Patent ID: 8453020

Claim:
A method for detecting validity of downlink control information in a telecommunications terminal, comprising the steps of: reverse encoding a bit output sequence of a Viterbi decoder of a baseband receiver of the terminal using a similar convolutional encoder as one used at a transmitting side to form a reverse encoded bit stream; determining hard bits from a soft-bit output sequence of a demapping operation of the baseband receiver to provide a determined hard bit stream; determining, for each of said hard bits, whether a soft-bit from which it was derived was a real received bit or was inserted at the receiver in a rate de-matching operation, to obtain a bit count of real received bits; comparing the reverse encoded bit stream to the determined hard bit stream and counting number of mismatches to obtain an error count; determining a bit error rate as a quotient of said error count and said bit count; comparing said bit error rate against a predefined threshold value; and assuming a payload to be invalid if said bit error rate is above said threshold value, even if a cyclic redundancy check of the payload gives a correct result.