Emerging cloud applications such as virtual reality and connected car fleets demand guaranteed connections, as well as low and stable latency, to edge data centres. Currently, user–cloud communications rely on time-scheduled data frames through tree-topology fibre networks, which are incapable of providing guaranteed connections with low or stable latency and cannot be scaled to a larger number of users. Here we show that a frequency-referenced multiplexing method can provide guaranteed bandwidth and low latency for time-critical applications. We use clock and optical frequency synchronization, enabled by frequency comb and signal processing techniques, to provide each user with dedicated optical bandwidth, creating scalable user–cloud upstream communications. As a proof of concept, we demonstrate a frequency-division multiplexing system servicing up to 64 users with an aggregate bandwidth of 160 GHz, exhibiting a data rate of up to 4.3 Gbps per user (240.0 Gbps aggregated capacity considering a 200 GHz wavelength band) with a high receiver sensitivity of –35 dBm
