An improved decoding of tail-biting convolutional codes for LTE systems

In this paper, we propose an improved decoding algorithm for tail-biting convolutional codes (TBCC), which combines the maximum a posteriori (MAP) algorithm and the ordered statistics decoding (OSD). The cyclic redundancy check (CRC) code used as a outer code in long term evolution (LTE) systems can be involved into the proposed decoding algorithm to get a better performance. Since CRC loses its ability of error detection in the proposed algorithm, an alternative detection method is employed to control undetected error rate (UER). A effective method to achieve the cancellation of CRC scrambling is also carried out, when the proposed decoding is applied into physical downlink control channel (PDCCH) and physical broadcast channel (PBCH) in LTE. Simulation results show that 0.8-1.6dB performance gain is obtained with a negligible UER.