The modified Max-Log-MAP turbo decoding algorithm by extrinsic information scaling for wireless applications

The iterative nature of turbo-decoding algorithms increases their complexity compare to conventional FEC decoding algorithms. Two iterative decoding algorithms, Soft-Output-Viterbi Algorithm (SOVA) and Maximum A posteriori Probability (MAP) Algorithm require complex decoding operations over several iteration cycles. So, for real-time implementation of turbo codes, reducing the decoder complexity while preserving bit-error-rate (BER) performance is an important design consideration. In this chapter, a modification to the Max-Log-MAP algorithm is presented. This modification is to scale the extrinsic information exchange between the constituent decoders. The remainder of this chapter is organized as follows: An overview of the turbo encoding and decoding processes, the MAP algorithm and its simplified versions the Log-MAP and Max-Log-MAP algorithms are presented in section 1. The extrinsic information scaling is introduced, simulation results are presented, and the performance of different methods to choose the best scaling factor is discussed in Section 2. Section 3 discusses trends and applications of turbo coding from the perspective of wireless applications.

The state and the development of an information society: Greek policy and experience

The paper looks into the dynamics of information society policy and its implementation in the Greek context. It argues that information society development is a contested process, influenced by pre-existing state, economy and society relations. Based on this, it looks into the different aspects of the idiosyncratic path which the evolution of the Greek information society has followed, particularly after 2000. Using Bob Jessop's strategic-relational approach (SRA) to the state as an analytical framework and drawing on a number of in-depth interviews with relevant political actors, it provides insights into policy implementation by examining: the public management of information technology projects, how such projects were received in bureaucratic structures and practices, as well as the relationship between the state and the information and communication technology (ICT) sector in public procurement processes. The emphasis is on the period 2000–2008, during which a major operational programme on the information society in Greece was put into effect. The paper also touches upon the post-2008 experience, suggesting that information society developments might include dynamics operating independently and even in contradiction to the state agenda.