Other Bluetooth Profiles
The RFCOMM protocol emulates the serial cable line settings and status of an RS-232 serial port and is used for providing serial data transfer. RFCOMM connects to the lower layers of the Bluetooth protocol stack through the L2CAP layer.
Example Products
Here are a few examples of the types of devices that you might find using the RFCOMM:
- Printer
- Modem
- PC
- Laptop
By providing serial-port emulation, RFCOMM supports legacy serial-port applications while also supporting the OBEX protocol among others. RFCOMM is a subset of the ETSI TS 07.10 standard, along with some Bluetooth specific adaptations.
The Bluetooth logical link control and adaptation protocol (L2CAP) supports higher level protocol multiplexing, packet segmentation and reassembly, and conveys quality of service information.
L2CAP permits higher level protocols and applications to transmit and receive upper layer data packets(L2CAP Service Data Units, SDU) up to 64 kilobytes in length. L2CAP also permits per-channel flow control and retransmission via the Flow Control and Retransmission Modes.
The L2CAP layer provides logical channels, named L2CAP channels, which are mapped to L2CAP logical links supported by an ACL logical transport.
The service discovery protocol (SDP) provides a means for applications to discover which services are available and to determine the characteristics of those available services.
A specific Service Discovery protocol is needed in the Bluetooth environment, as the set of services that are available changes dynamically based on the RF proximity of devices in motion, qualitatively different from service discovery in traditional network-based environments. The service discovery protocol defined in the Bluetooth specification is intended to address the unique characteristics of the Bluetooth environment.
DUN provides a standard to access the Internet and other dial-up services over Bluetooth technology.
The most common scenario is accessing the Internet from a laptop by using your mobile phone as a wireless dial-up modem.
The DUN defines two roles, that of a Gateway (GW) and a Data Terminal (DT):
- Gateway (GW) — This is the device that provides access to the public network.
- Data Terminal (DT) — This is the device that uses the dial-up services of the gateway.
Example Products
A few examples of the types of devices that you might find using the DUN:
- Laptop
- PC
- Mobile phone
- PDA
- Modem