Scale-up connectivity is crucial for the performance of rack-scale AI systems, but achieving high bandwidth and low latency for such interconnections using copper wires is becoming increasingly complicated with each generation. Using optical interconnections for scale-up connectivity is a possibility, but it may be an overkill, so start-ups Point2 and AttoTude propose to use radio-based interconnections operating at millimeter-wave and terahertz frequencies over waveguides that connect to systems using standard pluggable connectors, reports IEEE Spectrum.
Point2's implementation uses what it calls an 'active radio cable' built from eight 'e-Tube' waveguides. Each waveguide carries data using two frequencies — 90 GHz and 225 GHz — and plug-in modules at both ends convert digital signals directly into modulated millimeter-wave radio and back again. A full cable delivers 1.6 Tb/s, occupies 8.1mm, or about a half the volume of a comparable active copper cable, and can reach up to seven meters, more than enough for scale-up connectivity. Point2 says the design consumes roughly one-third the power of optical links, costs about one-third as much, and adds as little as one-thousandth the latency.
