A data packet comprises a header and a payload. At least one digital signal processor is used to configure the payload to transport at least one full service data unit, one or two service data unit fragments, or at least one full service data unit and at least one service data unit fragment. A service data unit fragment is only located (i) at the beginning of the payload or at the end of the payload or (ii) at the beginning of the payload and at the end of the payload. At least one digital signal processor is used to configure a single field in the header consisting of a first bit and a second bit, even when a number of full service data units and service data unit fragments in the payload is more than two, the single field indicating whether (i) the payload begins with a fragment of a service data unit and (ii) the payload ends with a service data unit fragment. At least one digital signal processor is used to form the data packet including the configured header and the configured payload. A transmitter transmits the data packet.