The Cumulative Method for Multiplication and Division

This paper provides a method of the process of computation called the cumulative method, it is based upon repeated cumulative process. The cumulative method is being adapted to the purposes of computation, particularly multiplication and division. The operations of multiplication and division are represented by algebraic formulas. An advantage of the method is that the cumulative process can be performed on decimal numbers. The present paper aims to establish a basic and useful formula valid for the two fundamental arithmetic operations of multiplication and division. The new cumulative method proved to be more flexible and made it possible to extend the multiplication and division based on repeated addition/subtraction to decimal numbers.

Modeling and Analysis of OFDMA-NOMA-RA Protocol Considering Imperfect SIC in Multi-User Uplink WLANs

To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios,this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal frequency division multiple access(OFDMA)and non-orthogonal multiple access(NOMA).The idea of this protocol is that OFMDA is used to divide the entire frequency field into multiple orthogonal resource units(RUs),and NOMA is used on each RU to enable more users to access the channel and improve spectrum efficiency.Based on the protocol designed in this paper,in the case of imperfect successive interference cancellation(SIC),the probability of successful competition subchannels and the outage probability are derived for two scenarios:Users occupy the subchannel individually and users share the subchannel.Moreover,when two users share the channel,the decoding order of the users and the corresponding probabilities are considered.Then,the system throughput is obtained.To achieve better outage performance in the system,the optimal power allocation algorithm is proposed in this paper,which enables the optimal power allocation strategy to be obtained.Numerical results show that the larger the imperfect SIC coefficient,the worse the outage performance of weak users.Compared with pure OFDMA and NOMA,OFDMA-NOMA-RA always maintains an advantage when the imperfect SIC coefficient is less than a specific value.

Multiple grain-size fraction analysis of heavy minerals and the provenance identification of sediments from the abandoned Huanghe River,eastern China

The quantitative analysis of sediment sources in a sink is an important scientific topic and challenge in provenance research.The characteristics of heavy minerals,combined with the geochemical constituents of detrital grains,provide a reliable provenance-tracing approach.We developed a mineral identification method to analyze the multiple grain-size fraction of sediments,from which the elemental geochemistry of hornblende was used to compare the characteristics of sediments from the Huaihe River and Huanghe(Yellow)River in eastern China.Elements that were statistically identified as being able to discriminate sediment provenance were employed to perform a quantitative analysis of the sources of sediments of the abandoned Huanghe River.Results reveal that the Huaihe River is characterized by a high amphibole content of>60%and that the Huanghe and abandoned Huanghe rivers have greater abundances of limonite and carbonate minerals compared with those of the Huaihe River.The contents of trace elements and rare earth elements in hornblende show that the sediments of the abandoned Huanghe River are similar to those of the Huanghe River but different from those of the Huaihe River.Furthermore,chemical mass balance was used to calculate the relative contributions of different provenances of sediment from the abandoned Huanghe River,and nine trace elements of hornblende were identified as discriminators of provenance.Approximately 2%of the hornblende in the abandoned Huanghe River is derived from the Huaihe River and 98%from the Huanghe River.Considering the proportion of hornblende in the total sediment,it is inferred that the contribution of Huaihe River sediment to the abandoned Huanghe River is approximately 0.5%.This study shows that mineral analysis using multiple grain-size fractions(within the wide range of 1Φto 6Φ)with assessment in elemental geochemistry of hornblende can characterize the provenance of fluvial material in coastal zones.

GDS-MIMO-OFDM雷达通信一体化波形设计

针对正交频分复用(OFDM)雷达通信一体化波形存在的通信速率较低、自相关旁瓣较高的问题,提出了一种基于Gold码扩频的多输入多输出-正交频分复用(MIMO-OFDM)雷达通信一体化波形。将MIMO-OFDM与扩频序列相结合,利用相关性较好的Gold码对通信信息进行扩频,再与OFDM脉冲符号进行调制,进而设计出一种既能提高通信速率又能改善雷达性能的一体化波形。仿真实验证明,较相同仿真条件下的Gold-OFDM、脉冲压缩-正交频分复用(PC-OFDM)一体化波形而言,所设计的一体化波形的通信速率能够倍数提高且可以在不影响通信性能的前提下降低信号模糊函数的旁瓣,从而改善一体化系统的雷达性能。

Analysis and Simulation for Capacity of Time Division-Synchronous Code Division Multiple Access System

Capcity both in uplink and downlink of TD-SCDMA (time division-synchronous code division multiple access) system is studied in a multi-cell environment. The theoretical expressions of the mean of intercell interference in uplink and the mean of sum of power allocation in downlink are given, by which uplink and downlink capacity is analyzed. Furthermore, we give the simulation models for both uplink and downlink capacity. The results from theoretical analysis and simulation fit very well. In the end, the maximum number of users that TD-SCDMA system can serve for 12.2 k speech service is given.

采用CNN的MIMO-OFDM可见光通信接收机

为了克服多输入多输出(MIMO)-正交频分复用(OFDM)可见光通信(VLC)系统中存在的信号串扰、高峰均功率比、发光二极管(LED)的带宽受限和非线性效应等问题,提出一种基于卷积神经网络(CNN)的VLC接收机.该接收机通过对接收端失真信号和发射端原始信号的学习,能够实现MIMO-OFDM可见光通信系统的信号解调,有效提升系统对非线性失真的抑制能力并具有较低的复杂度.实验结果表明,与最小二乘法接收机相比,CNN接收机能有效补偿信号受到的线性和非线性失真以及不同用户间的信号串扰,平均误码率提升超过一个数量级,同时有效克服LED带宽受限问题,比特传输速率提升53%.

混合NOMA/OFDMA可见光通信系统资源分配算法

为了进一步降低混合非正交多址/正交频分复用多址(NOMA/OFDMA)技术的多用户多小区可见光通信系统的误码率,提出了一种功率和子载波的联合分配算法。该算法以最小化系统误符号率为优化目标,实现了子小区间载波和用户功率的联合最优分配。首先,理论推导出系统的误符号率表达式;然后,使用Matlab软件进行仿真,模拟可见光通信系统模型,并借助遗传算法得到最优的分配结果;最后,将该算法与现有的算法进行了对比。仿真结果表明,所提算法的误符号率性能更优。

智能反射面辅助OFDMA云接入网的资源分配方法

本文研究了智能反射面(IRS)辅助OFDMA(Orthogonal Frequency Division Multiple Access,正交频分多址接入)云无线接入网(C-RAN)的下行链路传输系统,其中基带处理单元(BBU)池通过多个远端射频头(RRH)与多个用户进行通信.RRH到用户的接入链路采用OFDMA接入技术.对于BBU池到RRH,采用无线前传链路,并且部署多个IRS以增强链路传输能力.在BBU池和每个RRH发射功率约束下,本文提出通过联合优化前传链路和接入链路资源配置使下行用户和速率最大化.由于该资源配置问题是非凸的,首先采用连续凸逼近(SCA)对目标以及约束条件进行转换.其次,将转换后的问题拆分成三个子问题来交替性求解.最后,计算机仿真结果显示了所提出的联合资源分配方法与其他基准方案相比具有显著的传输性能增益.

Fraction of Missing Information (γ) at Different Missing Data Fractions in the 2012 NAMCS Physician Workflow Mail Survey

In his 1987 classic book on multiple imputation (MI), Rubin used the fraction of missing information, γ, to define the relative efficiency (RE) of MI as RE = (1 + γ/m)?1/2, where m is the number of imputations, leading to the conclusion that a small m (≤5) would be sufficient for MI. However, evidence has been accumulating that many more imputations are needed. Why would the apparently sufficient m deduced from the RE be actually too small? The answer may lie with γ. In this research, γ was determined at the fractions of missing data (δ) of 4%, 10%, 20%, and 29% using the 2012 Physician Workflow Mail Survey of the National Ambulatory Medical Care Survey (NAMCS). The γ values were strikingly small, ranging in the order of 10?6 to 0.01. As δ increased, γ usually increased but sometimes decreased. How the data were analysed had the dominating effects on γ, overshadowing the effect of δ. The results suggest that it is impossible to predict γ using δ and that it may not be appropriate to use the γ-based RE to determine sufficient m.

Multiple Solutions for a Class of Singular Boundary Value Problems of Hadamard Fractional Differential Systems with p-Laplacian Operator

This paper discusses the existence and multiplicity of positive solutions for a class of singular boundary value problems of Hadamard fractional differential systems involving the p-Laplacian operator. First, for the sake of overcoming the singularity, sequences of approximate solutions to the boundary value problem are obtained by applying the fixed point index theory on the cone. Next, it is demonstrated that these sequences of approximate solutions are uniformly bounded and equicontinuous. The main results are then established through the Ascoli-Arzelà theorem. Ultimately, an instance is worked out to test and verify the validity of the main results.

面向小型无人机的OFDM-MIMO雷达信号设计和处理方法

随着空域的逐渐开放,以小型无人机为代表的低慢小目标,其有效检测对维护安全非常重要。然而,低慢小目标具有飞行高度低、飞行速度慢及雷达散射截面积(Radar Cross Section,RCS)小的特点,加之电磁环境复杂多变,使其难以被传统低分辨雷达发现。为了提升雷达的低截获性能和成像分辨率,本文提出了一种基于步进正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)的多输入多输出(Multiple Input Multiple Output,MIMO)雷达信号设计和处理方法。该方法是将窄带OFDM信号与非线性步进方案相结合,通过非线性步进方案控制MIMO发射信号的载频,获得发射端正交波形和大射频带宽,使得雷达接收机的天线孔径获得明显扩展,从而提升雷达的低截获性能和角度分辨率,同时实现低采样速率下的高距离分辨率。在雷达接收端,利用发射波形之间的正交性分离各通道回波,然后基于改进离散傅里叶变换(Discrete FourierTransform,DFT)和解码的处理方法,校正了非线性步进方案产生的相位误差,生成目标的三维高分辨成像。本文在77 GHz载频下设计仿真,验证所提方法的有效性。仿真结果表明,所提方法相比现有方法,在低信噪比下具有较高的三维成像分辨率,而且没有明显增加信号处理的复杂度。然而,该方法减小了最大无模糊速度。此外,本文讨论了步长数对雷达性能的影响,仿真结果表明,随着步长数的增加,最大无模糊速度减小,角度分辨率提升,为实际应用场景下步进OFDM-MIMO雷达的信号设计提供理论指导。

BER Performance of Space-Time Coded MMSE DFE for Wideband Code Division Multiple Access (WCDMA)

In recent times, there has been growing interests in integration of voice, data and video traffic in wireless communication networks. With these growing interests, WCDMA has immerged as an attractive access technique. The performance of WCDMA system is deteriorated in presence of multipath fading environment. The paper presents space-time coded minimum mean square error (MMSE) Decision Feedback Equalizer (DFE) for wideband code division multiple access (WCDMA) in a frequency selective channel. The filter coefficients in MMSE DFE are optimized to suppress noise, intersymbol interference (ISI), and multiple access interference (MAI) with reasonable system complexity. For the above structure, we have presented the estimation of BER for a MMSE DFE using computer simulation experiments. The simulation includes the effects of additive white Gaussian noise, multipath fading and multiple access interference (MAI). Furthermore, the performance is compared with standard linear equalizer (LE) and RAKE receiver. Numerical and simulation results show that the MMSE DFE exhibits significant performance improvement over the standard linear equalizer (LE) and RAKE receiver.

低频部署下MIMO-OFDM通信系统的频谱利用效率分析

主要深入研究低频部署下多进多出-正交频分复用(Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing,MIMO-OFDM)通信系统的频谱利用效率,探讨低频部署对系统性能的影响,并提出相应的优化策略。详细分析低频部署对信号传输性能和频谱利用效率的影响,评估频谱利用效率,提出针对低频部署的MIMO-OFDM系统的优化策略,最后探讨低频部署下MIMO-OFDM系统的适用场景,为实际应用提供一些建议。

Performance of STBC-MC-CDMA system based on complex wavelet packet and turbo coding

On the basis of analyzing the principle of the space-time coding technique and the multi-carrier code division multiple access （MC-CDMA） technique, adopting the turbo codes as channel coding and the optimized complex wavelet packet as multi-carrier modulation, a novel space-time block coded the MC-CDMA system based on complex wavelet packet and turbo coding is proposed, and the system bit error rate （BER） performance in the Rayleigh fading channel is investigated. The system can make full use of space-time block codes＇ transmit diversity and turbo codes＇ good ability against fading channel to improve the BER performance significantly, and it can also avoid the decrease of spectrum efficiency of conventional MC-CDMA due to inserting cyclic prefix （CP） by utilizing superior characteristics of the optimized complex wavelet packet. Simulation results show that the proposed space-time block coded MC-CDMA system based on the complex wavelet packet performs better than the conventional space-time block coded MC-CDMA （STBC-MC-CDMA） system, and slightly outperforms the STBC-MC-CDMA with CP. Moreover, the application of the space-time block coding technique concatenated with turbo codes strengthens the system ability to combat various interferences in fading channel further.

Design of integrated radar and communication system based on MIMO-OFDM waveform

Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output (SISO) systems. To solve these problems, an integrated radar and communication system (IRCS) with multiple input multiple output (MIMO) OFDM waveform is proposed. The different limitations of radar and communication in designing such a system are investigated. Then, an optimization problem is devised to obtain suitable system parameters, including the number of subcarriers, subcarrier spacing, number of symbols, pulse repetition frequency (PRF) and length of cyclic prefix (CP). Finally, to satisfy the requirements of both radar and communication, the IRCS parameters are derived in three typical cases. Several numerical results are presented to illustrate the demands of radar and communication, inconsistent or consistent, for the IRCS parameters and the superiority of the proposed system.

Environmental factors influencing snowfall and snowfall prediction in the Tianshan Mountains, Northwest China

Snowfall is one of the dominant water resources in the mountainous regions and is closely related to the development of the local ecosystem and economy. Snowfall predication plays a critical role in understanding hydrological processes and forecasting natural disasters in the Tianshan Mountains, where meteorological stations are limited. Based on climatic, geographical and topographic variables at 27 meteorological stations during the cold season(October to April) from 1980 to 2015 in the Tianshan Mountains located in Xinjiang of Northwest China, we explored the potential influence of these variables on snowfall and predicted snowfall using two methods: multiple linear regression(MLR) model(a conventional measuring method) and random forest(RF) model(a non-parametric and non-linear machine learning algorithm). We identified the primary influencing factors of snowfall by ranking the importance of eight selected predictor variables based on the relative contribution of each variable in the two models. Model simulations were compared using different performance indices and the results showed that the RF model performed better than the MLR model, with a much higher R^2 value(R^2=0.74; R^2, coefficient of determination) and a lower bias error(RSR=0.51; RSR, the ratio of root mean square error to standard deviation of observed dataset). This indicates that the non-linear trend is more applicable for explaining the relationship between the selected predictor variables and snowfall. Relative humidity, temperature and longitude were identified as three of the most important variables influencing snowfall and snowfall prediction in both models, while elevation, aspect and latitude were of secondary importance, followed by slope and wind speed. These results will be beneficial to understand hydrological modeling and improve management and prediction of water resources in the Tianshan Mountains.

Joint timing synchronization and frequency offset acquisition algorithm for MIMO OFDM systems

For multiple-input multiple-output （MIMO） orthogonal frequency division multiplexing （OFDM） systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform （FRFT） is proposed. The linear frequency modulation signals superimposed on the data signals are used as the training signals. By performing FRFT on the received signals and searching the peak value of the FRFT results, the receiver can realize timing synchronization and frequency offset acquisition simultaneously. Compared with the existing methods, the proposed algorithm can provide better timing synchronization performance and larger frequency offset acquisition range even under multi-path channels with low signal to noise ratio. Theoretical analysis and simulation results prove this point.

Hardware Implementation and Simulations of Joint Coding and Modulation Diversity MIMO-OFDM Scheme

This paper presents an efficient Joint Coding and Modulation Diversity ( JCMD ) scheme. The proposed scheme applied modulation diversity technique to MIMO-OFDM system which can effectively use time, frequency and space diversity combined with channel coding. In fading channel,the proposed scheme not only achieves high spectral efficiency,but also greatly enhances the reliability of wireless transmission. The self- developed hardware prototype system proves that the proposed scheme can be realized and has high reliability. Compared with traditional MIMO-OFDM scheme based on bit-interleaved coded modulation ( BICM) ,software and hardware simulation results show that the proposed scheme with the optimal rotational angle can obtain a significant performance advantage both for precoded and non-precoded system in the condition of non-perfect channel knowledge and non-ideal synchronization.

Identification and characterization of a novel isoform of hepatopoietin

AIM: To isolate a novel isoform of human HPO (HPO-205) from human fetal liver Marathon-ready cDNA and characterize its primary biological function. METHODS: 5'-RACE (rapid amplification of cDNA 5' ends) was used to isolate a novel isoform of hHPO in this paper. The constructed pcDNA(HPO-205), pcDNA(HPO) and pcDNA eukaryotic expression vectors were respectively transfected by lipofectamine method and the stimulation of DNA synthesis was observed by (3)H-TdR incorporation assay. Proteins extracted from different cells were analyzed by Western blot. RESULTS: A novel isoform of hHPO (HPO-205) encoding a 205 amino acid ORF corresponding to a translated production of 23 kDa was isolated and distinguished from the previous HPO that lacked the N-terminal 80 amino acids. The dose-dependent stimulation of DNA synthesis of HepG2 hepatoma cells by HPO-205 demonstrated its similar biological activity with HPO in vitro. The level of MAPK (Mitogen-activated protein kinase) phosphorylation by Western blot analysis revealed that HPO-205 might have the stronger activity of stimulating hepatic cell proliferation than that of HPO. CONCLUSION: A novel isoform of hHPO (HPO-205) was isolated from hepatic-derived cells. The comparison of HPO-205 and HPO will lead to a new insight into the structure and function of hHPO, and provide the new way of thinking to deeply elucidate the biological roles of HPO/ALR.

Novel Channel Estimation Method in Broadband MIMO-OFDM Systems

A least square （IS） parametric channel estimation method in broadband mt/ltiple input multiple output （MIMO） orthogonal frequency division multiplexing （OFDM） systems is proposed. The mean square error （MSE） performance using optimal training pilots is also given, which proves the method can improve the estimation precision greatly in sparse channel.. Since such method needs the multi-path time delays information of the channel, the probabilistic data association （PDA） method is employed to estimate the time delay of each path. Simulation results show that both the bit error rate （BER） and the MSE performance of the proposed method are better than the traditional LS channel estimation method.