Adaptive Synchronization Control with Multi-level Buffer in Wireless Multimedia Sensor Networks

In Wireless Multimedia Sensor Networks (WMSNs), data fusion and collaborative in-network processing operations often require effective multimedia synchronization control. Extensive researches have been done in the traditional networks. Most of these works assume that there exists a powerful synchronization controller in the network. However, for WMSNs, the in-network processing of the multimedia content is usually performed based on the resource-constrained sensors. Traditional synchronization control algorithms fail to run on the low-end hardware platform. In this paper, we propose an adaptive synchronization control scheme with multi-level buffer to address this problem. Main contributions of this paper are as follows. (i) To overcome the resource constraint of WMSNs, we perform the synchronization control in a distributed way by combining the sensors in the stream transmission path. (ii) By evaluating the current network state, we adjust the level number of the buffer adaptively to balance the delay and delay jitter. (iii) Through analyzing the buffer state of each level, we propose an efficient packet scheduling scheme to reduce the delay jitter actively. (iv) We implement the proposed scheme and verify its effectiveness in our practical WMSNs platform. The experiment results show that the proposed scheme can maintain the streams synchronization effectively with the low-end sensors.