Network node, method and computer program for unlicensed spectrum operation

Abstract

A network node is arranged to provide communication at least in an unlicensed band where clear channel assessment, CCA, is required before transmissions. The unlicensed band comprises a plurality of carriers, or sets of carriers, defining channels. The network node is arranged to prepare code block groups comprising code blocks from transport blocks, which transport blocks each comprises a payload intended for a respective receiver, wherein each code block comprises a checksum enabling a hybrid automatic repeat request, HARQ, procedure on a per code block group basis, map the code block groups to a wideband signal comprising a consecutive set of channels on the carriers of the unlicensed band, assess whether the channels, respectively, are clear, and transmit the code block groups mapped on the channels which are clear and omit transmissions of code block groups mapped on channels that are not clear, wherein the assessment and the transmissions are performed within a first time interval, and transmit code blocks groups omitted to be transmitted using the HARQ procedure for retransmission prior receiving a non-acknowledgement, NAK, from a respective receiver of the code block group.