WIRELESS CONNECTIVITY AND MOBILE APPLICATIONS generate, create data matrix 2d barcode none with java projects Console application and data transmi jboss 2d Data Matrix barcode ssion, so it is very well suited for short-range multichannel communication. Finally, the other very important part of the Bluetooth [Bluetooth] speci cation is that it is designed to enable ad hoc networking. In other words, various Bluetooth-enabled devices can connect to one another in an ad hoc manner.

In this section, we are aiming only to give a short introduction to Bluetooth. Our purpose is to provide enough information so that you can recognize how Bluetooth and the functionality that it offers may be relevant to your project. The Bluetooth speci cation was designed by the Bluetooth SIG (Special Interest Group) as a joint effort among several different commercial entities including Ericsson, Nokia, IBM, Intel, and Toshiba corporations.

With its origins deeply embedded in the Scandinavian countries, Bluetooth gets its name from King Harald Blatand (which means Bluetooth in English and refers to his dark complexion), the king of Denmark more than 1,000 years ago. Historically, the Bluetooth SIG was rst of cially formed in 1998 and intended to solve several problems including specifying an air interface, an application-layer protocol stack, and an interoperability speci cation. Since then, the SIG has reorganized several times and is composed of several different working groups.

Today, Bluetooth is also supported by the IEEE. Speci cally, it is covered under the IEEE 802.15 speci cation, where the concepts of WPANs is covered.

The key idea of these personal area networks (PANs) is to allow connectivity among a set of devices located within the radius of a user s personal operating space while keeping the implementation cost and power usage to a minimum. Although 802.15 is a superset of Bluetooth speci cations, and although these efforts began separately, they have now merged and the Bluetooth speci cation is now part of the IEEE 802.

15. Currently, IEEE 802.15 is broken into six different task groups, the rst of which focuses on Bluetooth.

The speci cations of the rst task group is also referred to by IEEE 802.15.1.

Let us look at the speci cation of the physical communication among Bluetoothenabled devices. Bluetooth operates on the 2.56-GHz ISM band and uses Frequency Hop Spread Spectrum (FHSS) and GFSK modulation.

Bluetooth receivers must be sensitive to signals as low as 70 dBm. Bluetooth devices are sometimes referred to as rude radios because they do not check to see if someone else is using the spectrum in that range. A Bluetooth radio simply broadcasts its messages radially 1,600 times per second.

Frequency hopping occurs among seventy-nine channels (the number of channels into which the Bluetooth speci cation breaks its available spectrum). The smallest PAN in Bluetooth is also referred to as a Piconet. A Piconet allows up to eight devices to be connected to one another (seven slaves and one master).

The slaves use the master s clock to correctly perform hopping among different frequencies (FHSS). Scatternets are collections of up to ten Piconets. Ampli ers can be used to extend the reach of Bluetooth to as far as 100 meters (approximately 330 feet).

Bluetooth signals are transmitted radially in all directions (also called omnidirectional); it does not require line-of-sight positioning of two peer units connecting to one another. Figure 10.4 shows the formation of a Bluetooth Scatternet.

. 10.3 Survey of Wireless Networking Technologies Piconet B S M Piconet A S FIGURE 10.4. Formation of a Scatternet with Multiple Piconets. The conceptual a rchitecture of Bluetooth (see Figure 10.5) can be broken into the following eight parts [Bannon et al. 2002]: 1.

Bluetooth Baseband, LMP (Link Management Program), Radio: This is basically the implementation speci cation for the hardware and the physical communication layer. This portion is implemented by the device manufacturers. 2.

HCI: In this text, we have typically referred to HCI as a human-to-computer interface. Within the discussion of Bluetooth architecture, HCI refers to the abstraction between the hardware and the software layer. Basically, the HCI functionality is provided through device drivers.

HCI within Bluetooth is really a HAL (Hardware Abstraction Layer). 3. L2CAP (Logical Link Control and Adaptation Protocol): This layer sits directly on top of the hardware abstraction layer.

L2CAP is an adaptation layer for hiding the baseband protocols from higher layer transport protocols and applications [Bisdikian 1999]. 4. SDP: Service Discovery Protocol (SDP) is a protocol that allows Bluetooth devices to discover the services that other Bluetooth devices are willing to share [Scott 2001].

SDP provides the basic functionality of discovery for ad hoc networking techniques implemented at the application layer. 5. Serial Port Layer: This layer provides RS232 [RS232 2003] emulation on the top of the physical layer implemented above.

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