Low-Complexity Antenna Diversity Receivers for Mobile Wireless Applications

This paper describes low-complexity diversity receiver techniques suitable forhandsets and other wireless mobile applications. The techniques areillustrated using two branches of diversity feeding aparameter-combining RF circuit at the front-end, followed by asingle digital receiver chain. A baseband processing algorithm isused to adjust the front-end combining parameters, allowing the receiver toadaptively choose among three different diversity techniques. The method aspresented is primarily targeted for indoor environments where handset movementis slow and delay spread is small. We present algorithms for efficientco-phasing and equal-gain combining as well as a novel cochannelinterference-reduction algorithm. These are implemented in a system simulationat 900 MHz which conforms to the PACS standard. Link performance for selectiondiversity (SD), equal-gain combining (EGC), and interference-reductioncombining (IRC) is presented. The algorithm's performance is compared withoptimal combining parameters, and its performance as a function of Dopplerfrequency is enhanced. The results show that EGC and IRC yield asignal-to-noise improvement of 1 dB and a signal-to-interference improvementof 4 to 5.5 dB respectively, compared with SD. The receiver also lowers theirreducible word error rate due to multipath delay spread for Doppler shiftsof 6 Hz and below. Finally, algorithm behavior is characterized and discussed.     

宽带无线Mesh网络中的多扇区天线阵列设计

在宽带无线Mesh网络中,为了扩展传输距离和提升链路速率,天线的性能至关重要。提出了一种多扇区天线阵列,每个扇区天线为带反射板的微带偶极子阵列天线,工作频段为5.1～5.9 GHz,其水平主瓣张角为45°,增益为18 dbi。多扇区天线阵列共包括8个扇区,信号在各扇区天线间进行动态切换,从而实现水平360°全向覆盖。通过采用HFSS三维电磁场仿真工具进行仿真及实际生产并在微波暗室中进行测试,结果表明和传统无线Mesh网络所采用的全向天线相比,在满足全向覆盖的同时,天线的方向性有了很大的改善。     

无线智能报警器的设计

本文介绍一种基于AT89S52、CM8880PI、MC34118的无线智能报警器。     

Maximizing Cooperative Diversity Energy Gain for Wireless Networks

We are concerned with optimally grouping active mobile users in a two-user-based cooperative diversity system to maximize the cooperative diversity energy gain in a radio cell. The optimization problem is formulated as a non-bipartite weighted-matching problem in a static network setting. The weighted-matching problem can be solved using maximum weighted (MW) matching algorithm in polynomial time O(n³). To reduce the implementation and computational complexity, we develop a Worst-Link-First (WLF) matching algorithm, which gives the user with the worse channel condition and the higher energy consumption rate a higher priority to choose its partner. The computational complexity of the proposed WLF algorithm is O(n) while the achieved average energy gain is only slightly lower than that of the optimal maximum weighted- matching algorithm and similar to that of the 1/2-approximation Greedy matching algorithm (with computational complexity of O(n² log n)) for a static-user network. We further investigate the optimal matching problem in mobile networks. By intelligently applying user mobility information in the matching algorithm, high cooperative diversity energy gain with moderate overhead is possible. In mobile networks, the proposed WLF matching algorithm, being less complex than the MW and the Greedy matching algorithms, yields performance characteristics close to those of the MW matching algorithm and better than the Greedy matching algorithm.     

无线网络中基于多用户分集的机会调度研究

机会调度(Opportunistic Scheduling,OS)是对无线衰落信道通信的一种现代认识观点。与基于链路/速率自适应的方案不同,机会调度利用无线信道的时空变化特性来提高无线通信系统的性能,而不是减轻它的影响。本文介绍一种引入了业务流参数的机会调度方案,可以保证调度的公平性,并满足不同类型业务流的QoS(Quality of Service)要求。在瑞利衰落信道中的研究数据显示,采用机会调度达到的系统吞吐量要优于轮询(Round-Robin,RR)方案的吞吐量,并保证了不同等级业务流之间的公平性。     

智能无线防盗报警系统的设计

利用现有的电话网络,并结合单片机控制技术和射频无线通信以及传感器技术,开发出了一种适应于智能小区的智能无线报警系统,该系统经济、可靠,依探头的类型来反映不同的报警信息。他具有广阔的市场前景。实践证明,本文讨论的系统是可行的、有效的。     

Optimal Joint Diversity and Power Control for Wireless Networks

We propose in this paper an efficient method to derive the optimal feasible power and weight for joint diversity and power control. Instead of solving a constrained optimization problem where both the variables of power and the variables of weight are involved, this method simply solves a set of equations where only the variables of power are involved. It is proven that the power and weight obtained from the proposed method can minimize the power consumption. To reduce the computational complexity, we further propose another method where the number of equations can be reduced from the number of users to the number of base stations.

分簇无线传感器网络中根校验全分集LDPC码设计与能效分析

高效的差错控制编码技术(ECC)可以增强无线传感器网络传输稳定性、网络的能量利用效率。为了充分利用无线传感器网络中蕴含的分集资源应对恶劣信道环境导致的高差错概率,该文研究了基于根校验全分集LDPC码的差错控制编码技术。首先,提出在分簇无线传感器网络中,基于根校验全分集LDPC码的编码方案;其次,设计了适用于所提方案的速率兼容全分集LDPC码字结构。最后,分析了所提编码系统的能效。仿真结果表明,在信道条件较差的环境中(仿真中,信道噪声大于410-4 mW),采用该文的编码方案,能够显著提高无线传感器网络的能效。     

基于无线传感网络的瓦斯监控报警系统

该文设计了以CC2430为核心的无线传感网络的瓦斯监控报警系统。该系统通过放置大量的无线传感器网络采集节点,实时进行节点处瓦斯浓度的采集和换算,并通过模糊PID控制实现节点附近的瓦斯浓度的智能化控制。     

工业环境无线传感器网络分集技术

在工业环境应用无线传感器网络,将面临设备及器材引起的大量散射电磁波带来的无线信道随机衰落。该文对工业环境无线信号进行了分析,针对传感器节点体积及成本受限的情况,在极化分集基础上提出一种天线姿态寻优方案,对极化分集与天线姿态寻优带来的分集增益进行了仿真和对比,并设计了适用于无线传感器网络的天线优化方案。通过工业环境实际测量,验证了无线传感器网络天线分集方案的有效性。     

智能无线防盗报警器的设计

介绍一款功能丰富、易于扩展的家居智能电子系统,由AT89C51单片机控制电路、无线收发电路、DTMF（双音多频）电路、语音录放电路、电话接口电路等部分组成。系统核心功能是防盗报警,由无线门磁探测盗情,通过带编码、解码芯片的无线射频模块收发信号,进行现场报警,同时通过固定电话线以DTMF方式自动拨号,电话接通后向对方播放预先录制的报警信息。系统还可自动接通户主打回的电话,利用DTMF解码远程电话按键信号,传送到单片机,对室内开关电路进行控制。     

室内天燃气泄漏无线报警系统设计

燃气作为清洁能源广泛应用于家庭、工业和餐饮等众多领域。为确保在建筑室内安全使用天燃气,针对室内天然气浓度进行检测,同时实现无线报警。系统选用可燃气体传感器和温度传感器,应用AT89C51微处理器和全球移动通信系统(GSM)传输模块,完成燃气泄漏检测和无线报警功能的软硬件设计,对建筑室内环境燃气浓度和温度实时检测、显示,当超过限幅值时报警。测试结果表明,系统天然气浓度和室内温度检测精度高,可实现数据无线传输,设计结构简单、成本低、操作方便,极大提高了天燃气使用的安全性。     

一种在宽带无线网络环境下的协作分集方法

协作通信可以使单天线的移动终端共享它们的天线而产生虚拟多发射天线阵列以获得发射分集。提出了一种在频率选择性衰落信道条件下的协作分集方法,信宿不仅利用转接节点转发的信号而且还利用了信源直接传来的信号来进行解码。通过计算机仿真,比较了考虑信源到信宿的直接传输的协作方法和未考虑信源到信宿的直接传输的协作方法的误比特率性能。结果表明,考虑信源到信宿的直接传输可提高系统的协作分集增益。     

Connectivity Analysis for Wireless Sensor Networks with Antenna Array Integrated Central Node

In a wireless sensor network (WSN), after gathering information, tiny sensor nodes need to transmit data to a sink. It is important to guarantee that each node can communicate with a sink. Due to the multi-hop communication of WSNs, an essential condition for reliable transmission is completely connectivity of a network. Adaptive or smart antenna (SA) techniques in WSNs have been a topic of active research in recent years. These techniques have been shown to be effective with respect to decreasing energy consuming via specified regions which are formed by the SA beams. In this paper, we propose a probabilistic technique to determine the network connectivity probability of the SA integrated WSN. We employ the geometric shape model to evaluate the network connectivity probability of the WSN using the SA beam specifications. The sensor node density to satisfy the desired network connectivity is determined in terms of the beam-width of the antenna array and node transmission range. The analytical results agree with the simulation results by less than 4.7 % error in the average.     

A Six-Beam-Switched Array Antenna for 5.2 GHz High-Speed Wireless Local Area Networks

A six-beam-switched array antenna witha flat profile was designed for the application of high-speed wirelesslocal-area networks in the range of 5–6 GHz. This six-beam-switchedarrayantenna is composed of an analog beamformer and a microstrip-slot array. Thebeamformer, including single-pole double-throw switches, quadrature couplers,and power splitters, was implemented on a single substrate, while the arraywas designed with three pairs of microstrip slots for the ease of integrationwith the beamformer as a low-profile two-layer structure. The circuitsimulator and the full-wave numerical electromagnetic simulator were employedfor circuit and antenna design to generate six spatially oriented antennabeams. Measurement of the six-beam-switched antenna was also conductedand showed the accurate generation of six switchable antenna beams.     

一种适用于无线网络的倒F天线设计

设计了一种用于无线传感器网络的结构紧凑的倒F天线，该天线能够满足无线传感器网络尺寸小、价格低廉、功耗低的要求。通过有限元法进行数值仿真和设计，该天线可达到较好的效果。设计制作的天线经测试，在2．45GHz的中心工作频率下，回波损耗为。25dB，带宽为120MHz，满足了IEEES02．15．4协议的要求。     

A Design of Planar Monopole Antenna for Wireless Applications

Wireless Personal Communications - This paper demonstrates the design of a planar monopole antenna with reduced size and high gain for wireless applications. In this design, a partial ground plane...     

Diversity Analysis of Relay Selection Schemes for Two-Way Wireless Relay Networks

One-way wireless relay networks have recently received a lot of attention due to their ability to provide spatial diversity in fading wireless environment. Moreover, performing single-relay selection is a very attractive method due to its cost effective implementation and superior performance. However, one-way relay networks with the half-duplex signalling suffer from a spectral efficiency loss. To overcome such a drawback, two-way wireless relay networks have been proposed and these are also the networks considered in this paper. The paper analyzes the diversity orders of various relay selection schemes, including the best-relay selection, best-worse-channel selection, and maximum-harmonic-mean selection. The analysis is done for the amplify-and-forward protocol and under the two-step and three-step transmission procedures. In particular, it is shown that full diversity orders of R and R + 1 can be achieved in a R-relay wireless network with the two-step and three-step procedures, respectively. Numerical and simulation results are provided to verify our analysis.     

基于HN911无线多路报警系统的设计

为满足普通对多布控点报警器的需求,运用传感器技术、电子技术与频分复用技术、无线电技术成功设计了无线多路报警系统。介绍了系统总体框架、调制与解调原理、编码锁存等硬件结构的设计。通过Multisiml0仿真软件建立电路模型,通过多次模拟仿真实验证明,该报警系统性能指标达到设计要求,在安全防护领域中具有一定的应用价值。