Frame Based Memory Access Interpolation for A Digital Communication Modulator

This paper introduces an improved method for pulse shaping filtering in a digital communication modulator. This method uses memory to store different waveform frames instead of the FIR filter coefficients. At the run time, the interpolation for pulse shaping can be directly done by retrieving these waveforms from the memory without any arithmetic operations which are needed in the conventional FIR filter. Therefore, this method takes advantage of memory access to reduce the circuitry, and thus the time and power for these computations in the conventional FIR structure. Totally, N=K*L computations can be saved for every input symbol period, where N is the FIR order, K is the convolution order and L is the interpolation order. Frame based memory access interpolation can be generally used for all digital communication modulators, such as QPSK, 16-QAM and etc. This method has been implemented and verified by an integrated base band modulator for IEEE 802.15.4 868/912 MHZ band.