Applied Mechanics and Materials Vols. 475-476

Abstract: Vehicular environment with the fast varying and fast moving character calls for the support of security communication technologies. The solutions based on watermark and VPN (Virtual Private Network) are discussed to realize security communication of DSRC (Dedicated Short Range Communication), which is earmarked for motor vehicles to exchange information with each other in the area of ITS (Intelligent Transport System).Finally this paper analyses the characteristics of the solutions.

Abstract: A novel self-mixing homodyne detection 60GHz radio over fiber (RoF) scheme with 5Gb/s 32QAM-OFDM downlink signals using discrete multitone (DMT) modulation is proposed and demonstrated by experiment. 5Gb/s 32QAM-OFDM downstream signals are transmitted over 42km SMF-28. The peak-to average power ratio (PAPR) characteristic, and the BER performance of 5Gb/s 32QAM-OFDM signals with different subcarriers generated DMT modulation and self-mixing homodyne detection are analyzed. The experimental results show the transmission performance of 5Gb/s 32QAM-OFDM signals with different subcarriers, and this RoF scheme is a suitable method for future 60GHz access system applications.

Abstract: With the rapid development of OFDM (Orthogonal Frequency Division Multiplexing) technology and its own advantages, this technology has been studied actively in underwater acoustic communication recently to improve the data transfer rate and reliability. This paper introduces the key technology of high speed OFDM underwater acoustic communication, analyzes the advantages and disadvantages, design a high-speed underwater acoustic OFDM communication coding scheme based on TURBO code, and proceeding the simulation and analysis for the OFDM system. Finally, the reliability of TURBO code in high speed underwater acoustic OFDM communication is analyzed.

Abstract: The acoustic noise induced linewidth broadening phenomenon of distributed feedback fiber laser (DFB FL) is experimentally studied in this paper. Using the delayed self-homodyne method, we performed linewidth measurements on one unpackaged short cavity asymmetrical DFB FLs under increasing acoustic noise influence. The experiment results show the linewidth of tested laser increased from 5.8 KHz at 50 dB sound level to 32.5KHz at 80 dB sound level. This proves acoustic noise can drastically change the linewidth performance of unpackaged DFB FL. In addition, we performed another experiment on the same DFB FL to measure its linewidth with increasing tensile loads at fiber ends; the result shows a linewidth increase from 5.8 KHz at 0g tensile force to 51.2 KHz at 50g tensile force.

Abstract: Firstly Cognitive radio (CR) communication technology is introduced. Then the current research situation of CR-based anti-interference communication are reviewed and analyzed. The two CR-based anti-interference radio structures are given. Then CR-based anti-interference transceivers are introduced and analyzed. Further analysis shows that the future research for CR-based anti-interference radio system should consider the difference between anti-interference user and cognitive user, more environment information interceptions and the combinations of CR and other anti-interference technologies.

Abstract: The wireless programmer based on the NRF9E5 chip is proposed, designed and applied. The circuit board doesnt connect to the computer with any cable, and it connects to the computer through the wireless transmission of the NRF9E5. The circuit board can realize to update the program online through the exquisite programmer. The programmer can download the program for 5.97 seconds and it is widely applied to the product development and quantity production area.

Abstract: As a promising way to the certain area surveillance, the application of wireless sensor network on the unknown subsea observation is becoming more significant. After placing the sensor nodes, each sensor node will generate a common communication frame and choose the next hop neighbor node randomly, which could results in redundant energy consumption. In this paper, a data transmission strategy is proposed including routing scheme, frame format and the corresponding topology structure. By considering the transmitting distance, energy consumption and transmission probability, the introduced strategy can reduce the redundant energy consumption, balance the network payload and prolong the subsea observation network lifetime. The simulation results show that the strategy is more efficient than the common one.

Abstract: Due to the further development in recent years, VoWLAN(VoIP over Wireless LAN) will achieve convergence with other service inevitably and has a higher requirement for network performance. Service focused on the whole converged network is different, so the measure of network status has different demands, we should set parameters reasonably and make it adaptive network in order to realize the optimization of network performance according to the current channel load level and distribution of service condition. Therefore, we can adjust the Contention Window(CW) dynamically, according to the slot utilization rate to estimate the channel load and the concept of backoff discontinuation rate. Simulation results prove that this scheme is simple and effective, largely improved QoS performance of the throughput and delay of each service.

Abstract: Explorations on ultraviolet (UV) communication field are relatively little among wireless communication for lacking of suitable simulation equipments. Possible mode was investigated on UV by combining mature coding techniques with gradually improved multiple-input multiple-output (MIMO) technology. A candidate modulation method, the 16-ary quadrature-amplitude modulation (16QAM), was analyzed for UV communication using MIMO technology. Comparisons between 16QAM and OOK were presented to better depict characteristics of 16QAM through simulation. The result shows that under specific bit error rate (BER) requirements for most communication environments, 16QAM can help save transmitting power and enlarges transmission capacity.

Abstract: The paper describes development of System SMPSL for analog communication. The system consists of hardware and software parts. The system is used for measurement of analog quantities using a computer. Communication is via libraries. System is very cheap to assemble the hardware. Available software is free. The paper describes the basic connections and the source code for creating an analog input and output.