3D bluetooth(VHGOHEL)


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3D bluetooth(VHGOHEL)

  2. 2. ABSTRACT It is desired to get rid of the spaghetti of wires connecting the various devices used daily and so Bluetooth technology provides a low cost, low power and low complexity solution for ad-hoc wireless connectivity. Bluetooth is a short range wireless technology that forms the basis of communication platform which needs to be flexible, self organizing, highly scalable and energy efficient. The Bluetooth technology is capable of connecting a wide variety of devices like Personal Digital Assistants (PDA), mobile and cordless phones, headsets, desktops and notebook PCs, digital cameras, home appliances etc. The applications include eliminating cables/wires between devices like PCs, printers, modems, projectors, self synchronization between PDAs and PCs, wirelessly connecting to local area networks (LANs) through access points and internet through mobile phones, providing home networking solutions etc. In this paper, the author presents an overview of Bluetooth technology and its applications. The Bluetooth system is introduced and its various modes of operation are also discussed. A description of functionalities of Bluetooth layers and the protocol specifications is presented. The various links for communication among Bluetooth devices are also illustrated. The author has made an attempt to enlighten various important issues related to error correction, security and personalization of Bluetooth devices. The literature is enriched by discussion of other wireless technology, WiFi working together with Bluetooth. Thus the paper will provide helpful evaluation of Bluetooth technology, for the budding engineers.
  3. 3. CHAPTER 1 INTRODUCTION  Definition of Bluetooth .  Why Bluetooth ?  How need arise of Bluetooth?  History.  What is SIG ? What is Bluetooth? What is it - a technology, a standard, an initiative, or a product? Bluetooth wireless technology is a de facto standard, as well as a specification for small form factor, low-cost, short range radio links between mobile PCs, mobile phones and other portable devices. The Bluetooth Special Interest Group is an industry group consisting of leaders in the telecommunications, computing, and networking industries that are driving development of the technology and bringing it to market.
  4. 4. How did the need arise? In phase with the IT boom, the mobility among people has constantly grown and wireless technologies for voice and data have evolved rapidly during the past years. Countless electronic devices for home, personal and business use have been presented to the market during recent years but no widespread technology to address the needs of connecting personal devices in Personal Area Networks (PANs). The demand for a system that could easily connect devices for transfer of data and voice over short distances without cables grew stronger. Bluetooth wireless technology fills this important communication need, with its ability to communicate both voice and data wirelessly, using a standard low-power, lowcost technology which can be integrated in all devices to enable total mobility. The price will be low and result in mass production. The more units around, the more benefits for the customer. Why Bluetooth ? What will Bluetooth wireless technology deliver to end users? It will enable 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 will virtually eliminate the need to purchase additional or proprietary cabling to connect individual devices. Because Bluetooth wireless technology can be used for a variety of purposes, it will also potentially replace multiple cable connections via a single radio link. It creates the possibility of using mobile data in a different way, for different applications such as "Surfing on the sofa", "The instant postcard", "Three in one phone" and many others. It will allow them to think about what they are working on, rather than how to make their technology work. The solution eliminates the annoying cable and its limitations regarding flexibility (often
  5. 5. specific for a brand or pair of devices) and range. But, Bluetooth implies more than that. The technique provides the means for connecting several units to each other such as setting up small radio LANs between any types of Bluetooth devices. A number of user scenarios are described. They highlight more possibilities that reach far beyond just an elimination of the point-topoint cable. History By the way if, you're wondering where the Bluetooth name originally came from , it is named after a Danish Viking and King of Denmark between 940 and 981 AD, Harald Blåtand (Bluetooth in English), who lived in the latter part of the 10TH century. Harald Blåtand united and controlled Denmark and Norway (hence the inspiration on the name : uniting devices through Bluetooth The idea that resulted in the Bluetooth wireless technology was born in 1994 when Ericsson Mobile Communications decided to investigate the feasibility of a low-power, low-cost radio interface between mobile phones and their accessories. The idea was that a small radio built into both the cellular telephone and the laptop would replace the cumbersome cable used today to connect the two devices. A year later the engineering work began and the true potential of the technology began to crystallize. But beyond unleashing devices by replacing cables, the radio technology showed possibilities to become 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. The requirements regarding price, capacity and size were set so that the new technique would have the potential to outdo all cable solutions between mobile devices. Initially a suitable radio interface with a corresponding frequency range had to be specified. A number of criteria for the concept were defined regarding size, capacity and global uniformity. The radio unit should be so small and consume such low power that it could be
  6. 6. fitted into portable devices with their limitations. The concept had to handle both speech and data and finally the technique had to work all around the world. The study soon showed that a short-range radio link solution was feasible. When designers at Ericsson had started to work on a transceiver chip, Ericsson soon realized that they needed companions to develop the technique. The associates strove not only to improve the technical solutions but also to get a solid and broad market support in the business areas of PC hardware, portable computers and mobile phones. Fear for a market situation with a multitude of non-standard cable solutions, where one cable is designed specifically for one pair of devices, was one of the motives that made competing companies join the project. Ericsson Mobile Communications, Intel, IBM, Toshiba and Nokia Mobile Phones formed a Special Interest Group (SIG) in 1998. What is SIG? In February 1998 the Special Interest Group (SIG) was formed. Today the Bluetooth SIG includes promoter companies 3Com, Ericsson, IBM, Intel, Lucent, Microsoft, Motorola, Nokia and Toshiba, and thousands of Adopter/Associate member companies. By signing a zero cost agreement, companies can join the SIG and qualify for a royalty-free license to build products based on the Bluetooth technology. This group represented the diverse market support that was needed to generate good support for the new Bluetooth technology. In May of the same year, the Bluetooth consortium announced itself globally. The assignment of the SIG originally was to monitor the technical development of short-range radio and to create an open global standard, thus preventing the technology from becoming the property of a single company. This work resulted in the release of the first Bluetooth Specification in July 1999. The intention of the Bluetooth SIG is to form a de facto standard for the air interface and the software that controls it. The further development of the Specification still is one of the main
  7. 7. tasks for the SIG, other important ones being interoperability requirements, frequency band harmonization and promotion of the technology. The Bluetooth wireless technology was developed by the Bluetooth Special Interest Group, to define an industry-wide specification for connecting personal and business mobile devices. More than 1,4000 companies are now members of the Special Interest Group, signifying the industry‟s unprecedented acceptance of the Bluetooth wireless technology. To avoid different interpretations of the Bluetooth standard regarding how a specific type of application should be mapped to Bluetooth, the SIG has defined number of user models and protocol profiles. These are described in more detail in the section entitled Bluetooth Usage Models and Profiles.The SIG also works with a Qualification Process. This process defines criteria for bluetooth product qualification that ensures that products that pass this process meet the Bluetooth specification.
  8. 8. CHAPTER 2. OVERVIEW OF BLUETOOTH SYSTEM.  Technology overview.  Network architecture.
  9. 9. TECHNOLOGY OVERVIEW: The technology is an open specification for wireless communication of data and voice. It is low cost short range radio link, built into a 9X9 mm microchip, facilitating protected ad hoc connections for stationary and mobile communication environment. Bluetooth technology allows for the replacement of the many proprietary cables that connect one device to another device with one universal short range radio link. For instance Bluetooth radio technology built in both the cellular telephone and the laptop would replace the cumbersome cables used today to connect the laptop to a cellular telephone. Printers, PDA‟S, desktops, fax machines, keyboard, joysticks and virtually any other device can be part of the Bluetooth system. But beyond untethering devices by replacing the cables, Bluetooth radio technology provides a universal bridge to existing data networks, a peripheral interface, and a mechanism to form small private ad hoc grouping of connected devices away from fixed network infrastructures. Designed to operate in noisy radio frequency environment, the Bluetooth radio uses a fast acknowledgement and frequency hopping scheme to make the link robust. The 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 robust than the other system. Short packages and fast hopping also limit the impact of random noise and long distance links. The encoding is optimized for uncoordinated environment. Bluetooth radios operate in the unlicensed ISM band at 2.4GHz. a frequency hop transceiver is applied to combat interference and fading. A shaped binary FM modulation is applied to minimize transceiver complexity. The gross data rate is 1mbps. A Time Division Duplex scheme is used for full duplex
  10. 10. transmission. The Bluetooth base band protocol is a combination of circuit and packet switching. Slots can be reserved for synchronous packet. Each packet is transmitted in a different hop frequency. A packet nominally covers a single slot, but can be extended to cover up to 5 slots. Bluetooth can support an asynchronous data channel, up to 3 simultaneous synchronous voice channels, or a channel that simultaneously supports asynchronous data synchronous voice. Each voice channel supports 64 kbps synchronous (voice) link. The asynchronous channel can support an asymmetric link of maximally 721 kbps in either direction while permitting 57.6 kbps in the return direction, or a 432.6 kbps symmetric link. INTRODUCTION : The Bluetooth technology answers the need for short range wireless connectivity within three areas :  Data and voice access points .  Cable replacement  Ad hoc networking The Bluetooth technology specification specifies a system solution comprising hardware, software and interoperability requirements. The Bluetooth radio operates in a globally available 2.4GHz ISM band, ensuring communication compatibility worldwide. Data and voice access point : The Bluetooth technology facilitates real time voice and data transmission. The technology makes it possible to connect any portable and stationary communication device as easily as switching on the light. You can, for instance, surf the Internet & send e-mail on your potable PC or notebook regardless of whether you are wirelessly connected through a
  11. 11. mobile phone or ISDN,LSN,XDLS). through a wire bound connection (PSTN, Voice channel use the Continuous Variable Slope Delta Modulation (CVSD) coding scheme, and never retransmit voice packets. The CVSD was chosen for its robustness in handling dropped and damaged samples. Rising interference levels are experienced as increased background noise; even at bit error rate up to 4% the CVSD coded voice is quite audible. CABLE REPLACEMENT: The Bluetooth technology eliminates the use for numerous often proprietary cable attachments for connection of practically any kind of device. Connections are instant and they are maintained even when devices are not within line of sight. The range of each radio is approximately 10 meters but it can be extended around 100 meters with an optional amplifier. AD-HOC NETWORKING: A device equipped with Bluetooth radio establishes instant connection to another Bluetooth radio as soon as it comes into range. Since Bluetooth technology supports both point to point and point to multi point connection, several piconets can be established and linked together ad hoc. The Bluetooth technology is best described as multiple piconet structure. Piconet is a connection of devices connected via Bluetooth technology in an ad hoc fashion . A piconet starts with two connected devices ,such as portable PC and cellular phone and may grow into eight connected devices. All Bluetooth devices are peer units and have identical implementation. However, when establishing a piconet, one unit will act as a master and the other as a slave for the duration of piconet connection. NETWORK ARCHITECTURE:
  12. 12. Scatternet, ad-hoc combinations in a point-to-multipoint and point-to-point piconet. Bluetooth units that come within range of each other can set up ad hoc point-to-point and/or point-to-multipoint connections. Units can dynamically be added or disconnected to the network. Two or more Bluetooth units that share a channel form a piconet. Several piconets can be established and linked together in ad hoc scatternets to allow communication and data exchange in flexible configurations. If several other piconets are within range they each work independently and each have access to full bandwidth. Each piconet is established by a different frequency-hopping channel. All users participating on the same piconet are synchronized to this channel. Unlike infrared devices, Bluetooth units are not limited to line-of-sight communication. To regulate traffic on the channel, one of the participating units becomes a master of the piconet, while all other units become slaves. With the current Bluetooth Specification up to seven slaves can actively communicate with one master. However, there can be almost an unlimited number of units virtually
  13. 13. attached to a master being able to start communication instantly. CHAPTER 3 BLUETOOTH PROTOCOL STACK.  Bluetooth protocol stack & network architecture.  The Bluetooth architecture strategy.
  15. 15. Figure 1 The Bluetooth Protocol Stack Abbreviations Used OBEX OBject Exchange Protocol WAP Web Application Protocol UDP User Datagram Protocol IP Internet Protocol PPP Point to Point Protocol RFCO Serial Cable emulation protocol based on HCI Host Controller MM ETSI TS 07.10 Interface LLCA Logical Link Control and Adaptation SDP Service P Protocol Discovery Protocol TCP Telephony Control Protocol LMP Link Manager Protocol This section describes the Bluetooth architecture. The complete protocol stack comprises, as seen in Figure 1, of both Bluetooth specific protocols and non-Bluetooth specific protocols. In the figure, nonBluetooth specific protocols are shaded. Baseband The Baseband and Link Control layer enables the physical RF link between Bluetooth units forming a piconet. This layer controls the Bluetooth unit's synchronization and transmission frequency hopping sequence. The two different link types defined in Bluetooth, Synchronous Connection
  16. 16. Oriented, SCO, and Asynchronous Connectionless, ACL, described in the section Link types, are also managed by this layer. The ACL links, for data, and the SCO links, mainly for audio, can be multiplexed to use the same RF link [17]. Audio Audio transmissions can be performed between one or more Bluetooth units, using many different usage models. Audio data do not go through the L2CAP layer (described below) but go directly, after opening a Bluetooth link and a straightforward set-up, between two Bluetooth units. Host Controller Interface, HCI The Host Controller Interface, HCI, provides a uniform interface method for accessing the Bluetooth hardware capabilities. It contains a command interface to the Baseband controller and link manager and access to hardware status. Finally, it contains control and event registers [8]. Link Manager Protocol, LMP The Link Manager Protocol, LMP, is responsible for link set-up between Bluetooth units. It handles the control and negotiation of packet sizes used when transmitting data. The Link Manager Protocol also handles management of power modes, power consumption, and state of a Bluetooth unit in a piconet. Finally, this layer handles generation, exchange and control of link and encryption keys for authentication and encryption [9]. Logical Link Control and Adaptation Protocol, L2CAP The Bluetooth logical link control and adaptation protocol, L2CAP, is situated over the Baseband layer and beside the Link Manager Protocol in the Bluetooth protocol stack. The L2CAP layer provides connection-oriented and connectionless data services to upper layers. The four main tasks for L2CAP are:  Multiplexing – L2CAP must support protocol multiplexing since a number of protocols (e.g. SDP, RFCOMM and TCS Binary) can operate over L2CAP.
  17. 17.  Segmentation and Reassembly – Data packets exceeding the Maximum Transmission Unit, MTU, must be segmented before being transmitted. This and the reverse functionality, reassemble, is performed by L2CAP.  Quality of Service – The establishment of an L2CAP connection allows the exchange of information regarding current Quality of Service for the connection between the two Bluetooth units.  Groups – The L2CAP specification supports a group abstraction that permits implementations for mapping groups on to a piconet.  An L2CAP implementation must be uncomplicated and implying low overhead since it must be compatible with the limited computational resources in a small Bluetooth unit [10]. Service Discovery Protocol, SDP The Service Discovery Protocol, SDP, defines how a Bluetooth client's application shall act to discover available Bluetooth servers' services and their. Bluetooth characteristics. The protocol defines how a client can search for a service based on specific attributes without the client knowing anything of the available services. The SDP provides means for the discovery of new services becoming available when the client enters an area where a Bluetooth server is operating. The SDP also provides functionality for detecting when a service is no longer available [11].  Cable replacement protocol RFCOMM The RFCOMM protocol is a serial port emulation protocol. The protocol covers applications that make use of the serial ports of the unit. RFCOMM emulates RS-232 control and data signals over the Bluetooth
  18. 18. baseband. It provides transport capabilities for upper level services, e.g. OBEX that use a serial line as the transport mechanism. Telephony control protocol Telephony Control – Binary The Telephony Control protocol – Binary, TCS Binary or TCS BIN, is a bit-oriented protocol, which defines the call control signalling for the establishment of speech and data calls between Bluetooth units. The protocol defines the signalling for establishment and release of calls between Bluetooth units. As well as signalling to ease the handling of groups of Bluetooth units. Furthermore, TCS Binary provides functionality to exchange signalling information unrelated to ongoing calls. Establishment of a voice or data call in a point-to-point configuration as well as in a point-tomultipoint configuration is covered in this protocol (note, after establishment, the transmission is from point to point). The TCS Binary is based on the ITU-T Recommendation. Telephony Control – AT Commands A number of AT-commands are supported for transmitting control signals for telephony control. These use the serial port emulation, RFCOMM, for transmission. Adopted protocols This section describes a number of protocols that are defined to be adopted to the Bluetooth protocol stack. Note some of these adaptations are at the moment incomplete. PPP The IETF Point-to-Point Protocol (PPP) in the Bluetooth technology is designed to run over RFCOMM to accomplish point-to-point connections. PPP is a packet-oriented protocol and must therefore use its serial mechanisms to convert the packet data stream into a serial data streams.
  19. 19. TCP/UDP/IP The TCP/UDP/IP standards are defined to operate in Bluetooth units allowing them to communicate with other units connected, for instance, to the Internet. Hence, the Bluetooth unit can act as a bridge to the Internet. The TCP/IP/PPP protocol configuration is used for all Internet Bridge usage scenarios in Bluetooth 1.0 and for OBEX in future versions. The UDP/IP/PPP configuration is available as transport for WAP. OBEX Protocol IrOBEX, shortly OBEX, is an optional application layer protocol designed to enable units supporting infrared communication to exchange a wide variety of data and commands in a resource-sensitive standardized fashion. OBEX uses a client-server model and is independent of the transport mechanism and transport API. The OBEX protocol also defines a folder-listing object, which is used to browse the contents of folders on remote device. RFCOMM is used as the main transport layer for OBEX. Content formats The formats for transmitting vCard and vCalendar information are also defined in the Bluetooth specification. The formats do not define transport mechanisms but the format in which electronic business cards and personal calendar entries and scheduling information are transported. vCard and vCalendar is transferred by OBEX. Wireless Application Protocol, WAP The Wireless Application Protocol (WAP) is a wireless protocol specification that works across a variety of wide-area wireless network technologies bringing the Internet to mobile devices. Bluetooth can be used like other wireless networks with regard to WAP, it can be used to provide a bearer for transporting data between the WAP Client and its adjacent WAP Server. Furthermore, Bluetooth‟s ad hoc networking capability gives a WAP client unique possibilities regarding mobility compared with other WAP bearers.
  20. 20. The traditional form of WAP communications involves a client device that communicates with a Server/Proxy device using the WAP protocols. Bluetooth is expected to provide a bearer service as specified by the WAP architecture. The WAP technology supports server push. If this is used over Bluetooth, it opens new possibilities for distributing information to handheld devices on location basis. For example, shops can push special price offers to a WAP client when it comes within Bluetooth range.he Bluetooth air interface This section describes the Bluetooth air interface. It is a continuation of the introduction to the air interface and is based on [12]. The Bluetooth architecture strategy A number of profiles have been defined by the Bluetooth standardization organization. These profiles have been developed in order to describe how implementations of user models are to be accomplished. The user models describe a number of user scenarios where Bluetooth performs the radio transmission. These profiles specify how applications and devices shall be mapped onto the Bluetooth concept. A profile defines a selection of messages and procedures from the Bluetooth specifications and gives an unambiguous description of the air interface for specified services and use cases. A profile can be described as a vertical slice through the protocol stack. It defines options in each protocol that are mandatory for the profile. It also defines parameter ranges for each protocol. The profile concept is used to decrease the risk of interoperability problems between different manufacturers' products. The profile defined for exchanging of vCard information is illustrated in Figure 2, where an application, vCard, is defined to operate over a certain subset (OBEX, RFCOMM and so on) of the Bluetooth protocol stack. Some of the user models and their profiles are described in section Bluetooth Usage Models and Profiles.
  21. 21. vCARD OBEX RFCOMM SDP TCS Binary L2CAP LMP Base Band Figure 2: The Object Push Profile There are four general profiles defined, on which some of the highest prioritized user models and their profiles are directly based on. These four models are; the Generic Access Profile (GAP), the Serial Port Profile, the Service Discovery Application Profile (SDAP) and the Generic Object Exchange Profile (GOEP). Protocols such as OBEX and UDP have been included in the protocol architecture to facilitate the adaptation of applications using such existing protocols. This gives for instance a number of existing applications supporting UDP an interface to the Bluetooth technology.
  22. 22. CHAPTER 4. DIVISION AS FUNCTIONAL UNIT     Software architecture. Hardware architecture. Link types. Authentication, Privacy & Security.
  23. 23. DIVISION AS FUNCTIONAL UNITS The different functional units in the Bluetooth system are:     A radio unit A link control unit Link management Software function NETWORK TOPOLOGY: As already mentioned, the Bluetooth system support both point to point and point to multi point connections. In this, each piconet is identified by a different hopping signal. All users participating on the same piconet are synchronized to this hopping sequence. The full duplex data rate within a multiple piconet structure with 10 fully loaded, independent piconets is more than 6 mbps. This is due to a data throughput reduction rate of less then 10% according to system simulation based on 0 dbm transmitting power (at the antenna). RADIO UNIT: The Bluetooth air interface is based on a nominal antenna at 0 dBm. The air interface compiles with the FCC rules for the ISM band at power levels up to 0 dBm. Spectrum spreading has been added to facilitate optional operation at power levels up to 100 mw worldwide. Spectrum spreading is accomplished by frequency hopping in 79 hops displaced by 1 MHz, starting at 2.402 MHz and stopping at 2.480GHz. Due to local conditions the bandwidth has been reduced in Spain, France and Japan. BASEBAND:
  24. 24. The baseband describes the digital signal processing hardware-the Bluetooth link controller, which carries out the baseband protocols and other low level link routines. Before establishing any network connections in a piconet structure, all devices are in the stand-by mode. In this mode an unconnected unit periodically „listens‟ for messages every 1.28 seconds. Each time a device wakes up, it listens on a set of 32 hop frequencies defined for that unit. The number of frequencies varies in different geographical regions ; 32 is a number for most countries ( except Spain, France and Japan). The connection procedures are initiated by any of the devices which then become master. A connection is made by a page message if the address is already known, or by an enquiry message followed by a subsequent page message if the address is already known. The master unit is the device in the piconet structure whose clock and hopping frequencies are used to synchronize all other units in the piconet. The devices other than master are called the slave units. In the initial page state, the master unit will send a train of 16 identical page messages on 16 different hop frequencies defined for the device to be paged(slave unit ). If no response, the master transmits a train on the remaining 16 hop frequencies in the wake up sequence. The maximum sequence before the master reaches the slave is twice the wake up period (2.56 sec.), while the average delay is the wake up period (0.64 sec.). The enquiry typically used for finding Bluetooth devices, including public printers, fax machines and similar devices with an unknown messages, but may require 1 additional train period to collect all the responses. A power saving mode can be used for connected units in a piconet if no data need to be transmitted. This power saving mode is the sniff and hold mode in which the device activity is lower. The master unit can put the slave units into the hold mode, Data transfer restarts instantly when units transits out of the hold mode. The hold is used when connecting several piconet or managing a low power device such as temperature sensor. Two more low power modes are available, the sniff and the park mode. In the sniff mode, the slave devices listens to the piconet reduced rate thus reducing its duty cycle. The sniff interval is programmable and depends on the application. In the park mode a device is still synchronized to the piconet but dose not participate in the traffic. Such a device is the parked device and does not have a MAC address. The MAC address is a three bit address to distinguish the units participating in the piconet structure. Parked device have given up their MAC addresses and occasionally listen to the traffic of the master to
  25. 25. resynchronize and check on broadcast messages. If we list modes in increasing order of power efficiency, the sniff mode has the higher duty cycled followed by the hold mode with a lower duty cycle . LINK MANAGEMENT: The link manager software entity carries out link set up, authentication, link configuration and other protocols. The Link Manager discovers other remote Link Managers and communication with them via the Link Manager protocol. To perform its service provider role, the Link Manager uses the service of the under lying controller. Services provided are : 1. Sending and receiving of data. 2. The link manager has an efficient means to inquire and report a name or device ID up to 16 characters in length. 3. Link address inquiries. 4. Connection set up. 5. Authentication. 6. Link Mode negotiation and set up, e.g. data or data/voice. This may be changed during a connection. 7. The Link Manager decides the actual frame type on a packet to packet basis. 8. Setting a device in sniff mode ; In sniff mode, the duty cycle of the slaves reduces. It listen only every M slots, where M is negotiated at the Link Manager. The master can start transmission in specified time slots spaced at regular intervals. 9. Setting a link device on hold ; In hold mode, turning off the receiver for long periods saves power. Any device can wake up the link again, with an average latency of 4 seconds. This is defined by the link Manager and handled by the Link Controller. 10.Setting a device in park mode ; It wakes up at regular intervals to listen to the channel in order to resynchronize with the rest of the piconet, and to cheek page messages. SOFTWARE FRAMEWORK: Bluetooth devices will be required to support baseline interoperability feature requirements to create a positive consumer experience. For some devices, these requirements will extend from radio module compliance and
  26. 26. air protocols and object exchange formats. For other devices, such as headset, the feature‟s requirements will be significantly less. Ensuring that any device displaying the Bluetooth „logo‟ interpolates with other Bluetooth devices is the goal of the Bluetooth program. Software interoperability begins with the Bluetooth link level protocol responsible for multiplexing , device and service discovery, segmentation and reassemble, Bluetooth devices must be able to recognize each other and load the appropriate software to discover the higher level abilities each device supports. Interoperability at the application level requires identical protocol stacks. Different classes of Bluetooth devices(PC‟s, handheld, headsets, cellular telephones) have different compliance requirements. For example, a Bluetooth headset is not expected to contain an address book. Headsets compliance implies Bluetooth radio compliance, audio capability and device discovery protocols. More functionality would be expected from cellular phones, handheld and notebook computer. To obtain this functionality, the Bluetooth software framework will reuse existing specifications such as OBEX, Vcard/Vcalender, Human Interface Device and TCP/IP rather than inventing yet another set of new specifications. Device compliance will require conformation to both, the Bluetooth specification and existing protocols. The software framework is contemplating the following functions: 1.Configuration and diagnosis utility 2. Device discovery 3.Cable emulation 4.Peripheral communication 5.Audio communication and call control 6.Object exchange for business cards and phone books Networking protocols. LINK TYPES AND PACKET TYPES: The link defines “what” of packets can be used on a particular link. The Bluetooth baseband technology supports two link types:  Synchronous connection oriented (SCO) type (used primarily for voice)
  27. 27.  Asynchronous connectionless (ACL) type (used primarily for packet data) Different master slave pairs of the same piconet structure can use different link types and the link type may change arbitrarily during a session. Each link “supports up to 16 different packet types. Four of these are control packets and are common for both SCO and ACL links. Both link types use a Time Division Duplex (TDD) scheme for full duplex transmission. SYNCHRONOUS CONNECTONS ORIENTED TYPE: The SCO link is symmetric and typically supports time bound voice traffic. SCO packets are transmitted over reserved intervals. Once the connection is established, both master and slave units may send SCO packets without being polled. One SCO packet type allows both voice and data transmission ; with only the data portion being retransmitted when corrupted. ASYNCHRONOUS CONNECTIONLESS LINK TYPE: The ACL link is packet oriented and supports both, symmetric and asymmetric traffic. The master unit controls the link bandwidth and decides how much piconet bandwidth is given to each slave, and the symmetry of the traffic. Slaves must be polled before they can transmit data. The ACL link also supports broadcast messages from the master to all slaves in the piconet. In order to make different hardware implementations compatible, Bluetooth devices use the HCI as a common interface between the Bluetooth host (e.g. a portable PC) and the Bluetooth core. Higher-level protocols like the SDP, RFCOMM (emulating a serial port connection) and the TCP are interfaced to baseband services via the LLCAP. Among the issues LLCAP takes care of, is segmentation and reassemble to allow larger data packets to be carried over a Bluetooth baseband connection. The service discovery protocol allows
  28. 28. applications to find out about available services and their characteristics when e.g. devices are moved or switched off. HARDWARE ARCHITECTURE : The Bluetooth hardware consists of an analog radio part and a digital part - the Host Controller. The Host Controller has a hardware digital signal processing part called the Link Controller (LC), a CPU core and interfaces to the host environment . The Link Controller consists of hardware that performs baseband processing and physical layer protocols such as ARQ (Automatic Repeat reQuest) protocol and FEC (Forward Error Correction) coding. The function of the Link Controller includes Asynchronous transfers, Synchronous transfers, Audio coding and Encryption. The CPU core allows the Bluetooth module to handle Inquiries and filter Page requests without involving the host device. The Host Controller can be programmed to answer certain Page messages and authenticate remote links. The Link Manager (LM) software runs on the CPU core. The LM discovers other LMs and communicates with them via the
  29. 29. Link Manager Protocol (LMP) to perform its service provider role and to use the services of the underlying Link Controller. ERROR CORRECTION: There are three error correction schemes defined by the Bluetooth baseband controllers.  1/3 rate Forward Error Correction code (FEC)  2/3 rate Forward Error Correction code  automatic repeat request (ARQ) scheme for data FORWARD ERROR CORRECTION: The purpose of the FEC on the data payload is to reduce the number of retransmission. However, in a reasonably error free environment, FEC creates unnecessary overhead that reduces the throughput. Therefore, the packet definitions have been kept flexible as to whether or not to use the FEC in the payload. The packet header is always protected by a 1/3 rate FEC; it contains valuable link information and should survive bit errors. AUTOMATIC REPEAT REQUEST: An unnumbered ARQ scheme is applied in which the data transmitted in one slot is directly acknowledged by the recipient in the next slot. For a data transmission to be acknowledged, both the header error check and the cyclic redundancy check must be maintained otherwise a negative acknowledge is returned. AUTHENTICATION, PRIVACY & SECURITY: The Bluetooth baseband provides user protection and information privacy mechanism at the physical layer. Authentication and privacy is implemented in the same way in each Bluetooth device, appropriate for the ad-hoc nature of the network. Connections may require a one way, two ways or no authentication. Authentication is based on a challenge-response algorithm. Authentication is a key component of any Bluetooth system, allowing the user to develop a domain of trust between a personal Bluetooth
  30. 30. device, such as allowing only the owners notebook computer to communicate through the owners cellular phone. Encryption is used to protect privacy of the connection. Bluetooth uses a string cipher well-suited for a silicon implementation with secret key lengths of 0, 40 or 64 bits. Key management is left to higher layer software. The goal of Bluetooth‟s security mechanism is to provide an appropriate level of protection for Bluetooth short-range nature and use in a global environment. Users requiring stalwart protection are encouraged to use stronger security mechanisms available in network transport protocols and application programs. Bluetooth security Introducing the Bluetooth technology as a cable replacement technique exposes the need for security functionality in the wireless solution. By replacing the cable and introducing radio signals there is a need for the Bluetooth device to have built-in security to prevent eavesdropping and falsifying the message originator. Therefore, functionality for authentication and encryption has been added to the Bluetooth technology. Authentication is used to prevent unwanted access to data and to prevent falsifying of the message originator. Encryption is used to prevent eavesdropping. These two techniques combined with the frequency hopping technique and the limited transmission range for a Bluetooth unit, usually 10 m, give the technology higher protection against eavesdropping.. Since the need for security is dependent on what kind of application is executed, three levels of security are defined in the Bluetooth concept. 1. Non-secure: This mode bypasses functionality for authentication & encryption. 2. Service-level security; Security procedures are not initiated until L2CAP channel establishment. 3. Link-level security; Security procedures are initiated before the link set-up at the LMP level is completed. Service-level security
  31. 31. In the Service-level security mode, it is suggested to introduce a Security Manager that controls the access to services and units. This security mode provides the possibility to define trust levels for the services and units used respectively. The access is restricted according to the defined trust levels. Link-level security The Link-level security mode is based on the concept of link keys. These keys are secret 128 bit random numbers stored individually for each pair of devices in a Bluetooth connection. Each time two Bluetooth units communicate, the link key is used for authentication and encryption. CHAPTER 5.
  32. 32. COMMUNICATION – FREQUENCY HOPPING. & BLUETOOTH NETWORKS.  The frequency hopping technique.  Bluetooth networking. The Frequency Hopping Technique Interference is avoided by using a frequency-hop, FH, spread spectrum technology. This technology is well suited for low-power, low-cost radio implementations and is used in some wireless LAN products. The main advantage with Bluetooth's choice of parameters is the high hop rate, 1600 hops per second, instead of just a few hops per second. The shorter packet length in the Bluetooth technology is another benefit. The frequency
  33. 33. band in FH systems is divided into a number of hop channels. Every hop channel is just a fraction of the total frequency band. In Bluetooth one channel is used in (one slot) followed by a hop in a pseudo-random order to another channel for another transmission, repeated constantly. In this way the hopping spreads the Bluetooth traffic over the entire ISM band and a system with good interference protection is achieved. If one of the transmissions is jammed by, for instance, a microwave oven, the probability of interference on the next hop channel is very low. Error correction algorithms are used to correct the fault caused by jammed transmissions. Modulation/Transmission and packet definition A Gaussian shaped binary FSK modulation is used to reduce the transceiver complexity in Bluetooth units. Full duplex transmission capability is achieved by using time division duplex, subsequent slots are used for transmitting and receiving. The Bluetooth baseband protocol is a combination of circuit and packet switching. Reservation of slots can be done for synchronous packets. One packet typically uses one slot, but a multi-slot method is also defined in the Bluetooth specifications. Multi-slot packets can cover three or five slots. Packets are always sent on one single hop channel. That means that when multi-slot packets are transmitted the hopping frequency is reduced and there is no hop until the whole packet is sent. This is illustrated in Figure 5. The channel using the white packet. starts the illustrated sequence with a multi-slot packet covering three slots. Note that the hopping channel after the multi-slot packet is the same (compare with Figure 4) as if there had not been a multi-slot packet. Bluetooth networking When Bluetooth units are communicating, one unit is master and the rest of the units act as slaves. The master unit's system clock and the master identity are the central parts in the frequency hop technology. The hop channel is determined by the hop sequence and by the phase in this sequence. The identity of the master determines the sequence and the master unit's system clock determines the phase. In the slave unit, an offset may be added to its system clock to create a copy of the master's clock. In this way every unit in the Bluetooth connection holds synchronized clocks and the master identity, that uniquely identifies the connection. Hops synchronized
  34. 34. Hop selection Hop slave clock Phase Sequence Off set Master identity with the master can therefore be achieved as described in Figure 6. 79 hop carriers have been defined for the Bluetooth Technology except for France and Spain where 23 hop carriers have been defined, because the ISM-band is narrower there. Slave Figure 6 The hop selection The Bluetooth packets have a fixed format. A 72-bit access code comes first in the packet. The access code is based on the master's identity and the master's system clock, i.e. it provides the means for the synchronization. This code is unique for the channel and used by all packets transmitting on a specific channel. A 54-bit header follows the access code. This header contains error correction, retransmission and flow control information. The error correction information can. be used for correcting faults in the payload and in the header itself. Finally Comes he payload field with anything between zero and 2,745 bits, i.e. up to 340 bytes. f n+2 f n+1 Access code Packet header Payload fn 72 Bits t 625 ms Figure 7 The Bluetooth packet format 54 bits )-2745 bits
  35. 35. Radio parameters Bluetooth units operate on the ISM band, at 2.45 GHz. The transmitting power is between 1 and 100 mW. The radio-frequency transmitters are very small. Ericsson's 1 mW Bluetooth radio module is only 10.2x14x1.6 mm. The low power consumption implies that a Bluetooth unit can operate on the power from a small battery for a long time (months). These hardware characteristics make it possible to fit a Bluetooth unit in many electrical devices. The maximum Bluetooth range is 10 m, with a possibility to extend it to 100 m. The maximum bit rate is 1 Mbit/s. Maximum effective payload is lower because the different protocol layers require data payload for signalling to their Corresponding layers in the unit with which the device is communicating. Estimates have indicated data transfer rates up to 721 kbit/s. Data packets are protected by an Automatic Retransmission Query, ARQ, and scheme. This scheme implies that at every packet reception an error check is done. If an error is detected, the receiving unit indicates this in the return packet; thus lost or faulty packets only cause a one-slot delay. In this way, retransmission is in this way selective, only faulty packets are retransmitted. Since retransmission is not optimal for voice transmissions due to its vulnerability for delays, a voice-encoding scheme is used. This scheme is highly resistant to bit errors. The errors that cannot be corrected result in an increasing background noise. Piconet and Scatternet Any two Bluetooth devices that come within range of each other can set up a so-called ad hoc connection. When such a connection is established a piconet is formed. There is always a master unit in a piconet and the rest of the units act as slaves. Up to eight active units can form a piconet, which is defined by the channel these units share. The number of devices in a piconet is actually unlimited even though you can have only eight active devices at any given moment. There is no difference in hardware or software between a master and a slave, hence any unit can be master. The unit that establishes the piconet becomes the master unit. The roles in a piconet can change but there can never be more than one master. The master unit controls all traffic in the piconet. It allocates
  36. 36. capacity for SCO links and handles a polling scheme for ACL links. Slave units may only send in the slave-to-master slot after being addressed in the preceding master-to-slave slot. If the master does not have any information to send in the master-to-slave slot, a packet with access code and header only is sent. That is, every slave unit is addressed in a specific order, and polling scheme, and may only send upon being addressed. In this way, packet collisions between sending slave units are eliminated. Establishing network connections Before a unit has joined a piconet it is in standby mode. In this mode, an unconnected unit periodically wakes up and listens for messages every 1.28 seconds. Paging messages are transmitted on 32 of the 79 (16 of 23 for Spain and France) hop carriers which are defined as wake-up carriers (the unit's identity determines which of the hop carriers it is). A connection is made by a page message if the address is already known, or by an inquiry message followed by a subsequent page message if the address is unknown. The wake-up sequence is transmitted by the master over the 32 (or 16 for Spain and France, below is the 32 hop carrier system described) wake up carriers. Initially, the 16 first hop carriers are used, if there is no response, the rest of the carriers are used. The slave's system clock determines the phase in the wake-up sequence. The slave listens for 18 slots on the wake-up carrier and compares the incoming signal with the access code derived from its own identity. If there is a match, the unit invokes a connection-set-up procedure and enters Connected mode. The master unit must know the slave's identity and its system clock. This is required to calculate the proper access code and the wake-up sequence and to predict the wake-up sequence phase. To keep track of the slaves' system clocks, a paging procedure is defined for the master unit. It defines how identities are. transmitted between master and slave units and how the slaves' current system clocks are distributed to the master. To connect units with an unknown address an inquiry signal is transmitted initially. This signal is used to inform the master unit of the slave's identity within transmission range. The paging unit on the inquiry wake-up carriers sends an inquiry access code. Units receiving this message respond with their identity and system clock. The inquiry message is typically used for finding Bluetooth devices, including public printers, fax machines and similar devices with an unknown address.
  37. 37. Power saving modes Three different power saving modes have been defined, Hold, Sniff and Park. They can be used if there is no data transmission ongoing in the piconet. A slave can either demand to be put in Hold mode or be put in Hold by the master unit. In Hold mode only an internal timer is running. Data transfer restarts instantly when units make the transition out of Hold mode. The mode is used when connecting several piconets or managing a low power device such as a temperature sensor. In the Sniff mode, a slave device listens to the piconet at reduced rate, thereby reducing its duty cycle. In the Park mode a unit remains synchronized in the piconet but does not participate in the traffic [13]. Scatternet To optimize the use of the available spectrum, several piconets can exist in the same area. This is called Scatternet. Within one Scatternet all units share the same frequency range but each piconet uses different hop sequences and transmits on different 1 MHz hop channels. Thus, a way to optimize the data transmission capability is to keep the piconets small (i.e. few units). All piconets share the 80 MHz band, where each piconet uses 1 MHz, thus, as long as the piconets pick different hop frequencies, no sharing of 1 MHz hop channels occurs. Why B CHAPTER 6. BLUETOOTH USAGE MODELS.
  38. 38.  Bluetooth usage models. Bluetooth Usage Models In this section a number of Bluetooth usage models are described. For each usage model there is one or more corresponding profiles defining protocol layers and functions to be used. The profiles are not described in detail in this document, for more information refer to the Bluetooth standardization documents. File Transfer The File Transfer usage model offers the capability to transfer data objects from one Bluetooth device to another. Files, entire folders, directories and streaming media formats are supported in this usage model. The model also offers the possibility of browsing the contents of the folders
  39. 39. on a remote device. Furthermore, push and exchange operations are covered in this usage model, e.g. business card exchange using the vCard format. The File Transfer model is based on GOEP. Internet Bridge The Internet Bridge usage model describes how a mobile phone or cordless modem provides a PC with dial-up networking capabilities without the need for physical connection to the PC. This networking scenario requires a two-piece protocol stack, one for AT-commands to control the mobile phone and another stack to transfer payload data.. LAN Access The LAN Access usage model is similar to the Internet Bridge user model. The difference is that the LAN Access usage model does not use the protocols for AT-commands. The usage model describes how data terminals use a LAN access point as a wireless connection to a Local Area Network. When connected, the data terminals operate as if it they were connected to the LAN via dial-up networking. Synchronization The synchronization usage model provides the means for automatic synchronization between for instance a desktop PC, a portable PC, a mobile phone and a notebook. The synchronization requires business card, calendar and task information to be transferred and processed by computers, cellular phones and PDAs utilizing a common protocol and format. Three-in-One Phone The Three-in-One Phone usage model describes how a telephone handset may connect to three different service providers. The telephone may act as a cordless telephone connecting to the public switched telephone network at home, charged at a fixed line charge. This scenario includes making calls via a voice base station, and making direct calls between two
  40. 40. terminals via the base station. The telephone can also connect directly to other telephones acting as a “walkie-talkie” or handset extension i.e. no charging needed. Finally, the telephone may act as a cellular telephone connecting to the cellular infrastructure. The cordless and intercom scenarios use the same protocol stack. Ultimate Headset The Ultimate Headset usage model defines how a Bluetooth equipped wireless headset can be connected, to act as a remote unit‟s audio input and output interface. The unit is probably a mobile phone or a PC for audio input and output. As for the Internet Bridge user model, this model requires a twopiece protocol stack; one for AT-commands to control the mobile phone and another stack to transfer payload data, i.e. speech. The AT-commands control the telephone regarding for instance answering and terminating calls.
  41. 41. CHAPTER 7. COMPETING TECHNIQUES & BLUETOOTH.  Competing techniques.  Bluetooth strength.
  42. 42. Competing techniques There are a number of competitors to the Bluetooth technology. However, there is no obvious single competitor in all the market segments in which the Bluetooth technology can operate. IrDA The main competitor in the cable replacement market segment is IrDA. IrDA is an infrared interface standard providing wireless solutions between, for instance, mobile phones and PDAs. The technique is well known in the market but has had problems because some IrDA manufacturers have made implementations incompatible with standard implementations. The maximum payload in the IrDA technology exceeds the maximum Bluetooth payload. The two main disadvantages with IrDA are that it is limited to point-to-point connections (only two parties in a connection) and its need for line of sight (since it is based on infrared light). Implementations based on IEEE 802.11 The main competitors in the market segment for wireless LAN are the implementations based on the IEEE 802.11 standard. Some of these implementations also use the frequency hopping technology. The main differences between Bluetooth and these implementations are: capacity * The number of simultaneous users is higher for IEEE 802.11-based systems * The Bluetooth hardware size is considerably smaller * The five Euro unit is 10 to 20 times cheaper than an IEEE 802.11 unit * The number of frequency hops is considerably higher for Bluetooth than for an IEEE 802.11 implementation. Ultra-Wideband Radio, UWB
  43. 43. Ultra-Wideband Radio, UWB, is a new radio technology. The concept is similar to radar. Short pulses are transmitted in a broad frequency range. The information is modulated by the pulses' time and frequency. The technique is not fully developed but might be a threat to the Bluetooth concept since its superiority in capacity and power consumption. UWB prototypes indicate payloads up to 1.25 Mbit/s with 70 meters range at just 0.5 mW power consumption. Home RF Home RF is a technique developed by a consortium with, among others, Microsoft, Intel, HP, Motorola and Compaq. The technique is developed from the. DECT concept and operates in the 2.4 GHz frequency band (the same as Bluetooth). The intention has been to develop a technique for the home market. There are many similarities with Bluetooth, price per unit, range, transmitting power etc. The major differences are that Home RF can handle up to 127 units per net and it uses just 50 frequency hops per second. The figures for Bluetooth are 8 and 1600 respectively. TECHNOLOGY Bluetooth DECT IR Bluetooth strengths MAX BANDWIDTH 1 mbps(gross rate) 144 kbps 4 mbps COMMENT Packet oriented for data applications,max full duplex data rate is 432 kbps, arranged as 64 kbps channels for speech Primarily designed as noice service, not packet, expensive (typically $100 for a handset and home base station) Very cheap (now ariund $1 to $2 per installation) low range (~1m) and line of sight only
  44. 44. The Bluetooth concept offers several benefits compared with other techniques. The main advantages of Bluetooth are: * The minimal hardware dimensions * The low price on Bluetooth components * The low power consumption for Bluetooth connections. The advantages make it possible to introduce support for Bluetooth in many types of devices at a low price. The diversity in product offerings (mobile phones, PDAs, computers, computer hardware, notebooks etc) from companies in the Bluetooth SIG and their broad support for the technique creates a unique market position. Both hardware and device manufacturers will work for the introduction of Bluetooth in many different devices. The capabilities provided by Bluetooth, approximately 720 kbit/s, can be used for cable replacement and several other applications such as speech, LAN and so on, as described in the use cases, described in the section entitled Bluetooth Usage Models. Figure 8 indicates in what areas the Bluetooth concept can be used. Defining of specific user models and corresponding profiles combined with the four general profiles will most likely lead to a market situation where applications covered by the user models will use the defined user models and their profiles. Furthermore, it is likely that new applications will use the standard profiles and thereby avoid interoperability problems between different manufacturers. The Bluetooth baseband protocol is a combination of circuit and packet switching. Slots can be reserved for synchronous packet. Each packet is transmitted in a different hop frequency. A packet nominally covers a single slot, but can be extended to cover up to 5 slots. Bluetooth can support an asynchronous data channel, up to 3 simultaneous synchronous voice channels, or a channel that simultaneously supports asynchronous data synchronous voice. Each voice channel supports 64 kbps synchronous (voice) link. The asynchronous channel can support an asymmetric link of maximally 721 kbps in either direction while permitting 57.6 kbps in the return direction, or a 432.6 kbps symmetric link.
  45. 45. CHAPTER 8. APPLICATION ON 3-G WORLD.  Possible 3-G support application.  The specification  Technical definition.
  46. 46. MAJOR APPLICATIONS IN THE 3-G WORLD Possible 3G Support Applications The following examples demonstrate how 3G and Bluetooth work together, providing local intercommunication as well as wide area connectivity in a wide range of applications. These are not definitive and by no means exhaustive, but aim to show how complementary standards can work together to provide a greater level of service than either could achieve separately. Vending machines in shopping mall All the automatic vending machines within a confined area can, through a Bluetooth access system, be connected to a central vending machine administration unit, that in turn uses a 3G access system to call for maintenance or supplies. Minor problems can be relayed to the Mall technician directly through his Bluetooth communicator. Pricing changes can be sent from central administration and locally “broadcast” to all Bluetooth vending machines. E-mail delivery to the PC 3G terminals will be able to handle several channels simultaneously (e.g. voice, fax and data each requiring different channel characteristics and speeds). With predictions of terminal penetration being very high (every member of the population above the age of 12 in a few years), the PC itself does not have to be a 3G terminal in order to receive e-mails on the move. A Bluetooth/3G terminal can receive e-mail as a data transmission and forward it, via Bluetooth to the PC (assuming it is within close proximity). When the reception is complete, the PC can notify the user via Bluetooth and a short message to his mobile terminal that he has e-mail, and if an item is urgent, this fact can be forwarded too. This concept allows the 3G terminal to be the local “headend” for a variety of applications that are locally interconnected via Bluetooth. If for example, such an e-mail was received while waiting for a train or plane, the user could approach a Bluetooth services booth (example new commercial enterprise for business travelers). Here, for a fee chargeable to his charge/credit card or e-Wallet, he can instruct his PC to print the e-mails of interest (using his 3G/Bluetooth terminal to control it, leaving the PC in the briefcase).
  47. 47. The e-Wallet Many people believe that the mobile phone can become the portal of first choice to the e-commerce world. At present however a separate Smart Card is required to hold electronic cash - no-one wants to remove their SIM from the phone in order have it read by a Point of Sale terminal. Bluetooth of course will allow the SIM (which now becomes a multi-function Smart Card) to be read while it remains in the phone. With 100 Kbytes Smart Cards on the horizon we can foresee our mobile phones becoming the main repository for our cash, health info, personal preferences, season tickets, etc. etc. The wide area cellular world will be one of the main routes for updating it. The Underground Train Underground facilities suffer from “poor” coverage on cellular systems. Many underground rail operators are overcoming this by installing systems designed to provide driver and station staff with a reliable communication network. Systems such as TETRA (TErrestrial Trunked Radio) provide sufficient capacity that there is spare to carry some passenger traffic too. Carriages equipped with Bluetooth transceivers would provide a gateway between the train TETRA system and the user‟s 3G/Bluetooth terminal, and the TETRA system would provide the gateway to the surface public networks. For the convenience of other passengers, not all carriages would be enabled for support of voice over Bluetooth (though the use of Bluetooth for broadcasting timetable information, advertising etc. could be available in all carriages). The Bluetooth Headset The 3G/Bluetooth terminal mentioned in the above example does not in fact need to be in the user‟s hand or pocket during most of the noted transactions. The user will have a Bluetooth headset (a product already announced by Ericsson) allowing him to leave the terminal in his briefcase too. This may provide voice control/recognition functionality, removing most of the need for a keyboard or display on the 3G terminal. These suggestions may raise the question as to where the terminal (3G) in fact should reside. Much of the functionality delivered by 3G systems will be
  48. 48. directed towards a data terminal device such as a PC or palm top computer and it may be logical to build the 3G terminal into it. With an external (Bluetooth) headset, there would be nothing to hold, though a simple MMI (Man Machine Interface) device to allow dialing and displaying of short messages (connected to the main terminal by Bluetooth of course) may be required. If this could be made credit card sized it becomes a small version of the bpad discussed above and may well replace the handset/terminal as we know it. Alternatively, as has been suggested previously in this paper, the PC and 3G terminal may be physically separate devices while being functionally connected when in close proximity to each other. This perhaps offers greater flexibility (it wouldn‟t be necessary to carry a PC everywhere simply to make and receive calls), while losing none of the functionality of the combined device. In some cases it may even be possible to leave the PC at home connected to the Home Base Station (via Bluetooth), and retrieve data from it directly to the bpad using Bluetooth and 3G together. THE SPECIFICATION IS AS FOLLOWS: Frequency band :2.4 GHz (unlicensed ISM band) Transmitting power: 1 milliwatt(0dBm) Technology : spread spectrum ; hybrid direct sequence and frequency hopping. Maximum voice channels : 3 per piconet Data speed : 721 kbps per piconet Expected system range : 10 meters (40 feet) Number of devices supported : 8 per piconet, 10 piconets in coverage area. Security : Yes, link layer. Power requirements :2.7 volts. Power consumption : 30 uA sleep, 50 uA hold, 300uA stand by, 830mAtransmitting. Module size : 0.5 square inches. Interference : Bluetooth minimize potential interference by employing fast frequency hopping –1600 times a second. TECHNICAL DEFINITIONS :
  49. 49. PICONET : A collection of devices connected via Bluetooth technology in an ad hoc fashion. A piconet starts with grow to eight connected devices. All Bluetooth devices are peer unit and have identical implementations. However, when establishing a piconet connection. The Bluetooth system supports both point-to-point and point-to-multi point connections. SCATTERNET : Multiple independent and non-synchronized piconets form a Scatternet. MASTER UNIT : The devices in the piconet whose clock and hopping sequence are used to synchronize all other devices in the piconet. SLAVE UNITS : All devices in the piconet that are not the master. MAC ADDRESS : 3-bit address to distinguish between units participating in the piconet. PARKED UNITS : Devices in a piconet, which are synchronized but do not have a MAC address. SNIFF AND HOLD MODE : Devices synchronized to a piconet can enter power saving modes in which device activity is lowered.