In the dual-fiber bidirectional 5G pre-transmission optical direct-drive solution, the DU is directly connected to the AAU. Each AAU needs to connect two fibers to the DU to implement the transmission and reception. A total of 6 optical fibers and 12 10G/25G gray-light modules are required. This solution is applicable to short-distance D-RAN scenarios. The industry is mature and mainstream module vendors have already supported it. It has mass production capability and low optical module cost. However, it consumes a lot of fiber resources and is suitable for use in places where fiber resources are sufficient.

In order to save fiber resources, the 5G pre-transmission fiber direct drive solution can also introduce a single-fiber bidirectional (BiDi) optical module, and the connection between each AAU and the DU is carried by one optical fiber. The cost of a single BiDi optical module is slightly higher than that of a normal gray optical module. However, considering the half of the number of optical fibers and the number of optical modules, this solution can be applied to D-RAN and C-RAN scenarios where some core resources are tight.

For C-RAN scenarios with tight core resources, an active point-to-point WDM/OTN solution can be used to transmit transmissions up to 10 km in length by introducing new active WDM/OTN equipment or WDM/OTN equipment that is old 4G. Effectively reduce fiber cost by carrying a fiber. The solution introduces two WDM/OTN devices, the cost is higher than that of the fiber direct drive solution. The AAU and the outdoor WDM/OTN devices, the DU and the access WDM/OTN devices still need to connect through 6 fibers, but because The distance is short, the core resources are low, and the working environment of 24 25G gray light modules is required to be loose and relatively low in cost. At present, this program is more mature, and mainstream equipment manufacturers have samples and have mass production capabilities.

Passive CWDM is also a WDMDM solution that supports transmission scenarios up to 5km, which reduces core cost, but because of the use of passive WDM devices, equipment costs are lower. Since the entire transmission process is multiplexed in the optical layer, a 25G color light module is required between the AAU and the OADM, and between the DU and the OADM. At present, operators have also proposed their own point-to-multipoint WDM (WDM-PON/G.metro/Open WDM) pre-transmission scheme, which has the lowest fiber cost and high equipment cost. At present, the solution technology is not yet fully mature, and there is no commercial equipment for the time being.

According to the above analysis, the pre-transmission scheme of the fiber direct drive method has a relatively large demand for the core resources, and the demand for the optical modules is relatively small. Assuming that each base station is connected to three AAUs and each AAU has a pair of transceiver interfaces, the number of optical modules required per base station in the direct fiber drive mode is 6 or 12. Other pre-transmission schemes for introducing transmission equipment can reduce the demand for optical fibers, and the demand for optical modules is improved. Under the same conditions, point-to-multipoint WDM/OTN requires 24 25G optical modules per base station, and passive CWDM requires 12 25G opticals. Module, point-to-multipoint WDM mode requires 18 25G optical modules. Assuming that a DU carries only one base station, it can be calculated that the size of the 25G optical module required to carry 500 5G base stations is at least 30 million.

Recently, operators have begun to intensively carry out direct mining related to optical modules. The operators of the transmission network equipment are also increasingly emphasizing the requirements of decoupling and opening up. The business model of the optical module will change greatly in the future. The original equipment supplier's import supply chain model will be changed to the operator's import supply chain mode. There are big differences between the supplier's supply chain management and the equipment supplier's supply chain management, including pricing strategy and supplier selection. This is likely to affect the market environment, competition pattern and market share of various optical modules in the future. Considering the capital expenditure pressure of operators, optical module companies with strong cost control capabilities and delivery capabilities will benefit from this.