Data of a time transmission interval is to be transmitted in a wireless communication system. The wireless communication system uses adaptive modulation and coding and has automatic repeat request mechanism. A transmission time interval has a plurality of transport block sets. The transport block sets are transmitted with a first specified modulation and coding scheme. Each transport block set is received and a determination is made as to whether the transport block sets meet a specified quality. When the specified quality is not met, a repeat request is transmitted. The specified modulation and coding scheme is changed to a second specified modulation and coding scheme that may support a reduced number of TBS's within the transmission time interval. In response to the repeat request, at least one of the transport block sets is retransmitted. The retransmitted transport block set is received. The retransmitted transport block set may be combined with a corresponding previously received transport block set.