SCO Synchronous connection-oriented

SCO stands for Synchronous Connection-Oriented. It is a communication protocol used in Bluetooth technology for establishing a symmetric point-to-point connection between two devices. SCO is primarily designed for transmitting voice data or other time-sensitive information over Bluetooth connections.

Here is a detailed explanation of SCO and its key characteristics:

1. Purpose: The primary purpose of SCO is to support real-time audio streaming, such as voice calls or music playback, over Bluetooth connections. It ensures a reliable and time-bounded connection between devices to maintain the quality of audio data.
2. Connection Type: SCO is a connection-oriented protocol, which means it establishes a dedicated link between two devices. Unlike other Bluetooth protocols like ACL (Asynchronous Connection-Less), SCO guarantees a fixed bandwidth and time slot for data transmission, providing a constant stream of data.
3. Symmetric Connection: SCO connections are symmetric, meaning both the transmitting and receiving devices have an equal role in the communication. In a SCO link, both devices alternate sending and receiving data, allowing bidirectional audio communication.
4. Time Division Duplex (TDD): SCO utilizes a Time Division Duplex scheme for transmission. It means that the available frequency band is divided into time slots, and each device takes turns transmitting and receiving within its assigned time slot. This ensures that both devices have an equal opportunity to send and receive data during the connection.
5. Fixed Bandwidth: SCO connections offer a fixed bandwidth, typically 64 kbps. This fixed rate is suitable for transmitting voice data, as it provides a consistent stream of audio samples. The fixed bandwidth ensures that there is no variation in the data rate, which is crucial for maintaining audio quality.
6. Prioritizing Real-Time Data: Since SCO is primarily designed for real-time audio streaming, it has mechanisms to prioritize time-sensitive data over other types of Bluetooth traffic. This prioritization ensures that the audio data is transmitted and received without delays, reducing the chances of audio distortion or interruptions.
7. Limited Capacity: One important aspect to note is that Bluetooth devices have a limited number of SCO connections they can support simultaneously. This limitation is due to the fixed bandwidth and time slots available in the Bluetooth radio spectrum. The specific number of supported SCO connections may vary depending on the Bluetooth version and the capabilities of the devices involved.
8. Coexistence with ACL: In Bluetooth, there are two primary types of connections: SCO and ACL (Asynchronous Connection-Less). ACL is used for transmitting non-real-time data, such as file transfers or general data communication. SCO connections can coexist with ACL connections, allowing simultaneous voice transmission (using SCO) and data transfer (using ACL) between two devices.

In summary, SCO (Synchronous Connection-Oriented) is a Bluetooth protocol designed for real-time audio streaming. It establishes a symmetric, fixed-bandwidth connection between two devices, ensuring a reliable and time-bound transmission of voice data. It utilizes a Time Division Duplex scheme, prioritizes real-time data, and can coexist with ACL connections for simultaneous voice and data communication.