Applied Mechanics and Materials Vols. 416-417

Abstract: Computer network is an advanced platform of communication transmission, in which the different transmission modes such as point-to-point and point-to-multipoint can be implemented by relying on the wide coverage scope of the Internet. In this paper, the functions (e.g. data processing, signal transmission, and comprehensive control) of network communication are firstly introduced, and then the digitalized transformation trend of computer network communication system is analyzed, and finally the comprehensive measures for the construction of new communication system are proposed. Hopefully, this paper can play a help in the further studies.

Abstract: Because of the large span of the distance between wireless communication networks, many kinds of interference are encountered in the network signal transmission process, so that the accuracy of receiving the information is affected by the weakened signals and also the communication service quality for the users is reduced. Under this background, the advantages such as remoteness and convenience of wireless communication are first introduced. In the meantime, the factors influencing the signals of the wireless communication network are affected. Finally, the measures for enhancing the signals of the wireless communication network sites are proposed. It is expected that this paper is helpful for the future studies.

Abstract: The Link Access Procedures on Dm channel (LAPDM) is the data link layer of GSM (Global System for Mobile Communications) cellular network. According to the requirements of virtual base station and 3GPP protocols, we proposed an improved scheme for implementing LAPDM on GSM virtual base station platform. The scheme has higher reliability and efficiency by reducing the useless data link status and operational flow. This paper introduced a framework for realizing the proposed scheme and presented detailed analyses about its program structure, status transition, errors detection and correction approach, timer and retransmission mechanism. Finally, the program was ported to the hardware platform and monitored by OT Drive software. Experimental results show the improved scheme has good performance on each required signaling flow.

Abstract: GPRS is the dominant mobile Internet access in China. However, the nature of GPRS traffic characteristics remains unexamined for many reasons. In this paper, we present observations at both LLC-level and cell-level from passive monitoring of more than 2700 GPRS/EGPRS cell sites connected to the same SGSN at Gb interface. The traffic traces are from a major China ISP in one urban area of Northern Province during an ongoing 24 h period in August 2012. We found that user traffic averages at about 95% of overall traffic in both directions. Furthermore, we defined a cell-time record to measure the dynamic utility of radio resource and found that most cell sites have low traffic at most time, with the growth of total traffic load, the proportion of signal traffic declined correspondingly. All the conclusions in the paper are meaningful for researchers, network operators, and other members of the GPRS community.

Abstract: This paper expounds the rational allocation of the limited network bandwidth resources in between the embedded terminal application, and puts forward a kind of embedded terminal application of cyber source distribution protocol. According to the application characteristics, classify network packets; combined with the available bandwidth real-time detection, add different delay time for each type of data packet; according to the size of delay, schedule data packet. The protocol is applied to the actual IP set-top box, at the same time it is running HTTP streaming media applications and downloads the FTP application environment, to give priority to ensuring the application of streaming media playback smooth. The experimental results show that, the protocol in the application environment can give priority to the needs of users about application of high bandwidth network, and achieve a reasonable distribution of cyber source in embedded terminal.

Abstract: The vector algebra algorithm has been conducted in - depth study, through the vector algorithm to adjust the conversion of vector data and raster data, it can finally realize the quantization scheme of vector algebra algorithms that are applied to network coding, vector algebra algorithm will be conducive to the network and retrieval analysis, the graphical display also has good quality and high precision. At the same time, data structure is simple and easy to spatial analysis and surface modeling.

Abstract: This paper introduces the College Employment Network system architecture and application of key technologies , applied research on the part of the innovative technical, focuses on the system requirements analysis and design implementation.At the same time,employment site change employment websites to focus only on release of employment information in the past,focus on improving students' ability to work in employment,Establish between business with graduates. Both JSP engine, Oracle has built for the back-end database server information interactive website,it will improve the efficiency and quality of traditional employment information,realize exchange of information between students, teachers, and parents. Practice has proved that Usefulness of the system has a very stable and achieve the expected goals of the system design.

Abstract: Multiple export link in campus network, The common DNS server analyze campus network Web server domain to education network IP address, there is no good use of multiple export link. According to the users network, the intelligent DNS server designed in this paper can analyze different IP address. when different operator's network user access campus network Web server, It is through their own operators network, not all users must pass through the education network, therefore, the intelligent DNS server can effectively solve Multiple export link in campus network.

Abstract: The digital communication system; timing recovery loop for research, is mainly directed against the application performance and design. Through a variety of different loop filter test were carried out and positioning. The invention of a universal filter, and the filter and the original combined to form a new loop filter. The timing recovery loop searching and positioning performance is passed through the filter in the sync pulse and conversion. The experimental results show, as long as certain conditions, the new loop filter in 64 symbols within the time to achieve the positioning, and a good effect on. The filter has the advantages of simple structure. In a digital receiver demodulation, the A / D converter timing recovery can achieve the best state of digital receiver demodulation performance. When the timing recovery frequency is low, the bit error rate performance has certain effect. [ Through the analog-digital hybrid timing recovery circuit and digital timing recovery circuit is studied. Digital timing recovery circuit is compared with the mixed analog digital timing recovery circuit is easy to design, and little noise when running. Therefore the digital timing recovery circuit is studied.

Abstract: An adaptive distributed linear dispersion code is proposed in this article. In the first place, each relay code selects modulation type adaptively according to channel capacity. Then the candidate dispersion matrixes are selected based on the channel state weight. Finally the best transmission scheme is selected according to the system information rate and reliability. Simulation results show that the proposed adaptive coding scheme gives a more good performance.