Push-to-Talk over Bluetooth

Push-to-Talk over Cellular (PoC) is an emerging service enabling a walkie-talkie-like service over GPRS. An open standard for PoC has been specified by the Open Mobile Alliance (OMA) [1]. OMA PoC is based on an IP/UDP/RTP protocol stack and a client-server based architecture. Group management, floor control1 etc are administered by PoC servers. The systems exploits the SIP signalling capabilities of the IP Multimedia Subsystem (IMS) [2]. The objective of this paper is to propose an outline for a Push-to-Talk (PTT) system that utilizes a Bluetooth scatternet and the Personal Area Networking (PAN) profile for data communications [3], [4]. The proposed system is thus fully independent of cellular networks. A reasonable range of several hundred meters can be obtained with multihop communications between Bluetooth class 1 devices, whose range is up to 100 m. The proposed outline for Push-to-Talk over Bluetooth (PoB) comprises e.g. methods for group formation, network formation, communication, and floor control. The network formation method, which can be utilized in other applications as well, is based on creating a scatternet among a predefined set of devices and on avoiding loops. This approach enables usage of a simple broadcasting based communication method, in which the devices bridging the piconets into a scatternet act as repeaters.