A client terminal sends a signal to a wireless access device. The wireless access device receives the signal, determines channel state information corresponding to the client terminal according to identity information of the client terminal in the signal, and calculates data sent by the client terminal according to the channel state information and the signal. The client terminal sends a request signal for acquiring channel state information, wherein the request signal includes identity information of the client terminal. The wireless access device receives the request signal, obtains the channel state information corresponding to the client terminal according to the identity information of the client terminal in the request signal, and sends the obtained channel state information to the client terminal. The client terminal receives the channel state information and the signal and calculates the data sent to the client terminal according to the channel state information and the signal.