What is Synchronous Connection-Oriented (SCO) Link

Over the last few years, we have witnessed the emergence of many wireless systems and devices such as cellular phones, personal digital assistants, pagers, and other portable devices. However, they are often used separately, and their applications do not interact. One of the goals of personal area networks (PANs) (Bluetooth SIG, 2002a; Gavrilovska & Prasad, 2001) is to enable such a diverse set of devices to exchange information in a seamless, friendly, and efficient way. The emergence of Bluetooth (Bluetooth SIG, 2001b; Roberts, 2003) wireless technology promises such seamless networking. Bluetooth is an open industry standard that can provide short-range radio communications among small form factor mobile devices. Bluetooth is based on a high-performance, low-cost integrated radio transceiver and has been designed to provide a cable replacement technology with emphasis on robustness and low cost. Bluetooth supports two types of links: the synchronous connection-oriented (SCO) link and the asynchronous connectionless link (ACL). Figure 1 illustrates the Bluetooth protocol stack. The link manager protocol (LMP) performs link setup and configuration functions. The logical link and control adaptation (L2CAP) layer supports protocol multiplexing and connection-oriented/connectionless data services. The host controller interface (HCI) layer provides an interface to access the hardware capabilities of Bluetooth. In this article, we focus on the design and implementation of an architecture that (a) provides interoperability and connectivity of Bluetooth networks with other networks using Internet protocol (IP) technology and (b) enables Bluetooth mobile devices to wirelessly stream high-quality audio (greater bandwidth than toll quality voice) content from other Internet devices. We also investigate the efficiency of different design approaches that can be used by Bluetooth-enabled devices for high-quality audio streaming.