A data reception unit for receiving a plurality of data streams over a data channel, the data streams being received as amounts of data and each amount of data comprising a data portion including data from a data stream and an identity portion identifying that data stream, the data reception unit comprising: a data stream memory comprising a plurality of data stream storage areas, each for storing data from a respective one of a set of the data streams, and an escape buffer; a first storage information memory for holding first storage information for facilitating storage in the respective data stream storage area of data from the set of the data streams; and a data storage controller for, for each received amount of data, receiving the identity portion of the amount of data and performing a storage operation comprising: accessing the first storage information memory; and if the first storage information memory holds first storage information for the data stream identified by the identity portion, storing the data portion of the amount of data in the data stream storage area corresponding to that data stream; and if the first storage information memory does not hold first storage information for the data stream identified by the identity portion, storing the data portion of the amount of data in the escape buffer; and a processing unit connected to the escape buffer for performing an assembly operation comprising executing steps to assemble the information stored in the escape buffer into respective data streams.