wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

Bluetooth 49-3
49.1.2.5 Bluetooth 2.1 + EDR
The additional features are the added security features and the improved latency for encrypted channels
and power consumption, as well as an enhanced quality of service.
49.1.2.6 Bluetooth 3.0 + HS
Bluetooth 3.0 + HS (high speed) is the latest Bluetooth technology standard operating since April 22,
2009. The interesting fact is that it did not deprecate any existing Bluetooth technology-supported
feature. Bluetooth 3.0 has significantly improved its speed, and now, it is no longer a mere dream to
be able to wirelessly transfer a bulk of music libraries between a PC and a music player, to download
a bulk of images from a camera to a PC, and to send video files from a cameraphone to a computer or
a television. The said standard has incorporated the following major improvements:
• An 802.11 protocol adaptation layer—to offer compatibility with existing high-speed wireless
networks, and which can now support up to a 24.Mbps data transfer rate
• Unicast connectionless data—a challenge for wireless communications media to support
Bluetooth, instead of multicast data
• An enhanced retransmission and a streaming mode—to support real time services (audio and
video) over a low-speed and a short-range network
49.2 Bluetooth Core Architecture Blocks
The Bluetooth core system covers the four lowest layers and the associated protocols defined by the
Bluetooth specification, as well as one common service layer protocol, the service discovery protocol
(SDP), and the overall profile requirements that are specified in the generic access profile (GAP). A complete
Bluetooth application requires a number of additional services and higher layer protocols that are
defined in the Bluetooth specification [1].
The common implementation of Bluetooth is shown in Figure 49.1. The three lowest layers are known
as the Bluetooth controller and are typically found on a single chip, while the uppers are known as the
Bluetooth host. In order to achieve interoperability between different Bluetooth device interfaces, the host
controller interface (HCI) is specified, which uses a UART or a USB interface as the transport layer. The
implementation of the protocols should conform to the following logical structure and not exactly what is
shown in the diagram. These logical units work together as the core controllers of Bluetooth technology.
49.2.1 Channel Manager
The channel manager block has the following responsibilities:
• It uses the L2CAP protocol to interact with a remote device and to connect its end points to the
appropriate entities.
• It interacts with its local link manager to create new logical links.
• It configures the above links for the provision of quality of service of the transported data.
49.2.2 L2CAP Resource Manager
This block is responsible for the following:
• Managing the ordering of the PDU fragments sent to the baseband.
• Maintaining some scheduling between channels for QoS. This is required as the Bluetooth
controller does not have limitless buffering or an HCI, which is a pipe of infinite bandwidth.
• Offering policing services by the L2CAP resource manager to the submitted L2CAP SDUs against
their QoS settings.
© 2011 by Taylor and Francis Group, LLC