Transmission of data from a portable communication device to a base station via a radio frequency signal uses a plurality of modulation and coding schemes and a protocol that has recurring frames. Each frame has a plurality of transmission slots, different numbers of which can be used to transmit data. When it is desired to transmit data, a higher rate than was used previously, an attempt is made to increase the number transmission slots being used. If doing so, produces a transmission results in a specific absorption rate limit being exceeded, then the modulation and coding scheme is changed to one having a greater data coding rate. The power level and the number transmission slots then are set so that the data transmission does not exceed the specific absorption rate limit. The data is then transmitted by the portable communication device.