BLUETOOTH
Bluetooth is another industry group developing a specification for low-cost, short-range radio links between mobile computers, cameras, and other portable in-home devices. Bluetooth technology is the result of cooperation between leaders in the telecommunications and computer industries. It is the code name for a technology specification for small form factor, low-cost, short-range radio links between mobile PCs, mobile phones, and other portable devices. It enables home networking users to connect a wide range of computing and telecommunications devices easily and simply, without the need to buy, carry, or connect cables. It delivers opportunities for rapid ad hoc connections, and the possibility of automatic, unconscious, connections between devices. It virtually eliminates the need to purchase additional or proprietary cabling to connect individual devices. Because Bluetooth can be used for a variety of purposes, it will also potentially replace multiple cable connections via a single radio link. Bluetooth is being promoted and has been adopted by a group of companies called the Bluetooth Special Interest Group (SIG). This includes promoter companies 3Com, Ericsson, IBM, Intel, Lucent, Microsoft, Motorola, Nokia, and Toshiba and 1,665 adopter companies (at the time of writing).
Technology Overview
The Bluetooth 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 9 mm 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, table-sized handhelds, 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 acknowledgment and frequency hopping scheme to make the link robust. Bluetooth radio modules avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet. Compared with other systems operating in the same frequency band, the Bluetooth radio typically hops faster and uses shorter packets. This makes the Bluetooth radio more robust than other systems. Short packages and fast hopping also limit the impact of domestic and professional microwave ovens. Use of Forward Error Correction (FEC) limits the impact of random noise on long-distance links. The encoding is optimized for an uncoordinated environment. Bluetooth radios normally operate in the unlicensed ISM band at 2.4 GHz. From a security perspective, Bluetooth provides user protection and information privacy mechanisms at the lower layers of its protocol stack. Authentication is based on a challenge-response algorithm. Authentication is a key component of any home networking system, allowing you to develop a domain of trust between Bluetooth devices, such as allowing only your personal notebook to communicate through your cellular telephone.
Building Blocks of a Bluetooth Solution
The role of each component in a Bluetooth-based home network is briefly outlined in the following categories.
Piconets
The Bluetooth system supports both point-to-point and point-to-multipoint connections. A collection of devices that are connected to a home network via Bluetooth technology is called a piconet. A piconet starts with two connected devices, such as a digital set-top box and cellular phone, and may grow to eight connected devices. All Bluetooth devices are peer units and have identical implementations. However, when establishing a piconet, one unit will act as a master and the other(s) as slave(s) for the duration of the piconet connection. Several piconets can be established and linked together ad hoc, where each piconet is identified by a different frequency-hopping sequence. All users participating on the same piconet are synchronized to this hopping sequence.
Protocols
The Bluetooth protocol stack can be logically divided into four different layers according to their purpose in a wireless home networking environment.
Software Framework
The software framework used by Bluetooth devices creates a positive experience for consumers. Interoperability between different devices is seen as an essential part of a successful home networking solution. The software that is integrated into Bluetooth devices allows them to discover each other and load appropriate in-home applications. To obtain this functionality, the Bluetooth software framework reuses existing specifications such as Human Interface Device (HID) and TCP/IP rather than invent sets of new specifications. Device compliance requires conformance to both the Bluetooth specification and existing protocols.
For a more detailed description of Bluetooth technical components, we suggest that you download the entire specification from the following Web address: http:// www.bluetooth.com/developer/specification/specification.asp.
Practical Uses of Bluetooth Technologies within the Home
General PC Applications
The Bluetooth specification defines interfaces where the radio modules may be integrated into notebook personal computers or attached using PC-Card or USB port. Notebook PC usage models include:
Remote networking using a Bluetooth cellular phone
Speakerphone applications using a Bluetooth cellular phone
Personal card exchange between Bluetooth notebooks, handhelds, and phones
Calendar synchronization between Bluetooth notebooks, handhelds, and phones
File transfers (file types include, but are not limited to, .xls, .ppt, .wav, .jpg, and .doc formats)
Bluetooth technology is platform-independent and not tied to any specific operating system. Implementations of the Bluetooth specification for several commercial operating systems are in development. For notebook computers, the implementation of the Bluetooth specification in Microsoft Windows 98 and Windows 2000 using Windows Driver Model (WDM) and NDIS drivers is being contemplated.
Telephone Applications
The Bluetooth specification defines interfaces where the radio modules may be integrated directly into cellular handsets or attached using an add-on device. Phone usage models include, but are not constrained to:
Wireless hands-free operation using a Bluetooth headset
Cable-free remote networking with a Bluetooth notebook or handheld computer
Business card exchange with other Bluetooth phones, notebook, or handheld computers
Automatic address book synchronization with trusted Bluetooth notebooks or handheld computers
The Bluetooth compliance document will require digital cellular phones to support some subset of the Bluetooth specification. The Bluetooth contingents within the telephony promoter companies are working with their fellow employees involved in the WAP Forum to investigate how the two technologies can benefit from each other.
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
Integrated digital televisions
The wireless headset will support untethered audio for phones and provide phone-quality audio for notebook computers operating in sound-sensitive environments.