25-06-2012, 12:17 PM
Bluetooth Technology Overview
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The technology is an open specification for wireless communication of data and voice. It is based on a low-cost, short-range radio link built into a 9 x 9mm microchip, facilitating protected ad hoc connections for stationary and mobile communication environments.
Bluetooth technology allows for the replacement of the many proprietary cables that connect one device to another with one universal short-range radio link. For instance, Bluetooth radio technology built into both the cellular telephone and the laptop would replace the cumbersome cables used today to connect a laptop to a cellular telephone. Printers, PDAs, desktops, fax machines, keyboards, joysticks, and virtually any other digital device can be part of the Bluetooth system.
Bluetooth radio technology provides a universal bridge to existing data networks, a peripheral interface, and a mechanism to form small private ad hoc groupings of connected devices away from fixed network infrastructures. Designed to operate in a noisy radio frequency environment such as a home, the Bluetooth radio uses a fast acknowledgement and frequency-hopping scheme to make the link robust.
Building Blocks of a Bluetooth Solution
The role of each component in a Bluetooth based home network is briefly outlined in the following categories.
Personal Area Networks
Bluetooth was originally conceived to replace the myriad of cables that are synonymous with a PC-based home network. However, as the Bluetooth evolved it became clear that it would also enable a totally new networking paradigm, Personal Area Networks (PANs). With PAN technology, a home networking user will be able to organize a collection of personal electronic products ( PDA, cell phone, laptop, desktop, MP3 player, etc.) to automatically work together. Over time, PANs will revolutionize the user experience of consumer electronics.
Piconets
The Bluetooth system supports both point-to-point and point-to-multi-point connections. A collection of digital appliances that are connected to a home network via Bluetooth technology is called a piconet. A piconet starts with two connected appliances, such as a digital set-top box and cellular phone, and may grow to eight connected devices. All users participating on the same piconet are synchronized to this hopping sequence. The range of Bluetooth and hence the size of the piconet is only ten meters. There is, however, a plan to extend this to 100 meters. This extension in range will however increase the power and interference levels for appliances connected to the piconet.
Scatternets
Several piconets can be established and linked together ad hoc, where each piconet is identified by a different frequency hopping sequence. The resulting structure is called a scatternet.
Software Framework
Every Bluetooth system is comprised of a host-based application and a Bluetooth moduleThe Bluetooth protocol stack can be logically divided into four different layers according to their purpose in a wireless home networking environment. Each layer performs a specific, well- documented, and function in much the same manner as an Ethernet stack. This well-definedarchitecture makes system design much easier and has enabled many implementation variations to emerge. The four layers comprise the following:
Other Applications
Usage models and implementation examples centered on other contemplated Bluetooth devices include:
• Headsets
• Handheld and wearable devices
• Human Interface Device (HID) compliant peripherals
• Data and voice access points
Digital set-top boxes
Enabling a system for Bluetooth requires an RF-chip and a baseband controller. Several variations of Bluetooth modules exists with single RF and baseband controller chips and separated variations.
In Bluetooth products, Xilinx Spartan-II FPGAs and CoolRunner CPLDs provide solutions in traditional component integration (i.e., system interface) role and fully integrated Bluetooth system logic (less the analog radio). Xilinx Virtex devices have been a pervasive vehicle for Bluetooth prototype design.