  The sixth-generation (6G) mobile networks must increase coverage and improve
spectral efficiency, especially for cell-edge users. Distributed multiple-input
multiple-output (D-MIMO) networks can fulfill these requirements provided that
transmission/reception points (TRxPs) of the network can be synchronized with
sub nanosecond precision, however, synchronization with current backhaul and
fronthaul digital interfaces is challenging. For 6G new services and scenarios,
analog radio-over-fiber (ARoF) is a prospective alternative for future mobile
fronthaul where current solutions fall short to fulfill future demands on
bandwidth, synchronization, and/or power consumption. This paper presents an
experimental validation of coherent joint transmissions (CJTs) in a two TRxPs
D-MIMO network where ARoF fronthaul links allow to meet the required level of
synchronization. Results show that by means of CJT a combined diversity and
power gain of +5 dB is realized in comparison with a single TRxP transmission.
