Study On The Performance Of Bluetooth Data Transmission Based On Error Control

Bluetooth technology is a short-range wireless voice and data communication open global specification, devices can communicate with each other through Bluetooth technology fast and conveniently, and Bluetooth technology has many advantages such as low cost, small size, free spectral bandwidth and simple networking. Bluetooth technology is now widely used in wireless communications, including voice communications, data transmission, Internet access, intelligent home and so on.Although Bluetooth technology has been applied widely, but it is not perfect, there are still many areas that need to be improved. The proposed goal of Bluetooth technology is to be universal, cheap and compact in structure, therefore the technology in use is not the most advanced itself on many levels, and when in the process of practical application there are some insurmountable problems. Such as the error control mechanism defined in Bluetooth specification includes 1/3 code rate forward error correction, 2/3 code rate forward error correction and ARQ mechanism. In the case of poor channel quality, the performance of anti-interference is difficult to meet with the practical applications. As a user, we always want to use products with high technology and good performance.When we use Bluetooth devices to transmit data, the data from the upper application, mainly passes through Bluetooth Logical Link Control and Adaptation layer (L2CAP), HCI, Baseband layer and RF layer to complete the interaction of data successfully. In order to ensure the performance of data transmission during the process, the specification has introduced the error control mechanism in the L2CAP layer and Baseband layer in order to ensure the reliability of data transmission. In this paper we have done research on the process of Bluetooth data transmission deeply, and analyzed the existing problems concretely, then according to the problems we finally have given out the solutions that improve the performance of Bluetooth data transmission.The innovation of the thesis work can be concluded in 2 aspects: 1. In the Baseband layer, according to the problems of DH packets defined in Bluetooth specification 2.0 + EDR, we gave out the improved error control mechanism which could resolve the problems by means of extended Golay Code and MSK modulation. Then in the case of low SNR, the improved DH packets could maintain a higher throughput, at the same time had improved the performance of anti-interference of Bluetooth data packets.2. In the L2CAP layer, mainly according to the problem of low throughput rate in L2CAP layer when the error data was retransferred, the thesis introduced the SR + ST hybrid ARQ mechanism to improve the retransmission mechanism of L2CAP layer, through analyzing the simulation result, the solution had improved the throughput rate of data transmission and the required buffer space was limited, so the data overflow could not occur.This thesis consists of 6 chapters, as follows:Chapter 1 is the Introduction. In this part we introduced the Bluetooth technology briefly and also included the applications and prospects, at the same time analyzed research status and problems of error control mechanism of Bluetooth data transmission. Finally the content and structure of this thesis were presented.Chapter 2 is the analysis of Bluetooth protocol. We mainly introduced the architecture of Bluetooth protocol, including the protocol specification and the framework of practical application. Then we had a systemic analysis of Bluetooth protocol separately from three parts including the RF protocol, the core protocols and non-core protocols of Bluetooth.Chapter 3 is the study on the error control mechanism of Bluetooth data transmission. Firstly we described the error control technology in detail, including the principles and basic form, then we introduced the error control codes which are used frequently in error correction, and in view of several error control codes we made a detailed analysis. Finally we analyzed the realization form and the existing problems of error control mechanism of Bluetooth data transmission respectively from the Bluetooth Baseband layer and Logical Link Control and Adaptation layer (L2CAP), which can be considered as the basis of future research.Chapter 4 is the improved algorithm of error control about Bluetooth Baseband layer. Firstly we have made a research on the problems of DH packets transmission in Bluetooth Baseband layer, and then we separately analyzed the performance of DH packets which were encoded by extended Golay Code and also the bit error rate of packets using MSK modulation. At the end of this chapter we put forward the improved error control algorithm which was based on extended Golay Code and MSK modulation, through the simulation we obtained that the improved DH packets of Bluetooth have good performance of anti- interference, and in the case of low SNR they could also maintain high throughput.Chapter 5 is the improved algorithm of error control about Bluetooth L2CAP layer. Firstly we have proposed the problems of retransmission mechanism about Bluetooth L2CAP layer, and we then analyzed the advantages and disadvantages of existing traditional ARQ mechanisms. On the basis of research, we finally introduced SR + ST hybrid ARQ mechanism to improve the throughput rate of data transmission about Bluetooth L2CAP layer. Through the analysis of results obtained by simulation, we have confirmed that the improved algorithm can take advantage of limited buffer space to achieve the high efficiency retransmission of Bluetooth data.Chapter 6 is the summary and prospects. In this part we have made a summary of the thesis, and given out the problems about Bluetooth data transmission which have to be solved in the future.