PlaySharing: A group synchronization scheme for media streaming services in hierarchical WLANs

This paper proposes a media sharing scheme for scalable media streaming and precise group synchronization services among adjacent mobile smart devices in wireless local area networks. For scalable media streaming, the structure of a hierarchical wireless media streaming network (HSN) is introduced to distribute streaming traffic to multiple wireless channels. It consists of a single IEEE 802.11 infrastructure network and multiple WiFi‐Direct networks. For group synchronization on a scale of milliseconds in the HSN, we propose PlaySharing, which combines event‐based synchronization, local adjustment of playback position errors, and rare and periodic synchronization. The goal of this paper is to demonstrate sustained precise synchronization by minimizing synchronization control packets during network congestion. Event‐based synchronization manages the synchronization between a media source device and client devices using event messages from the source device. To reduce the number of synchronization control packets, the local adjustment of playback position errors corrects those on the media client devices according to the expected playback position for the time elapsed since the last synchronization. Rare and periodic synchronization is applied in preparation for control packet loss, correcting the local adjustment errors when no event occurs. To evaluate the performance of the proposed scheme, the average synchronization errors between the source device and the client devices are measured using the user datagram protocol unicast and broadcast for control packet transmission in an IEEE 802.11 infrastructure network configuration and an HSN configuration. The experimental results show that the proposed scheme, with user datagram protocol unicast transmission of control messages in the HSN, has the lowest synchronization errors in the experiments.