A Novel Area-Efficient T-Decoders For Recursion Computation

Abstract

Long Term Evaluation (LTE) has been used to achieve peak data rates in wireless communication system. Turbo codes are utilized as the channel encoding scheme. MAP algorithm has been used as a decoding scheme. Complexity in MAP algorithm is minimized by implementing the algorithm in log domain giving rise to Log MAP algorithm. The main purpose is for reducing the difficulty of state metric computation by employing of numerous algorithms and these algorithms differ only by their implementation of correction terms. By utilizing constant log MAP algorithm, linear log MAP algorithm, MAX log MAP algorithm, multi step log MAP algorithm and hybrid log MAP algorithm ACS unit is implemented.  The state metric calculation is implemented with the help of radix-4 Add -Compare-Select (ACS) unit. The distance calculation is involved between two concurrent computations of state metric can be shared among them which give rise to Maximum Shared Resource (MSR) architecture. The proposed implementation of these algorithms leads to reduction in the power dissipation, propagation delay and the number of logical elements used for the recursion computation in turbo decoders used in LTE system.