Millimetre-wave radio over fibre for broadband distribution

Engineers at BT have been considering the evolution from narrowband radio delivery. It is generally considered that the increase in bandwidth that needs to be delivered will necessitate a move to ever higher frequencies. The focus of the BT work has been on frequencies at or above 29 GHz, partly due to the heavy demand for spectrum below these frequencies in the UK. A key issue is the very important consideration of the amount of remotely located electronics required. Radio over fibre (RoF) offers the potential to greatly simplify the remote equipment, and also provide for a sharing of a large part of the radio electronics among a number of remote sites. A simplistic comparison of the remote electronics required is shown. We have built a number of demonstration systems to illustrate this concept, and to understand the capabilities of the technology and how to design optimum systems. As the technology has matured, we have used such systems operationally to provide IF feeds to satellite earth station antennas, but “broadband” delivery still remained the preserve of the laboratory. However, in the summer of 1994 we demonstrated the use of radio to provide delivery of video-on-demand (VoD) in a real urban environment (to employees of BT) as part of a small scale technology trial