5G is the fifth generation cellular network technology. The industry association 3GPP defines any system using "5G NR" (5G New Radio) software as "5G", a definition that came into general use by late 2018. Others may reserve the term for systems that meet the requirements of the ITU IMT-2020. 3GPP will submit their 5G NR to the ITU.[1] It follows 2G, 3G and 4G and their respective associated technologies (such as GSM, UMTS, LTE, LTE Advanced Pro and others).
The air interface defined by 3GPP for 5G is known as New Radio (NR), and the specification is subdivided into two frequency bands, FR1 (below 6 GHz) and FR2 (mmWave),[110] each with different capabilities.
Frequency range 1 (< 6 GHz)
The maximum channel bandwidth defined for FR1 is 100 MHz, due to the scarcity of continuous spectrum in this crowded frequency range. The band most widely being used for 5G in this range is around 3.5 GHz. The Korean carriers are using 3.5 GHz although some millimeter wave spectrum has also been allocated.
Frequency range 2 (> 24 GHz)
The minimum channel bandwidth defined for FR2 is 50 MHz and the maximum is 400 MHz, with two-channel aggregation supported in 3GPP Release 15. In the U.S., Verizon is using 28 GHz and AT&T is using 39 GHz. 5G can use frequencies of up to 300 GHz.[111] The higher the frequency, the greater the ability to support high data transfer speeds without interfering with other wireless signals or becoming overly cluttered. Due to this, 5G can support approximately 1,000 more devices per meter than 4G.[112]
FR2 coverage
5G in the 24 GHz range or above use higher frequencies than 4G, and as a result, some 5G signals are not capable of traveling large distances (over a few hundred meters), unlike 4G or lower frequency 5G signals (sub 6 GHz). This requires placing 5G base stations every few hundred meters in order to utilize higher frequency bands. Also, these higher frequency 5G signals cannot easily penetrate solid objects, like cars, trees and walls, because of the nature of these higher frequency electromagnetic waves.[113]
Massive MIMO (multiple input and multiple output) antennas increases sector throughput and capacity density using large numbers of antennas and Multi-user MIMO (MU-MIMO). Each antenna is individually-controlled and may embed radio transceiver components. Nokia claimed a five-fold increase in the capacity increase for a 64-Tx/64-Rx antenna system. The term "massive MIMO" was coined by Nokia Bell Labs researcher Dr. Thomas L. Marzetta in 2010, and has been launched in 4G networks, such as Softbank in Japan.[114]
Of over 562 separate 5G demonstrations, tests or trials globally of 5G technologies, at least 94 of them have involved testing Massive MIMO in the context of 5G.[115]
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