【作者】 付炜；

【导师】 马建国；

【作者基本信息】 电子科技大学 ， 电路与系统， 2009， 博士

【摘要】 短距离无线通信以无线个域(Wireless Personal Area,WPA)应用为核心特征。随着RFID技术、ZigBee技术、蓝牙V3.0技术以及60 GHz毫米波通信等低、高速无线应用技术的发展,短距离无线通信正深入到通讯应用的各个领域,表现出广阔的应用前景。短距离无线通信具有高速率大容量、低速率高可靠性以及低功耗、低成本等特点,这使得电源管理技术、链路预算技术、以及多径时延分析等相关技术成为优化低、高速短距离无线通信性能,降低短距离无线通信成本,提高短距离无线通信质量的关键技术。决定这些关键技术的因素很多,其中无线传输信道作为电波传播的路径对无线通信技术性能的影响至关重要。对于工作距离在毫米级到千米级的短距离无线应用而言,虽然无线电波仍是经由无线传输信道,通过反射、衍射和散射等传播机制到达接收端,但是由于传输距离和应用环境的限制,短距离无线应用更容易受到多种实际环境因素的影响。此外,由于短距离无线收发端的机动特性,无线信道不仅具有随机性,还呈现出时变性,体现出短距离无线传输信道的复杂性。如何正确描述短距离无线传输信道,建立高效的短距离无线传输信道模型,准确提取短距离无线传输信道参数,并针对具体的短距离无线技术应用,基于短距离传输信道模型解决电源管理,链路预算等相关关键技术中的问题是本文工作的意义所在。围绕上述研究目的,本文系统而深入的研究了以下内容:第一、通过对无线传输信道的描述,以及短距离窄带信道和宽带信道的理论研究,系统地分析了短距离无线传输信道测试建模和参数提取理论。深入研究和比较了短距离无线信道时域和频域测试建模技术。重点分析了适合短距离无线传输信道的频域测试建模技术,并详细分析和总结了频域测试建模系统的原理、设置以及后处理过程等关键技术。第二、针对短距离无线应用工作的射频微波2.4 GHz和5.8 GHz ISM频段进行了短距离无线传输信道频域测试建模。通过建模后处理过程及统计分析过程提取了短距离无线传输信道模型参数,建立了适合描述射频微波频段短距离无线传输信道的信道模型,完成了分析研究射频微波频段短距离无线电波传播相关技术的必要步骤。第三、通过对射频微波频段短距离无线传输信道模型的分析,提出了一种基于短距离视距传输信道的电源管理算法。将无线传输信道模型参数和射频通信模块本身特性相结合进行双向动态功率调节,实现实时电源管理。完成电源管理算法的软硬件实现,并通过理论分析和测试,验证了电源管理算法的性能。第四、通过对射频微波频段短距离无线传输信道模型的分析,针对无源微波RFID技术的特点,提出一种基于内部连续反射模型的RFID标签距离的计算算法。对附着在被识别物体表面的标签应用,特别是当识别物体材料厚度与波长可比拟时,推导了射频识别物体材料反射系数与标签距离之间的关系,并通过物理有限元模型对算法进行了仿真及分析比较。第五、通过对IEEE 802.15 TG3c 60 GHz无线个域应用的研究,提出了适用于60 GHz桌面短距离无线传输信道模型。推导了随收发端距离变化的反射系数表达式及基于距离的链路损耗表达式,并将得到的理论预测数据与IEEE 802.15 TG3c发布的相同桌面环境测试数据进行了比较,验证了链路损耗理论预测模型的准确性。本文围绕上述工作,对短距离无线传输信道进行了理论分析和测试建模。针对具体的短距离无线应用相关关键技术,提出了基于短距离无线传输信道的算法和模型,并通过理论分析、软硬件实现和测试仿真等方法进行了分析和验证。更多还原

【Abstract】 Along with the rapid development of kinds of wireless communications technologies, such as RFID, Zigbee, Bluetooth3.0 and 60 GHz millimeter wireless communication etc., short-range wireless applications taking WPA(Wireless Personal Area) as the characteristic got the extensive study and has become more and more wide in various fields.Power management, link budget and the analysis of delay profile for low and high throughput wireless applications are the key technologies for short-range wireless communications, since the characteristics of high speed and high throughput or low speed but high reliability for short-range wireless communication systems. There are many factors important to these key technologies, but propagation channel, which is the path of radio wave propagation, is more crucial. Although radio waves are propagated with reflection, diffraction and scattering, the wireless radio channel poses a severe challenge as a medium for reliable short-range communication. It is not only susceptible to noise, interference, and other channel impediments, but these impediments change over time in random way due to transceivers movement. How to overcome these challenges and resolve the problems existing in those key technologies are the main purpose of this research.Based on above analyses, the main works and contributions of the thesis include:1. The wireless propagation channel modeling and channel parameters extraction for short-range radio wave propagation are analyzed based on narrowband and wideband propagation channel model. The comparisons of channel modeling in time domain and in frequency domain are conduct. Channel sounding in frequency domain is analyzed especially, since its feature of short-range measurement. The principle, process, and postprocess are analyzed and summarized.2. Radio wave propagation researches are performed at 2.4 GHz and 5.8 GHz both are ISM frequency bands and are usually used in short-range wireless applications under radio and microwave frequency bands. The goal is to determine short-range propagation channel properties and models that suitable to characterize propagation channel for RF and microwave frequency bands.3. A two-way power management algorithm based on real-time path loss of propagation channel was implemented and validated in a point-to-point wireless system worked at 2.45 GHz. The performance of the power management are testified and evaluated by theoretical analysis and indoor measurements. It is shown that the proposed algorithm can prolong the battery lifetime effectively and adjust the transmitting power dynamically in different short-range multipath environments.4. A calculation approach for tag range of passive microwave RFID based on a multi-ray model are proposed. We show the relationship between the tag range and the reflection coefficients of the tagged object material. The distance-dependent reflection coefficients are proposed, especially when the thickness of the object surface is comparable to the wavelength. A precise simulations based on the 3-D physical finite element model is taken to verify the validity of the approach.5. A site-specific desktop propagation model is presented for IEEE 802.15 TG3c 60 GHz WPA. The reflection coefficients versus Tx-Rx separation distance using vertical and horizontal polarization are investigated. Path loss data are then computed using improved two-ray propagation model. Obtained values are compared with the measured data published in IEEE 802.15 TG3C and shown to have a more precise fitting than that predicted by conventional model.Theoretical analysis and modeling for short-range wireless propagation channel are taken in the investigation. Algorithms and models are proposed based on the short-range propagation channel. The validity of the algorithms and models are verified by the theoretical analyses, measurements, and simulations.更多还原