Efficient FPGA Implementation of Equalizer for Finite Interval Constant Modulus Algorithm

This paper deals with the optimization of iterative algorithms with matrix operations or nested loops for hardware implementation in Field Programmable Gate Arrays (FPGA), using Integer Linear Programming (ILP). The method is demonstrated on an implementation of the Finite Interval Constant Modulus Algorithm, proposed for 4G communication systems. We used two pipelined arithmetic libraries based on the logarithmic number system or the floating-point number system, using the widely known IEEE format for the floating-point calculations required in the algorithm. Traditional approaches to the scheduling of nested loops lead to a relatively large code, which is unsuitable for FPGA implementation. This paper presents a new high-level synthesis methodology, which models both, iterative loops and imperfectly nested loops, by means of the system of linear inequalities. Moreover, memory access is considered as an additional resource constraint. Since the solutions of ILP formulated problems are known to be computationally intensive, important part of the article is devoted to the reduction of the problem size.