Generating error detection information for determining sequence lengths

摘要

Error detection information is used to determine the slot lengths of received control information sequences by performing cyclic redundancy checks (CRC) for all possible control information sequence lengths (1, 2 or 4 time slots corresponding to data packets of 1, 2 or 4/8 time slots respectively). When generating the error detection information at the transmitter, an initial value controller 400 provides registers 211-218 with different initial values corresponding to different control information sequence lengths in order to assist with the length detection process at the receiver, in particular to distinguish between 2 slot and 4 slot control sequences. For each control information sequence an operator generates a feedback bit sequence by sequentially adding bits of the control information to output bits of the final register and provides the feedback to adders. Application is to packet data control channels in a mobile communication system.