Page 614 - 5G Basics - Core Network Aspects

2 Transport aspects

9 System design for supporting a radio access system over an optical access network

9.1 Measurement test model for mobile front-hauling over an optical distribution network

Figure 9-1 shows a general test model for physical-level quality measurement of RF signal in MFH with the
RoF technology, which is based on the RF-band subcarrier signals transmission shown in Figure 6-1-a. As
shown in Figure 9-1-a, the measurement set-up basically consists of two radio signal generators (SGs), two
radio signal analysers (SAs), two E/O converters, two O/E converters, two MUXs/DEMUXs, a standard
single-mode optical fibre (SMF), and a variable optical attenuator (VOA). Here, thin and thick lines
represent electrical and optical wirings, respectively. In this model, it is assumed that the OAN under test
corresponds to a link between service network interface (SNI) and user network interface (UNI). The output
of radio SG is input into the OAN under test and the output of the OAN under test is input into the radio SA.
Their signals, which should be radio signals, are delivered via the SNI or the UNI. For the purpose of
transmitting a RoF signal, a set of one E/O converter, one O/E converter, and one MUX/DEMUX at the
network side corresponds to an OLT, and another set of one E/O converter, one O/E converter, and one
MUX/DEMUX at the user side corresponds to an ONU. An ODN consists of the SMF and the VOA, where the
VOA emulates a splitting loss of splitters and the other excess losses between the OLT and the ONU, except
for the SMF transmission loss. Figure 9-1-b and -c show the general configurations of E/O converter for
direct modulation and O/E converter for incoherent detection, respectively. In each converter, an electrical
amplifier, an electrical bandpass filter (BPF), an optical amplifier, and an optical BPF are optional
components, which may be selectively used to meet the physical requirement at the point of SNI and UNI.

SNI S/R R/S UNI
OLT ODN ONU

E/O O/E
Radio SG SMF Radio SA
MUX/DEMUX VOA MUX/DEMUX
converter converter
O/E E/O
Radio SA Splitting and excess Radio SG
converter loss emulation converter
Optical access network under test
a)

E/O converter (for RoF transmission)
Bias
Electrical Optical
input Electrical Electrical Light Optical Optical output
amplifier BPF source amplifier BPF

b)

O/E converter (for RoF transmission)
Bias
Optical Electrical
input Optical Optical Photo- Electrical Electrical output
amplifier BPF detector amplifier BPF

c) G Suppl.55(15)_F9-1

Figure 9-1 – General test model for RoF transmission over ODN: a) block diagram of measurement set-up;
b) general configuration of E/O converter for direct modulation; and c) general configuration of O/E
converter for incoherent detection

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