Design and implementation of alow complexity NCO based CFO compensation unit

The use of Orthogonal Frequency Division Multiplex (OFDM) modulation has become increasingly important for actual and future mobile communication systems [1]. Within this scope, Carrier Frequency Offset (CFO) compensation is indispensable [2]. Its underlying algorithm requires the calculation of trigonometric functions, which is difficult to achieve by hardware implementation in general. In this paper we propose a CFO compensation approach based on low complexity and hardware optimized linear function approximation. The Multiplier-less nonuniform Piecewise function Approximation (MPA) methodology significantly reduces the calculation effort of crucial algebraic terms. Matlab simulation is performed in order to prove the results in terms of feasibility. The compensation algorithm is also implemented in VHDL and synthesized as hard-wired Integrated Circuit (IC). A chip area of 0.034mm², a frequency of 181MHz and a total power consumption of 18.62μW/MHz are obtained.