Novel Digital Radio Over Fiber (DRoF) System With Data Compression for Neutral-Host Fronthaul Applications

Abstract

Digital radio-over-fibre transmission has been studied extensively as a way of providing seamless last-mile wireless connectivity by carrying digitised radio frequency (RF) services over broadband optical infrastructures. With the growing demand on wireless capacity and the number of wireless services, a key challenge is the enormous scale of the digital data generated after the digitisation process. In turn, this leads to optical links needing to have very large capacity and hence, high capital expenditure (CAPEX). In this paper, we firstly present and then experimentally demonstrate a multiservice DRoF system for a neutral-host fronthaul link where both forward and reverse links use data compression, multiband multiplexing and synchronisation algorithms. The effect of a novel digital automatic gain control (DAGC) is comprehensively analysed to show an improved RF dynamic range alongside bit rate reduction. In this case, the system allows all cellular services from the three Chinese mobile network operators (MNOs) to be converged onto a single fiber infrastructure. We successfully demonstrate 14 wireless channels over a 10Gbps 20km optical link for indoor and outdoor wireless coverage, showing a minimum error value magnitude (EVM) of <8% and >60dB RF dynamic range. It is believed that the technology provides an ideal solution for last-mile wireless coverage in 5G and beyond. INDEX TERMS Digital radio over fiber, neutral host, cloud radio access network (C-RAN), multiband multiplexing, automatic gain control, 4G, 5G, fronthaul.

Real-time Experimental Demonstration of Timestamped Digitised Radio over Switched Optical Ethernet Fronthaul

“…The signal is then digitised by a 16-bit ADC (TI ADC16DX370) in-turn connected to a master NetFPGA development platform incorporating a Xilinx Virtex 7 FPGA for data processing [5]. The digital data is compressed via a two-stage compression mechanism including sample rate reduction and non-linear resolution suppression [4]. The resultant I/Q data rate per 20MHz-bandwidth LTE service is 400Mbps (~1/3 that of common public radio interface or CPRI).…”

Photonically Generated Millimetre-Wave and THz Links for Wireless Fronthaul and Backhaul

“…As discussed earlier, the CPRI protocol results in a fronthaul data rate many times that of the rate of the wireless data carried, making its scalability to high-rate 5G applications challenging. Compression of the digitised I and Q signals by a factor of around 3 has been demonstrated by various techniques [13], allowing a single 20 MHz LTE channel to be transmitted at a line rate of around 400 Mb/s. An additional problem with CPRI is that its commercial implementations are often vendor specific.…”

“…An additional problem with CPRI is that its commercial implementations are often vendor specific. A neutral-host DRoF system with data compression and a novel digital automatic gain control has recently demonstrated simultaneous transmission of 14 wireless services from three mobile network operators over a 20km 10 Gb/s optical link [13].…”

“…The data feeding the SFP+ transmitter was generated from a novel DRoF unit using a compression technique that reduces the fronthaul transmission rate by a factor of three compared to the CPRI protocol [4,13]. The DRoF unit consists of an analogue front end to convert an applied RF signal to an IF, which is then digitised at 150 MSa/s with 14-bit resolution.…”

A Review on MIMO Wireless Signals over Fibre for Next Generation Fibre Wireless (FiWi) Broadband Networks

“…Both ARoF and DRoF solutions have been studied to provide the last-mile wireless coverage [98]. ARoF based systems also suffer from chromatic dispersion, nonlinearity, and losses in the optical sources, detectors, links, and other passive or active components [99]. On the other hand, DRoF system can completely remove these effects on the analogue carrier for long-distance transmission by conveying digital bits, which present the radio frequency (RF) carriers over optical fibre with an error-free transmission till bit error rate (BER) is intolerable.…”