A method comprising: determining, by user equipment (3000, 5000) UE, a first index corresponding to an average transmission rate supported by a channel between the UE and a base station (4000, 6000); determining, by the UE, a second index corresponding to a difference between an instantaneous transmission rate supported by a data stream on the channel and an average transmission rate supported by the data stream on the channel; sending, by the UE, the first index to the base station (4000, 6000); and sending, by the UE, the second index to the base station (4000, 6000), characterized in that the method is for determining a transmission rate supported by a data stream and the determining, by the UE, a second index corresponding to a difference between an instantaneous transmission rate supported by a data stream on the channel and an average transmission rate supported by the data stream on the channel comprises: determining, by the UE based on a second relationship table, that a CQI index corresponding to the difference between the instantaneous transmission rate supported by the data stream on the channel and the average transmission rate supported by the data stream on the channel is the second index, wherein the second relationship table is used to indicate a correspondence between the difference between the instantaneous transmission rate supported by the data stream on the channel and the average transmission rate supported by the data stream on the channel and a CQI index, wherein the channel comprises N data streams, wherein an eigenvalue corresponding to an (N-1)th data stream is greater than an eigenvalue corresponding to an Nth data stream, wherein N is an integer greater than 1, and the determining, by the UE based on a second relationship table, that a CQI index corresponding to the difference between the instantaneous transmission rate supported by the data stream on the channel and the average transmission rate supported by the data stream on the channel is the second index comprises: determining, by the UE based on a second index corresponding to at least one of a first data stream to the (N-1)th data stream, a fluctuation range of a difference between an instantaneous transmission rate supported by the Nth data stream and an average transmission rate supported by the Nth data stream; and determining, by the UE within the fluctuation range of the difference, that a CQI index corresponding to the Nth data stream is a second index corresponding to the Nth data stream. determining, by user equipment (3000, 5000) UE, a first index corresponding to an average transmission rate supported by a channel between the UE and a base station (4000, 6000); determining, by the UE, a second index corresponding to a difference between an instantaneous transmission rate supported by a data stream on the channel and an average transmission rate supported by the data stream on the channel; sending, by the UE, the first index to the base station (4000, 6000); and sending, by the UE, the second index to the base station (4000, 6000), characterized in that the method is for determining a transmission rate supported by a data stream and the determining, by the UE, a second index corresponding to a difference between an instantaneous transmission rate supported by a data stream on the channel and an average transmission rate supported by the data stream on the channel comprises: determining, by the UE based on a second relationship table, that a CQI index corresponding to the difference between the instantaneous transmission rate supported by the data stream on the channel and the average transmission rate supported by the data stream on the channel is the second index, wherein the second relationship table is used to indicate a correspondence between the difference between the instantaneous transmission rate supported by the data stream on the channel and the average transmission rate supported by the data stream on the channel and a CQI index, wherein the channel comprises N data streams, wherein an eigenvalue corresponding to an (N-1)th data stream is greater than an eigenvalue corresponding to an Nth data stream, wherein N is an integer greater than 1, and the determining, by the UE based on a second relationship table, that a CQI index corresponding to the difference between the instantaneous transmission rate supported by the data stream on the channel and the average transmission rate supported by the data stream on the channel is the second index comprises: determining, by the UE based on a second index corresponding to at least one of a first data stream to the (N-1)th data stream, a fluctuation range of a difference between an instantaneous transmission rate supported by the Nth data stream and an average transmission rate supported by the Nth data stream; and determining, by the UE within the fluctuation range of the difference, that a CQI index corresponding to the Nth data stream is a second index corresponding to the Nth data stream. determining, by the UE based on a second index corresponding to at least one of a first data stream to the (N-1)th data stream, a fluctuation range of a difference between an instantaneous transmission rate supported by the Nth data stream and an average transmission rate supported by the Nth data stream; and determining, by the UE within the fluctuation range of the difference, that a CQI index corresponding to the Nth data stream is a second index corresponding to the Nth data stream.