As the deployment of wireless networks becomes more and more intensive, the scale of large-capacity distributed base stations is also expanding. The deep coverage of base stations requires the location of the deployment to be closer to users. The traditional pre-transmission scheme of optical fiber direct drive between the BBU and the RRU has a series of problems such as serious consumption of optical fiber resources and difficulty in expanding the capacity. The 1U compact WDM device introduced effectively solves the practical problem of lack of resources for fiber-optic remote transmission cable between BBU and RRU in C-RAN architecture, and meets the requirements for deep coverage and flexible expansion of carrier base stations.