A communication node arranged to communicate with another communication node using communications resources that are arranged in subframes, the communication node comprising: means for generating and outputting a control message for the other communication node which control message allocates communications resources within a plurality of subframes over which the communication node will transmit at least one codeword in each subframe for the other communication node, wherein the generating and outputting means is configured to use a plurality of HARQ processes to control transmission of data to the other communication node, such that a different HARQ process is used for each subframe within which communications resources are allocated to the other communication node by said control message; means for transmitting the codewords to the other communication node using the allocated communications resources within the plurality of subframes; and means for receiving, from the other communication node, ACK/NACK feedback for each codeword indicating acknowledgment of receipt or non-receipt of the codeword, wherein the receiving means is arranged to receive, during a subframe, aggregated ACK/NACK feedback from the other communication node indicating acknowledgment of receipt or non-receipt of each of a plurality of codewords transmitted by the communication node in different subframes, and is arranged to process the aggregated ACK/NACK feedback and to cause any codewords that were not received to be retransmitted to the other communication node; wherein the generating and outputting means is further configured: i) to split a plurality of available HARQ processes into two or more groups, the HARQ processes in each group being different; ii) to generate a first control message that allocates resources within a first plurality of subframes and a second control message that allocates resources within a second plurality of subframes; iii) to use HARQ processes from the first group for communications made using the resources allocated by the first control message; and iv) to use HARQ processes from the second group for communications made using the resources allocated by the second control message. means for generating and outputting a control message for the other communication node which control message allocates communications resources within a plurality of subframes over which the communication node will transmit at least one codeword in each subframe for the other communication node, wherein the generating and outputting means is configured to use a plurality of HARQ processes to control transmission of data to the other communication node, such that a different HARQ process is used for each subframe within which communications resources are allocated to the other communication node by said control message; means for transmitting the codewords to the other communication node using the allocated communications resources within the plurality of subframes; and means for receiving, from the other communication node, ACK/NACK feedback for each codeword indicating acknowledgment of receipt or non-receipt of the codeword, wherein the receiving means is arranged to receive, during a subframe, aggregated ACK/NACK feedback from the other communication node indicating acknowledgment of receipt or non-receipt of each of a plurality of codewords transmitted by the communication node in different subframes, and is arranged to process the aggregated ACK/NACK feedback and to cause any codewords that were not received to be retransmitted to the other communication node; wherein the generating and outputting means is further configured: i) to split a plurality of available HARQ processes into two or more groups, the HARQ processes in each group being different; ii) to generate a first control message that allocates resources within a first plurality of subframes and a second control message that allocates resources within a second plurality of subframes; iii) to use HARQ processes from the first group for communications made using the resources allocated by the first control message; and iv) to use HARQ processes from the second group for communications made using the resources allocated by the second control message.