On the Tail-Biting Convolutional Code Decoder for the LTE and LTE-A standards'

In this paper, we consider the design of the Tail-Biting Convolutional Code Decoder (TB-CCD) for the Long Term Evolution (LTE) system. Tail-biting convolutional coding is used for channel coding on two downlink channels, namely the Physical Broadcast Channel (PBCH) and the Physical Downlink Control Channel (PDCCH). The decoding in the latter channel occurs blindly, with the decoder having no prior knowledge of the location of the desired bits. The crucial constraint on the TB-CCD design will be the required decoding time and the exhaustive processing for the PDCCH blind decoding. The TB-CCD will be required to carry out at most 44 decoding attempts per LTE subframe, which has a duration of 1 ms. In this paper, we describe the various aspects of our design that result in savings in processing time and complexity while showing negligible performance degradation. We then provide a description of the implementation architecture for the selected TB-CCD design and briefly describe the verification process.