A method of frame synchronization comprises receiving a stream of bits, the stream comprising a sequence of frames, wherein each frame comprises a frame counter value representing the number of the frame in the sequence, and frame check bits for checking the validity of the frame counter value. The method comprises decoding a first section of bits, and trailing a first portion of the first section of bits as a trial counter value, and a second portion of the first section of bits as trial check bits. The method comprises checking if the trial counter value corresponds to a valid frame counter value using the trial check bits, and synchronizing based on whether the trial counter value is determined to correspond to a valid frame counter value.