Improvements in combined radio over multimode fibre and radio over FSO systems by applying mode filtering

In this paper, the combination of radio over multimode fibre and radio over free space optical systems are experimentally investigated. A mode filtering technique is adopted in order to deal with the modal effects in such hybrid systems. Considering mode filtering effect, we have determined transfer function and performed link budget analysis. Measurement of the error vector magnitude (EVM) was accomplished to verify the efficiency of the proposed systems in dealing with the modal effect. The obtained results are below the 8% 3GPP-LTE EVM requirement for different free space optical channel conditions including fog and turbulence.