On The Scheduling Algorithm Of Bluetooth Piconet

Bluetooth is a global open standard for wireless data and voice transmission.As a low cost and short-range wireless communication technology, Bluetoothprovides a special way to connect and exchange information between land andmobile equipments. The foundation of it is to build general wireless air interfaceand the control software. So the communications and computer technology can beintegrated and the electronic devices produced by different companies areallowed to work with each other in a short distance without wire connections.A Bluetooth device with the role of "master" can communicate with up to 7enabled devices with the role of "slave". This network of "group of up to 8devices" (1 master + 7 slaves) is so called a piconet. A scatternet is composed of 2or more piconets. Because of its low cost, low power consumption, strongrobustness to interference and building net convenience, Bluetooth has been oneof the fastest developed technologies in recent years.The overall transmission performance of the piconet is mostly depended onthe adopted polling scheduling algorithm. It is a specific method by which themaster can access and serve the slaves. There are two types of schedulingalgorithms. One type is the traditional scheduling algorithm including PPR (PureRound Robin), ERR (Exhaustive Round Robin), GRR (Gated Round Robin) andDRR (Deficit Round Robin), etc.. The other type includes PP (Priority Policy),KFP (K-Fairness Policy), SLQ (Stochastically Largest Queue), EPM (ExhaustivePseudo-Cyclic Master Queue Length) and LARR (Look-Ahead Round Robin),etc., namely the adaptive scheduling algorithms.The traditional polling scheduling algorithms can be implemented easilyusing the low cost hardware, and it is widely used by the current Bluetoothproducts. Comparing with traditional polling technique, the adaptive pollingtechnique is more complex. It requires host equipments to know the latest queueinformation on Internet at any moment. Since the current Bluetooth standarddoesn't provide corresponding protocol, many adaptive techniques are theidealized solutions at this stage.This paper investigates both the traditional and adaptive polling schedulingalgorithms. First, the general information of the Bluetooth technology, currentresearch, the trend of the scheduling algorithm and the contribution of thisresearch are briefly introduced. Second, the Bluetooth base band criteria on thephysical link route, base band grouping, logic channel, and link controller stateare described thoroughly. Finally these two types of scheduling algorithm areinvestigated in more detail.The primary task of this research is to analyze and compare the traditionaland the adaptive polling scheduling algorithms. Because of the complexity of themedium accessing control layer, simulation is utilized for research andperformance analysis about the scheduling algorithms. For the traditional pollingscheduling algorithms, this thesis investigates currently adopted Limited-1polling scheduling algorithm and Exhaustive polling algorithm in detail. Thework includes building piconet scheduling model, analyzing specific workingmechanism, deriving the formula of average waiting time and suggestingsolutions for future improvements. For the adaptive scheduling algorithms, thisthesis investigates FPQ and equity algorithm in depth following a briefintroduction. A polling algorithm is proposed with the overall consideration of theneeds of piconet, time delay, channel utilization rate and equity. Based on thesame piconet performance evaluation criteria, the simulations are conducted withthree models: up model, down model and mixed model. And their performancesare compared with that of the traditional algorithm. By analyzing, deriving andsimulating the traditional and adaptive scheduling algorithms, the goal to achieveperformance gain in terms of advancing throughput, reducing time delay andimproving network capability is reached.Though this research is based on Bluetooth piconet, these analyzing methodsand conclusions can also be applied to the other wireless networks, especially thenetwork model with single sever, multi-queues and random size of packets.