On the design of Doppler filters for next generation radio channel simulators

Real-time wireless channel simulators are necessary for radio prototyping. Doppler filter is one of the basic building blocks in correlation-based channel simulators. Enormous computational complexity of channel models for new wireless standards like MIMOs prohibit their software realizations (which have traditionally been the case). In first part of this work, we dimension and compare two alternative implementations of the Doppler filter, one using FIR and the other using IIR. Next we provide hardware implementations to come up with area and power requirements for Doppler filters for channels as complicated as 10 × 10 MIMOs to conclude that 5th order IIR filters with 32-bit fixed-point MAC provide near optimum accuracy, area and power consumption and become a logical choice for hardware implementations for wireless channel simulators. We also provide FPGA implementation of our design to indicate their strength and potential role in future simulators. Finally we extrapolate our results to indicate future trends in wireless channel simulator implementation.