An FPGA Implementation of Stochastic Computing-based LSTM

As a special type of recurrent neural networks (RNN), Long Short Term Memory (LSTM) is capable of processing sequential data with a great improvement in accuracy and is widely applied in image/video recognition and speech recognition. However, LSTM typically possesses high computational complexity and may cause high hardware cost and power consumption when being implemented. With the development of Internet of Things (IoT) and mobile/edge computation, lots of mobile and edge devices with limited resources are widely deployed, which further exacerbates the situation. Recently, Stochastic Computing (SC) has been applied into neural networks (NN) (e.g., convolution neural networks, CNN) structure to improve the power efficiency. Essentially, SC can effectively simplify the fundamental arithmetic circuits (e.g., multiplication), and reduce the hardware cost and power consumption. Therefore, this paper introduces SC into LSTM and creatively proposes an SC-based LSTM architecture design to save the hardware cost and power consumption. More importantly, the paper successfully implements the design on a Field Programmable Gate Array (FPGA) and evaluates its performance on the MNIST dataset. The evaluation results show that the SC-LSTM design works smoothly and can significantly reduce power consumption by 73.24% compared to the baseline binary LSTM implementation without much accuracy loss. In the future, SC can potentially save hardware cost and reduce power consumption in a wide range of IoT and mobile/edge applications.