On The Scheduling And Network Formation Algorithms Of Bluetooth Personal Area Network

Bluetooth technology is an open global specification for wireless data and voice communication. Based on low cost short distance wireless communication, Bluetooth becomes a communication technology that provides special connections for fixed and mobile devices. The Bluetooth personal area network, which is composed of multi-devices, is one of the typical Ad hoc. There are two kinds of network formations, piconet and scatternet. The Bluetooth personal area network can either work independently or connect to Internet and other wireless networks. The Bluetooth personal area network is designed for the application scenes of home and small offices. It can be used for voice communication, data communication, the connection and automatic information exchange of electrical devices and etc. The Bluetooth piconet polling-scheduling algorithm, adaptive scheduling algorithm, scatternet network formation algorithm and performance analysis of packet transmission are all current leading and important research issues of Bluetooth technology.Comprehensive research work for Bluetooth personal area network was made in this paper and the important issues of currect research were summarized and compared. A series of algorithms and new analysis methods for existing difficult problems were also presented. The creative work of this dissertation includes four aspects: 1) It was the first time that we systemally applied the theoretic analysis methods of classical Limited-1, Exhaustive and Gated polling algorithm to the analysis of Bluetooth piconet scheduling algorithm. The exact expressions of the mean waiting time for Limited-1, Exhaustive and Gated polling algorithm were derived for different traffic modes that established the theory foundation for other piconet research work. 2) As for the research work of Bluetooth piconet adaptive scheduling algorithm, we presented a Polling-on-Demand scheduling algorithm that harmonizes delay, channel utilization and fairness simultaneously. 3) Also it was the first time that the transmission performance of ACL packets defined by Bluetooth 2.0+EDR new specification, for different signal-to-noise ratio in AWGN channel was derived that was. An Adaptive packet selection strategy in AWGN channel was also presented that can efficiently optimize the system transmission performances with different signal-to-noise ratio. And 4) A chain structure Bluetooth scatternet algorithm for topology formation was presented. The scatternet formed by this algorithm has excellent characteristics: comparably less number of piconets, less average number of roles every node and less number of maximum degree of nodes.This thesis includes seven chapters:The research developments for four important research contents of Bluetooth personal area network were summarized in the fist chapter. The main research work and the chapter structure of this thesis were specified.In the second chapter, some necessary basical knowledge was introduced, such as Bluetooth specification and application profile, node states and link establishing process and etc. Then the network property of Bluetooth personal area network was summarized and, the formation structure and character of piconet and scatternet were also analyzed. These knowledges provide the theory foundation for the following chapters.In the third chapter, the Limited-1, Exhaustive and Gated polling algorithm were studied. A Bluetooth piconet polling algorithm model was set up and then the mechanism of above three polling algorithm were investigated. The performance standards were also defined. The exact expression of the mean packet waiting time for Limited-1 algorthm was derived theoretically by means of pure probability mathematics method. The expression can be used for any traffic distribution. According to Pseudo-conservation theorem, the exact expression of the mean waiting time for Exhaustive polling algorithm was derived theoretically, which can be used for half-symmetrical traffic modes. Moreover, the exact expressions of the mean waiting time for Exhaustive polling algorithm in half-general traffic modes, and for Gated polling algorithm in general traffic modes were presented, based on the decomposition theorem and analytical approaches of M/G/1 queues with vacations.In the fourth chapter, the adaptive scheduling algorithm for Bluetooth piconet was investigated. Firstly, some main adaptive scheduling algorithms currently used for Bluetooth piconet were analysed. And then a Polling-on-Demand scheduling algorithm for Bluetooth piconet was presented, which has good characters of low delay, high channel utilization and desired fairness. A scheduler computes out estimate of packet arrival rates for upstream links by the rate estimating process defined in the algorithm, and then the algorithm works out the estimate of packet arrival number and latency for every link pair from its last poll time through present moment. According to the dynamic polling selection regulation presented in the paper, the scheduler selects a link pair that has the highest priority to poll, and computes the next polling time according to the adaptive polling interval regulation. The algorithm harmonizes delay, channel utilization and fairness simultaneously. A set of performance evaluation standards is proposed. Three traffic modes, mixed, downstream and upstream are used to compare the performance between this algorithm and other classical algorithms by simulations. The results indicate that this algorithm has the best integral performance in the first two traffic modes, and particularly, delays decrease by at least 24.1% and 41.4% respectively. The algorithm also has relatively good behaviors in the third traffic mode.The Bluetooth packet transmission performance was studied in the fifth chapter. The Bluetooth packet transmission performance can significantly determine the transmission performance of the Bluetooth network and it is an important component of Bluetooth PAN research. The function expression of bit error rate and average signal-to-noise ratio of three modulation modes, defined by Bluetooth 2.0+EDR new specification, were analysised in this paper. And the transmission performance of ACL packets, including average throughput, average retransmission times and average transmission delay, were derived through the retransmission probabilities and characteristics of packets. An Adaptive packet selection strategy in AWGN channel was also presented. The maximum throughput was obtained by selecting the appropriate packet types to transmit in different SNRs. The SNR threshold values for packet type switching were also presented. The analysis results and strategy presented adapt to optimizing Bluetooth data transmission performances.In the sixth chapter, the network formation of Bluetooth scatternet was investigated. The research of network formation of Bluetooth scatternet is one of the issues yet to be resolved for Bluetooth personal area network. This paper presents a novel chain structure Bluetooth scatternet algorithm for topology formation: all Bluetooth nodes turn into Inquiry or Inquiry Scan states with identical probability, 0.5, then set point-to-point connections up simultaneously. As a result, as large as possible numbers of temporary piconets are made up, and furthermore, some larger piconets and groups composed of several piconets are made up through varieties of merging and recomposing repeatedly. Finally, a chain structure scatternet with only one group will be formed after operating the algorithm several times. Simulations and performance analysis indicate that the scatternet formed by this algorithm has excellent characteristics: comparably less number of piconets, less average number of roles every node and less number of maximum degree of nodes, shorter networking establishment time, easier to maintain topology dynamically and dispensable for all nodes to be in communication range, etc.A conclusion for the entire thesis was made in the seventh chapter. And the issues that need to be investigated and solved in the future research work of Bluetooth personal area network were pointed.