An apparatus comprising means for: receiving a first bandwidth part configuration caused to support dynamic adaptation of transmission bandwidth part in listen before talk communication systems, the first bandwidth part configuration comprising at least two bandwidth parts: a first bandwidth part and at least one associated temporal bandwidth part; determining which of the at least two bandwidth parts is used for a transmission burst; determining for the transmission burst a second, temporal, bandwidth part configuration caused to determine the transmission parameters for the transmission burst based on the at least one associated temporal bandwidth part and the determining which of the at least two bandwidth parts is used for the transmission burst.