1. A method for minimizing errors in communicating packets, for use in a multiple-input-multiple-output (MIMO) space-time coded (STC) packet radio communications system having at least three transmit antennas, the method comprising: a) determining a sequence of at least three distinct transmitter STC code mappings for at least three time slots, the transmitter STC code mappings comprising at least three transformed STC symbols derived from at least three base STC symbols; b) transmitting a packet using a first STC code mapping in the sequence; c) detecting a first transmission error and retransmitting the packet using a subsequent STC code mapping in the sequence; d) detecting a subsequent transmission error and, if there are further STC code mappings, retransmitting the packet using a further subsequent STC code mapping in the sequence, else retransmitting the packet using the first STC code mapping in the sequence; e) repeating the step d) as necessary; wherein the sequence of at least three distinct transmitter STC code mappings is such that each of the at least three transformed STC symbols is transmitted over the at least three antennas in the at least three time slots.