结合GPRS/GSM技术的WSN组网策略

针对典型WSN网络中路由计算复杂、节点管理困难的问题,提出了终端节点,汇聚节点和监控中心三层次的硬件结构.用带有GPRS/GSM模块的汇聚节点充当WSN终端节点和监控中心的联络节点,并将终端节点分为1类、2类节点,用直接或多跳方式同汇聚节点联络,并给出了详细的处理流程.工程应用结果表明,这种硬件和软件设计可以节省大量软件算法,增强了对终端节点的实时监控及报警处理能力,扩展了典型WSN的功能和应用范围.     

基于GSM/GPRS远程通讯的GPS车辆综合监控调度管理系统

基于已建系统的工程实践，阐述了以GSM／GPRS为远程通信网络的GPS车辆综合监控调度管理系统的系统组成、主要功能，并从GSM／GPRS无线通信系统、有线网络通信系统、监控中心及GPS车载单元4个部分叙述了系统的实现。该系统经济可行，可靠实用，结构合理，技术先进，对建设GPS综合集成应用系统具有参考借鉴意义。     

GPRS/GSM网络中的无线信道分配算法研究

随着GPRS/GSM移动接入网的广泛应用,有效的信道分配算法在保证网络服务质量中的重要性开始凸现。该文描述了GPRS/GSM移动接入网的信道分配过程,对固定信道分配算法和动态信道分配算法进行了详细分析,并采用自行开发的GPRS/GSM网络仿真软件模拟语音业务与分组数据业务动态共享信道资源的过程,从而比较了不同的信道分配算法对接入网服务质量的影响,结果显示动态信道分配方案在增加系统运算量的同时可以很好地支持网络通信的质量。     

A buffered-bandwidth approach for supporting real-time video streaming over cellular networks

In this paper, we study the admission and bandwidth allocation problems in real-time video streaming in a cellular network. Admission control in a cellular network is a complex issue due to the mobility of the clients, and the additional workload imposed by incoming clients could exceed the network capacity of a cell and seriously degrade the quality of services provided to the resident clients. To minimize the number of forced terminations of real-time video playback, we incorporate the notion of buffered bandwidth in the admission test for handoff client. Using this approach, we can balance the video workload among adjacent cells to minimize the impact of overloading as the result of handoff operations. We also examine techniques to maintain fairness in services especially under overload situations even though the requested videos from various types of clients could generate very different workload. Simulation experiments confirm the effectiveness of our approach compared to widely used schemes.     

A buffered-bandwidth approach for supporting real-time video streaming over cellular networks

In this paper, we study the admission and bandwidth allocation problems in real-time video streaming in a cellular network. Admission control in a cellular network is a complex issue due to the mobility of the clients, and the additional workload imposed by incoming clients could exceed the network capacity of a cell and seriously degrade the quality of services provided to the resident clients. To minimize the number of forced terminations of real-time video playback, we incorporate the notion of buffered bandwidth in the admission test for handoff client. Using this approach, we can balance the video workload among adjacent cells to minimize the impact of overloading as the result of handoff operations. We also examine techniques to maintain fairness in services especially under overload situations even though the requested videos from various types of clients could generate very different workload. Simulation experiments confirm the effectiveness of our approach compared to widely used schemes.     

Performance of ad hoc networks with two-hop relay routing and limited packet lifetime (extended version)

We consider a mobile ad hoc network consisting of three types of nodes (source, destination and relay nodes) and using the two-hop relay routing. This type of routing takes advantage of the mobility and the storage capacity of the nodes, called the relay nodes, in order to route packets between a source and a destination. Packets at relay nodes are assumed to have a limited lifetime in the network. Nodes are moving inside a bounded region according to some random mobility model. Closed-form expressions and asymptotic results when the number of nodes is large are provided for the packet delivery delay and for the energy needed to transmit a packet from the source to its destination. We also introduce and evaluate a variant of the two-hop relay protocol that limits the number of generated copies in the network. Our model is validated through simulations for two mobility models (random waypoint and random direction mobility models), and the performance of the two-hop routing and of the epidemic routing protocols are compared.     

基于GSM/GPRS网络的路灯监控系统

介绍了公共路灯远程监控系统的结构原理、工作过程、硬件组成和软件设计,增加的措施提高了系统的可靠性。根据系统可实时掌握路灯的电压高低、电流大小、是否工作、警告等状况,从而实现对公共路灯的实时远程监控。     

Snoop在GPRS网络中性能的提高

仿真测试显示Snoop协议在GPRS网络中性能低下,文章测试分析了Snoop在GPRS网络中的性能,修改了Snoop协议的重传触发条件和实现机制,显著提高了Snoop在GPRS网络中的性能。     

GSM税务监控系统前端的设计

本文介绍了在目前应用较为广泛的GSM，介绍了SonyErrison的GM47模块，以及在税务发票监控上面的应用，讨论了前台打印系统的硬件组成，前台由单片机系统，打印机模块，液晶模块构成操作界面，以及TCP／IP协议模块，GSM模块，该系统采用串口发送信息，然后通过一个TCP／IP模块进行协议封装，再通过GM47发送给后台监控中心。整个系统有较好的人机界面，通过AT指令进行无线通信。     

Performance prediction for OFDMA systems with dynamic power and subcarrier allocation

It is well known that channel-dependent OFDMA resource assignment algorithms provide a significant performance improvement compared to static (i.e., channel-unaware) approaches. Such dynamic algorithms constantly adapt resource assignments to current channel states according to some objective function. Due to these dynamics, it is difficult to predict the resulting performance for such schemes given a certain scenario (characterized by the number of terminals in the cell and their average channel gains). In this paper we provide a novel, analytical framework for performance prediction, which takes dynamic power and subcarrier allocation into account. The analysis is based on fundamental transformations of the channel gains caused by the dynamic subcarrier allocations. This insight allows for deriving probability functions of the achieved rate per subcarrier which ultimately yields expressions for the expected minimal rates as well as outage probabilities for certain rate demands. Hence, the methods presented in this paper for performance prediction can be employed for admission control in systems with dynamic resource allocation. We illustrate the applicability of our derivations with respect to the capacity of 802.16e systems for Voice-over-IP and video streams. The results demonstrate a significant improvement compared to state-of-the art approaches but also reveal room for improvement of this approach compared to the optimal system performance.     

Performance analysis of cut-through buffered banyan networks with finite buffer size

In this paper, we present an analytic model to estimate the performance of cut-through buffered banyan networks with finite buffer size. Two conflict resolution policies are considered in order to resolve conflicts when two packets are destined to the same output link, and their performances are compared. Our analytic model enables analysis of the networks in which buffers are unevenly distributed, i.e., each stage has a different buffer size. It is shown that if buffers are properly distributed in the network, higher throughput and lower delay are possible, although the improvement is considered small. Finally, in order to validate our model, some analytic results are compared to simulation.     

基于GSM的双向汽车防盗系统的研究与设计

提出了一种基于GSM通信模块和无线射频模块双向通信的汽车防盗系统设计方案。该设计以GSM网络为通信媒介,将车载主控制器检测到的各种汽车状态传送至预先设定的车主手机中,实现了车主对汽车的跟踪及监控,可有效防止汽车盗窃事件的发生。     

基于AVR MCU与GSM/GPRS的航标灯监控系统设计

采用AVR MCU与专用GSM/GPRS模块设计了无线航标终端监控系统。该系统通过GSM短信或GPRS无线网络设置航标终端的工作参数,并可将终端的工作状态与位置时间信息定时传送给监控中心。试验证明系统工作稳定可靠,能够对较大范围的航标终端实现低成本低辐射的智能监控,具有良好的应用前景。     

IC卡加密控制技术在GSM移动电话通讯中的应用

简要介绍了ＩＣ卡及其硬、软件所能实现的安全控制技术,并就其在ＧＳＭ移动电话中的个人身份识别、安全认证、安全（加密）传输等方面的具体应用作了较全面的论述。     

Traffic simulation in urban cellular networks of Manhattan type

A theoretical study of traffic in cellular networks usually requires long and complex calculations. For this reason, simulation appears to be a practical alternative for analyzing traffic in mobile radio systems. This paper presents a traffic simulator for urban cellular networks of Manhattan type. The model implemented includes network organization, distinct consumers, and a classification process for frequency assignment. Several simulations have been realized in order to measure network performances in different situations. Different channel assignment techniques that are both fixed and dynamic, including those that are with or without channel reservation for handoffs are compared. The results of this traffic simulator comparison confirm the efficiency of this study tool for traffic in cellular systems used in an urban environment.     

GSM网络的室内空气质量监测系统设计

设计使用气体传感器针对室内空气中的PM 2.5和甲醛含量进行检测,通过微处理器进行处理与分析,在液晶显示屏上显示数据,并根据设定阈值进行声光报警,利用全球移动通信系统GSM无线网络进行远程通信,实现远程实时监测室内空气质量.     

Simulation of congestion avoidance and routing in packet switching networks

The development of a flexible computer simulation package for packet switching computer networks that enables the evaluation of different congestion avoidance methods and routing strategies is discussed. The package is presented in terms of the factors involved, the operations required, and the simulation execution considerations. Use of the package for the evaluation of congestion avoidance methods and routing strategies is described. The congestion avoidance methods considered include isarithmic methods with static and dynamic control. In addition, static and dynamic routing strategies are taken into account. The relative differences between the various methods and strategies considered are presented. It has been found that the results obtained agree with previous results, and this confirms the suitability of the package for future investigation. The package would be useful to students and researchers in the field, especially since it uses the widely known computer language Pascal, and is run on an IBM PC(AT).     

Performance evaluation of multicast communication in packet-switched networks

In this paper we describe the theoretical background and practical application of QNA-MC (queueing network analyser supporting multicast), a tool for the analytical evaluation of multicast protocols. QNA-MC is based on the QNA method, which (approximately) analyses open networks of GI|G|m queues. In contrast to standard QNA, QNA-MC allows for the specification and evaluation of multicast routes. As in real multicast communication, packets leaving a particular node can be copied and deterministically routed to several other nodes. In order to analyse such queueing networks, QNA-MC converts the multicast routes to a suitable input for standard QNA. From the results delivered by QNA, QNA-MC then derives several performance measures for multicast streams in the network. A validation of QNA-MC, via a comparison to simulation results, shows that QNA-MC yields very good results. Finally, we give a detailed application example by evaluating different multicast routing algorithms for a realistic video conferencing scenario in the European MBONE.     

GSM田间多地点多数据采集系统设计

利用STC89S52单片机和GSM网络设计了一种智能监控系统.通过单片机控制GSM模块收发短信,用户就可以实时采集到田间的温度、湿度等数据.该系统突破地理和环境上的限制,实现了集中监控,从而帮助用户合理配置资源.     

Performance modeling of Cartesian product networks

This paper presents a comprehensive performance model for fully adaptive routing in wormhole-switched Cartesian product networks. Besides the generality of the model which makes it suitable to be used for any product graph, experimental (simulation) results show that the proposed model exhibits high accuracy even in heavy traffic and saturation region, where other models have severe problems to predict the performance of the network. Most popular interconnection network can be defined as a Cartesian product of two or more networks including the mesh, hypercube, and torus networks. Torus and mesh networks are the most popular topologies used in recent supercomputing parallel machines. They have been widely used for realizing on-chip network in recent on-chip multicore and multiprocessors system.