Universal Serial Bus (USB), Bluetooth, Bluetooth Profiles

The USB initiative was an attempt by the IT industry to provide a simple, standardized
interface that could support many applications and was capable of plugand-
play operation. The outcome of this was the definition of the USB connection.
There are two major versions of USB: version 1.1, which supports
data rates of 1.5 Mbps (low-speed) and 12 Mbps (full-speed), was supplemented
recently by USB version 2.0, which supports 480 Mbps (high-speed).
USB is electrically and mechanically a very simple interface with data lines
and power connections that allows a USB host device to provide power to connected
devices. Although the USB standard has been modified over time to include
the possibility of USB ports on mobile phones and similar devices, many handset
vendors depart from the USB standard when it comes to the physical connection
of USB on the phone.

The standard USB connection is too large for mobile devices; and although a
small form-factor version is now in the standard, many handset vendors choose to
use a proprietary physical connection for the USB on their handset ranges. This
means that end users will require a manufacturer-specific cable to connect their
handsets to other USB devices.

Commonly, the USB port found on handsets operates at full-speed (12 Mbps),
with the handset acting as a USB device; some handsets support version 1.1 whereas

Bluetooth
Bluetooth is a radio-based connection option that aims to solve some of the issues
addressed by IrDA, in particular the number of different cables that users require
to interconnect the multitude of terminals they own.

To overcome some of the limitations of IrDA, Bluetooth operates in the 2.4-
GHz, Industrial, Scientific and Medical (ISM) band. The advantage
of this band is that it is license exempt, which means radio equipment operating in
this band can do so without users requiring operating licenses. However, to support
the coexistence of many radio applications in the band, it is regulated in terms of
usable power levels and spectrum parameters.

Bluetooth was developed by the telecommunications industry, so the initial focus
of the standard was to provide a means for mobile handsets to interconnect with
associated devices, such as headsets, PDAs, and laptop computers. However, because
of its ready availability, Bluetooth is finding its way into other consumer products.
The Bluetooth radio component operates across up to 79 channels in the 2.4-
GHz band and, to mitigate interference, frequency hops around these channels at
a rate of 1600 hops per second. It should be noted that the full range of Bluetooth
channels is not available in all countries because of local regulatory constraints. The
power classes defined for Bluetooth devices support typical ranges up to 10 meters,
although the class 1 devices at 20 dBm can achieve ranges greater than 100 meters.
more recent handsets support version 2.0.

Bluetooth Profiles
As the Bluetooth specifications were written, it became obvious that there were
numerous real-world applications for the technology and that it would be unrealistic
to include each and every one of these in the standards. Therefore, Bluetooth
is based on the concept of a series of defined profiles, where a profile specifies how
the Bluetooth protocols should operate to provide a set of functions. The profiles
can be viewed as a series of building blocks from which real applications can be
constructed. New profiles can be added to the Bluetooth standard after completing
an agreement process.

An example of the relationship between a usage model and profiles is the 3-
in-1 phone. The 3-in-1 phone has three operational modes: (1) it is able to act as a
normal mobile handset and access the cellular network; (2) it can use Bluetooth to
access a gateway device attached to a landline (therefore acting as a cordless phone);
and (3) it is able to connect directly to other handsets using Bluetooth (therefore
acting as an intercom device). This usage model is based on two Bluetooth profiles:
(1) the Cordless Telephony Profile (CTP) and (2) the Intercom Profile (IP)
Outside the profiles that support applications, there are two generic Bluetooth
profiles, known as the Generic Access Profile (GAP) and the Service Discovery
Application Profile (SDAP).

GAP concerns the discovery procedures that allow Bluetooth devices to find
one another, and includes functions for establishing a Bluetooth connection and
optionally adding security. SDAP is used by one Bluetooth device to discover what
services are offered by a remote Bluetooth device.

Although there are a number of WLAN standards on the market, the dominant
series are those produced by the Institute of Electrical and Electronic Engineers
(IEEE). The IEEE project 802 oversees standards for all LAN technologies,
both wired and wireless, and the working group 802.11 is responsible for WLAN
standards. IEEE 802.11 has defined three radio technologies for WLAN, known
as 802.11b, 802.11a, and 802.11g, and Draft 802.11n. These differ in terms of the
data rates they support and the spectrum band in which they operate. Two of the
WLAN standards are designed to operate in the 2.4-GHz ISM band, while the
third, 802.11a, operates in bands around 5 GHz.

The preexistence of radar systems at 5 GHz in Europe means that 802.11a systems
cannot be deployed in this region without suitable modification. Additional
interference mitigation techniques were added by the 802.11h standard, which
adapted 802.11a radio for use under European regulations.

The term “WiFi” (wireless fidelity) is often applied to 802.11 systems. WiFi is actually
a brand name that belongs to an industry association, the WiFi Alliance, whose role
is to test interoperability of WLAN products. Any device that carries the
WiFi mark will have been tested against a baseline implementation of the standards
and has been demonstrated to operate with products from other manufacturers.