Acceleration of FPGA Based Convolutional Neural Network for Human Activity Classification Using Millimeter-Wave Radar

Deep learning techniques have attracted much attention in the radar automatic target recognition. In this paper, we investigate an acceleration method of the convolutional neural network (CNN) on the field-programmable gate array (FPGA) for the embedded application of the millimeter-wave (mmW) radar-based human activity classification. Considering the micro-Doppler effect caused by a person’s body movements, the spectrogram of mmW radar echoes is adopted as the CNN input. After that, according to the CNN architecture and the properties of the FPGA implementation, several parallel processing strategies are designed as well as data quantization and optimization of classification decision to accelerate the CNN execution. Finally, comparative experiments and discussions are carried out based on a measured dataset of nine individuals with four different actions by using a 77-GHz mmW radar. The results show that the proposed method not only maintains the high classification accuracy but also improves its execution speed, memory requirement, and power consumption. Specifically, compared with the implementation of the same network model on a graphics processing unit, it could achieve the speedup of about 30.42% at the cost of the classification accuracy loss of only 0.27%.