KEYWORDS: Radio optics, Optical fibers, Fiber optics, Signal processing, Channel projecting optics, Modulation, Interfaces, Dispersion, Clouds, Antennas, Radio over Fiber
The paper presents basics of the C-RAN network architecture, based on fiber-optic networks, for solutions targeted at 5G mobile systems. Service aspects of work the optical fronthaul (FH) and optical midhaul (MH) are presented. Such networks will constitute main component connecting the virtual baseband unit (vBBU) cloud and the physical active antenna (AAU)/ optical remote radio head (O-RRH) nodes. Calculations were made to indicate the impact of optical fiber path/link delay parameters on the functioning of a interface using D-RoF or A-RoF formats. Simulations of 5GRFoF signal transmission over the fiber-optic FH path up to 20km in length were carried out. During the simulation, the 5G-NR signal according to Rel-15/16, i.e. CP-OFDM with the maximum number of subcarriers supported by 4096-point DFT/FFT was used in the radio channel. Selected simulation results have been summarized in tabular form and in the form of visualization of the 256-QAM constellation. The summary indicates the need to consider the static parameters of the FH/MH fiber-optic link when synchronizing signals delivered to gNB-DU as a remote AAU/O-RRH group.
The paper presents the need to introduce new network solutions that will be able to significantly increase the efficiency of product manufacturing and delivery in the near future. Under Industry 4.0, so-called private networks based on 5G and IoT technologies will be introduced in an increasing number of industrial plants around the world. The combination of private and public network resources will significantly increase the potential of IoT solutions, as this will enable the combination of production, analytical and logistics processes. Fast decision-making systems, efficient transmission of massive data can be realized only thanks to fast and capacious fiber-optic networks. The paper suggests that fiber networks, also based on multi-core fibers, be introduced where copper cabling is still used for communication. It was also indicated that in order to increase the security and capacity of links in the radio domain, part of the link should be replaced by an optical wireless interface working in the future Li-Fi standard or its evolutionary version based on invisible light communication (inVLC) mode.
The paper presents a comparative classification of reference models used in IoT technology. The layers that directly determine the effectiveness of providing information at a distance are indicated. Examples of the construction of cores used in telecommunications silica-fibers are presented. Exemplary simulation models of SM-MCF and FM-MCF modal structures has been presented. Attention was paid to the need to construct MCFs, which can be used in local access networks as well as in distribution and indoor networks. Applications of MCFs in the networks operating in FTTH, FTTA and FTTS configurations are presented. During the presentation of the network solutions, proposal for the construction of a hybrid fiber-optic cable consisting of MCFs, SCFs, and TMCs are described. The proposed cable construction has been also used in the presented FTTH/FTTA network solutions.
The paper presents methods for combining single and multi-channel fiber-optic links. On this basis, the architecture of the current and next generations of mobile communication systems, which should be strongly supported by all-optical networks, is presented. An example of a mobile system based on the EON/OTN/TSON backbone and edge optical networks operating in active and passive modes is presented. The current and future needs of mobile systems and networks were analyzed in terms of the quality of service parameters. Requirements for optical links used in separate networks of mobile systems such as NGC, BH, FH, and MH are presented. Calculations of the optical spectral efficiency of single-channel optical links used in the mobile systems were made. The calculations include the coherent modulations of single-carrier and multi-carrier OFDM formats, as well as D-RoF and A-RoF formats used in optical FH and MH. The results of the calculations are presented in diagrams. Application scenarios of the proposed network architecture and spectral effective modulation formats were discussed.
The paper presents an example of an optical RRH (Remote Radio Head) design, which is equipped with photonic
components for direct connection to an all-optical network. The features that can be fulfilled by an all-optical network
are indicated to support future 5G mobile networks. The demand for optical bandwidth in fronthaul/midhaul distribution
network links, working in D-RoF and A-RoF formats was performed. The increase in demand is due to the very large
traffic generated by the Optical Massive-MIMO RRH/RRU will work in format of an Active-Distributed Antenna
System (A-DAS). An exemplary next-generation mobile network that will utilize O-RRH and an all-optical backbone is
presented. All components of presented network will work in the Centralized/Cloud Radio Access Network (C-RAN)
architecture, which is achievable by control with the use of the OpenFlow (OF).
The paper presents the phenomena, that occur during the coupling of the cores included in the multi-core fibers (MCFs). It presents the design parameters of MCF, which have a major impact on their connection with each other and with the single-core single-mode optical fiber (SC-SMF), shortly called SMF. It has been demonstrated the need to constitute a new standard for multi-core fibers to the their mass coupling was simple and cheap. An analysis of use of fixed and reconnected techniques of the MCF and SMF coupling, have been presented. Attention was paid to the elements that affecting the quality of the MCF-to-MCF and MCF-to-SMF coupling, especially during fusion splicing. It presented the latest technologies used for connecting the optical fibers of new generation and proposes of new solutions and modifications, that can improve the work of future optical fiber fusion splicers.
The paper presents a comparison of two technologies, i.e. Digital Radio-over-Fiber (DRoF) and Analog Radio-over- Fiber (ARoF), for transporting of the radio signals over all-optical network. The methods of calculating the appropriate amount of bandwidth and frequency band of the modulated optical channel, have been presented. A proposal of network architecture of all-optical SDN, controlled using the OpenFlow (OF) protocol, which allows combining the functions of backhaul (BH) and fronthaul (FH) networks, have been highlighted. The solution allows building a hybrid Centralized Radio Access Network (C-RAN), in the area of which can be combined and coordinated eNodeB and Radio Remote Head (RRH) connections to the core network. In addition, an example of the OpenFlow message format that allows to configure the optical node in order to efficiently transfer the signal coming from the backhaul (BH) or fronthaul (FH) interface. It should be noted that the optical node controlled by OpenFlow controller and supporting given proposal of message, can also work in the area of Evolved Packet Core (EPC) network.
Thermally diffused areas of telecommunication single mode fiber core reduce loss of fiber-to-fiber or laser-tofiber
couplings indeed. Loss of such area is small if it remains single-modal. In the work, for step, Gaussian and power
refractive index profiles, for which fundamental mode LP01 distribution can be approximated by Gaussian function, the
so-called equal volume profiles were given. For these profile forms, it has been shown that the fibers remain single-modal
independently of changing values of core radius e.g. after diffusion. It has been shown that because Gaussian
profile approximates well diffusion distribution, this thermally diffused core area, which has constant quantity of dopant
in the diffusion area, remains single-modal.
In the work there were presented research referred to Gaussian refractive index profile which appears in thermal joint area of splicing different types of single mode fibers with circular symmetry and weakly guiding i.e. different types of telecommunication fibers. There were presented results of measurements of coupling loss appeared in thermal joint area of splicing different types of telecommunication fibers and their interpretation that takes into consideration diffusion of dopant from core and description of fundamental mode field and refractive index by Gaussian function.
In this paper, the influence of diffusion processes of Ge02 impurity during arc fusion splicing on the parameters of splices of single mode telecommunication fibers of different types are discussed. The calculated values of diffusion coefficients of Ge02 in Si02 for fusion temperature are given. Moreover, assuming different diffusion models, the parameters of the dopant diffusion area, from the core to the claddings of fused fibers, are calculated. On this basis, the optimal values for fusion times and currents for optical telecommunication fibers of different types, to fulfil the telecommunication requirements on splices regarding their loss, reflectance and resistance to tearing, are calculated as well. The results of measurements of loss and mechanical strength of splices for the automatic and optimized programs for spliced connections of the TrueWave® optical fiber with other single mode telecommunication fibers are presented.
In this paper, some results of optimization of process of arc fusion splicing of single mode optical telecommunication fibers in climatic circumstances characterized by temperature changes in the range t =-2 °C ÷ 32 °C and by relative humidity variations in the range RH = 30 ÷ 92 % are presented. The means of determining jointly the climatic circumstances: temperature, relative humidity and dew-point excluding possibility of performing a paper arc fusion splicing of optical fibers is reported. The results of measurements of attenuation, reflectivity and mechanical strength of arc fusion splicing of single mode telecommunication optical fibers produced in extreme climatic circumstances are presented as well.
Results of research on the influence of weather conditions (t equals 10 divided by 27 degree(s)C; H equals 30 divided by 90%) on the process of splicing of standard single mode fibers SM (G.652) and fibers with dispersion shifted DS (G.653) have been presented as well as the results of optimization of splicing SM and DS fibers.
Results of reflectometric measurements of the lengths of sectors of single mode telecommunication fibers. Significant extension even by a few meters, of the measured sections, as compared with their real lengths, have been discovered assuming that the measurement was made from the reflectometer towards the splice, and it was found out that the length was shortened if the measurement was made from the splice towards the event of the reflection type (the end of the route). Measurement were made on the band 1310 nm and 1550 nm with the use of a few reflectometers of different types. Analysis and possible reasons of measurement errors have been presented as well as a proposition how to correct them.
Results of measurement of True Wave fiber parameters have been presented. These results have been compared with the parameters of standard fibers and dispersion shifted fibers. Results of NZDF fiber splicing with single mode fibers of different types have been presented. Results of optimization of splicing process of these fibers have been presented.
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