The problem
Why millimetre wave is hard
The transition to 5G mobile is coming, driven by demand for higher-rate broadband at gigabits per second. Such bandwidth is made possible via new radio spectrum at 24 GHz and above, known as millimeter wave (mmWave) because its wavelengths are shorter than existing mobile radio at 6 GHz and below.
While opening much wider bands, this new spectrum is also more attenuated by the atmosphere and other objects. To overcome this attenuation, the propagated power can be aimed directly at each user with beamforming, electronically controlling an array of radios to focus energy only where it’s useful.
In three steps
The argument the company made
1. Wider bands
Spectrum at 24 GHz and above opens channels far wider than the bands below 6 GHz, which is where gigabit rates come from.
2. More loss
Those wavelengths are absorbed by the atmosphere and blocked by objects more readily than the spectrum in use today.
3. Beamforming
The answer is to aim the power: an electronically controlled array of radios focusing energy on each user in turn.
What that implies for a radio
Every element of the array needs its own phase and gain control, which pushes the design into integrated circuits; the beam weights have to be computed and applied in real time, which pushes it into high-speed digital logic; and the whole thing has to be brought up, calibrated and managed, which is software.