Research On Enhancing The Transmission Performance Of Bluetooth

As a commercial technology of short range wireless communication, Bluetooth has an unexampled advantage. It can be used in the occasion such as Wireless Personal Area Network. However, this does not mean that Bluetooth is perfect. Bluetooth still has some aspects need us to research. Aiming at the actual problems existed in data transmission of Bluetooth and research results from other people before, the reasons and results may lead by the problems are analyzed. Then some strategies are provided to enhance the reliability of data transcend in Bluetooth system. Some creationary research work is made in this paper from the following fields: data security, frequency-hopping security, anti-jamming in piconet and scatternet, coexistence with other devices and so on.In the aspect of data security, the E₀ Encryption System in Bluetooth is analyzed. A new algorithm is introduced to attack E₀ use the correlation of its sequence. The average time complexity of the basic and the advance attack respectively is O (2⁸³) and O (2⁷⁸). Base on the way of attacking means described in the paper, an improvement on EO is made.In the aspect of frequency-hopping, a method on the construction of frequency hopping sequence is purposed with arbitrary slots number based on the clock and address of communication device. Through the operation of confusion and slot number mapping, a frequency hopping sequence may be produced with fine uniformity and arbitrary slot number that less than 512. Simulation analysis and numerical experiment show that this method has merits of distribution uniformity, independence, stabilization of FH interval, ease to be implemented by hardware, etc, and can be widely used in FH multiple address communication system. A family of FH sequences base on SAFER+ cipher is proposed for FH communication. Simulation and analysis results show that the proposed FH sequences based on SAFER+ algorithm have good performance in security, uniformity, correlation, complexity and so on, agree well with the demand of the FH sequences. A family of FH sequences base on stream cipher is proposed for FH communication. Given an illustration of E₀ stream cipher algorithm, the FH slot numbers are composed by the output binary stream of E₀. Simulation and analysis results show that the proposed FH sequences based on stream cipher have good performance in security, uniformity, correlation, complexity etc., and agree well with the demand of the FH sequences.In the aspect of anti-jamming in piconet, the relation between Packet Error Rate (PER) and Bits Error Rate (BER) is analyzed. The average data rate under different Signal Noise Ratio (SNR) is deduced and the adaptive packet strategy is obtained. Then, a method adding 2-DM and 3-DM packet type to the Bluetooth 2.0+EDR specification is proposed to improve the anti-jamming ability of Bluetooth. The method of adding BCH coding to Bluetooth specification is presented improve the performance of Bluetooth data transmission, and then the transmission throughput of new added packet types with BCH coding is analyzed. The simulation results show that adding BCH coding method to Bluetooth specification can improve the transmission performance obviously. The broadcasting performance of Bluetooth is analyzed. The packet type need be used and the retransmission times are decided. The average maximal throughput is given. Simultaneity, a system level Simulink model of Bluetooth is presented. A wireless propagation indoor channel model is provided also. Then those models are used to simulate the performance of Bluetooth communications indoors.In the aspect of anti-jamming in scatternet, an analytical model of packet interference in Bluetooth Scatternet is presented. The throughput of data transmission on ACL packets is found. According the case whether adapted Frequency-hopping and network synchronous, packet send success rate of single packet is analyzed. In the end, the maximal throughput under using different data packets is obtained and the optimal packet when the scatternet reached the maximal throughput is found too. To alleviate the impact, an efficient method is proposed by interference-aware SAR (Segmentation/Reassembling) policies. Through comparing the frequency hopping sequence with others, the piconet can aware when the interference happens. Then it can avoid the collision of slots using the data packets segmentation and reassembling policies. Form the simulation, we found the method can improve the data throughput of Bluetooth scatternet evidently. In the end, Making use of the characteristic that the Bluetooth FH sequence has a bad correlation, an exhaustive quasi-orthogonal FH set is constructed with the same FH address and different clock. When the Bluetooth scatternet is working, the lead master will send its FH address, clock and the offset of clock, then all piconets can communication together without interfere from the other piconet. The throughput of data transmission in the scatternet is improved greatly.In the aspect of anti-jamming in scatternet, a new multi-band Bluetooth technology is presented to settle the more serious problem of coexistence in short range wireless communication. On the base of unchanged Bluetooth baseband protocol, 900MHz and 5.8GHz RF modules are also added so that the Bluetooth device can work on among 2.4GHz, 900MHz or 5.8GHz ISM band. This method is successfully implemented by material hardware and software systems. Simulation results show that the method not only meliorates the coexistence problem, but also improves the performance among wireless devices, such as net building, anti-track, and communication distance, etc.The research work in this paper gains some innovation and outcomes, and also uses for reference of other short range communication. We will continue our research. The works that is doing now and need to do in the future are listed as follows.First is that designing ASIC of Bluetooth baseband system. As the project is the Digital Single-Soldier System, our final aim is implementing the first martial wireless communication ASIC in China. The realization procedure of the whole project is three steps: base on Bluetooth, change Bluetooth and exceed Bluetooth. Only if the Bluetooth baseband is made ourselves, we can eliminate the disfigurements of Bluetooth from the original. The work we did in this paper can come into true drastically.Second is that transferring voice through the Bluetooth sccaternet. Though SCO links can be established in the piconet, but the main traffic in sccaternet is ACL packets. It is hard to realize SCO link in the sccaternet. But the voice is one of the main traffic in Bluetooth Communication System. How transfer voice through the Bluetooth sccaternet is a difficult problem. It is worth for us to discuss and research in the future.