  Millimeter-wave communication with high throughput and high reliability is
poised to be a gamechanger for V2X and VR applications. However, mmWave links
are notorious for low reliability since they suffer from frequent outages due
to blockage and user mobility. We build mmReliable, a reliable mmWave system
that implements multi-beamforming and user tracking to handle environmental
vulnerabilities. It creates constructive multi-beam patterns and optimizes
their angle, phase, and amplitude to maximize the signal strength at the
receiver. Multi-beam links are reliable since they are resilient to occasional
blockages of few constituent beams compared to a single-beam system. We
implement mmReliable on a 28 GHz testbed with 400 MHz bandwidth, and a 64
element phased array supporting 5G NR waveforms. Rigorous indoor and outdoor
experiments demonstrate that mmReliable achieves close to 100\% reliability
providing 2.3x improvement in the throughput-reliability product than
single-beam systems. This is an extended version of a paper published in
Sigcomm'21.
