VLSI Design of Multi Standard Turbo Decoder for 3G and Beyond

Turbo decoding architectures have greater error correcting capability than any other known code. Due to their excellent performance turbo codes have been employed in several transmission systems such as CDMA2000, WCDMA (UMTS), ADSL, IEEE 802.16 metropolitan networks etc. The computation kernel of the algorithm is very similar and we have exploited this commonality for a turbo decoder VLSI design suitable for deployment using platform based system on chip methodologies. Turbo and Viterbi components of the unified array are also individually reconfigurable for different standards. This supports the 4G concept that user can be simultaneously connected to several access technologies (for example Wi-Fi, 3G, GSM etc.) and can seamlessly move between them. A new normalization scheme for turbo decoding is presented to suit reconfigurable mappings. We have also shown dynamic reconfiguration methodology for a context switch between turbo and Viterbi decoders which does not waste any clock cycles. The reconfigurable turbo decoder fabric is implemented reusing components of Viterbi decoder on a 180 nm UMC process technology.