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What Is Bluetooth?

This chapter is from the book

Reader's Guide to This Book

This chapter has introduced the Bluetooth Special Interest Group, the technology, its chief characteristics and the history of its development. The remaining chapters of Part 1 provide additional background intended to aid in understanding the technology and what it can do.

Chapter 2 discusses wireless communication technologies in general and the Bluetooth radio frequency wireless solution in particular, including requirements and design choices for use of the 2.4-gigahertz spectrum, radio power consumption, "master/slave" radio relationship, adaptive radio range, "piconet" and "scatternet" topologies and global radio use.

Chapter 3 describes the significance of developing usage models for Bluetooth wireless communication and how these usage models relate to Bluetooth profiles. Each of the usage models is described, focusing on the benefits and value for a product's end user. Distinctions are drawn between those usage models enabled with versions 1.0 and 1.1 of the specification and those intended for future use, including representative usage models that illustrate profiles developed after version 1.x4 of the specification.

Chapter 4 briefly explains the purpose, scope, structure and relationships of the Bluetooth specification and profiles, serving as an introduction to Parts 2 and 3 where these topics are covered in detail. The various versions of the specification are described in this chapter.

Part 2, "The Bluetooth Specification Examined," introduces the Bluetooth protocol stack in Chapter 5, partitioning the stack into transport, middleware and application protocol groups.

Chapter 5 examines the relationships among the various layers of the stack, and each of the remaining chapters in Part 2 then covers one or more of these layers in detail. The intent is not just to reiterate information already available in the specification, but rather to provide information that supplements the specification and aids in its understanding. Wherever possible we include information about the history, rationale and justification of the technical contents of the specification based upon our participation in its development.

Chapter 6 describes the radio hardware, link controller, baseband and link manager layers of the protocol stack. Together these layers comprise the lower layers of the transport group of the protocol stack. Topics covered include the motivation and design trade offs behind the radio and baseband specifications, including the choice of the 2.4 gigahertz ISM frequency band; the reasons behind some of the radio and baseband parameters; the choice of the master/slave baseband model; the basis for the piconet and scatternet topologies; and the motivation and design tradeoffs for security features such as pairing and encryption.

Chapter 7 describes the logical link control and adaptation protocol (L2CAP) and host controller interface (HCI) layers of the protocol stack. We call these the upper layers of the transport group of the protocol stack, and they form the basis for the remainder of the software stack, including any new protocols that may be introduced in the future. Topics covered include the motivation and design tradeoffs leading to the development of the HCI and the situations in which this layer is relevant; issues with flow control and its architectural placement within the stack; and how higher-layer elements of the stack can use and benefit from L2CAP.

Chapter 8 presents the RFCOMM and service discovery protocol (SDP) layers of the protocol stack. These are middleware layers that provide abstractions in the form of logical interfaces and message transactions that can be used by application layers. Topics covered include the motivation and design tradeoffs for specifying a logical serial interface and its resulting benefits; how legacy applications could use Bluetooth wireless communication via RFCOMM; the motivation and design tradeoffs for specifying a new discovery protocol; and how SDP maps to other discovery protocols.

Chapter 9 describes the IrDA® Interoperability layers of the protocol stack. These are layers of the protocol stack that incorporate protocols and object formats specified by the Infrared Data Association (IrDA) into the Bluetooth specification. Topics covered include the motivation and design tradeoffs for reusing existing IrDA protocols and object formats; how existing IrDA applications could use Bluetooth wireless communications; and similarities and differences between IrDA and Bluetooth wireless communications.

Chapter 10 discusses the telephony control specification (TCS) layer of the protocol stack and also describes how voice and audio communications are managed. Together audio and TCS provide full telephony support for both voice and data calls. Topics covered include the motivation and design tradeoffs for specifying separate voice and data channels; reasons for the selection of voice encoding techniques, including tradeoffs of quality and efficiency; and alternative forms of telephony control protocols and why TCS was chosen.

In Part 3, "The Bluetooth Profiles Examined," we look into volume 2 of the Bluetooth specification, commonly known as the Bluetooth profiles, in the same manner in which we covered the core specification in Part 2.

Chapter 11 examines the motivation for, development of and relationships among the various profiles, which define how to use the protocol stack to achieve interoperable solutions. Each of the remaining chapters in Part 3 then covers one or more of these profiles in detail. Just as in Part 2, the intent of these chapters is not simply to reiterate information already available in the profile specification but rather to provide information to supplement the specification and aid in its understanding. So-called "version 2" profiles, or those developed after version 1 of the specification, are introduced here and described further in Part 5.

Chapter 12 describes the generic access profile (GAP) and the service discovery application profile (SDAP). These profiles define fundamental principles used to establish connections among devices with Bluetooth wireless communication capability and provide a basis upon which the remaining profiles are built. Topics covered include the motivation and design tradeoffs for security features such as pairing and encryption; the various possibilities for devices to be discovered; and how applications could access and make use of SDP for service location and browsing.

Chapter 13 discusses the telephony class of profiles, including cordless telephony, intercom and headset. These profiles define various ways to use voice communication and call control for telephony applications. Topics covered include the motivation and design trade-offs for selection of the version 1.0 telephony profiles; 10-meter versus 100-meter radio range with respect to the intercom profile; and current and future applications for voice headsets developed according to the headset profile.

Chapter 14 presents the serial port-based class of profiles, including generic object exchange, object push, file transfer and synchronization in addition to the common serial port profile itself. These profiles all define ways to use the RFCOMM virtual serial port to exchange and synchronize data between two peer devices. Topics covered include the serial port profile "family tree"; configuration of the serial port profile and the relevance of typical serial parameters in Bluetooth wireless communications; why the distinction among object exchange, object push and file transfer is important; and current and future possibilities for data synchronization.

Chapter 15 describes the networking class of profiles that includes dial-up networking, LAN access and fax. These profiles all deal with some variation on data networking between two or more peer devices. Topics covered include limitations of Bluetooth wireless communications relative to some fax requirements; the relevance and value of audio feedback for dial-up networking; and the many possibilities for networking with Bluetooth wireless communications and why LAN Access using PPP was chosen for version 1.0.

Part 4, "Bluetooth Technology in Context," examines other aspects of Bluetooth technology beyond the radio, protocol stack and profiles.

Chapter 16 discusses the relationship of Bluetooth wireless technology to other wireless communication mechanisms such as infrared, wireless LAN and others. We also explain the positioning of Bluetooth wireless communication within the IEEE 802.15 standards group.

Chapter 17 describes the Bluetooth qualification process, the Bluetooth logo program and other aspects of interoperability such as informal tests called unplugfests. Here we provide insight into the rationale behind the development of formal and informal interoperability testing procedures and certification marks.

Part 5, "The Future of Bluetooth Wireless Communications," looks at where the technology is headed.

Chapter 18 discusses future possibilities for the technology, including those that the SIG is currently developing: automotive, imaging, printing, extended service discovery and others. This chapter discusses how new usage cases might be realized using Bluetooth wireless communication and how industry innovators might go about developing new Bluetooth wireless communication solutions. Emerging applications domains for Bluetooth technology such as retail, medical and others are discussed. In addition, the product landscape for Bluetooth wireless technology is explored, including the current and projected marketplace.

Chapter 19 summarizes the book and offers concluding remarks about the future of Bluetooth wireless communication, including a short discussion of the Bluetooth marketplace and the opportunities that the technology presents.

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