Applied Mechanics and Materials Vols. 336-338

Abstract: For the linearization of power amplifiers, a digital pre-distorter is proposed to compensate nonlinear distortion in this paper. The pre-distorter is realized by Volterra series, and a restarted limited memory BFGS(LBFGS) algorithm is proposed for training the nonlinear pre-distorter. Training of Volterra series can be switched between gradient descend algorithm and quasi Newton algorithm by setting a switching condition, and LBFGS algorithm can be used for high dimensional iterative matrix of BFGS algorithm. These make the new algorithm much more stable with a fast convergence rate. The pre-distorter is used for OFDM power amplifiers and it high efficiency is proved by simulation results. Moreover, the convergence rate of the proposed algorithm is greatly faster than that of the gradient algorithm.

Abstract: According to characteristics that the vehicles move fast and topology changes quickly in Vehicular Ad hoc Networks (VANETs), a novel routing protocol GMGP based on the location is proposed for VANETs. Predicting the changes of the neighboring nodes positions and using greedy forwarding mechanism forward packet, and using a movement perimeter forwarding algorithm to select the next reliable hop node on the basis of direction and velocity of the mobile nodes when the greedy forwarding fails, it improves the reliability of routing. When a more realistic vehicles mobility model is applied to the NS-2 simulation platform, the simulation indicates that the improved routing protocol has better performance than the GPSR routing protocol.

Abstract: With the gradual application of RFID technology, the problems of privacy security arouse people's great attention. To address the problems of the existing RFID authentication protocol, such as the weakness on security and privacy, the high cost and the un-stabilizing systems performance, this paper puts forward a kind effective protection of privacy and low cost RFID security authentication protocol, analyses the security and performance of this protocol. This protocol can not only effectively solve the problems of replay attacks, location privacy attack and data synchronization, but also greatly use the Reader computing resources to reduce the cost of system construction, so it is appropriate for the application of RFID system.

Abstract: When there are multiple electronic tags in the reading range of reader, It arises problem of multiple tags data collision in the data communication process of RFID system, causing the data reader have obtained error. This paper will contrapose the problem of tag collision, analysizing the search number and the system throughput rate of the existing anti-collision search algorithm based on binary, to propose an improved anti-collision algorithm. The improved algorithm reduces the redundant information of the sequence number that the reader have sent, and no longer searchs the tags of one bit collided ,but identify the two collided tags directly, thus reducing the search number of algorithm. Matlab simulation show that this algorithm can reduce the search number of reader identifying tags, improving the identifying efficiency of the RFID system, solving the problem of tag collision effectively.

Abstract: It’s important to insure wireless network authentication security. Via model checking tool SPIN modeling 802.1x EAP-TLS authentication protocol, communication parts are defined with model checking language PROMELA, security properties are expressed by LTL formula, and the model is verified. With the attack track given by SPIN, the security vulnerabilities caused by the improper configuration is pointed out, meanwhile the new tunnel authentication protocol is proposed to reduce the occurrence of attack and to improve the agreement.

Abstract: This paper proposes a complete set of Urban Parking Guidance and Information System, which includes Parking Subsystem and City Parking Subsystem. The system adopts wireless sense network based on ZigBee technology for the communication network. The parking information terminals that set up in the parking areas automatically identify the parking vehicles and upload the parking information. After processing the data, the Central Control Module would distribute the parking information by LCD screens for the drivers. In terms of parking supply and demand status, the system sends the separately parking information to the corresponding phone number. The system achieves barrier-free intelligent parking management by realizing functions such as three ways of releasing the information of parking lots, inquiry of parking location and convenient register operation.

Abstract: Based on the ASAP standard, an ECU calibration system for diesel engine is developed in the paper. The implementation of KWP2000 protocol supports the diagnosis management and data transmission function subset. The A2L format file which is a standardized description used to declare the data storage format and the conversion relations of different kinds of ECU. Using the ECU communication technologies, the calibration system can access the measurement and calibration data in ECU memory safely and reliably. The calibration system is designed to employ various software modules respectively. The use of layer architecture in this system can reduce the complexity of the code and increase generality of the application.

Abstract: In order to investigate the influence of complex terrain on the quality of the unmanned aerial vehicle (UAV) communication link and simulate it accurately, the HITL simulation platform of the UAV-ground link, which was based on EXata software and Hardware-in-the-loop (HITL) module, was built. In the virtual terrain scenarios, the Free-space loss model and the Irregular Terrain Model (ITM) were used to modeling and conduct the semi-physical simulation experiments, respectively. Then, a new method of the HITL simulation for the wireless communication link was put forward, which achieved the real-time video stream interaction with the virtual networks. The simulation results showed the real-time changes of path loss in the complex terrain and the specific affection on the UAV-ground link communication quality from numerical and video transmission effect. The method enhanced the accuracy and rationality of the UAV-ground link simulation.

Abstract: The reliability of Radio Frequency Identification (RFID) mechanism is disturbed by illegal tracking and information intercepted.The paper proposed a new active RFID authentication protocol based on the dynamic tag ID and encryption key,which transforms the tag ID using chaotic transformation during authentication and communication between the reader and tags,and realizes mutual authentication of the reader and tags.Through the analysis of security, the protocol not only can ensure the integrity, fresh and confidentiality of data, but also can effectively prevent illegal tracking labels and replay attack.

Abstract: To satisfy the requirements of visible light wireless communication technology, designed LED visible light communication application system based on Ethernet. Influence factors of system performance were studied and took specific measures to optimize system performance. Reduced the influence of background light, improved the communication distance, inhibited LED light source tailing phenomenon, and improved the rate of the edge of the LED. The LED visible light communication technology blends into the Ethernet, provides a new solution for wireless broadband access, this solution has the broad application prospect.