There are several reasons why the advent of millimeter wave spectrum for 5G vastly increases bandwidth, and thereby creates new business opportunities for mobile operators. Not only will millimeter wave spectrum represent a vast increase in mobile capacity (an order of magnitude to two orders of magnitude effective new spectrum), but millimeter wave spectrum also is more efficient.
Where spectrum below about 2 GHz has a spectral efficiency up to 2.5 bits per Hertz in a 4G context, and up to 3.8 bits per Hertz on a 5G network, millimeter wave spectrum has an efficiency up to seven bits per Hertz. In principle, even better bits per Hertz performance should be possible. Use of bigger channels also helps.
Basically, not only does millimeter wave spectrum represent an order of magnitude more capacity (Hertz), it also represents more bits per Hertz, as much as double what is possible on a 5G network using spectrum below 2 GHz or so. The reason has much to do with frequency and its relationship to symbol representation.
To be sure, use of the millimeter wave bands is not the only change coming in the 5G era. Spectral efficiency (wider channels and higher-frequency signals) are part of the story. But so is the sheer amount of new unlicensed and licensed spectrum coming in the millimeter bands, plus spectrum sharing, as well as new ways to aggregate licensed and unlicensed spectrum.
Small cell architectures are the other big change. Traditionally, network engineers have two ways to dramatically increase useful capacity: shrink cell sizes or acquire additional spectrum. In the 5G era, mobile operators will use both tools.
Network offload (to Wi-Fi) will continue to be a factor, as will the deployment of better radios and modulation schemes.
The net effect is that a huge increase of commercially-usable capacity is coming, adding between an order of magnitude (10 times) to orders of magnitude (two or three orders of magnitude) more capacity for mobile networks.
It will be disruptive.
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