A downlink baseband signal generating method, comprising: performing channel coding and modulation on a downlink data stream of a user in a cell, and obtaining a downlink coded and modulated user signal of the cell; generating a downlink control channel signal according to physical-layer control information; forwarding a reference signal, a synchronization signal, a broadcast channel signal, the downlink coded and modulated user signal, and the downlink control channel signal; performing multi-input multi-output, MIMO, precoding on the downlink coded and modulated user signal, mapping the signal that has undergone the multi-input multi-output precoding, the downlink control channel signal, the reference signal, the synchronization signal, and the broadcast channel signal to their respective subcarriers; performing inverse fast Fourier transformation to obtain downlink a baseband signal; and sending the signal out, performing the downlink baseband signal generating method by a cloud radio access network node, C-RAN node; forwarding the reference signal, the synchronization signal, the broadcast channel signal, the downlink coded and modulated user signal, and the downlink control channel signal onto a corresponding cloud radio access network radio remote unit, C-RAN RRU, according to a preset forwarding configuration list, wherein the forwarding configuration list is used to record a mapping relationship between user information and radio remote unit information, wherein the user information includes a parameter indicating a user identity, and the RRU information includes an RRU identifier, so that the radio remote unit, RRU, performs multi-input multi-output precoding on the downlink coded and modulated user signal, maps the signal that has undergone the multi-input multi-output precoding, the downlink control channel signal, the reference signal, the synchronization signal, and the broadcast channel signal to their respective subcarriers, performs inverse fast Fourier transformation to obtain downlink a baseband signal, and sends the signal out. performing channel coding and modulation on a downlink data stream of a user in a cell, and obtaining a downlink coded and modulated user signal of the cell; generating a downlink control channel signal according to physical-layer control information; forwarding a reference signal, a synchronization signal, a broadcast channel signal, the downlink coded and modulated user signal, and the downlink control channel signal; performing multi-input multi-output, MIMO, precoding on the downlink coded and modulated user signal, mapping the signal that has undergone the multi-input multi-output precoding, the downlink control channel signal, the reference signal, the synchronization signal, and the broadcast channel signal to their respective subcarriers; performing inverse fast Fourier transformation to obtain downlink a baseband signal; and sending the signal out, performing the downlink baseband signal generating method by a cloud radio access network node, C-RAN node; forwarding the reference signal, the synchronization signal, the broadcast channel signal, the downlink coded and modulated user signal, and the downlink control channel signal onto a corresponding cloud radio access network radio remote unit, C-RAN RRU, according to a preset forwarding configuration list, wherein the forwarding configuration list is used to record a mapping relationship between user information and radio remote unit information, wherein the user information includes a parameter indicating a user identity, and the RRU information includes an RRU identifier, so that the radio remote unit, RRU, performs multi-input multi-output precoding on the downlink coded and modulated user signal, maps the signal that has undergone the multi-input multi-output precoding, the downlink control channel signal, the reference signal, the synchronization signal, and the broadcast channel signal to their respective subcarriers, performs inverse fast Fourier transformation to obtain downlink a baseband signal, and sends the signal out.