A novel trellis-based searching scheme for EEAS-based CORDIC algorithm

The CORDIC algorithm is a well-known iterative method for the computation of vector rotation. For applications that require forward rotation (or vector rotation) only, the Extended Elementary Angle Set (EEAS) Scheme provides a relaxed approach to speed up the operation of the CORDIC algorithm. When determining the parameters of EEAS-based CORDIC algorithm, two optimization problems are encountered. In the previous work, greedy algorithm is suggested to solve these optimization problems. However, for the application that requires high-precision rotation operation, the results generated by greedy algorithm may not be applicable. In this paper, we propose a novel searching algorithm to overcome the aforementioned problem, called Trellis-based Searching (TBS) algorithm. Compared with the greedy algorithm used in the conventional EEAS-based CORDIC algorithm, the proposed TBS algorithm yields apparent performance improvement. Moreover, derivation of error boundary as well as computer simulations are provided to support our arguments.