Seamless device handover for pervasive speech communication

Sustained growth in the smart speaker market has helped establish high quality, far-field speech communications as a viable alternative to the handset. Seamless handover offers a simple but effective way of improving the far-field communication experience by automatically switching to the best available device regardless of where a user is located. While the basic concept of seamless handover has been proven in a lab environment, this paper proposes two significant enhancements: reduction in media disruption during handover by introducing a parallel session on multiple devices through session initiation protocol (SIP) call forking; and, coherence-based signal processing to more accurately determine the most suitable device for the user. The solution proposed uses the magnitude square coherence (MSC) and results verified through simulation and real datasets show it has excellent performance. However, the raw MSC is found to have high variation due to room effects, consequently this work shows that a smoothing predictor is needed to significantly reduce the extraneous transitions that would otherwise be subjectively poor. Unlike a purely location based approach, the proposed solution selects the best smart device without any environment specific calibration making it ideal for straightforward deployment of a pervasive speech application that uses smart speakers.