The document describes the Huawei DBS3900 distributed base station solution. It consists of an indoor baseband unit called the BBU3900 and outdoor remote radio units called RRU3004. The BBU3900 provides centralized management and signaling processing for the system. It connects to the RRU3004 units via CPRI and provides the reference clock. The RRU3004 processes baseband and radio frequency signals. The solution supports flexible installation in various environments to provide wide coverage at low cost.