Multi-Rate Polling: Improve the Performance of Energy Harvesting Backscatter Wireless Networks

In recent years, Researchers have proposed the concept of Energy Harvesting Backscatter Wireless Networks (EHBWN). EHBWN usually consists of one sink and several backscatter nodes. Backscatter nodes harvest energy from their environment and communicate with sink through backscattering the carrier wave transmitted by sink. Although a certain amount of access protocols for Energy Harvesting Wireless Networks have been present, they usually do not take the sink’s receiver sensitivity into account, which makes those protocols unsuitable in practice. In this paper, we first give an analysis of the backscatter channel link budget and the relationship between the effective communication range and uplink data rate. After that, we point out that a single uplink data rate for all the backscatter nodes is no longer suitable due to the constraint of sink receiver sensitivity. Later we propose Multi-rate Polling which divides the network into different uplink data rata regions to make sure the correct packet reception by the sink and improve the network performance. Multi-rate Polling also introduces a parameter K, through adjusting it, we can achieve the trade-off between network throughput and fairness to meet the requirement under various scenarios. We validate Multi-rate Polling under different networks and average harvesting rates through simulation. The result shows that the proposed protocol can effectively improve the network performance and has excellent scalability, which makes it suitable for EHBWN.     

自适应MET-LDPC编码方案及FPGA实现

介绍自适应多边类型低密度奇偶校验码(MET-LDPC)多码率编码方案,在不改变编码器生成矩阵的基础上采用规则删余的方法构造多码率编码并硬件实现.在编码器硬件实现中,采用寄存器组比特交织方案,减少资源占用,提高了处理能力.在占用较低硬件资源的情况下,编码器吞吐量为100 Mbit/s,满足高速编码的要求.     

基于多采样率的频域倍频程研究

传统倍频程分析采用带通滤波器组算法实现,带通滤波器组算法仅能满足国家标准要求,并且用于分析分数阶倍频程时,滤波器组的数量及计算量成倍增长。提出了一种基于多采样率在频域分析倍频程及分数阶倍频程的算法。该算法首先对信号按通道重采样,并利用FFT转换到频域计算信号的倍频程及分数阶倍频程谱。仿真验证了算法的正确性,并与带通滤波器组算法做了比较。仿真及对比结果表明,相比于带通滤波器组算法,该算法能提供更好的谱分辨率,并且对于分数阶倍频程,该算法计算量明显少于滤波器组算法计算量。     

软件无线电中的多速率信号处理

介绍了软件无线电和多速率信号处理的概念,多速率信号处理能够改变软件无线电系统不同节点处的信号速率。多速率信号处理最基本的两种方法是抽取和内插,分析了他们的原理,并给出了相应的多相滤波结构。多相滤波器组使各个支路滤波器的阶数降至1/D(1/I),是实现信号实时处理的有效途径。     

High throughput route selection in multi-rate wireless mesh networks

Most existing Ad-hoc routing protocols use the shortest path algorithm with a hop count metric to select paths. It is appropriate in single-rate wireless networks, but has a tendency to select paths containing long-distance links that have low data rates and reduced reliability in multi-rate networks. This article introduces a high throughput routing algorithm utilizing the multi-rate capability and some mesh characteristics in wireless fidelity （WiFi） mesh networks. It uses the medium access control （MAC） transmission time as the routing metric, which is estimated by the information passed up from the physical layer. When the proposed algorithm is adopted, the Ad-hoc on-demand distance vector （AODV） routing can be improved as high throughput AODV （HT-AODV）. Simulation results show that HT-AODV is capable of establishing a route that has high data-rate, short end-to-end delay and great network throughput.     

多阶微分采样及其在高速ADC系统中的应用

首先阐明了多阶微分采样的原理，给出了更为简洁的完美重构条件。然后根据该条件导出了多阶微分采样完美重构滤波器组的频谱响应和理想的冲激响应。时理想滤渡器的冲激响应进行了延迟、截断和加窗来得到可实现的有限冲激（FIR）重构滤波器组，从而实现了高速的多阶微分采样型ADC系统。理论分析和仿真结果说明本文设计的重构滤波器组可以对多阶微分采样进行很好的重构，整个系统信纳比（SINAD）平均可迭83．3dB，无伪波动态范围（SFDR）平均达102．7dB。     

CDMA系统多速率判决技术

在CDMA移动通信系统中，由于采用了可变速率声码器，所以在接收端需要用多速率判定算法来获取速率信息，从而正确地接收数据。本文介绍了多速率判定算法，分析了信道误码计数度量(SER)、山本度量YQM(Yamamoto Quality Metric)和CRC校验度量3种判定度量的产生原理和软件无线电实现方法，同时使用DSP FPGA的结构对多速率判定进行了优化实现。     

Multi-rate optimal state estimation

This article formulates a multi-rate linear minimum mean squared error (LMMSE) state estimation problem, which includes four rates as follows: the state updating rate in the model, the measurement sampling rate, the estimate updating rate and the estimate output rate. This formulation is unique in two ways. First, the rate ratio between state measurement and state estimate is more general (a rational number), instead of just an integer or its reciprocal as considered in the existing literature. Second, state estimates are produced in blocks, which have never been considered before in the multi-rate estimator design. The multi-rate LMMSE estimation problem is solved by examining several distinctive cases for single-rate state estimation, obtained through the lifting technique. Also, sufficient conditions are given for asymptotic stability of the proposed multi-rate LMMSE estimators. An example in tracking a manoeuvering target is given to illustrate the proposed multi-rate state estimators.     

基于脉冲调制的GSM语音信道数据传输方法

针对全球移动通信系统 (GSM) 的安全机制不能实现端到端安全通信问题,提出了一种低复杂度基于脉冲调制的数据传输方案及优化方法。分别设计了基于脉冲位置调制及脉位结合极性调制的类语音信号,给出了基于跳时脉冲的帧同步方法。搭建了基于脉冲调制的GSM语音信道数据传输仿真平台,分析比较了不同调制阶数和不同自适应多速率编码 (AMR) 码率下系统的性能。为了提高系统可靠性,引入卷积码进一步降低了系统误码率。仿真结果表明,4阶脉冲调制最适用于语音信道,所提脉冲调制方法与传统低复杂度频移键控 (FSK) 调制方式误码率近似,但传输速率高,且提出的脉位结合极性调制进一步提高了传输速率,总提高比例达到36%。     

基于RTDS和FPGA联合仿真平台的多速率实时仿真方法

为实现含分布式电源的电力系统实时仿真,研究了一种基于实时数字仿真器(RTDS)和现场可编程门阵列(FPGA)联合仿真平台的多速率实时仿真方法。采用局部延迟插入方法分解电力系统网络,并利用拟合法和外插法实施并行多速率接口电气量交互。为减小通信延时对仿真精度的影响,提出了一种FPGA数据发送适当早于RTDS数据发送的接口电气量异步交互方法。在RTDS和FPGA联合仿真平台上以50μs/1μs混合仿真步长实时仿真了一个含2个光伏发电的IEEE 5节点电力系统,并与PSCAD平台下的仿真数据进行对比,验证了所提联合仿真平台的可行性和实时仿真方法的准确性。