Optical fiber direct drive scheme
Optical fiber direct drive means that AAU and Du are directly connected by optical fiber. AAU and Du are respectively installed with 25gbps white optical module, and the transmission distance can support 10km. In order to save optical fiber resources, a 25gbps bidi solution with integrated WDM function is proposed in the industry. The two-way data signals of AAU and Du are transmitted in one optical fiber with different wavelengths, which can save half of optical fiber resources
Passive WDM bearer scheme
In the passive WDM scheme, the passive combiner and demultiplexer are used in combination with the color optical direct drive. The color optical module with wavelength is used on the Du and AAU. The front end of the Du and the AAU nodes are respectively equipped with the optical combiner and demultiplexer. The use of WDM technology can greatly reduce the consumption of optical fiber resources.
Semi active WDM scheme
In the semi-active WDM bearing scheme, the color optical module is used at AAU side and transmitted in an optical fiber after passing through the passive WDM device; the active WDM device is used at Du side to forward the color optical signal and carry out operation and maintenance for the color optical module of AAU.
OTN bearing scheme
In order to reduce the wavelength planning between AAU and Du, OTN bearing solution can be adopted. OTN overhead bytes can provide rich OAM and fault diagnosis functions. At the same time, AAU and Du devices do not need color optical modules to avoid wavelength allocation and management of wireless devices. OTN bearing scheme has more protection technology, but the cost of equipment is high and the investment of network construction is large.
WDM-PON bearing scheme
WDM-PON is a broadband access network evolution technology. In this system, the optical line terminal OLT (optical line terminal) is deployed on the Du side, which can provide multiple light sources with different wavelengths, and realize the control, switching and management functions. The optical network unit ONU is deployed on the AAU side to provide a specific wavelength. OWDN (optical wavelength assignment network) is deployed between OLT and ONU to realize wavelength assignment.
5G forward transmission scheme involves huge investment in network construction and occupies a lot of optical fiber resources. The choice of scheme has a significant impact on resource occupation and construction cycle of each deployment point.
