1. A method for selecting a best transmission mode for frame between a base station and a mobile terminal in a wireless channel in every channel conditions, comprising receiving at the base station as a response to a request to the mobile terminal at least one condition figure indicating instantaneous condition of a channel, mapping at the base station the condition figure to a first threshold range, said first threshold range being limited with a first minimum threshold value and a first maximum threshold value and being predefined to correspond the condition figure, selecting at the base station a comparison value to be within the first threshold range, comparing at the base station the comparison value to at least one second threshold range being limited with a second minimum threshold value and a second maximum threshold value, wherein each of said second threshold ranges is stored in the base station and is pre-determined to correspond to a transmission mode of a best transmission data rate, selecting at the base station the transmission mode corresponding to the second threshold range within which the comparison value belongs in order to transmit the frame forwards, wherein the transmission mode comprises at least selection of one of multiple-input multiple-output mode, modulation and coding.