Towards Environment-Independent Activity Recognition Using Wi-Fi CSI with an Encoder-Decoder Network

Human Activity Recognition (HAR) has attracted considerable attention in recent years due to its potential applications in healthcare, smart homes, and security. Wi-Fi Channel State Information (CSI) is a promising sensor modality for HAR, providing a device-free and low-cost solution. However, building environment-independent models for HAR using Wi-Fi CSI remains a significant challenge. In this paper, we present a deep learning-based activity recognition system that exploits CSI measurements obtained from one or more environments to deliver consistent and accurate performance even in unseen environments. Our system employs a multi-task learning approach that is based on an encoder-decoder network architecture. This enables the encoder part of this architecture to mitigate the environment-dependent factors and extract a rich and environment-invariant representation. To evaluate the proposed system, we collected CSI samples for six activities pursued by three participants in four distinct environments. The results demonstrate the efficacy of the proposed system in achieving environment-independent HAR with an average accuracy of 80%. Additionally, the results validate the superiority of our method over environment-specific models by a minimum margin of 6% in cases of limited data.