In this contribution, the Doppler spectral properties are simulated and analyzed based on 3GPP Spatial Channel Model extension (SCME). SCME standard channel model is applied to the system evaluation and optimization in LTE and other future communication networks. Since future mobile communication systems demand for high moving speed, the simulation and analysis of Doppler characteristics become so significant. Therefore, we focus on the simulation of Doppler spectral properties in different scenarios of SCME channel model. The simulated Doppler power spectrum and Doppler delay spectrum are applicable to characterize Doppler properties of time-varying channels.

This paper introduces an energy conservation luminous intensity control system based on ZigBee sensor networks for smart home. The study is conducted to reduce unnecessary energy consumption by changing the luminous intensity of white LED according to the light coming into the room. A detecting circuit connected to the pin of CC2430 is set on the working face to collect the real-time luminous intensity signal. Then the ZigBee module adjusts the PWM signal to drive the white LEDs aiming at keeping a fixed and appropriate luminous intensity (e.g. 500Lux). Meanwhile, it transmits the data to the ZigBee coordinator through ZigBee wireless network. The monitoring PC get the data through the serial communication interface and display the states of the lights. Administrators can turn on or off the lights by clicking on the screen. This system can realize monitoring and controlling all the lights wirelessly so that users can save a lot energy and staff members. The system has been proved to be effective and convenient.

Securing data transmission is currently a widely researched topic. There are numerous facades in data security. Virtual Private Network (VPN) is one such strand that provides security for data that is in motion. Performance of a network that has VPN implementation is at the forefront of network design and choice of the operating systems and cryptographic algorithms is critical to enhancing network performance. In this research undertaking, three VPN techniques, namely DES, 3DES and AES, which are commonly used to implement IPSec VPNs, are performance analyzed on test-bed setup. These are implemented on a network with Linux Fedora and a router and Windows desktop operating systems on another node. The VPN algorithms tested show that there may be performance differences when implemented with different operating system combinations.

Knowing the quaternary structure of an uncharacterized protein often provides useful clues for finding its biological function and interaction process with other molecules in a biological system. Here, dimensionality reduction algorithm is introduced to predict the quaternary structure of proteins. Our jackknife test results indicate that it is very promising to use the dimensionality reduction approaches to cope with complicated problems in biological systems, such as predicting the quaternary structure of proteins.

The volume of published scientific literature available on Internet has been increasing exponentially. Some of them reflect the latest achievement of the specific research domain. In recent years, many projects have been funded aiming to online scientific literature mining, especially in biomedical research. Scientific literature covers most of the hot topics in the research field and has a very large domain-specific vocabulary. The exploitation of domain knowledge and specialized vocabulary can dramatically improve the result of literature text processing. The purpose of this paper is to identify the frequently used keywords in IT security literatures. The result then can be utilized to improve the performance of automatic IT security document retrieval, identification and classification. Our method is to query CiteseeX to retrieve source data of paper description information and build an artificially annotated corpus. Over the corpus, we perform words frequency statistics, word co-occurrence analysis, discrimination index computation, retrieval efficiency analysis and thus build a lexicon of IT security based on our experimental result. The lexicon can further be used in improving retrieval performance and assisting new words discovering and document classification.

In the last years, the deployment of embedded real-time communication systems has increased dramatically. At the same time, the amount of data that needs to be managed by embedded real-time main memory databases is increasing, thus requiring an efficient data management. However, system crash will cause data loss in main memory, which will seriously affect the normal operation of the entire communication system. This paper introduces an algorithm of system crash recovery applied in main memory database of embedded real-time communication system. This paper expatiates the software architecture of SDR base station, the cause of crash occurring, and proposes the flash recovery algorithm using for system recovery. A main memory database using this algorithm has been applied in a real communication system——multimode SDR base station communication system.

As the rapid development of Wireless Sensor Networks(WSN), the demands of frequency rose sharply, thereby how to deal with the frequency assignment of WSN is a difficult problem. A dynamical and real-time frequency assignment system is proposed, which was based on the network architecture of Internet of Things by the means of Cloud Computing technique. The system assigned the frequency dynamically and real-timely that it can improve the frequency utilization rate. This system is an efficient path to face the frequency needs of WSN.

Based on the analysis of the status of network public opinion, the features of short content and nearly real-time broadcasting velocity in this paper, it constructs a public opinion corpus on the content of micro-blog information, and proposes an approach to marking corpus on the basis of sentiment tendency from the semantic point of view; Furthermore, considering the characteristics of micro-blog, it calculates the sentiment intensity from three levels on words, sentences and documents respectively, which improves the efficiency of the public opinion characteristics analysis and supervision. So as to provide a better technical support for content auditing and public opinion monitoring for micro-blog platform.

We propose rate adaptation in the entire downlink process of transmission in channel-network combining coding systems. In current literatures, rate adaptation is discussed in channel coding or network coding separately and in traditional channel-network combining coding cases, network coding rates are generally 1. This paper is based on a one-source multi-destination wireless downlink communication system and a novel scheme of rate adaptation is applied. Our scheme of adaptation works between channel coding rate and network coding rate and its influence on system performance, which is given in form of simulation in the last chapter of this paper, shows that it works well for deducing system BER.

WiMAX networks based on IEEE 802.16 standard has expedited broadband wireless access surge in recent years. The traffic in these networks is identified in four types of class of service with different QoS requirements. Therefore, scheduling mechanism to manage these services in order to meet QoS requirements is a crucial fact and an important challenge. In this paper, for PMP mode of WiMAX networks, a two-level scheduling mechanism in MAC layer of Base Station (BS) has been proposed. The proposed scheduling algorithm takes into account hybrid unicast and multicast downlink traffic including three classes of service: rtps, nrtps and BE. In the first level of this scheduling mechanism, we have used the scheduling algorithms WRR and FCFS to schedule the connections and in its second level, the PQ algorithm based on Aging method is used to manage and schedule the packets. The functionality of the proposed scheduling algorithm is compared with priority queuing (PQ) algorithm. The resulting outcome of simulation shows that the proposed design has quite a better performance for Best Effort (BE) service class. Furthermore the delay of the rtps class and total throughput of the network is increased noticeably.