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            With the introduction of wireless communication, it has change the entire world; Bluetooth is such technology which has the ability to transmit both data and voice transmissions at same time. Bluetooth consists of a small microchip, and the technology behind it is short-range link to exchange information between two devices such as a computer to mobile device or mobile to mobile device. When two devices having Bluetooth come within short distance (10 meters) of each other, those two devices will detect each other and connections will be automatically. Since the technology was introduced, it has eliminated the need of connecting many wired devices; Bluetooth devices will connect instantly even if the device does not have a clear line of sight, and connection distance can be increased to 100 meters with the uses of an amplifier. The usage of this new technology is huge; when you are in the house PDA (Personal Digital Assistant) synchronizes with your house and the front door unlocks, when you approach your car; with a touch of a button the door unlocks, as you arrive near the reception of an hotel the door open itself automatically.

Introduction

            Handheld devices are increasing becoming part of people daily lives, and the mobile usage in the world is increasing exponentially; already people are using mobile phones, palmtop and laptop computers . Majority of these devices don’t have a compatible data communication interfaces, or, if they do, their interface will require cumbersome connections and configuration procedures, when you connect it with another device. A solution was created that was able to get rid of cumbersome connecting cables, and short-range wireless links was used to facilitate on-demand connectivity among different devices. The ideal technology was Bluetooth since it was inexpensive, enabling of compelling applications, and it has been universally adopted by device vendors. In 1998, a group of five major electronics companies- Nokia, Ericsson, IBM, Intel and Toshiba- created an open network technology that is used throughout the world to connect handheld devices. At the moment almost all the electronics manufacturing companies in the world have joined the Bluetooth Special Interest Group (SIG). This new technology has been named after a tenth century King of Denmark, Blatand Bluetooth who was able to unite his warring Viking tribes under a common rule in Denmark, while Bluetooth logo is based on Runes surrounding the King ruled. Bluetooth technology uses a radio frequency (RF) communication interface and other associated communication protocols and usage profiles which will be discussed later in this paper. The technology behind Bluetooth can operate in the 2.4 GHz ISM (industrial, scientific, and medical) radio frequency (RF) band, also this new technology can support low cost, its power efficient, and it is also a single-chip technology.

            Scatternet proposed here is based on a tree structure by designating a node leader to initialize the protocol and generate a centralized algorithm which will assign the roles of the network nodes. A tree topology network results to form a scatternet and develop coordinates devices. A device called the leader will start the piconet by acquiring all slaves in its range, a maximum of seven slaves. A master and its slaves form a piconet whose clock is synchronized with the clock of the master. Slaves and their master communicate through a piconet. During scatternet formation, the main issues that affect it are; how nodes will make discovery, how piconet sizes are balanced and how masters and gateways are chosen.

What is a Bluetooth?

            This is a wireless technology that will allow connectivity between two or more devices that are Bluetooth enabled, for example a mobile phone and a computer. This technology is utilizing a 2.4 GHz radio spectrum and the devices must be at a range of 10 meters or more when an amplifier is used. But, due to variations among the mobile service providers, not all the Bluetooth technology will offer the same of functionality in devices.  Bluetooth technology uses short- range communications technique which is intended to replace cable connecting portable at same time maintain a high levels of security.  The advantages of this technology are that, it consumes low power and the cost is also low, while its specifications will define a uniform structure that will be used for a wide range of devices to connect and communicate with other devices. This new technology  has achieve a global acceptance, this because Bluetooth device can connect to other Bluetooth enabled devices almost anywhere in the world, and at same time Bluetooth device can communicate at same time up to seven other Bluetooth enabled devices within a single piconet-ad hoc networks.  The strength of this new technology is its ability to handle both data and voice transmissions at same time, and this has enable people to enjoy various innovations that come with this new technology, such as hands-free headset for voice calls, mobile phone applications printing and fax capabilities.

History of Bluetooth

            In 1994, Ericsson company started developing a device that will connect mobile phones to other devices without a cable interface, but in 1998, a special group of companies going by the name Bluetooth Special Interest Group (SIG) was formed by five major mobile manufacturing companies: IBM, Intel, Nokia, Toshiba and Ericsson, with the aim of promoting widespread commercial acceptance of this new technology. Within six months, Bluetooth Special Interest Group (SIG) started inviting other telecommunication companies globally, and as a result of that they initiated a free access to Bluetooth technology, at same time these companies pledged to support any new specification of Bluetooth. Years later, with dollar signs gleaming in their eyes, the rest of telecommunication manufacturing companies quickly jumped on the bandwagon, In no time, almost 2,000 Bluetooth "adopters" to their ranks and the number continues to grow.  The initial aim of Ericsson Company to start developing Bluetooth was to unite computer devices and other telecommunication devices, such as mobile phones without the use of a cable. Thus, the Bluetooth Special Interest Group (SIG) thought it quite fitting to name this new technology after the Danish King Harald "Bluetooth" Blåtand; the Danish king was given that nick name “Bluetooth” because he used to love eating blueberries and that his teeth were stained blue due to the habit of eating blueberries; However, this is mere speculation. There are some IEEE standards which are found in Bluetooth technology, but the main difference about this new technology is that specifications or platform which Bluetooth operate is for a complete system; from physical layer to application layers found in other devices.

Bluetooth specification

            Since its inception, Bluetooth technology has maintained a global standard with known specifications. Bluetooth has heralded itself as a universal communicator and the technology can be used in any country in the world. The following are the standard specifications of Bluetooth technology:

  • Frequency Range

Bluetooth technology operates under the frequency of 2.4 GHz, globally, this band used by this technology is free and unregulated, except in countries such as Japan, France and Spain, this bandwidth has been reduced, but these restrictions have been eliminated in both Japan and Spain. In France, its military have rights over the 2.4 GHz frequency band, but the authority over 2.4 GHz band was relinquished in January, 2001. Most countries in the world are beginning to regulate 2.4 GHz frequency band, thus ensuring the band will be available for Bluetooth appliances.

  • Physical Layer

The Bluetooth hardware has been made with a single 9*9mm chip, this hardware is found in all the electronics that are Bluetooth enabled, and can communicate with any Bluetooth device that is found within a radius of ten meters or this distance can be increases to 100 meters only if an amplifier has been used. The maximum data rate that can be used to transmit data is 1Mbps for 1st generation technology, and at same time Bluetooth technology uses Gaussian Frequency Shift Keying (GSSK) for radio frequency modulation. In the near future, this technology should allow achievement of between 2- 12 Mbps transfer rate.

 

  • Noise Immunity

Bluetooth technology is designed to work in a noisy environment, there are two powerful techniques that has enable this Bluetooth technology to achieve this purpose of operating under a noisy environment. These techniques are as follows:

a. Frequency Hop (FH) spread spectrum; this is a technology which divides the frequency band into smaller channels. The technology will hop channels and in return it will minimize potential interference in Bluetooth technology operations. 

 Bluetooth device after transmitting packet of data, the device will hop to another frequency and this is determined by the master. The goodness of this technology will provide a low level transmission security that cannot be cracked; in fact this technique will prevent the E0 encryption scheme from being cracked.

b.Error control;  this technique will enable Bluetooth receiver not only to detect error received, but it will correct the same transmitted error. The technique has the capability of limiting any noise that is being transmitted over a long distance links. There are 3 errors which have been well defined in Bluetooth technology specifications: 1/3 Rate FEC, 2/3 Rate FEC, and Automatic Repeat Request (ARQ).  Although this technology has reduced the number of re-transmitted data, FEC has slow down transmissions, and therefore is not suitable to be used in a noise free environment. But, packet headers are exception for this technology because it can work well regardless of environmental factors. Automatic Repeat Request (ARQ) incurs less overhead than Forward Error Correction (FEC), but it is less effective in term of ability to correct errors. But if the transmitter will not receive an ACK the data will be resent after a predefined period of time.

  • Data Transmission

            Bluetooth technology will allow data to be transmitted in a synchronously way or asynchronously way. In voice transmission, The Synchronous Connection Oriented (SCO) method is widely used, since voice transmission need a smooth transmission and voice is transmitted via reserved intervals, in other words, packets of voice will be sent in groups without interruptions. Bluetooth technology is compatible to TCP/IP protocols and therefore can be well suited to traditional networking with other devices. In Bluetooth hardware; within a piconet, master-slave pair will have a different transmission mode and this transmission mode can change dynamically [3]. The frequency bandwidth is usually controlled by master unit- the slave unit does not have capability of transmitting data unless it has polled by the master unit. The master unit usually broadcast messages to the slave unit and this is via the ACL link, while Time-Division Duplex (TDD) technology will allow transmission in both direction in SCO and ACL.

 

  • Power

Bluetooth technology has a way of limiting its transmitting power to exactly what is needed; the signal strength of the transmitting power is dynamically modified to suit the required distance which information is transmitted. Trading off response time against battery usage; device that are Bluetooth enabled are reluctant to use unnecessary power. In comparison to a mobile phone, a Bluetooth device usually uses 3 per cent less power typically used by mobile phones.

  • Security

Bluetooth technology offers security through authentication of the devices involved in the connection and data exchange [4]. This is usually done at the Link Management Protocol (LMP) layer. Normally, this authentication based security utilizes the identification of the devices in use. Other ways of security involve implementing confidentiality and key derivation. Bluetooth PIN is what is generally used in creation of the Bluetooth key whereby the key is entered into both devices to be paired.

The E22 algorithm is the algorithm used to generate an initialization key also known as the master key whereas the encryption of packets and confidentiality granting is done with the E0 stream cipher. This cipher is supported by use of a cryptographic secret which is an earlier generated master key. Below is an image describing the Bluetooth encryption process between a master device and a slave by use of both keys?

Bluetooth utilizes three different encryption modes that are used to support the technology’s confidentiality security service [5]. The first mode commonly known as plainly Encryption Mode 1, allows no encoding of any data being exchanged or being transmitted. In other words, traffic between the devices involved is not encrypted. In this particular mode, a device does not initialize any security measure. Traffic moves to and fro in a raw state having no security procedure interfere with it. A device in this non-secure mode has its authentication and encryption functionalities totally disabled and traffic just bypasses them [2]. Encryption Mode 1 allows unrestricted access to the particular device, meaning that the device does not prompt another device to identify itself as it tries to connect to it nor does it encode the data it transmits to any device. This particular mode utilizes no key a slave Bluetooth device receives and as a result, no encryption whatsoever is performed on either individually addressed traffic or broadcast addressed traffic. This is the most non-confidential mode for Bluetooth devices and is not recommended by the authorities. This mode leaves all data packets in transmission accessible to any intruder or Bluetooth user within range of the master device [1].

Bluetooth Encryption Mode 2 performs encryption only on individually addressed traffic based on individual link keys [13]. However, these links have to be individual. This encryption mode does not perform encryption on broadcast traffic. In other words, encryption is only offered in the connection to only one device but when the devices to connect to are more than one, no encryption is performed. However, when the connection is point-to-multipoint, the traffic transmitted is not encrypted [12]. This mode as compared to the first mode, offers a little bit of confidentiality in that it allows encryption of data transfer. A security concern is however raised in that it only offers confidentiality when only two devices are involved in the data transfer[11]. This means that if more than two devices were in the same Bluetooth range and one of the devices (the master) wants to connect or transfer data to the rest of the devices (the slaves), the traffic would be open to intrusion even if authentication is enabled and verified. Thus it would be in order to declare that Bluetooth encryption mode 2, though confidential unlike Bluetooth Encryption Mode 1 that offers no confidentiality whatsoever, is still not satisfactorily confidential enough. This mode offers a leeway to intruders once the number of slaves exceeds one, thus challenging the security of the Bluetooth technology. The mode creates restrictions to data exchange [6].

Bluetooth Inquiry

            When two devices that are Bluetooth enabled want to start communicating they will do so by using Inquiry Phases, in inquiry phase one of the Bluetooth enable is assumed to be in master mode while the other one is assumed to be in slave mode [7]. The master will then send the packages and listen to respond that will come from the slave, also the slave mode listen package that is coming from the master and then send a return package. During the process of inquiry the Bluetooth enabled devices will change (“hop”) their frequencies a lot, but at a certain time during the hopping process Bluetooth enable devices will use the same frequency in the same time interval during the process, but further synchronization can be achieved in the process. The frequencies which are used during the inquiry are a subset of 79 frequencies which are widely used by the piconet in an operation. These frequencies are usually generated by resident counter and a GIAC or DIAC address [7]. The 32 frequencies that are used GIAC hop pattern are usually being spread across the spectrum by the scattering stage and it is usually at the end of the generation of frequency process in the Bluetooth. The inquiry process that are used in scattering are 0-5 and 53-78, but 32 frequencies are further divided into two trains, A and B and each will have 16 frequencies. The frequencies in a train usually changes over time, but the trains will exchange one frequency after every 1.28 seconds and this is based on changes in the free-running counter. After this period has elapses[10], the Bluetooth device enable will re-enters the scan substate and it will scan again, it will use a scan of length 11.23ms rather than 10ms which will allow a scan device to receive at least one full inquiry train, which will allow for timing misalignment.

Piconets and Scatternets

            The ad hoc network will consist of many wireless devices that are able to communicate to each other, without a central controlling device [11], and this is the method used by Bluetooth device. In Bluetooth there is no dedicated Access Point to control data transmissions, instead the first Bluetooth enabled device will initiates a transmission and thus becomes a temporary “master” of the network; master is not a dedicated device like an Access Point. In PANs, Bluetooth enable devices that are closer can discover each other and form a small network- piconet, and without the help of a user[11], and this will enable data to be transferred from one Bluetooth enable device to another, for example, between a mobile phone to a laptop; by coming near the user will instruct the mobile or computer what action to perform [11].

Piconet

            This network is usually formed when two or more Bluetooth enable devices discover each other and begin to communicate, this network can accommodate up to eight Bluetooth enable devices, this is because address is only 3 bits long; in binary only values upto 07 (slaves) can be stored in the address field [12], but the master will not have any address, but 0 will be reserved for broadcast messages. In this process one of the devices will act as a master and the rest of devices will act as slaves; this is usually the first device which start transmission will become the master.             

Scatternets

                A Bluetooth enabled device can be a master in one of piconet, but it can also be a slave in another piconet network that is within a reachable distance [2]. Also a slave device can also connect into two different piconets that are within its reachable distance. However, a Bluetooth enable device cannot be a master for more than one piconet; this is because master device determines the hopping pattern used for a piconet [2]

                If a Bluetooth enabled device connect to two piconets, it will keep track of both frequency-hopping patterns of both piconet so that it can stay in touch with both piconet [2]. A master will transmit packets to its slaves to maintain the link, and this is usually based on negotiations that are between the master and its slave’s devices. Thus, a Bluetooth device which is a member of two piconets must at all the time listen for these transmission that is coming from the master [2].

Scatternet protocol formation

Wang, 5, postulates that there are two protocols for forming connected scatternet protocols. The resulting topology in both cases is a Bluetree. Each node assumes two to three roles. The single node initiates a blueroot the first protocol which is the root of the bluetree. This is how a rooted span tree is built: the root is assigned the role of a master and one hop neighbor of the root will be its slave. The root’s children are then assigned additional aster role while the neighbors not assigned specific roles will be slaves of the new masters. The procedure is repeated until all the nodes are assigned. This happens by assigning only one node for each master.

The bluetree scatternet formation consists of three phases. In the first phase each node collects information about its neighbors and creates a visibility graph. Nodes randomly go into page scan states inviting a maximum of N nodes to join their piconets. Disconnected piconets are formed after the first case while the master collects slave’s information and share it with the slaves. During the second phase, Bluetooth nodes collect a maximum N slaves from piconets formed during the first phase. These nodes are then turned to bridges. During the last phase, piconets connect to form scatternet.     

A scatternet is formed by joining tree roots whereby each tree is a collection of nodes. The nodes alternate between three modes namely Comm, Comm/Scan and Inquire. Every root in the tree selects a leaf as the coordinator and the modes Scan and Inquire search for coordinators while noncoordinators do Comm/Scan. When they find each other, coordinators inform roots which enter page and page scans modes. This results to two roots to communicate and the master code becomes a new root. If a tree gets disconnected, the algorithm changes roles depending on who left the tree.

A Bluetooth sensor network is also called a Bluetooth node whose work is to collect sensed values from sensor. The formation process involves two processes; the first and second phases. During the first phase connections and information about neighboring nodes are made. Information sensed by each node is sent to the Super Master (the network node) which orchestrates the network collected from the internet. Each node makes an inquiry during this phase one at a time during which other nodes make an inquiry scan. Inquiring nodes establish a network through SDAP and information collected during an inquiry is sent to the parent forming the matrix. As the node finishes an inquiry, then the next device starts its inquiry. When all nodes have taken their turn, the device gives the parent its turn to and shares all the information. Running this backs the algorithm traverses tree nodes and returns information to the super master. This helps to collect network information as the super master chooses K nodes and the selection is done on every ode through the tree and coordinated by the super master. 

 

Alternating bit protocol [14]

Alternating bit protocol is a simple data layer protocol that is used in transmitting corrupted or lost messages in one direction between a pair of protocol entities. The messages sequences alternates between 0 and 1.

M= messages sent from sender to receiver and

A= acknowledgements sent from receiver to sender

The protocol uses positive acknowledgment and other information of one bit to each message that is exchanged. Only one bit of message can be sent at a time; stop and wait.

The model from this protocol is build from sender and receiver otherwise known as automata. The messages are exchanged between two fifo lossy channels, M and A.  The sender will be able to read messages by the producer and send it through M. Acknowledgment for the message is then waited through A. the sender will be required to resend the message with the same bit if the acknowledgement does not arrive. If received, the sender will be able to send the next message from producer with an incremented bit.

In this model, the A and M channels are unbounded because the resent data is not bounded as the figures below suggests in states s1, s3, r0, r2. The figures below give the automata of the receiver and sender.

M!m0= sending of a message with bit 0 through channel M

M?m0= reception of data with bit 0 through M

nop= transition has no effect on channels

 

Protocol validation

Validation protocol is defined as a means of testing processes to ensure that they are valid and effective. Its main purpose is to help determine if certain rules or procedures are followed correctly. The protocol employs certain instructions that are followed to accomplish an end result.

Computer networking protocol validation is done using some simulation and testing. To verify a protocol it has to be described in a structured way. There are usually two ways in doing this, use an implementation in a regular programming language and the use of a high level formalization language like PROMELA [15].

What is promela?

            This is a modeling language process which is used to verify the logic of parallel systems; the programming language is mostly used because it can be dynamically used to create a concurrent process in modeling, for example in distribution systems. In this

Modeling, communication via message channels can defined to be synchronous or asynchronous, and this system can be analyzed by a spin model checker to find out if the modeled system has produced a desired behavior; the spin will perform a random or iterative simulations of the system execution or it can use a C programming that will perform a fast verification of the system for correctness. During the verification processes , the spin checkers will check if the deadlocks are there in the system, unspecified receptions and unexecutable code in the system.

            There are good reasons for an individual to use this programmable language, first, in designing and verification coordination structures in the distribution system software is regarded as harder in practice than the design of a non-interactive sequential computation, for example computation of compound interests. Second, system computation can be done more thoroughly and more reliably today than the verification of even the simplest computational procedure. Promela program contain many features that are not found in other mainstream programming languages, and these features will help a programmer to construct a high level models of distribution systems as you compare with other programs. For example, it will include specification of non-deterministic control structures; in other words, the program will have fairly rich set of primitives for inter-process communication. The limitation for this program is that it lacks some features that other programming languages have, for example functions that will return values, expressions with side effects and functions pointers; this is for the simple reasons that PROMELA is not a programming language but it is used to create a verification models. The model differs in two ways from a program written in programming language such as java or C++.

  • A verification model will contain things that are not part of the implementation of the program, for example it can contain worst case assumptions about the characteristic of the environment that the verification model may interact with the system and this can either be implicitly or explicitly which will contain a specification of correctness properties of the program.

  • Verification model will represent an abstract of original design that contains only those aspects that are found in the system.

PROMELA is drives many characteristics from C program, for example syntax for Boolean and arithmetic operators, but POMELA has other differences that, is important to focus on the construction of high-level models of the interactions in distributed systems. The constructed model in PROMELA is made up of three basic types of objects: data objects, processes and message channels.  Processes in PROMELA are proctypes and are mostly used to define behavior, in the program, there must be at least one proctype which must be declared in a model, and for the verification to be of much use there must be at least one process instantiation. The body of proctype is made up of zero or, one or many statements and the execution of the statement in the program is somewhat special because it will double as the primary for enforcing process synchronizations. Data or message channels can either be declared either globally, and this is found outside the process type declarations, or locally within a process type declaration, these are the two types of levels of scope in PROMELA programming language: global and process local. It is not possible to restrict the scope of a local object to only part of a proctype body.

 

Conclusion

            This paper has allowed me to go thoroughly into the new emerging technology; Bluetooth, with time this new technology applications will keep developing this is because of the need of mobility. Bluetooth technology is among the many proximity technologies being employed all over the world, such proximity technologies are: Infrared, RFID, and contact less Smart cards. Most of people using this new emerging technology are concern about the various issues such as: usefulness, acceptance, applications, security, usability, and reliability of technology. In order for these concerns to be taken care of, many specialists working with this new technology are continuously working to improve profiles into the emerging technology. Version two of Bluetooth technology can handle most of these concerns, SRFT Bluetooth technology has been created for financial transactions used in short range, and this has been a major step in the improvement towards Mobile Financial transactions. At the moment, Bluetooth will provide auto connection between two devices that are Bluetooth enabled, with compromise to security. 

            A recent article may seem to spell some trouble on the future of this new technology; Bluetooth. “Recent Intel Development forum said the technology company was giving up on the deadlocked ultra-wideband IEEE task group, and the company has decided on going it alone with their new technology that will compete with Bluetooth technology, they are calling wireless USB. This new technology being initiated by Intel will do everything Bluetooth technology does and, but in term of Bluetooth found in PCs will be all dead. Ultra-wideband will able to provide a substantial performance benefits over Bluetooth technology, because it will be able to approach the speed of USB 2.0 and 1394. This means there will be faster connections, and at moment the faster connection is increasingly required by devices such as: apple iPod, digital cameras and removable hard drives.  The lack of this throughput is what ended the Intel/Bluetooth technology honeymoon”.

            If these new technologies were to be developed by Intel, they would give Bluetooth a run of its money. If the new technology will posses reliable compatibility, faster data transfer rate and the backing of a major player in the telecommunication industry- Intel, then surely Bluetooth will be in danger and may fall to the wayside in term of competition. However, at moment Bluetooth technology has already grabbed a large share of the market and it has a head start on whatever other new technologies that will come into being to compete.  This also means, Bluetooth technology will have price advantage because research and design phase of Bluetooth technology has already been completed. Also, those special interest groups that advocate for the use of Ultra-wideband are at deadlock and as for now, no progress on the device has been made, so, as for now Bluetooth technology has the monopoly on the short range, low power wireless technology that are Bluetooth enabled.

            Bluetooth technology is also getting better on itself, the special interest group (SIG) is working on a new version of specifications that are found in Bluetooth technology. The group at the moment is working on the version 1.1, also, a group by the name Radio2 is working on the problems Bluetooth technology has with bandwidth technology, interference and problems with setup connection.  If Radio2 can achieve their objectives of increasing the bandwidth, decreasing interference of Bluetooth with other technologies, and lastly correct the problems of connection setup, the future will be brighter for Bluetooth technology, and the technology will be able to compete well with the performance of new technology that will come into the market.

            Based on various evidences from all aspects of applications, this new technology is definitely a technology that has valuable uses in the world today. If Bluetooth technology continues to be unchallenged in the world, even though it has its drawbacks, it will grab a large share in wireless device technology.  With the backing of major telecommunications companies which has put their money in research and development, it will be extremely difficult for other emerging technology to overcome Bluetooth technology.

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