenberg, Splendora, Texas City and Willis, Texas.
AboveNet was a provider of high bandwidth telecommunication circuits primarily for large corporate enterprises and communications carriers in 17 markets in the United States and 4 markets in Europe. Its private optical network delivered key network and IP services and was used in financial and legal services, media, health care, retail, and government.
Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of infrared or visible light through an optical fiber. The light is a form of carrier wave that is modulated to carry information. Fiber is preferred over electrical cabling when high bandwidth, long distance, or immunity to electromagnetic interference is required. This type of communication can transmit voice, video, and telemetry through local area networks or across long distances.
The Internet in South Africa, one of the most technologically resourced countries on the African continent, is expanding. The internet country code top-level domain (ccTLD) .za is managed and regulated by the .za Domain Name Authority (.ZADNA) and was granted to South Africa by the Internet Corporation for Assigned Names and Numbers (ICANN) in 1990. Over 60% of Internet traffic generated on the African continent originates from South Africa. As of 2020, 41.5 million people were Internet users.
Iceland is among the top countries in the world in terms of Internet deployment and use. 99.68% of Icelanders used in the internet in 2021.
Infinera Corporation is a San Jose, California-based vertically integrated manufacturer of Wavelength division multiplexing (WDM)-based packet optical transmission equipment and IP transport technologies for the telecommunications service provider market. It is a pioneer in designing and manufacturing of large-scale photonic integrated circuits (PICs).
WaveDivision Holdings, LLC, doing business as Wave Broadband, is an American provider of residential, business, and enterprise class cable TV, broadband Internet, and telephone services to around 455,000 customers in Washington, Oregon, and California. Wave provides services via their own fiber-optic network and has approximately 1,300+ employees.
Lumen Technologies, Inc. is an American telecommunications company headquartered in Monroe, Louisiana, that offers communications, network services, security, cloud solutions, voice, and managed services. The company is a member of the Fortune 500 and has been on the S&P 500 index since 1999.
ADVA Optical Networking SE was a European telecommunications vendor that provides network equipment for data, storage, voice and video services. It was founded in 1994 by Brian Protiva. On August 30, 2021, it was announced that ADVA and Adtran Holdings would be merging, continuing business under the name Adtran.
In the context of wavelength-division multiplexing, an alien wavelength is a "colored" optical signal that is originated from equipment not under the direct control of the transmission network operator. This technique was first mentioned in 2009.
Zayo Group Holdings, Inc., or Zayo Group, is a privately held company headquartered in Boulder, Colorado, U.S. with European headquarters in London, England. The company provides communications infrastructure services, including fiber and bandwidth connectivity, colocation and cloud infrastructure. Zayo's primary customer segments include wireless carriers, national carriers, ISPs, enterprises and government agencies. Zayo Group was built largely through acquisitions; it took over thirty companies from 2007 to 2014, including AboveNet and 360networks. The company completed an initial public offering of stock raising $600 million in 2014. In 2020, Zayo Group was taken private by global investment firms EQT AB and Digital Colony Partners in a deal valued at $14.3 billion.
Phase 3 Telecom is an aerial fiber-optic network infrastructure provider, providing connectivity, network management, and data storage services to wholesale, enterprise, and retail customers across West Africa. The company was incorporated in 2003 and is headquartered in Abuja, Nigeria. Licensed by the Nigerian Communications Commission in 2006 - the company in 2014, 2018, and 2022, added more kilometers to its existing coverage area with footprint expansion of its backbone, enterprise network, and broadband services. Phase operates 6,000 kilometres (3,700 mi) and counting open-access aerial fiber-optic network. The company, for over two decades has been vital to growth in Africa's growing ICT market, implementing the Wire Nigeria Project—conceived by the Nigerian Communications Commission to help provide broadband communications access to rural communities. Phase 3 has a broad range of wholesale and enterprise clients including Glo, MTN, 9Mobile, Ntel, Airtel, Smile Communications, World Bank, Julius Berger, Unity Bank, etc. Some of the African countries where the company currently has partner operations include Nigeria, Benin, Togo, and the Republic of Niger.
EXA Infrastructure is a digital infrastructure platform and cable network connecting Europe and North America owning over 110,000 km of fibre network in 34 countries. It owns and manages extensive terrestrial and subsea fiber networks, like Dunant, Havfrue, and Amitie. It was established in 2000s as part of the joint projects by Hibernia Networks, Interoute, KPN to EXA.
