一种基于IEEE802.15.3协议物理层编码调制方案

本文分析了IEEE802．15．3协议的物理层采用的信道编码调制技术，给出了一种基于Turbo码编码思想的编码调制方案TTCM-MQAM。并与协议中采用的TCM-MOAM编码调制进行了性能比较。通过分析与仿真得出，TTCM-MOAM相比于TCM-MQAM在性能上有很大的提高．对于IEEE802．15．3微网的传输有很重要的意义。     

无人机通信中的非对称物理层网络编码研究

物理层网络编码可以提高无线通信系统的性能。针对无人机组网通信的环境特点,建立了无人机组网通信中的非对称双向中继信道模型,研究了该模型中的物理层网络编码,提出了非对称多阶相移键控物理层网络编码方案,推导出该方案的中断概率、误码率等无人机组网通信系统的主要性能指标的理论表达式。通过实验,验证了所提出方案及其理论分析的正确性,分析了各种非对称相移键控调制方式下的系统性能,为物理层网络编码在无人机组网通信中的设计以及性能评估提供了理论依据。     

一种卫星移动通信中的L/P跨层设计

针对卫星移动信道,提出了一种基于链路层(Link Layer)的混合自动请求重传(HARQ)技术联合物理层(Physical Layer)自适应编码调制(AMC)技术的L/P跨层设计;在Nakagami-m信道模型中验证其性能,并与非跨层设计结果作了对比。理论分析及仿真比较结果表明,这种跨层设计可以综合有效地优化卫星移动通信性能。     

一种基于BICM-ID的物理层网络编码联合设计方案

基于迭代比特交织编码调制(BICM-ID)提出了一种物理层网络编码与编码调制技术联合设计方案。该方案将编码调制技术和物理层网络编码联合设计,提高了网络吞吐量,通过设计一种星座映射方案,增大欧氏距离,降低误码率。此外,由于译码器部分只采用了一个SISO译码模块,编码译码方式采用卷积码,使得译码复杂度大大降低。     

基于LV-BPL传输的Internet宽带接入系统研究

宽带低压电力线（LV-BPL）通信是一种重要的Internet接入技术,基于数字喷泉码与正交小波包编码调制提出了一种新的LV-BPL物理层系统模型。系统采用数字喷泉码作外码,块编码作内码,按块编码调制（BCM）映射到正交小波包调制时频平面。由于小波包稳定的正交性、自由的时频铺砌,数字喷泉码与码率无关的性质及BCM抗脉冲干扰的特点,系统在LV-BPL信道具有比编码DFT-OFDM更好的性能。     

2.45G RFID阅读器的设计与实现

介绍了目前RFID系统的发展趋势,分析了ISO/IEC18000-4协议中被动反向散射式RFID系统的工作原理和技术规范,提出了一种遵循该协议的2.45G RFID阅读器的设计方案,支持飞利浦的UCODE HSL标签.文章重点介绍了编码解码技术、调制解调方式、防碰撞算法和零中频技术等.     

应用虚拟仪器技术的超高频 RFID 读写器设计*

射频识别技术在资产管理领域中逐渐受到青睐,针对现有识别技术开发周期长、测试速度慢的弊端,论文提出采用虚拟仪器和数字信号处理技术,结合自定义超高频协议,研究了一种新的读写器系统。该系统用软件代替硬件实现超高频射频识别,能对超高频RFID标签自动测试,能够实现电子标签从物理层到应用层的一致性测试,能对多种宏观参数测量和分析。实验结果表明,该系统在单标签及多标签的情况下能克服单一标准的限制,很好地模拟读写器调制、解调、编码、解码、循环冗余校验、逻辑控制等基本功能,具有成本低、集成度高和扩展性好等优势。     

DVB-RCS网络中的跨层协议优化研究

由于DVB-RCS网络长传播延迟以及高误码率的特点,会造成所承载TCP业务的性能下降。传统的分层协议设计方式已经不适合这种动态变化的网络特点。采用跨层协议设计方式优化TCP协议性能。跨层设计方式结合了传输层上TCP协议的工作特点,MAC层的接入策略以及物理层上的自适应调制编码策略。仿真结果显示了跨层协议设计相对于传统协议设计方式性能上的优势。     

基于Simulink的WiMAX物理层性能仿真

针对WiMAX物理层基带仿真模型未采用SUI信道的问题,在理想同步情况下,综合考虑影响系统性能的各种因素,包括SUI信道、循环前缀（CP）长度、RS＋CC编码和信道估计,运用Simulink对其进行评估。仿真结果表明,采用自适应调制编码或改变CP长度能平衡BER和数据速率。     

一种新的基于MQAM的PLNC去噪映射算法

物理层网络编码(Physical Layer Network Coding,PLNC)在高阶幅度和相位调制中存在星座点模糊现象。针对这一问题提出了一种物理层网络编码去噪映射算法。在该算法中,中继节点对接收信号进行星座点重新布局,按一定规律将星座点合并,经过处理后的信号星座点降低了一半,进而下行链路的调制阶数也降低了一半,星座图相邻点之间的欧氏距离变大,系统误码率性能得到提高;且中继节点只需解调-重映射-调制,处理复杂度低。通过计算机仿真验证了该算法的有效性。     

Error-Resilient Video Encoding and Transmission in Multirate Wireless LANs

In this paper, we present a cross-layer approach for video transmission in wireless LANs that employs joint source and application-layer channel coding, together with rate adaptation at the wireless physical layer (PHY). While the purpose of adopting PHY rate adaptation in modern wireless LANs like the IEEE 802.11a/b is to maximize the throughput, in this paper we exploit this feature to increase the robustness of wireless video. More specifically, we investigate the impact of adapting the PHY transmission rate, thus changing the throughput and packet loss channel characteristics, on the rate-distortion performance of a transmitted video sequence. To evaluate the video quality at the decoder, we develop a cross-layer modeling framework that considers jointly the effect of application-layer joint source-channel coding (JSCC), error concealment, and the PHY transmission rate. The resulting models are used by an optimization algorithm that calculates the optimal JSCC allocation for each video frame, and PHY transmission rate for each outgoing transport packet. The comprehensive simulation results obtained with the H.264/AVC codec demonstrate considerable increase in the PSNR of the decoded video when compared with a system that employs separately JSCC and PHY rate adaptation. Furthermore, our performance analysis indicates that the optimal PHY transmission rate calculated by the proposed algorithm, can be significantly different when compared with rate adaptation algorithms that target throughput improvement.     

基于UWB的无线传感器网络跨层优化模型研究

跨层设计是提高无线传感器网络整体性能的一种有效方法。在综合考虑MAC层调度、物理层功率控制、网络层路由三方面因素的基础上,结合超宽带技术大带宽、低信号功率的特点,以实现网络最大数据传输速率为目标,构建了基于超宽带技术的无线传感器网络跨层优化模型。仿真实验表明：模型最优解可有效提高网络数据传输速率;物理层功率控制对优化结果有着至关重要的影响。这证明以构建、求解优化模型的方式解决跨层设计问题是切实可行的,同时也为解决大规模超宽带传感器网络数据传输问题提供了一条新的解决思路。     

下一代高速无线局域网标准IEEE802．11n的关键技术

IEEE802．11系列标准代表了WLAN技术的主流发展方向。1EEE802．11n作为下一代高速无线局域网标准,物理层采用MIMO—OFDM技术,并对MAC层性能进行优化,大大提高了数据的传榆速率。文中讨论了IEEE802．11n的关键技术。     

Guest Editorial on Vehicular Networking Protocols

Vehicular communications is receiving an increased interest by the research community both from industry and academia. These technologies known as Vehicular Ad hoc Networks (VANET) include vehicle-to-infrastructure (V2I), and vehicle-to-vehicle (V2V) communications and can be based on various communications technologies. This special issue on Vehicular Networking Protocols technologies highlights new trends on networking protocols and their issues, further focusing on the Medium Access Control (MAC) layer and Physical (PHY) layer challenges. It also underlines on algorithms and protocols for data aggregation and group-based networking in vehicular networks.     

CuSora: Real-time software radio using multi-core graphics processing unit

The Sora platform, which is a fully programmable, high-performance software radio platform based on a commodity general purpose PC, has recently received significant attention. However, acceleration techniques used in Sora are too complicated for developers, which can prevent researchers from modifying physical layer (PHY) processing. This paper presents the CuSora platform, which integrates the Sora platform with a popular multi-core graphics processing unit (GPU) as the modem processor to achieve high-speed PHY signal processing. CuSora also exploits software techniques to fulfill requirements for real-time communication. A software controller is presented to achieve multi-mode communication. The features of the single-instruction multiple data parallel computation of the GPU are also employed to accelerate PHY processing. Several wireless protocols, such as WiFi (802.11a) or WiMAX (802.16), are demonstrated on the CuSora platform for verification. CuSora meets the requirement of real-time communication and has an excellent bit error ratio performance. CuSora has a higher performance, shorter development cycle, and better coding flexibility than the Sora platform.     

MIMO MAC协议PHY/MAC联合仿真性能研究

多输入多输出（Multiple-Input Multiple-Output,MIMO）技术是能够实现多包接收（Multi-Packet Reception,MPR）功能。提出MIMO系统的MAC协议,该协议基于数据流控制方法实现多包接收功能,并在同一通信领域内支持多对一和并行通信。网络仿真中采用调用信道模型的方法,并利用OPNET和MATLAB进行了PHY/MAC跨层动静态联合仿真分析。仿真结果表明,所提协议能够有效地提高移动Ad Hoc网络吞吐量、端到端分组延迟等性能。     

IEEE 802.11p车载自组网络协议的EDCA自适应退避算法研究

IEEE 802.11p是IEEE针对车辆网络颁布的物理层与MAC层标准,网络中车辆密度是动态变化的,而IEEE 802.11p协议没有提出根据网络情况动态调整EDCA参数来优化网络性能。为了解决网络中节点密度变化带来的吞吐量低、碰撞率高的问题,提出一种EDCA自适应退避优化算法。仿真实验结果表明,该算法相对于传统EDCA算法,性能大幅度提高。     

An adaptive cross-layer design for multiservice scheduling in OFDMA based mobile WiMAX systems

We consider a cross-layer scheme for the downlink multiuser Orthogonal Frequency Division Multiple Access (OFDMA) for mobile WiMAX (Worldwide Interoperability for Microwave Access) based on IEEE802.16e standard. We propose an intelligent Medium Access Control (MAC) that adapts with the physical layer (PHY) in response to the different QoS requirements of the diverse service flows in the system. This adaptation is represented by a joint packet scheduling and slot allocation scheme interaction in both MAC and PHY layers. Based on this interaction, a fair and efficient QoS guaranteed resource allocation for a mixture of real-time and non real-time service flows is achieved. We provide extensive simulation results showing the performance aspects of the proposed cross-layer scheme.     

一种IEEE1394物理层IP的FPGA原型验证方法

符合IEEE1394协议的物理层IP主要完成总线连接检测、连接管理、仲裁、数据收发等功能,是一款集成高速Ser-des的数模混合SoC。由于在Serdes的测试芯片设计完成前无法对1394物理层IP进行全面验证,因此文中在介绍1394 PHY物理层IP各部分功能的基础上,提出了一种以Xilinx的GTP代替1394物理层Serdes,构建FPGA原型验证平台,采用专用硬件逻辑和软件结合的方式,对1394物理层IP进行充分验证的方法。使用该平台可在Serdes设计未完成前对数字逻辑进行验证,大大缩短物理层IP的开发周期;通过软件控制下的测试项生成、测试过程监控、测试结果判断,可显著提高验证效率。