Performance assessment of a wideband code-division multiple access-based radio-over-fibre system with near–far effect: downlink scenario

The impact of a radio-over-fibre subsystem on the total degradation (TD) performance of downlink wideband code-division multiple access with near-far effect is evaluated. The study investigates the use of pilot-aided channel estimation to compensate for the optical subsystem non-linearities for different channel conditions, estimation intervals, load factors (LFs) and near-far factors (NFFs). The results show that pilot-aided channel estimation is an effective method for compensating the composite impairments of the optical subsystem and the radio frequency channel. It is found that there is always a suitable quiescent point that optimises the system performance regardless of aforementioned conditions, however, the optimum achievable performance depends on the LF, spreading factor (SF) and NFF. Also, LF has more impact on the system performance in comparison to SF. Further, the optimum TD performance is only slightly affected by a decrease in the estimation interval over the optimum output backoff range.