Lightweight Transformer in Federated Setting for Human Activity Recognition.

Human Activity Recognition (HAR) has been a challenging problem yet it needs to be solved. It will mainly be used for eldercare and healthcare as an assistive technology when ensemble with other technologies like Internet of Things(IoT). HAR can be achieved with the help of sensors, smartphones or images. Deep neural network techniques like artificial neural networks, convolutional neural networks and recurrent neural networks have been used in HAR, both in centralized and federated setting. However, these techniques have certain limitations. RNNs have limitation of parallelization, CNNS have the limitation of sequence length and they are computationally expensive. In this paper, to address the state of art challenges, we present a inertial sensors-based novel one patch transformer which gives the best of both RNNs and CNNs for Human activity recognition. We also design a testbed to collect real-time human activity data. The data collected is further used to train and test the proposed transformer. With the help of experiments, we show that the proposed transformer outperforms the state of art CNN and RNN based classifiers, both in federated and centralized setting. Moreover, the proposed transformer is computationally inexpensive as it uses very few parameter compared to the existing state of art CNN and RNN based classifier. Thus its more suitable for federated learning as it provides less communication and computational cost.