A low latency SISO with application to broadband turbo decoding

نویسندگان

  • Peter A. Beerel
  • Keith M. Chugg
چکیده

The standard algorithm for computing the soft-inverse of a finite-state machine [i.e., the soft-in/soft-out (SISO) module] is the forward–backward algorithm. These forward and backward recursions can be computed in parallel, yielding an architecture with latency ( ), where is the block size. We demonstrate that the standard SISO computation may be formulated using a combination of prefix and suffix operations. Based on well-known tree-structures for fast parallel prefix computations in the very large scale integration (VLSI) literature (e.g., tree adders), we propose a tree-structured SISO that has latency (log 2 ). The decrease in latency comes primarily at a cost of area with, in some cases, only a marginal increase in computation. We discuss how this structure could be used to design a very high throughput turbo decoder or, more generally, an iterative detector. Various subwindowing and tiling schemes are also considered to further improve latency.

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عنوان ژورنال:
  • IEEE Journal on Selected Areas in Communications

دوره 19  شماره 

صفحات  -

تاریخ انتشار 2001