Editing 4G (section)

== Background ==
In the field of mobile communications, a "generation" generally refers to a change in the fundamental nature of the service, non-backwards-compatible transmission technology, higher peak bit rates, new frequency bands, wider channel frequency bandwidth in Hertz, and higher capacity for many simultaneous data transfers (higher [[system spectral efficiency]] in [[bit]]/second/Hertz/site).

New mobile generations have appeared about every ten years since the first move from 1981 analog (1G) to digital (2G) transmission in 1992. This was followed, in 2001, by 3G multi-media support, [[spread spectrum]] transmission and a minimum peak bit rate of 200 [[kbit/s]], in 2011/2012 to be followed by "real" 4G, which refers to all-IP [[packet switching|packet-switched]] networks giving mobile ultra-broadband (gigabit speed) access.

While the ITU has adopted recommendations for technologies that would be used for future global communications, they do not actually perform the standardization or development work themselves, instead relying on the work of other standard bodies such as IEEE, WiMAX Forum, and 3GPP.

In the mid-1990s, the [[ITU-R]] standardization organization released the [[IMT-2000]] requirements as a framework for what standards should be considered [[3G]] systems, requiring 2000&nbsp;kbit/s peak bit rate.<ref name=":65">{{cite web |title=IMT-2000 |url=https://networkencyclopedia.com/imt-2000/ |website=Network Encyclopedia |date=September 8, 2019 |access-date=4 March 2022}}</ref> The fastest 3G-based standard in the [[UMTS]] family is the [[HSPA+]] standard, which has been commercially available since 2009 and offers 21&nbsp;Mbit/s downstream (11&nbsp;Mbit/s upstream) without [[MIMO]], i.e. with only one antenna, and in 2011 accelerated up to 42&nbsp;Mbit/s peak bit rate downstream using either [[Dual-Cell HSDPA|DC-HSPA+]] (simultaneous use of two 5&nbsp;MHz UMTS carriers)<ref name="LteWorld">[http://lteworld.org/blog/62-commercial-networks-support-dc-hspa-drives-hspa-investments 62 commercial networks support DC-HSPA+, drives HSPA investments] LteWorld February 7, 2012</ref> or
2x2 MIMO. In theory speeds up to 672&nbsp;Mbit/s are possible, but have not been deployed yet. The fastest 3G-based standard in the [[CDMA2000]] family is the [[EV-DO Rev. B]], which is available since 2010 and offers 15.67&nbsp;Mbit/s downstream.

In 2008, ITU-R specified the [[IMT Advanced]] (International Mobile Telecommunications Advanced) requirements for 4G systems.