The most representative DWDM technology solution suitable for 5G fronthaul is a wavelength adaptive access type DWDM system based on ITU-T G.698.4 (formerly G.metro) standard. This solution uses a wavelength-tunable optical module with port-independent and wavelength-adaptive characteristics. The end equipment (TEE) has the ability to automatically adapt the working wavelength of its optical module to its connected OD/OM or OADM port; Connect the fiber to the correct physical port, and it can work normally after power on without wavelength configuration, which greatly simplifies network construction, operation and maintenance work, and reduces the number and types of spares.
The passive WDM solution uses colored optical modules on AAU and DU equipment. Multiple passive wavelengths are multiplexed to save fiber resources. In bus-type networking, OADM only needs the drop function, and the remaining wavelengths collide to the next drop location. The solution supports mixed transmission of 4G/5G services and achieves unified 4G/5G fronthaul.
Based on the current network status, optical cable resource status, and fronthaul technology requirements, combined with 5G fronthaul network maintenance and management requirements, based on the passive WDM solution, an innovative construction of a semi-active WDM solution is proposed.
Active system solutions are mainly divided into active WDM solutions, simple OTN solutions, and SPN solutions. This article mainly discusses active WDM solutions and simple OTN solutions. The networking architecture is shown in Figure.
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