Internal data width in SISO decoding module with modular renormalization

For the implementation of the soft-input soft-output (SISO) maximum a posteriori (MAP) decoding algorithm, it is important to simplify computation while selecting a minimum internal data width that does not affect the correctness of the soft output. This paper provides an estimation of the minimum internal data width and applies a modular renormalization technique to SISO decoders. Modular renormalization, which takes advantage of the inherent module operation in two´s complement arithmetic, is used as an alternative to subtractive normalization to accommodate the overflow of the forward path metrics and the backward path metrics without hardware cost