Wordlength optimization with complexity-and-distortion measure and its application to broadband wireless demodulator design

Many digital signal processing algorithms are first developed in floating point and later mapped into fixed point for digital hardware implementation. During this mapping, wordlengths are searched to minimize total hardware cost and maximize system performance. Complexity and distortion measures have been separately researched for optimum wordlength selection. This paper proposes a complexity-and-distortion measure (CDM) method that combines these two measures. The CDM method trades off these two measures using a weighting factor. The proposed method is applied to wordlength design of a fixed broadband wireless demodulator. For this case study, the proposed method finds the optimal solution in one-third the time that exhaustive search takes. The contributions of this paper are: (1) a generalization of search methods based on complexity or distortion measures; (2) a framework of automatic wordlength optimization; and (3) a wireless demodulator case study.