Design of Novel Automatic Gain Control for Multi-service Low-bit Rate Digital Radio-over-Fibre System

Taking the advantage of the parallel development of electronic sampling systems and signal processing, Digital Radio-over-Fiber (DRoF) is studied extensively as a way of providing multi-service transmission at low- bit rate through data compression. However, the dynamic range is greatly lowered after data compression in the system. Based on the theoretical analysis of the compression parameters, a novel FastSettling Two-stage Automatic Gain Control (FST-AGC) algorithm is proposed, in which gain adjustment settling is carried out by multi-threshold decision mechanism with a fast-settling times, high stability and great accuracy. By introducing a novel gain control mechanism which simultaneously adjusts the gain in digital domain and Radio Frequency (RF) domain, the dynamic range of the system increases significantly. This algorithm has been applied to a DRoF system which supports the low-bit rate transmission of all services of 3 China Mobile Network Operators (MONs) successfully. The theoretical analysis, the simulation results and the experimental data all prove the validity of the proposed algorithm. Its promising properties and excellent performance enable its potential application to emerging networks, such as Internet of Things (IoT), Radio Frequency Intification (RFID) and the incoming 5G network.