A comparative study on the modified Max-Log-MAP turbodecoding by extrinsic information scaling

A simple but effective technique to improve the performance of the Max-Log-MAP algorithm is to scale the extrinsic information exchanged between two MAP decoders. A comprehensive analysis of the selection of the scaling factors according to channel conditions and decoding iterations is presented in this paper. Choosing a constant scaling factor for all SNRs and iterations is compared with the best scaling factor selection for changing channel conditions and decoding iterations. It is observed that a constant scaling factor for all channel conditions and decoding iterations is the best solution and provides a 0.2-0.4 dB gain over the standard Max- Log-MAP algorithm. Therefore, a constant scaling factor should be chosen for the best compromise.

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.

Law’s spatial turn: geography, justice and a certain fear of space

This is a critical reading of the current literature on law and geography. The article argues that the literature is characterized by an undertheorization of the concept of space. The focus is either on the specific geography of law in the form of jurisdiction, or as a simple terminological innovation. Instead, the article suggests that law’s spatial turn ought to consider space as a singular parameter to the hitherto legal preoccupation with time, history and waiting. This forces law into dealing with a new, peculiarly spatial kind of uncertainty in terms of simultaneity, disorientation, materiality and exclusionary corporeal emplacement. The main area in which this undertheorization forcefully manifests itself is that of spatial justice. Despite its critical potential, the concept has been reduced by the majority of the relevant literature into another version of social, distributive or regional justice. On the contrary, if the peculiar characteristics of space are to be taken into account, a concept of justice will have to be rethought on a much more fundamental level than that.