Insert one end of the CPRI optical cable into the optical module, and then lead the CPRI optical cable out of the cabinet along the right side of the cabinet. Wrap the fiber tail with the winding pipe. For details about how to install a GPS SPD in other scenarios, please see “ (Optional) Installing a GPS SPD” in eNodeB Product Documentation. Install a ground cable for the GPS SPD. Page 9 About This Document Purpose This document provides an overview of the BBU3900 GSM hardware for the planning and deployment of the BBU3900 GSM. It describes the BBU3900 GSM boards and modules, ports and related functions, categories of cables, and specifications and installation positions of. Preferentially installed in the slot4.