Distributed audio synchronization scheme using audio endpoint inWASNs

In Wireless Audio Sensor Networks (WASNs), many applications such as target tracking, data fusion and localization, often require precise synchronization among audio streams. Extensive researches have been done under the assumption that wireless channel is well enough and the cluster head is power supplied. However, these conditions can not be satisfied in many applications. When audio event occurs, the burst of data is usually coupled with a high packet loss rate. Besides, the cluster head is usually battery-powered, especially in the wild environment. In this paper, we propose a distributed audio synchronization scheme to address these challenges. By dynamically detecting the endpoint of the audio streams and marking the start point of the audio synchronization obviously at the reporting sensor, we can eliminate the sound propagation delay effectively and synchronize the audio streams precisely even under the high packet loss rate. Moreover, by handling the synchronization task in a distributed way, we can lighten the burden of the cluster head and prolong the lifetime of the whole network greatly. To improve the flexibility of the scheme, we also propose a self-adaptive algorithm which can adjust the parameters of the synchronization according to the network condition. Experimentally, we show that the proposed scheme can synchronize the audio streams under different conditions with low energy cost.