Design and Implementation of Implanted Log Periodic Spiral PIFA in Liver

A design of a log periodic SPIFA （spiral planar inverted-F antenna） is proposed. A way of tuning the SPIFA to work in the ISM band （2.45 GHz） is discussed. The purpose of the antenna is to detect any tumor in the liver depending on the change in the conductivity and the permittivity of the liver after being infected. Detecting liver cancer on its early stages will help in the treatment process and makes it much faster as cancer in early stages can be treated easily. The antenna is designed, simulated and measured in a rabbit＇s liver. The simulated and measured results show great agreement with each other.     

Wideband Rectangular and Circular Microstrip Antennas Loaded with U-Shaped Slot

In this paper, a dual frequency resonance antenna is analysed by introducing U-shaped slot in a rectangular and circular patch, the results in terms of return loss, input impedance and radiation pattern are given. It is observed that various antenna parameters are obtained as a function of frequency for different value of slot length and width; it is easy to adjust the upper and the lower band by varying these different antenna parameters. The coaxial feed is used to excite the patch antenna. All the theoretical results using Matlab are compared with the simulated results obtained from Ansoft HFSS which are in close agreement. Furthermore, comparative study between our results and those available in the literature is done and showed to be in good agreement.     

空时码在Rician衰落信道下性能分析

基于Alamouti提出的BPSK调制下空时分组码在Rayleigh衰落信道中的简单分集方案。推导出多发射和多接收天线系统中正交空时分组码在Rician衰落信道的BPSK调制下的比特差错率的最小距离球界,并推广到在高阶调制下衰落信道中系统符号差错率的性能。仿真分析和比较了空时分组码的多天线系统中发射和接收天线分集增益,以及信道相关参数的变化对系统误比特性能的影响。     

A new method of micro-motion parameters estimation based on cyclic autocorrelation function

Abstract Signals with sinusoidal frequency modulation （FM） are the general form of micro-Doppler signals in radar echoes from targets with micro-motions. This paper derives the cyclic autocorrelation function of a sinusoidal FM signal using its cyclostationary characteristics, and estimates the parameters of amplitude, modulation index, micro-motion period and noise power based on cyclic autocorrelation function. The estimation method is robust in noise environment when compared with conventional time-frequency analysis methods. Finally, the performances of estimation by utilizing the simulation data and darkroom measurement are shown in tables. The Monte-Carlo simulation results show that the estimator is asymptotically optimal at SNR above -6 dB.     

Design of efficiently encodable nonbinary LDPC codes for adaptive coded modulation

This paper is concerned with constructions of nonbinary low-density parity-check （LDPC） codes for adaptive coded modulations （ACM）. A new class of efficiently encodable structured nonbinary LDPC codes are proposed. The defining parity-check matrices are composed of scalar circulant sub-matrices which greatly reduce the storage requirement when compared with random LDPC codes. With this special structure of parity- check matrix, an efficient encoding algorithm is presented. Based on the proposed codes, a family of variable- rate/variable-field nonbinary LDPC codes is designed for the ACM system. When combined with matched-size signal constellations, the family of constructed codes can achieve a wide range of spectral efficiency. Furthermore, the resultant ACM system can be implemented via a set of encoder and decoder. Simulation results show that the proposed nonbinary LDPC codes for the ACM system perform well.     

A 2.4 GHz low power CMOS transceiver for LR-WPAN applications

A 2.4 GHz low power transceiver for low-rate wireless personal area network(LR-WPAN)applications is presented.The optimized low-IF receiver consists of a novel current reuse RF front-end with an inductor-less-load balun LNA and quadrature mixer,and an adaptive analog baseband to reduce power and area.It achieves-94 dBm of sensitivity,-9 dBm of IIP3 and 28 dBc of image rejection.The phase-locked loop based direct phase modulated transmitter is proposed to reduce power and deliver a+3 dBm output power.The phase noise of the low power frequency synthesizer with current reuse stacked LC-VCO achieves-107.8 dBc/Hz at 1 MHz offset.An ultra-low power nonvolatile memory is used to store configuration data and save power.The chip is implemented in a 0.18μm CMOS process,and the area is less than 2.8 mm2.The transceiver consumes only 10.98 mW in the receiving mode and 13.32 mW in the transmitting mode.     

Performance of orthogonal STBC-MIMO with variable-power adaptive modulation and delayed feedback in Nakagami fading channels

A variable-power （VP） adaptive modulation （AM） scheme with space-time block code （STBC） is developed in MIMO systems, and the corresponding performance is investigated in Nakagami fading channels. The optimum switching thresholds are derived so that the spectrum efficiency （SE） under an average power and a target bit error rate （BER） constraint is maximized. By the switching thresholds, average BER and SE are further derived. As a result, closed-form expressions are obtained. Besides, the exact and approximate BER expressions of VP AM and constant-power （CP） AM systems with delayed feedback are respectively derived. Simulation results show that the theoretical SE and BER can match the corresponding simulation well. The results indicate that VP-AM with STBC provide higher spectrum efficiency than the CP counterparts, and has slighter bite error rate performance degradation when the normalized delay is less than 0.01.     

Examining Impacts of Spatial Correlation in Forward Error Correction Code

ABSTRACT

The utilization of Multiple Input Multiple Output – Orthogonal Frequency Division Multiplexing (MIMO-OFDM) has rapidly gained popularity because of its improved performance capabilities in terms of enhanced spatial diversity gain, reliability as well as the spatial multiplexing Gain. This paper discusses the effect of spatial correlation in Forward Error Correction of MIMO-OFDM system. Here, the four error correction codes, namely, Convolutional Code (CC), Low-Density Parity Check (LDPC-CC), and Reed-Solomon code (RSC-CC) is validated under three channel models, namely, Rayleigh, Rician and Additive White Gaussian Noise (AWGN). The analysis is performed using four modulation schemes such as Quadrature Phase Shift Keying (QPSK), Binary Phase Shift Keying (BPSK), Quadrature Amplitude Modulation (QAM)-16, and QAM-64. It is performed under three antenna configurations like 2 × 2, 2 × 4, and 4 × 4. Moreover, the Peak Signal to Noise Ratio (PSNR) is exploited to identify the image transmission, as well as the Bit Error Rate (BER), is exploited to identify the data transmission. In experimental results, the Turbo-CC displays better performance.     

瑞利信道下基于累积量的调制识别方法

针对瑞利信道下调制方式分类的问题,提出了一种基于累积量的识别方法。该方法利用四阶累积量和六阶累积量的组合作为特征参数,采用决策树分类器,能够实现二相相移键控(BPSK)、四相相移键控(QPSK)、四进制幅移键控(4ASK)、四阶正交幅度调制（16QAM）、五阶正交幅度调制（32QAM）、六阶正交幅度调制（64QAM）和正交频分复用（OFDM）七种调制方式的识别分类,且计算量小,易于实现。从理论上进行推导与分析,所提方法对瑞利衰落和加性高斯白噪声干扰不敏感。计算机仿真结果表明：信噪比大于4dB时,正确识别率达到90%以上,说明了所提方法的可行性及有效性。     

基于多标签分类算法的多输入多输出智能接收机模型

传统无线通信系统由发射机和接收机组成,待传输的信息经过信道编码、调制、成型后通过天线发射出去。由于信道衰落、噪声和干扰等因素的影响,到达接收机的信号会存在较严重的失真,接收机需要从失真的信号中尽可能地恢复出原始信息。为解决此问题,提出基于多标签分类神经网络的多输入多输出（MIMO）智能接收机模型。该模型利用深度神经网络（DNN）替代接收机从信号到信息之间的整个信息恢复环节,并采用多标签分类算法代替多个二分类器实现多个比特的信息流恢复,而训练数据集为包含二进制相移键控（BPSK）与正交相移键控（QPSK）两种调制方式以及汉明编码与循环编码两种方式的正交信号。实验结果表明在噪声、瑞利衰落、干扰等情况下,使用传统Alamouti译码方法的接收机误码率（BER）为1E-3时,智能接收机已经实现了BER为0的恢复信息;在保持BER性能相同时,所提多标签分类算法比对比模型的多个二分类器算法在每个批次的训练时间上减少了约4 min。     

瑞利衰落信道最大比合并的误码率改进新方法

通过分析瑞利衰落信道模型,以及BPSK在最大比合并瑞利衰落信号下的误码率解析结果,提出了在最大比合并之前添加自动增益控制模块,弥补接收过程带来的信噪比损失,从而改善误码率性能。通过Matlab数值仿真的方法,证明采用在最大比合并之前添加自动增益控制过程的分集接收策略能有效地改善瑞利衰落对无线信道传输信号的影响。     

信噪比失配对若干码型误比特性能的影响

比较分析了高斯信道下信噪比失配对以下三种码型Log-MAP译码算法误比特性能的影响:Turbo码、比特交织Turbo编码调制以及基于符号的Turbo网格编码调制。其中Turbo码采用BPSK调制,比特交织Turbo编码调制和基于符号的Turbo网格编码调制采用16-QAM调制。仿真结果显示,信噪比失配对基于符号的Turbo网格编码调制误比特性能的影响和对Turbo码的相似,而比特交织Turbo编码调制的误比特性能对于SNR过估计比前两者要更加敏感。     

基于软件无线电和神经网络的RFID调制制式测试研究

RFID测试技术的发展对RFID技术的成熟和广泛应用具有重要的理论意义和实用价值;RFID调制制式测试(识别)则是RFID测试技术重要研究内容之一;文中提出了一种新的基于软件无线电的RFID调制方式测试方法;`在软件无线电的基础上,采用4个特征参数,用BP神经网络实现对2ASK、4ASK、2FSK、4FSK和BPSK等RFID系统典型调制方式进行识别;讨论了方案设计,给出了仿真实验结果;仿真结果表明该方法具有较好的准确性和稳健性。     

结合天线选择的空间调制及性能仿真

提出了一种分组映射空间调制方案。每个时隙中有多个发射天线被同时激活,结合幅度相位调制技术,每根选中的天线发射不同的符号,并且所激活的特定天线序列也携带相应信息。相对传统空间调制技术而言,该方案可以有效地提高空间调制系统的频带利用率和传输速率。Rayleigh衰落信道的仿真结果表明,所提方案的误比特率（Bit Error Rate,BER）性能优于传统的空间调制与多输入多输出（Multi-Input Multi-Output,MIMO）技术。方案可进一步结合发射天线选择（Antenna Selection,AS）技术,提高系统的传输质量。实际多极化MIMO信道的测量和仿真结果表明,在发端天线选择数目均相同时,分组映射调制的性能明显优于空间调制,结合AS的调制系统性能明显优于未结合AS的系统。     

两种LDPC译码算法在OFDM系统应用中的改进

低密度校验码是一种基于稀疏校验矩阵的线性码，此码性能接近Shannon限，并具有简单有效的迭代译码算法。大部分文献提到的LDPC迭代译码算法均基于BPSK调制，相对于MQAM／MPSK调制，BPSK调制频谱利用率太低。在未来的3G＋高速无线通信中，最广泛运用的物理层技术OFDM必然采用频谱利用率较高的多电平调制。因此。如何把LDPC码用于多电平调制下的OFDM是一个关键，将目前较为简化的基于二进制调制的两种译码算法作改进，也即扩展，使之能够应用到基于多进制调制的OFDM系统中．     

空间分集技术在CFBM-MC-CDMA系统中的应用研究

给出了一种简单的空时编码方案，提出了应用该方案的基于复数滤波器组调制的多载波码分多址(CF-BM-MC-CDMA)通信系统的模型。理论分析可知，采用空时编码天线发射分集技术的CFBM-MC-CDMA系统与未采用天线分集的系统相比，其多址干扰功率降低了一半。仿真结果表明，系统采用天线分集技术能显著提高其误比特率性能，在低信噪比区域，系统采用两天线分集接收的性能要比采用两天线分集发射的性能好得多。     

低密度校验码在瑞利衰落信道中的性能分析

低密度校验（LDPC）码具有编码增益高，译码速度快，可并行译码等特点，是当前编码界的一个研究热点，但是目前已有的研究成果都集中在高斯信道上，该文分析和讨论了LDPC码在瑞利衰落信道下的性能，应用联合界技术推导了一个规则友的性能限，并给同了仿真结果，且发现LDPC码在瑞利衰落信道下也具有非常好的性能。     

Ka频段移动卫星星地链路误码统计分析

针对Ka频段移动卫星星地链路的特性,全面考虑天气和移动终端周边环境的影响,建立了Ka频段移动卫星星地信道模型。对二进制相移键控(BPSK)调制方式下的星地信道进行仿真和数字基带误码图案的统计分析,并采用最小二乘法对误码发生次数的概率进行了拟合。研究表明：信道误码发生次数服从泊松分布,在Ka频段移动卫星星地信道的数字基带模拟中,BPSK调制方式下的系统误码由突发误码和服从泊松分布的随机误码组成。     

A refinement for the Rayleigh radiance computation with variation of the atmospheric pressure

The Rayleigh scattering radiance at the top of the atmosphere (TOA) depends on the surface atmospheric pressure. In processing the Coastal Zone Color Scanner (CZCS) imagery, Gordon et al. (Applied Optics, 27, 862–871, 1988 Gordon, H. R., Brown, J. W. and Evans, R. H. 1988. Exact Rayleigh scattering calculations for use with the Nimbus‐7 Coastal Zone Color Scanner.. Applied Optics, 27: pp. 862–871. [Crossref] , [Google Scholar]) developed a simple formula to account for the Rayleigh radiance changes with the variation of the surface atmospheric pressure. For the atmospheric pressure changes within ±3%, the accuracy of the Gordon et al. (1988 Gordon, H. R., Brown, J. W. and Evans, R. H. 1988. Exact Rayleigh scattering calculations for use with the Nimbus‐7 Coastal Zone Color Scanner.. Applied Optics, 27: pp. 862–871. [Crossref] , [Google Scholar]) formula in computing the Rayleigh radiance is usually within 0.4%, 0.3%, 0.15% and 0.05% for the wavelengths 412, 443, 555 and 865 nm, respectively. This could result in up to ～3% uncertainty in the derived water‐leaving radiance at the blue wavelengths for very clear atmospheres. To improve the performance, a refinement to the Gordon et al. (1988 Gordon, H. R., Brown, J. W. and Evans, R. H. 1988. Exact Rayleigh scattering calculations for use with the Nimbus‐7 Coastal Zone Color Scanner.. Applied Optics, 27: pp. 862–871. [Crossref] , [Google Scholar]) formula is developed based on the radiative transfer simulations. The refined scheme can produce Rayleigh radiance with an uncertainty within 0.1% (often within 0.05%) at the blue, while uncertainty is within 0.05% for the green to near‐infrared wavelengths. The refined algorithm has been implemented in the Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) data processing system. Results from the SeaWiFS data show the improved ocean colour products in the southern oceans where consistently low atmospheric pressures are usually observed. This could also significantly improve the performance of the Rayleigh radiance computations over the high altitude lakes. In addition, with the refined algorithm, the same Rayleigh radiance tables can be possibly used for the various ocean colour satellite sensors in which there are slightly different sensor spectral band characterizations.     

Towards estimating computer users＇ mood from interaction behaviour with keyboard and mouse

The purpose of this exploratory research was to study the relationship between the mood of computer users and their use of keyboard and mouse to examine the possibility of creating a generic or individualized mood measure. To examine this, a field study （n = 26） and a controlled study （n = 16） were conducted. In the field study, interaction data and self-reported mood measurements were collected during normal PC use over several days. In the controlled study, participants worked on a programming task while listening to high or low arousing background music. Besides subjective mood measurement, galvanic skin response （GSR） data was also collected. Results found no generic relationship between the interaction data and the mood data. However, the re- suits of the studies found significant average correlations be- tween mood measurement and personalized regression models based on keyboard and mouse interaction data. Together the results suggest that individualized mood prediction is pos- sible from interaction behaviour with keyboard and mouse.