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CORNER |
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Cathal Mc Daid
December 2002 |
2006 Introduction: In the Fall of 2003, the Bluetooth SIG
Board of Directors adopted the current version of the Bluetooth
specification. Version 1.2 is the fourth generation of the
specification. The article below is from 2002, prior to the final
adoption of version 1.2.
Bluetooth Additional Profiles - Overview
Currently in the final stages of evaluation and approval, the Bluetooth
SIG is in the process of releasing 12 new profiles. In conjunction with
this, palowireless.com has also published on-line new
tutorials to these profiles. However, with the proliferation of
profiles and acronyms it is sometimes hard to see what these profiles
are designed to do. As an entry-level introduction, this article gives a
very brief outline of these new profiles and what roles they will allow
Bluetooth units to fill.
Bluetooth Profiles
Before we examine the new profiles, it is worthwhile
to recap what a Bluetooth Profile actually is. The Profiles
describe how the technology is used (i.e how different parts
of the specification can be used to fulfil a desired function for a
Bluetooth device). A profile can be described as a vertical slice through
the protocol stack. It defines options in each protocol that are mandatory
for the profile. It also defines parameter ranges for each protocol. The
profile concept is used to decrease the risk of interoperability problems
between different manufacturers' products. These profiles do not
(normally) define any additions to the Bluetooth specification, which is
why new profiles can be added where desired. The underlying Bluetooth
technology is the same, only the specific way that it is used is defined
and clarified.
Bluetooth Profile Dependency Stack
Above is a diagram of all the profiles currently
listed by the Bluetooth SIG website. (More are being developed, but they
are still under development/review and so are not yet open to the general
public.) The new profiles, like the existing profiles, can be divided into
different categories by many means. In this article the additional
profiles are going to be subdivided depending on whether their
underlying Profile is the Generic Access Profile (GAP), the Serial Port
Profile (SPP) or the Generic Object Exchange Profile (GOEP).
The full text of these additional
profiles are kept in the bluetooth.org website [2].
Alternatively, click on the profile's name below to get the palowireless
tutorial on each (Note: palowireless Premium Membership is required in
many cases).
Generic Access Profile (GAP) - Based Profiles.
Strictly speaking, all Bluetooth profiles are based
on the GAP Profile - the Generic Access Profile. However the additional
profiles covered here differ from the other additional profiles (in
general), in having the GAP profile as their immediate underlying profile.
(An exception to this case is the A2DP & VDP Profile - see
later). There are 9 profiles which fall into this category. They are:
- AVRCP - Audio/Video Remote Control Profile
- ESDP - Extended Service Discovery Profile
- CIP - Common ISDN Access Profile
- PAN - Public Area Network Profile
- HCRP - Hardcopy Cable Replacement Profile
- GAVDP - Generic Audio/Visual Distribution Profile
- A2DP - Advanced Audio Distribution Profile
- VDP - Video Distribution Profile
- HID - Human Interface Device Profile
AVRCP - Audio/Video
Remote Control Profile
Based on the GAP Profile, it uses a Controller (CT) - PDA, computer
mobile phone etc., that sends a command to a Target (TG) -
TV, discman, headphone etc. The command can be to Play, record, colour
control, volume control etc., depending on the nature of the devices
involved and the scenario. The commands are transported by a new
additional protocol, called the Audio/Video Control Transport Protocol
(AVCTP). Some scenarios defined are Remote Control from a Separate
Controller, Remote Control and Audio Stream Between Two Devices,
Remote Controller with LCD.
ESDP - Extended Service
Discovery Profile
This profile specifies an enhanced mechanism for service discovery and
control within Bluetooth environments , based on Universal Plug and Play
(UPnP). The profile defines two approaches to implementing UPnP
within a Bluetooth system either over the L2CAP layer, or an IP-based
solution based over the LAN Profile or PAN Profile - this is why the ESDP
profile appears in 3 places in the Profile Dependencies stack. In either
case the Local Device (LocDev) initiates the service discovery
while the Remote Device (RemDev), responds to the LocDev.
CIP - Common ISDN Access
Profile
Based on the GAP Profile, this profile uses an ISDN Client (IC)
to access the external network via an Access Point (AP). This
allows Bluetooth enabled devices to access ISDN services over a Bluetooth
link.
PAN - Public Area
Network Profile
This profile allows Bluetooth units to participate in a Personal Area
Network. This profile handles 2 types of PANs. The first, Network Access
Points, involves a Network Access Point (NAP), a device that
contains one or more Bluetooth radio devices that acts as a bridge between
a network (10baseT, GSM, etc) and the Bluetooth network units, called PAN
Units (PANUs). The second type of PAN handled is Group Ad-Hoc
Networks, which involves a master Bluetooth device, called a Group
Ad-Hoc Network point(GN) communicating with the Bluetooth network
units, again called PANUs. A new additional protocol, called the Bluetooth
Network Encapsulation Protocol (BNEP), is used to allow Ethernet
traffic to flow in the 2 different types of PANs.
HCRP - Hardcopy Cable
Replacement Profile
The aim of this profile is to allow a simple protocol for
communicating with hardcopy devices as if they were connected over a
locally attached cable. Typically a Client (such as a laptop),
sends data to a Server (such as a printer or scanner). Other other
profiles could cover this scenario, this profile, amongst other things,
provides a very lightweight flow control mechanism appropriate for the
high data volume of printing and scanning.
GAVDP - Generic
Audio/Visual Distribution Profile
This profile uses an Initiator (INT) – a device (such as a
portable player) that initiates a signalling procedure to send a request
to an Acceptor (ACP), - such as headphones etc. Although this
profile specifies signalling transaction procedures between two devices to
set up, terminate and reconfigure streaming channels, using to use the
GAVDP alone; it is required to use GAVDP in combination with profiles that
depend on this profile - the AVRCP and the VDP.
A2DP - Advanced Audio
Distribution Profile
This profile is based on the GAVDP, and allows advanced audio to be
transmitted (audio streaming) from a Source (SRK) - such as a CD
player, to a Sink (SNK), such as headphones.
VDP - Video Distribution Profile
This profile, also based on the GAVDP, is still under development and
not released at time of writing, bascially it resembles the A2DP but
specifies video streaming instead.
HID - Human Interface
Device Profile
This profiles, specifies the use of a Human Interface Device (HID),
such as a mouse, keyboard, joystick, etc, communicating human input in or
out to a Host - typically a PC, handheld,
etc. There are a variety of scenarios detailed in this scenario, such as
Desktop Computing, Remote Monitoring etc.
Serial Port Profile (SPP) - Based Profiles.
The second level of additional profiles is based on
the Serial Port Profile. The two profiles which fall into this
category are primarily concerned with control of cellular phones.
- HFP - Hands-Free Profile
- SIM - SIM Access Profile
HFP - Hands-Free Profile
This profile, based on the Serial Port Profile, allows hands-free use
of an Audio Gateway (AG) - typically a cellular
phone, by a Hands-Free unit (HF). The Hands-Free
unit acts as the AG's remote audio input/output mechanism. One use
case covered in this scenario is Operating a Phone via an In-Car Device,
whereas as the HF is a device installed in a car that allows control over
a mobile phone somewhere in the car.
SIM - SIM Access Profile
The aim of this profile is to allow remote access and control of a SIM
card (typically used to configure a mobile phone) via a Bluetooth link.
The SIM Access Server has direct access to the SIM card, and acts
as the SIM card reader, whereas the SIM Access Client can access
and control the SIM card via the Bluetooth link. A typical scenarios
involve a Client making a call using the subscription information from the
Server, (see below).
Generic Object Exchange Profile (GOEP) - Based Profiles.
The third and final level of additional profiles are
based on the Generic Object Exchange Profile. The two profiles which fall
into this category primarily enable pushing or browsing of data (either
image or text) on a remote device via a Bluetooth link.
- BIP - Basic Imaging Profile
- BPP - Basic Printing Profile
BIP - Basic Imaging
Profile
This profile is designed to optimise transfer of image information or
control. It involves using an Imaging Initiator, such as a
handheld. PC , etc. to select an image feature on a Imaging Responder,
such as a digital camera etc. One scenario covered is using a PC, (as the
Imaging Initiator), selecting and downloading content on a digital
camera, (the Imaging Responder).
BPP - Basic Printing
Profile
This profile is designed to enable wireless printing. The client
device that contains the information (the Sender), pushes the
object to be printed to the server device to be printed (the Printer).
A variety of scenarios are supported including printing of information
obtained by the Sender, which could be a mobile
phone, PDA, PC etc.
Conclusion
From the above brief overview, it can be clearly
seen that Bluetooth is being optimised for a myriad of different roles.
With these 12/13 new profiles, in addition to the 13 existing profiles,
Bluetooth's abilities are being solidified from vague goals to practical
real-world implementations. As more and more products implementing these
profiles are released, the true potential of Bluetooth should be realised,
showing to the user the practical uses of Bluetooth-enabled devices, as
opposed to industry promises & newspaper predictions of what Bluetooth
can do. If a picture is worth a thousand words, then a digital camera
transmitting a image to a mobile phone, via a Bluetooth link, is worth
even more to Bluetooth's future user up-take.
References:
[1] Bluetooth, The Bluetooth Specification, v.1.1 http://www.bluetooth.com/dev/specifications.asp
[2]
Bluetooth.org, Bluetooth Additional Profile Specifications
http://www.bluetooth.org/specifications.htm
[3] InfoTooth Profiles Tutorial
http://www.palowireless.com/infotooth/tutorial/profiles.asp
[3] InfoTooth Knowledge Base
http://www.palowireless.com/infotooth/knowbase.asp
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