Telecom Principle Animation:5G Massive MIMO Lab

A conventional antenna spreads power over the whole sector and serves one phone at a time, so eight users each get an eighth of the airtime. When the neighbouring cell switches on, phones at the edge of the block drop below 0 dB.

With every antenna in phase the beam points straight ahead; a phase step of 180°·sinθ between neighbours swings it to angle θ. Sixty-four antennas add 18 dB of gain and squeeze the beam to under 2°.

Phones send pilots so the base station knows each direction, then zero-forcing computes weights so each beam cancels exactly toward the others. Eight users share the same frequencies at the same moment without disturbing each other. Switch to maximum-ratio and watch the sidelobes leak onto others.

The bright patches on the ground are where each beam lands, with a phone inside each. A car at 10 m/s leaves a 2° beam within seconds; re-measuring the direction every few milliseconds keeps the beam on it. Switch off beam tracking to see what happens.

A conventional antenna’s total throughput stays flat however many users there are; massive MIMO adds a data stream per user, so throughput climbs almost in proportion—until users crowd into directions the array can no longer separate. More antennas separate more users.