Fronthaul Synchronization Requirements for Distributed MIMO in LiFi Systems

We assess the impact of synchronization errors in distributed multiple-input multiple-output (D-MIMO) LiFi systems when using Ethernet as fronthaul. To this end, we perform a sensitivity analysis of a distributed multiple-input single-output (D-MISO) LiFi system model by running link level simulations of a joint transmission scheme in a worst-case scenario. Specifically, we investigate the impact of timing errors between distributed transmitters (TXs) on the frame synchronization rate and the block error rate (BLER) for the two IEEE Std 802.15.13 physical layers (PHYs). It is found that timing errors should not exceed the inverse system bandwidth in order to enable reliable communication. This allows a quantification of the synchronization accuracy requirements of distributed TXs in a D-MIMO realization of IEEE 802.15.13 networks using Ethernet as fronthaul. We also show that the required synchronization accuracy is achieved by using the IEEE 1588 Precision Time Protocol (PTP) together with synchronous Ethernet (SyncE).