Evaluation of BLE-based audio broadcasting under probabilistic interference

Abstract

Wireless Bluetooth audio communication has become an inherent part of everyday life, from listening to a podcast on our headphones to streaming music on multiple speakers. Up until now, broadcasting audio to multiple receivers has always required a proprietary implementation. Therefore, recent advances in the specification allow Broadcast Audio streams to be set up on top of Bluetooth Low Energy (BLE). To cope with the unpredictability of wireless media, audio frame retransmission opportunities are provided. However, determining the applicable number of retransmissions for a broadcast stream that is exposed to volatile environmental conditions, is a complex research challenge. This paper presents a model that is capable of simulating a BLE broadcast stream schedule, exposed to various environmental conditions while using a variable number of audio frame retransmissions. The evaluation employs several existing Packet Loss Concealment (PLC) techniques to cope with audio frame losses. The results provide insights into the impact of various frame loss patterns on the audio quality and intelligibility of broadcasted speech. The more advanced PLC techniques can handle a higher frame loss rate threshold. The analysis also shows that large audio frames requiring fragmentation exhibit a higher amount of frame loss for the same BLE packet loss rate and that overlap with in-use 802.11 channels can lead to a large variability in frame loss behavior. The model provides a baseline for the next research challenge related to continuous management of Broadcast Audio streams operating under volatile environmental conditions.