Serial Progressive Hierarchical Turbo Codes

Abstract

Future radio technologies are expected to deliver ever higher bit rates and a wider range of data applications to an increasing number of subscribers. Flexible and high performance unequal error protection techniques are necessary for better application level perceived quality with lower data rates. In this paper, we present a new generalized mechanism for enhanced usage of available spectral resources by embedding unequal error protection in serial turbo codes. The proposed coding scheme allows a progressive and hierarchical encoding of data, considering the prioritizations of information bits. A modified iterative decoding is also proposed. The turbo iterative gain fully benefits all decoding levels, even the least protected data encoded by a single recursive systematic convolutional code. The progressive and hierarchical transmission of extrinsic information from higher levels decoders strongly profit lower priority bits corrections due to inter-data contamination behavior. The prioritized data are hierarchically estimated. The proposed serial progressive hierarchical turbo code has been designed for maximum flexibility and for any number of unequally protected data.