diagram of a mobile station device for transmitting reverse data rate information on an r rich in a 1xev dv system according to an embodiment of the present invention the r rich is a channel that transmits information about the data rate of a reverse sch to a base station the base station recovers the original data received from a mobile station by obtaining information about the presence of data or the absence of data modulation and channel encoding through recovery of an r rich received from the mobile station a method of transmitting receiving an r rich according to the present invention is also applicable to systems other than 1xev dv referring to fig3 the mobile station receives information regarding its available maximum data rate from the base station and the data rate information transmitter in the mobile station transmits reverse data rate information in relation to the maximum data rate to the base station a controller 301 determines the number of available data rates less than or equal to the maximum data rate based on the received reverse data rate information referring to a set of data rates stored in a memory table 306 or 307 and then determines a number of bits for an r rich sequence based on the number of available data rates the bit number is a minimum integer determined by the number of the available data rates the controller 301 maps the available data rates to r.