• AT: Attention sequence
• OBEX: Object Exchange
• TCS BIN: Telephony control protocol specification – binary
• BNEP: Bluetooth network encapsulation protocol
• SDP: Service discovery protocol
• RFCOMM: Radio frequency comm.
Radio Layer
• Radio layer defined the carrier frequencies and output power
• Bluetooth uses 2.4 GHZ license free band.
• Frequency hopping and TDD (time division duplex) is used for transmission with fast hopping rate of 1600 hops/s.
• It uses 79 hop carriers equally spaced with 1 MHz.
• Gaussian FSK used for modulation.
Baseband Layer
• Baseband layer performs frequency hopping to avoid interference and to access the medium.
• Defines physical links and many packet formats.
• It controls:
o Device Addressing
o Channel control through paging and inquiry methods
o Power saving operations
o Flow control and synchronization among Bluetooth devices.
Link Manager Protocol (LMP)
• The Link Manager protocol manages various aspects of the radio link between master and slave.
• The following functions are covered by LMP:
o Authentication, pairing and encryption
o Synchronization
o Capability negotiation
o QoS negotiation
o Power control
o Link Supervision
o State and transmission mode change
Logical Link Control and Adaptation Layer Protocol (L2CAP)
• L2CAP is layered over the Baseband Protocol and resides in the data link layer.
• L2CAP provides:
o Connection-oriented and connectionless data services to upper layer protocols with protocol multiplexing capability.
o Segmentation and reassembly operation.
o Group abstractions.
• L2CAP provides three different types of logical channels that are transported via ACL link between master and slave, these are:
o Connectionless used for broadcast
o Connection-oriented for data transfer with QoS flow specification.
o Signaling used to exchange signaling messages between L2CAP entities.
Host Controller Interface (HCI)
• The HCI provides a command interface to the baseband controller and link manager.
• It provides access to hardware status and control registers.
• Essentially this interface provides a uniform method of accessing the Bluetooth baseband capabilities.
• The HCI exists across 3 sections, The Host, Transport Layer, and Host Controller. Each of the sections has a different role to play in HCI system.
• HCI defines the set of functions of a Bluetooth module that are accessible to the host and its application.
• HCI can be seen as a software/hardware boundary.
RFCOMM
• The RFCOMM protocol provides emulation of serial ports over the L2CAP protocol.
• It is a cable replacement protocol that provides a serial line interface to all the applications.
• The protocol is based on the ETSI standard TS 07.10.
• It supports multiple serial ports over a single physical channel.
Service Discovery Protocol (SDP)
• The service discovery protocol helps the applications to discover which services are available and to determine the characteristics of those available services.
• SDP defines only the discovery of services, not about their usage.
• New service is discovered as follows:
o Client sends a request to search for an interested service.
o Then the server responds to the client with the list of available services that match to the client’s criteria.
o The client uses the list to retrieve additional service attribute for the service of interest.
Profiles
• Profiles are specifications which describe how Bluetooth should be used in a specific application and thus ensures that all devices from different manufacturers can seamlessly work with one another.
• There are about a dozen profiles:
Generic Access, Serial Port, Dial up Networking, FAX, Headset, LAN, Access Point, Generic Object Exchange (OBEX), File Transfer, Object Push, Synchronization, Cordless Telephony, and Intercom.
• The profile concept is used to decrease the risk of interoperability problems between different manufacturers’ products.
Telephony Control Protocol Specification Binary (TCS-BIN)
• To define call control signaling for the establishment of voice and data calls between Bluetooth devices TCS-BIN describes a binary, packet-based, bit-oriented protocol.
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