MAP decoder with bidirectional sliding window architecture

Abstract

A MAP decoder, or a turbo decoder having constituted MAP decoders, is configured with bi-directional sliding windows. A sliding window architecture is applied to the forward state metric (FSM) calculation of an encoded data block having a trellis with N time-steps. The data block is divided into smaller sub-blocks and a forward recursion of two or more of the sub-blocks are performed in parallel to obtain FSMs. Each sub-block overlaps with a previous sub-block by k time-steps, where k is an integer value greater than zero. This provides a good approximation of the FSMs at time-step k + t of the sub-block. The FSMs associated with the first k time steps of each sub-block, other than the first sub-block, are discarded. A reverse recursion of each sub-block is also performed to obtain reverse state metrics (RSM) for the sub-block. Likelihood ratios are then calculated based on the FSMs and RSMs.

Description

[0001] Priority claims under 35 USC 119 [0002] This patent application claims the benefit of provisional patent application No. 60 / 762,764, filed January 27, 2006, entitled "MAP Decoder with Bi-Directional Sliding Window Architecture" (MAP decoder with Bi-Directional Sliding Window Architecture) priority; this application is assigned to the present assignee, which application is expressly incorporated by reference into this specification. technical field [0003] Various embodiments of the present invention are applicable to communication systems, and more specifically, to devices and / or methods for decoding data in digital communication systems. Background technique [0004] Various techniques are used in communication systems to increase the amount of information transmitted while minimizing transmission errors. In these communication systems, information is usually represented as a sequence of binary bits or as blocks of bits called frames. Binary information is modul...

AI Technical Summary

Problems solved by technology

[0009] Another difficulty of the traditional MAP algorithm is that sequential processing (i.e., forward recursion and reverse recursion) cannot satisfy the constraint of decoding time

In particular, forward recursion and subsequent reverse recursion over the binary trellis of blocks may take longer than rate-sensitive applications will allow

Decoding of data blocks may take longer than expected by rate-sensitive applications

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