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Global network
A global network is any communication network which spans the entire Earth. The term, as used in this article refers in a more restricted way to ''bidirectional'' communication networks, and to technology-based networks. Early networks such as international mail and unidirectional communication networks, such as radio and television, are described elsewhere.
The first global network was established using electrical telegraphy and global span was achieved in 1899. The telephony network was the second to achieve global status, in the 1950s. More recently, interconnected IP networks (principally the Internet, with estimated 2.5 billion users worldwide in 2014 〔http://export.gov/northcarolina/build/groups/public/@eg_us_nc/documents/webcontent/komarketingpresentation065541.pdf〕), and the GSM mobile communication network (with over 6 billion worldwide users in 2014) form the largest global networks of all.
Setting up global networks requires immense, costly and lengthy efforts lasting for decades. Elaborate interconnections, switching and routing devices, laying out physical carriers of information, such as land and submarine cables and earth stations must be set in operation. In addition, international communication protocols, legislation and agreements are involved.
==Satellite global networks==
Communication satellites are an important part of global networks. However, there are specific low Earth orbit (LEO) global satellite constellations, such as Iridium, Globalstar and Orbcomm, which are comprised by dozens of similar satellites which are put in orbit at regularly spaced positions and form a mesh network, sometimes sending and receiving information directly among themselves. Using VSAT technology, satellite internet access has become possible.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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