Best-retransmission count selection for environment optimization over wireless heterogeneous networks

This paper proposes an environment-aware best- retransmission count selected optimization control scheme over IEEE 802.11 multi-hop wireless networks. The proposed scheme predicts the wireless resources by using statistical channel state and provides maximum retransmission count optimization based on wireless channel environment state to improve the packet delivery success ratio. The media access control （MAC） layer selects the best-retransmission count by perceiving the types of packet loss in wireless link and using the wireless channel charac- teristics and environment information, and adjusts the packet for- warding adaptively aiming at improving the packet retransmission probability. Simulation results show that the best-retransmission count selected scheme achieves a higher packet successful delivery percentage and a lower packet collision probability than the corresponding traditional MAC transmission control protocols.

Optimized transmission coordination mechanisms for opportunistic routing

The successful rate of transmission coordination of opportunistic routing （OK） is analyzea systematically, and then two efficient transmission coordination mechanisms （TCMs） are proposed for OR： a batch sliding window-based TCM and a bit map-based TCM, to reduce the total number of packet transmissions and improve end-to-end throughput for OR. The batch sliding window-based TCM avoids the oscillation of the successful rate of transmission coordination by transmitting packets in continuous batch mode so as to improve the average successful rate of transmission coordination efficiently, while the bit map-based TCM improves end-to-end throughput of OR by reducing the overhead of transmission coordination. Exhaustive simulations show that the average end-to-end throughput gains of the two proposed TCMs are 15.4% and 6.4% over the batch map-based TCM, respectively.

Weak node protection to maximize the lifetime of wirelesssensor networks

Wireless sensor networks （WSN） provide an approachto collecting distributed monitoring data and transmiting them tothe sink node. This paper proposes a WSN-based multi-hop networkinfrastructure, to increase network lifetime by optimizing therouting strategy. First, a network model is established, an operatingcontrol strategy is devised, and energy consumption characteristicsare analyzed. Second, a fast route-planning algorithm isproposed to obtain the original path that takes into account the remainingenergy of communicating nodes and the amount of energyconsumed in data transmission. Next, considering the amount ofenergy consumed by an individual node and the entire network,a criterion function is established to describe node performanceand to evaluate data transmission ability. Finally, a route optimizingalgorithm is proposed to increase network lifetime by adjusting thetransmission route in protection of the weak node （the node withlow transmission ability）. Simulation and comparison experimentalresults demonstrate the good performance of the proposed algorithmsto increase network lifetime.

An Adaptive Wireless Power Sharing Control for Multiterminal HVDC

Power sharing among multiterminal high voltage direct current terminals(MT-HVDC)is mainly developed based on a priority or sequential manners,which uses to prevent the problem of overloading due to a predefined controller coefficient.Furthermore,fixed power sharing control also suffers from an inability to identify power availability at a rectification station.There is a need for a controller that ensures an efficient power sharing among the MT-HVDC terminals,prevents the possibility of overloading,and utilizes the available power sharing.A new adaptive wireless control for active power sharing among multiterminal(MT-HVDC)systems,including power availability and power management policy,is proposed in this paper.The proposed control strategy solves these issues and,this proposed controller strategy is a generic method that can be applied for unlimited number of converter stations.The rational of this proposed controller is to increase the system reliability by avoiding the necessity of fast communication links.The test system in this paper consists of four converter stations based on three phase-two AC voltage levels.The proposed control strategy for a multiterminal HVDC system is conducted in the power systems computer aided design/electromagnetic transient design and control(PSCAD/EMTDC)simulation environment.The simulation results significantly show the flexibility and usefulness of the proposed power sharing control provided by the new adaptive wireless method.

光纤与无线──通信传输的两大支柱

本文先是概述通信传输技术的变迁，接着分别说明固定通信光纤传输技术和移动通信无线传输技术的最新动态，认为光纤与无线是通信传输的两大支柱，在今后的年代里将并驾齐驱、加快发展。

世纪之交看固定与移动两类通信一同快速前进

指出新世纪的通信将是固定与移动两类一同快速发展。先说明有线传输的固定通信网的发展进程。再说明无线移动通信的蜂窝网和卫星系统的情况。最后说明固定与移动两类通信网必将结合前进。

SZK 339型新华闸微机自动控制系统研究

为新华闸运行管理的实际需要设计了计算机监控系统.取水计量采用先进的超声流量计和无线传输系统,通过上位机进行实时监控,由PLC对闸位、液位进行具体控制;并设计了实时动态监控画面,可根据实际需要选择手动、自动操作,系统实现提高了新华闸的自动化管理水平.

无线电能传输系统阻抗动态补偿机理及实现方法

针对无线电能传输系统在过耦合区因耦合距离变化导致传输性能劣化的问题,为了以定频方式实现最大功率输出,提出通过调节初级回路内的2个平面螺旋线圈间广义耦合因子变量实现系统阻抗动态补偿的方法,并对阻抗动态补偿机理进行了研究。首先,以一个E类双管LLC谐振逆变电路为研究对象,采用电路理论建模并分析系统输出功率、传输效率与特性参数的相互作用机理,获得了系统输出功率特性曲线与传输效率特性曲线的变化规律,得到了2个补偿线圈之间的广义耦合因子对系统输出功率曲线和传输效率曲线的直接影响关系;其次,分析了阻抗动态补偿机理,给出了系统在定频工作方式下的具体实施方案;最后,通过实验验证了理论分析的正确性和有效性。

短距离蓝牙通信在智能家居中的应用设计

基于BlueCore3-Multimadie微控制器和无线蓝牙V1.2技术,设计了工作频率在2.4GHz的无线蓝牙转换系统,将无线蓝牙通信具体应用到实际的智能家居环境中,让人们在享受音乐,进行Skype聊天的同时,能够方便快捷地实现固话的转接;极大地方便了人们的生活。

专用无线采集网络系统设计

本文主要讨论了一种基于TDMA/扩频的固定多跳无线传感器采集网络系统,文章就系统的网络结构,功能框图,部分硬件结构,系统的协议体系以及基于TDMA的信道访问方式等作了简要介绍,列举了系统的优越性,搭建了一个实验平台验证了方案的可行性,并且展望了未来的应用前景以及提出了相应的技术升级方案。

Multi-Constrained QoS Opportunistic Routing by Optimal Power Tuning in Low Duty-Cycle WSNs

Designing a multi-constrained QoS (Quality of service) communication protocol for mission-critical applications that seeks a path connecting source node and destination node that satisfies multiple QoS constrains such as energy cost, delay, and reliability imposes a great challenge in Wireless Sensor Networks (WSNs). In such challenging dynamic environment, traditional routing and layered infrastructure are inefficient and sometimes even infeasible. In recent research works, the opportunistic routing paradigm which delays the forwarding decision until reception of packets in forwarders by utilizing the broadcast nature of the wireless medium has been exploited to overcome the limitations of traditional routing. However, to guarantee the balance between the energy, delay and reliability requires the refinement of opportunistic routing through interaction between underlying layers known as cross-layer opportunistic routing. Indeed, these schemes fail to achieve optimal performance and hence require a new method to facilitate the adoption of the routing protocol to the dynamic challenging environments. In this paper, we propose a universal cross-layered opportunistic based communication protocol for WSNs for guaranteeing the user set constraints on multi-constrained QoS in low-duty-cycle WSN. Extensive simulation results show that the proposed work, Multi-Constrained QoS Opportunistic routing by optimal Power Tuning (MOR-PT) effectively achieves the feasible QoS trade-off constraints set by user by jointly considering the power control and selection diversity over established algorithms like DSF [1] and DTPC [2].

一种超声波局部放电检测辅助装置的研制

为了克服现有GIS设备局部放电测试仪的不足,提出在不改变原有超声波测试仪结构的基础上,增加可拆卸的伸缩绝缘杆、超声波传感器固定组件、传感器与绝缘杆连接部分组件、无线传输信号组件以及伸缩绝缘杆固定底座的设计理念。经过组装之后应用到某变电站,现场检测数据表明,该装置与传统装置比较,现场测试数据偏差不大,同时节省了时间,提高了工作效率,避免了人员登高作业风险。