Bluetooth profiles

- definition and overview of Bluetooth profiles giving details how they operate and information about major Bluetooth profiles including Bluetooth Headset Profile.

In order to enable Bluetooth devices to communicate properly with each other, Bluetooth profiles are used. A Bluetooth profile is effectively a wireless interface specification for communication between Bluetooth devices.

In order to be able to operate, a Bluetooth device must be compatible with a subset of the profiles available sufficient to enable it to utilise the desired Bluetooth services.

Bluetooth profile basics

A Bluetooth profile resides on top of the Bluetooth Core Specification and possibly above any additional protocols that may be used. While a particular Bluetooth profile may use certain features of the core specification, specific versions of profiles are rarely linked to specific versions of the core specification. In this way upgrades are achieved more easily.

The way a particular Bluetooth device uses Bluetooth technology depends on its Bluetooth profile capabilities. The Bluetooth profiles provide standards which manufacturers follow to allow devices to use Bluetooth in the intended manner.

At a minimum, each Bluetooth profile specification contains details of the following topics:

  • Dependencies on other formats
  • Suggested user interface formats
  • Specific parts of the Bluetooth protocol stack used by the protocol. To perform its task, each profile uses particular options and parameters at each layer of the stack. This may include an outline of the required service record, if appropriate.

Bluetooth profiles

Overviews of the different Bluetooth profiles are tabulated below:


Bluetooth Profile Details
Advanced Audio Distribution Profile (A2DP) This Bluetooth profile defines how stereo quality audio can be streamed from a media source to a sink.

This Bluetooth profile defines two roles of an audio device: source and sink:

  1. Source (SRC):   A device is the SRC when it acts as a source of a digital audio stream that is delivered to the SNK of the piconet.
  2. Sink (SNK):   A device is the SNK when it acts as a sink of a digital audio stream delivered from the SRC on the same piconet.
Audio/Video Remote Control Profile (AVRCP) This Bluetooth profile provides a standard interface to control audio visual devices including televisions, stereo audio equipment, and the like. It allows a single remote control (or other device) to control all the equipment to which a particular individual has access.

The AVRCP Bluetooth profile defines two roles:

  1. Controller:   The controller is normally the remote control device
  2. Target:   As the name suggests, this si the device that is being controlled or targeted and whose characteristics are being altered

This Bluetooth profile protocol specifies the scope of the AV/C Digital Interface Command Set that is to be used. This protocol adopts the AV/C device model and command format for control messages and those messages are transported by the Audio/Video Control Transport Protocol (AVCTP).

When using AVRCP, the controller detects the user action, i.e. button presses, etc and then translates them into the A/V control signal. This control signal is transmitted it to the remote Bluetooth enabled device. In this way, the functions available for a conventional infrared remote controller can be realized over Bluetooth, thereby providing a mode robust form of communications.

Basic Imaging Profile (BIP) This Bluetooth profile details how an imaging device can be remotely controlled, how it may print, and how it can transfer images to a storage device. This Bluetooth profile is naturally intended for cameras and other devices that can take pictures, including mobile phones now.

The Basic Image Profile, BIP defines two roles:

  1. Imaging Initiator:   This is the device that initiates this feature.
  2. Imaging Responder:   As the name implies, this si the device that responds to the initiator.

The overall profile may be considered to have the following actions:

  1. Image Push:   This function allows the sending of an image from a device controlled by the user.
  2. Image Pull:   This function within the Bluetooth profile allows browsing nd retrieval of images from a remote device, i.e. pulling images from a remote source.
  3. Advanced Image Printing:   This provides for the printing of images using a number of advanced options.
  4. Automatic Archive:   This function enables the automatic backup of all new images from a target.
  5. Remote Camera:   This function allows the remote control of a camera by an initiator.
  6. Remote Display:   This allows for the Imaging Initiator to push images to another device for display.
Basic Printing Profile (BPP) This Bluetooth profile allows devices to send text, e-mails, v-cards, images or other information to printers based on print jobs.

As would be expected te Basic Printing Profile, BPP defines two roles:

  1. Printer:   This is the device that manipulates the data to be printed. Typically this would be a physical printer.
  2. Sender:   This is a device, possible a mobile phone or other form of user equipment, UE, that needs to print some data, but without wanting the full overhead of a print driver.

The advantage of using the Basic Print Profile, BPP rather than the HCRP is that it does not need any printer-specific drivers. This makes it particularly applicable for use with embedded devices such as mobile phones and digital cameras.

Common ISDN Access Profile (CIP) This Bluetooth profile details the way in which ISDN traffic can be transferred via a Bluetooth wireless connection. It is typically used in Bluetooth enabled office equipment that is ISDN enabled.

The CIP defines two roles within the Bluetooth profile:

  1. Access Point (AP):   This node is connected to the external network and acts as an endpoint for it. It handles all the interworking associated with the external ISDN
  2. ISDN Client (IC):   This is the remote node accessing the Access Point via the Bluetooth wireless network or link
Cordless Telephony Profile (CTP) This Bluetooth profile defines how a cordless phone can be implemented using Bluetooth. This Bluetooth profile is aimed at use for either a dedicated cordless phone or a mobile phone acting as a cordless phone when close to a CTP enabled base station. The aim of this Bluetooth profile was to allow a mobile phone to use a Bluetooth CTP gateway connected to a landline when within the home or office, and then use the mobile phone network when elsewhere.

Two roles are defined within this Bluetooth profile:

  1. Terminal (TL):   This is the user equipment, and may be a cordless phone or a mobile phone, etc.
  2. Gateway (GW):   The gateway acts as the access point for the terminal to the landline or other network.
Dial-Up Network Profile (DUN) This Bluetooth profile details a standard for accessing the Internet and other dial-up services via a Bluetooth system. This may be required when accessing the Internet from a laptop by when using a mobile phone, PDA, etc as a wireless dial-up modem.

This user Bluetooth profile defines two roles for the Bluetooth nodes:

  1. Gateway (GW):   This is the Bluetooth node or device that provides the access to the public network and ultimately the Internet.
  2. Data Terminal (DT):   This is the remote node that interfaces with the Gateway via the Bluetooth wireless link.
Fax Profile (FAX) This Bluetooth profile defines how a FAX gateway device can be used. This Bluetooth profile may be needed when a personal computer uses a mobile phone as a FAX gateway to send a FAX.

There are two roles for this Bluetooth profile

  1. Gateway (GW):   This is the Bluetooth enabled device that provides facsimile services.
  2. Data Terminal (DT):   This device connects via the Bluetooth wireless link to be able to send its FAX.
File Transfer Profile (FTP) This Bluetooth profile details the way in which folders and files on a server can be browsed by a client device. This Bluetooth profile may be used for transferring files wirelessly between two PCs or laptops, or browsing and retrieving files on a server.

Two roles are defined for this Bluetooth profile:

  1. Client:   This is the device that initiates the operation and pushes or pulls the files to or from the server.
  2. Server:   This is the target device and it is remote from the device that pushes or pulls the files.
General Audio/Video Distribution Profile (GAVDP) This Bluetooth profile provides the basis for the A2DP and VDP Bluetooth profiles. These are used for systems designed for distributing video and audio streams using Bluetooth technology. This may be used in a variety of scenarios, e.g. with a set of wireless stereo headphones and a music player - the music player sends messages to the headphones to establish a connection or adjust the stream of music, or vise versa.

Two roles are defined within this Bluetooth profile:

  1. Initiator (INT):   This device initiates the signalling procedure.
  2. Acceptor (ACP):   This device responds to the incoming requests from the initiator.
Generic Object Exchange Profile (GOEP) This Bluetooth profile is used to transfer an object from one device to another. One example may be in the exchange of vCards between devices such as mobile phones, PDAs, etc.

Two roles are defined within this Bluetooth profile:

  1. Server:   For this Bluetooth profile, this is the device that provides an object exchange server for which data objects can be pushed or pulled.
  2. Client:   This is the device that can pushes or pulls data to and from the server.
Hands-Free Profile (HFP) The HFP Bluetooth profile details the way in which a gateway device may be used to place and receive calls for a hands-free device. This profile adds considerable additional functionality over the original Headset Profile, HSP, allowing remote control, etc. The Bluetooth profile defines two roles:

  1. Audio Gateway (AG):   The audio gateway is normally the mobile phone of car kit and it provides connectivity to the source of the voice data.
  2. Hands-Free Unit (HF):   This is the device which acts as the remote audio input and output mechanism for the Audio Gateway. It also provides some remote control means.

The Handsfree Bluetooth profile uses a CVSD codec for voice transmission cross the Bluetooth link and it also defines a number of voice control features including volume.

Hard Copy Cable Replacement Profile (HCRP) This Bluetooth profile defines how driver-based printing is achieved over a Bluetooth link. As might be expected, it is used for wireless links for printing and scanning.

Two roles are defined within this Bluetooth profile:

  1. Server:   This is the server device that offers the HRCP service - typically it is a printer.
  2. Client:   The client is a device containing a print driver on which the client device wishes to print - typically this may be a laptop or other computer wishing to print documents.
Headset Profile (HSP) The Bluetooth Headset Profile details how a Bluetooth enabled headset communicates with a Bluetooth enabled device. As might be anticipated the Bluetooth Headset Profile was aimed at defining how Bluetooth headsets may connect to a mobile phone or installed car kit. It defines two roles:

  1. Audio Gateway:   The device that is the gateway of the audio both for input and output. This would typically be a mobile phone, car kit, or a PC.
  2. Headset:   The Headset is defined within the Bluetooth Headset Profile as the device acting as the remote audio input and output connected to the gateway via the Bluetooth link.
Human Interface Device Profile (HID) This Bluetooth profile details the protocols, procedures and features to be used by Bluetooth keyboards, mice, pointing and gaming devices and remote monitoring devices.

Two roles are defined within this Bluetooth profile:

  1. Human Interface Device (HID):   The device providing the human data input and output to and from the host. Typical examples may be a keyboard or a mouse.
  2. Host:   The device using the services of a Human Interface Device. This may typically be a computer or laptop, etc
Intercom Profile (ICP) This profile details the way in which two Bluetooth enabled mobile phones in the same network can communicate directly with each other, i.e. acting as an intercom. As the intercom usage is completely symmetrical, there are no specific roles defined for this Bluetooth profile. However when using the Intercom Profile, the devices at either end of the link will be denoted as a Terminal (TL).
Object Push Profile (OPP) This Bluetooth profile details the roles of a push server and a push client. These roles need to interoperate with the server and client device roles defined within the GOEP Bluetooth profile.

The OPP defines two roles:

  1. Push Server:   This is the device within this Bluetooth profile that provides an object exchange server
  2. Push Client:   This device pushes and pulls objects to and from the Push Server and initiates the actions.
Personal Area Networking Profile (PAN) This Bluetooth profile details the way in which two or more Bluetooth enabled devices can form an ad-hoc network. It also details how the same mechanism can be used to access a remote network through a network access point.

The PAN is somewhat more complicated than other Bluetooth profiles and requires the definition of three roles:

  1. Network Access Point (NAP) and NAP Service:   In view of the similarities with Ethernet networks, the NAP can be considered as being equivalent an Ethernet bridge to support network services.
  2. Group Ad-hoc Network (GN) and GN Service:   - A Bluetooth device that supports the GN service is able to forward Ethernet packets to each of the Bluetooth devices that are connected within the PAN.
  3. PAN User (PANU) and PANU Service:   As the name indicates the PANU is the Bluetooth device that uses either the NAP or the GN service
Service Discovery Application Profile (SDAP) The SDAP is a Bluetooth profile that describes how an application should use the Service Discovery Procedure, SDP to discover services on a remote device. SDAP can adopt a variety of approaches to managing the device discovery via Inquiry and Inquiry Scan and service discovery via SDP. The ideas contained in the SDAP specification augment the basic specifications provided in GAP, SDP, and the basic processes of device discovery.

The SDAP defines two roles as given below:

  1. Local Device (LocDev):   This is the Bluetooth deveice that initiates the service discovery procedure.
  2. Remote Device (RemDev):   There may be one or more RemDevs and these are any device that participates in the service discovery process by responding to the service inquiries it may receive from a LocDev.
Service Port Profile (SPP) This Bluetooth profile details the way in which virtual serial ports may be set up and how two Bluetooth enabled devices may connect.

This Bluetooth profile defines two roles for communication to proceed:

  1. Device A:   The Device A is recognised as the device that initiates the formation of a connection to another device. It may also be thought of as the Initiator.
  2. Device B:   This may be thought of as the Acceptor and it is the device that responds to an Initiation process.
Synchronization Profile (SYNC) This Bluetooth profile is used in conjunction with GOEP to enable synchronization of calendar and address information (personal information manager (PIM) items) between Bluetooth enabled devices.

There are two main roles within this Bluetooth profile:

  1. IrMC Server:   The device that takes on the role of object exchange server will become the IrMC Server. Typically this device will be the mobile phone, PDA, etc.
  2. IrMC Client:   This device is typically a PC, and it is the device that contains the sync engine and pulls and pushes the PIM data to and from the IrMC server.
Video Distribution Profile (VDP) This Bluetooth profile details how a Bluetooth enabled device is able to stream video over a Bluetooth link. It could be used in a variety of scenarios such as streaming video data from a storage areas such as on a PC to a mobile player, or from a video camera to a television, etc.

There are two roles defined within this Bluetooth profile:

  1. Source (SRC):   As the name suggests the SRC is the origination point of the streamed video on the piconet.
  2. Sink (SNK):   Within this Bluetooth profile, the SNK is the destination for the digital video stream on the same piconet as the SRC.

There are over twenty different Bluetooth profiles, each having their own function. Naturally some of these Bluetooth profiles are used more than others, but each one may be used in a variety of different places and applications.

By Ian Poole


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