二元探测传感器网络的递推加权质心目标定位算法

为进一步降低二元探测传感器网络质心定位算法的计算复杂度和通信量、提高定位精度,推导出一种质心算法的递推公式,使用该递推公式可以大大减少定位的计算、存储和通信量;在递推质心公式的基础上,提出了一种基于节点探测到目标的次数的递推加权质心定位算法,从而提高了定位精度.对递推公式和加权质心算法进行了模拟仿真,结果验证了递推公式和加权递推质心算法的有效性.     

Competing with channel partners: Supply chain conflict when retailers introduce store brands

Private‐label products are of increasing importance in many retail categories. While national‐brand products are designed by the manufacturer and sold by the retailer, the positioning of store‐brand products is under the complete control of the retailer. We consider a scenario where products differ on a performance quality dimension and we analyze how retailer–manufacturer interactions in product positioning are affected by the introduction of a private‐label product. Specifically, we consider a national‐brand manufacturer who determines the quality of its product as well the product's wholesale price charged to the retailer. Given the national‐brand quality and wholesale price, the retailer then decides the quality level of its store brand and sets the retail prices for both products. We find that a manufacturer can derive substantial benefits from considering a retailer's store‐brand introduction when determining the national brand's quality and wholesale price. If the retailer has a significant cost disadvantage in producing high‐quality products, the manufacturer does not need to adjust the quality of the national‐brand product, but he should offer a wholesale price discount to ensure its distribution through the retailer. If the retailer is competitive in providing products of high‐quality, the manufacturer should reduce this wholesale price discount and increase the national‐brand quality to mitigate competition. Interestingly, we find the retailer has incentive to announce a store‐brand introduction to induce the manufacturer's consideration of these plans in determining the national‐brand product quality and wholesale price. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

基于6LoWPAN与MQTT的无线传感网络设计

针对目前6LoWPAN无线传感网络设计与应用存在的可扩展性较差、与IPv4环境不兼容等问题,设计并实现了基于6LoWPAN与消息队列遥控传输(Message Queuing Telemetry Transport, MQTT)的无线传感网络。其中,无线传感网络节点作为MQTT客户端与MQTT服务器通信,边界路由器通过NAT64(Network Address Translation IPv6 to IPv4)实现无线传感网络节点与IPv4网络的通信。将所设计的无线传感网络应用到智能家居场景,评估了无线传感网络和边界路由器的性能,测试了系统功能的实现。结果表明,无线传感网络具有良好的连通性和稳定性,无线传感节点的数据上传与指令接收稳定可靠,边界路由器工作稳定,系统具有较好的性能。     

Anti-follower jamming wide gap multi-pattern frequency hopping communication method

This paper deals with the follower jamming (FJ) resistance for the frequency hopping (FH) communication system over additive white Gaussian noise (AWGN) channel. Conventional FH systems are susceptible to be jammed by FJ, and multi-pattern frequency hopping (MPFH) has good resistance to FJ. To further improve the FJ rejection capability of MPFH, we propose a wide gap multi-pattern frequency hopping (WGMPFH) scheme. WGMPFH uses channels to represent messages, and the data channel and complementary channel are hopping on orthogonal frequency slots according to wide gap FH patterns. The transmitted signal lures FJ to aim at the data channel and the complementary channel is away from FJ by adopting wide gap frequency patterns. FJ does not affect the complementary channel but increases the signal energy in the data channel, thus the effect of FJ is reduced. Its bit error rate (BER) is derived under FJ and the effects of three FJ parameters (tracking success probability, jamming duration ratio and jamming bandwidth ratio) on the BER performance of WGMPFH are investigated versus the conventional FH/BFSK and MPFH system. Numerical and simulation results show that when under the worst-case FJ, the proposed WGMPFH outperforms the MPFH by about 1–3 dB and outperforms the conventional FH/BFSK by more than 4 dB. The proposed WGMPFH shows superior jamming rejection performance under FJ especially in severe signal-to-jamming ratio (SJR).     

星地非理想通道下的导航信号测距偏差分析

针对广义信道下伪码测距偏差与各部分通道测距偏差叠加值的等效性问题,研究星地叠加通道和部分通道特性对伪码测距偏差的影响,并对实际通道中伪距"分层"现象的成因展开分析。通道非理想特性会对导航信号伪码跟踪性能产生影响,综合考虑星地两端通道的非理想特性,通过对导航信号伪码跟踪函数和不同类型通道建模,研究了星地叠加通道和部分通道特性对伪码测距偏差的影响。结合几类典型星地非理想通道,利用软件接收机展开仿真验证。通过分析几类典型通道对伪码测距偏差的影响,解释了零基线双差观测量中伪距"分层"现象的成因。文中模型与相关分析方法可用于解释相关信号质量问题,并指导接收机通道的最优化设计。     

卫星移动通信信道模型及仿真

对移动卫星通信的三种典型信道进行了完整的理论分析.通信信号在不同的信道参数条件下,经过瑞利(Rayleingh)信道、莱斯(Rician)信道和阻挡效应下的莱斯信道(Rician/Lognormal)进行了计算机仿真,得到了仿真结果.经分析比较发现,信道参数不同,得到的误码率曲线不同.信道的性能主要取决于信道参数,各种因素的影响可以归结到这些参数的影响,理论分析和仿真实验结果一致.     

潜艇自航模水下长波遥控系统

提出了利用无线长波对水下潜艇自航模进行长波遥控的通信技术,阐述了长波遥控的发射、接收及天线系统的硬件组成和系统设计。对发射天线的现场测试结果进行了分析,提出了实际电路的阻抗匹配实现方法;对接收信号的噪声和灵敏度等有关问题进行了分析,采用天线的方向性自适应控制技术解决了潜艇水下接收,在实际应用中取得较好的效果。     

AGWN信道中相关干扰对JTIDS接收机干扰效果分析

相关干扰是目前研究的对抗联合战术信息分发系统(JTIDS)比较有效的干扰样式,文中主要针对相关干扰对JTIDS接收机的干扰效果问题进行了深入研究。在建立了AGWN信道中相关干扰下JTIDS接收机模型的基础上,推导了接收机输出误比特率公式,并通过仿真和分析,得到了不同信噪比条件下接收机的最佳检测门限值以及误比特率与干信比的关系曲线,最后研究了干扰频偏对干扰效果的影响。研究表明,相关干扰对JTIDS接收机有着良好的干扰效果,并且对干扰频偏敏感。     

基于多元高斯概率分布的无线局域网定位方法研究

针对无线局域网环境及室内目标定位需求,研究了基于接收信号强度指示的定位技术,提出了一种基于多元高斯概率分布的信号强度模式匹配方法,讨论了定位系统框架。试验结果表明,该方法具有较好的室内定位效果。     

Information disclosure with endogenous channel structure

This article investigates the firms' optimal quality information disclosure strategies in a supply chain, wherein the supplier may encroach into the retail channel to sell products directly to end consumers. We consider two disclosure formats, namely, retailer disclosure (R-C) and supplier disclosure (S-C), and examine the optimal disclosure format from each firm's perspective. We show that either firm prefers to delegate the disclosure option to its partner when the supplier cannot encroach. However, the threat of supplier encroachment dramatically alters the firm's preference of disclosure. The supplier may prefer the S-C format to the R-C format when the entry cost is low and the disclosure cost is high to achieve a higher quality information transparency. Meanwhile, the retailer may prefer the R-C format to the S-C format when the entry cost is intermediate to deter the possible encroachment of the supplier. In this sense, the firms' preferences of disclosure format can be aligned due to the threat of supplier encroachment. The consumer surplus is always higher under the S-C format while either disclosure format can lead to a higher social welfare. We also consider an alternative scenario under which the supplier encroaches after the product quality information is disclosed. An interesting observation appears that the supplier may encroach when the product quality is low but foregoes encroachment when the product quality gets higher.