Multiple frequency detection in undersampled complex-valuedwaveforms with close multiple frequencies

The determination of multiple frequencies in undersampled waveforms is studied, where the multiple frequencies are close to each other. Given multiple undersampling rates, the maximal range of the detectable multiple frequencies is the least common multiple of these multiple rates under the assumption that these rates are larger than twice the maximal distance between the multiple frequencies     

基于信息融合的多目标单站无源跟踪新技术研究

跟踪起始与数据关联是多目标无源单站跟踪的关键技术.本文提出了一种基于目标多特征信息融合的自适应跟踪起始算法,通过构造多维动态可变的跟踪门,进行自适应跟踪起始检测,然后根据序列概率比检验准则进行轨迹确认.同时提出了一种基于多目标多特征信息融合的数据关联算法,首先通过定义多个特征数据关联度,将单个有效观测的多特征信息进行融合,再对多目标进行综合数据关联.计算机仿真表明,该跟踪起始算法能够快速有效地启动航迹,数据关联算法的性能要优于传统的NN方法和扩展的NN方法.     

基于三级调制的多带OFDM-UWB多址算法

根据多带OFDM-UWB通信系统的特点，提出一种基于三级调制的多带OFDM-UWB多址算法—TSM-MA算法。该算法通过MC-CDMA、OFDMA与FHMA技术的融合，实现多种技术的优势互补，减少了多用户间的干扰，充分利用了各子载波的可用资源。为了降低接收机的复杂度，TSM-MA算法采用了二级扩频与二级跳频的机制。结果表明，TSM-MA算法的多址性能要明显优于时频多址算法的性能，可以改善系统信噪比3dB左右，并且在接收机的复杂度方面也有一定的优势。     

基于多兴趣区域的图像多质量编码方法研究

结合JPEG2000的感兴趣区域编码分析了实现图像多兴趣区域多质量压缩的方法。这些方法可以区分ROI和背景区域在每个分解级中的相对重要性,而且在同一幅图像中有多个感兴趣区域时,能够提供多个优先级,可以支持任意形状的ROI编码,同时不需要编码形状信息。这些多区域多质量的压缩编码方法具有很高的应用价值。     

基于扩频与跳频的多带OFDM-UWB多址技术

根据多带OFDM-UWB通信系统的特点,提出一种基于扩频与跳频的多址技术。该多址技术将多载波码分多址和跳频多址相结合,构成一种新颖的多址技术-正交频分多址(OFDMA),实现多载波码分多址技术和跳频多址技术的优势互补,此接收机的复杂性明显小于常规时频码的多用户接收机。仿真结果表明,基于OFDMA多址技术方案的UWB系统在系统误比特率性能上优于常规时频码方案约5dB。     

A tutorial on multiple access technologies for beyond 3G mobile networks

In this article, some fundamental technical concepts of the main multiple access schemes for wireless mobile systems are reviewed, and a path for the development of appropriate multiple access technologies for next-generation mobile networks, or so-called beyond 3G (B3G), is established. We first review the multiple access technologies in second- and third-generation wireless cellular systems from historical and technical points of view. This review is followed by a novel formulization of the multiple access schemes through mathematical expressions that could simplify the process of development of new multiple access schemes for B3G wireless cellular systems. We then list the most important features of multiple access schemes in 3G mobile systems. Finally, we conclude the article by reviewing the most promising multiple access technologies for B3G mobile cellular systems     

基于IEEE 802.16a的OFDM-FDMA与OFDM-TDMA的性能比较

对于使用OFDM传输技术的多载波系统,将OFDM技术与传统的多址接入方案,FDMA和TDMA相结合,可以实现多用户OFDM系统,这样派生出两种多址接入方案:OFDM-FDMA和OFDM-TDMA。研究了这两种多址技术,并基于IEEE 802.16a协议比较了他们的性能,用Matlab语言仿真实现了这两种多址系统。仿真结果表明OFDM-FDMA系统的误比特率性能要优于OFDM-TDMA系统。     

Multiple assignment of component types to feeder slots on automatedprinted circuit card placement machines

This paper investigates the benefits of allowing specific component types to be assigned to more than one feeder location on a printed circuit card automated placement machine. Until this experimental work, no known study has ever reported the relative improvement in cycle time when multiple assignment of component types is allowed. An experiment was designed to find the card specifications and machine operational characteristics under which the benefits of multiple assignment would be most advantageous. An integer programming heuristic was used to solve industry representative data sets for a variety of operational characteristics. For these data, it was found that multiple assignment of component types could reduce cycle time. Over all operational scenarios considered, an approximate 8% reduction in cycle time could be realized by allowing multiple assignment of component types versus not allowing multiple assignment. For those operational scenarios found to be most benefited by multiple assignment, such as card type families with a high coefficient of component variation, allowing multiple assignment across machines showed reduction of the cycle time by approximately 15% versus the alternative where no multiple assignment is allowed     

MIMO-OFDM接力通信系统的最优功率分配

针对两跳多入多出-正交频分复用(MIMO-OFDM)接力通信系统进行研究,每一跳传输采用奇异值分解将多载波上的MIMO信道转化为多个独立子通道,并提出最大化系统容量的最优功率分配问题,其中源节点和中继节点能够在多个子通道上进行联合功率分配;继而采用拉格朗日算法提出最优功率分配算法.由于最优算法涉及一元四次方程组,目前的数学方法不能提供其通解的闭合表达式,因此提出采用迭代过程实现最优功率分配的方法,为MIMO-OFDM接力系统提供了系统容量的上限.数值仿真结果显示,最优功率分配算法能大大提升系统容量,增强系统的传输能力.     

Secrecy Capacity Analysis of MIMO System over Multiple Destinations and Multiple Eavesdroppers

Wireless Personal Communications - In this paper we address physical layer security of multiple input multiple output (MIMO) communication system in presence of multiple destinations and passive...     

Advantages of CDMA and spread spectrum techniques over FDMA andTDMA in cellular mobile radio applications

A unified theoretical method for the calculation of the radio capacity of multiple-access schemes such as FDMA (frequency-division multiple access), TDMA (time-division multiple access), CDMA (code-division multiple access) and SSMA (spread-spectrum multiple access) in noncellular and cellular mobile radio systems is presented for AWGN (additive white Gaussian noise) channels. The theoretical equivalence of all the considered multiple-access schemes is found. In a fading multipath environment, which is typical for mobile radio applications, there are significant differences between these multiple-access schemes. These differences are discussed in an illustrative manner revealing several advantages of CDMA and SSMA over FDMA and TDMA. Novel transmission and reception schemes called coherent multiple transmission and coherent multiple reception are briefly presented     

SDMA系统FD方案阻塞率的仿真

现代无线移动通信系统广泛考虑采用空分多址（SDMA）多址接入技术来提高系统容量。比如在频分复用（FDMA）时分复用（TDMA）,码分复用（CDMA）。分析研究SDMA系统中的FD信道分配机制,给出了理论推导,并在此基础上进行了仿真。仿真结果表明：采用该机制以后,用户可以在同一时间共享同一信道。     

PDH同步数字系列

系统地介绍了数字复接系统中准同步复接方式，并对我国和欧洲采用的基于2．048Mb／s．30／32路的数字系列的高次群复接原理进行了简述。     

Multisource, Multidestination, Multirelay Wireless Networks

Networks with multiple source-destination pairs, involving possibly multicast, and where there are multiple nodes that can serve as potential relay nodes, are considered. A multisource, multirelay coding scheme is developed. In this scheme, each source's information is sent to its destination nodes via a multirelay route, with the multiple multirelay routes operating concurrently even when they intersect with each other, in the same spirit as code-division multiple access (CDMA). It is found that in the generalization to multiple sources, backward decoding achieves higher rates than sliding-window decoding. The routing structure where a joint backward decoding can be performed is characterized. The achievable rate region is found to combine aspects of both multiple relay and multiple access. Potential applications of this coding scheme to sensor networks are discussed. In particular, the exact capacity for the data downloading problem in sensor networks, where there are multiple sensor sources and one sink or collector node, is established for certain geometries when there is phase fading that is unknown to the transmitter.     

基于相关面特征的多子区异谱图像匹配算法

为实现用于异谱图像之间的精确匹配,提出一种基于相关面特征的多子区关系约束匹配算法。首先在实时图上选择出边缘信息丰富的区域作为待匹配子区,然后进行相关匹配,分析相关面特征找到符合形态特征的多个个局部最大值位置,将各子区位置关系作为约束条件对得到的局部最大值位置进行聚类,对匹配结果进行综合和可信度判断。试验表明,该方法可有效提高多子区相关匹配方法的性能,具有更高的匹配概率和更好的图像尺度和旋转适应性。     

GSM多载波技术与设备演进

本文从多载波技术的引入背景出发,对其技术特点和厂家支持情况做了具体介绍,就其应用策略进行了详细分析,并对多载波设备的未来演进进行了初步探讨.     

Wireless digital communication: a view based on three lessonslearned

The implications of Shannon's information theory for personal communication network (PCN) design are outlined. Examples of improvements in satellite communication, magnetic recording, and modem technologies that have increasingly approached information-theoretic limits are given. The emphasis is on the application of Shannon's work to control of four types of interference: multi-user, multiple cell, multipath, and multiple media. Code-division multiple access (CDMA), time-division multiple access (TDMA), and frequency-division multiple access (FDMA) techniques in personal communications are compared     

ISSAMAC: a High Speed MAC Protocol for B3G Systems

1IntroductionWith the development of high-performance devices,the demand for providing high-speed and high-qualityservices over future wireless communication networkshas been rapidlyincreasing.Inthe blue print of BeyondThird Generation Mobile Systems(B3G)…     

FibGeoPresent: A Highly Secured and Geographic Coordinate System Based Authenticated Lightweight Block Cipher for Smart System

Wireless Personal Communications - Multi-user multiple input multiple output (MU-MIMO) serves multiple users simultaneously by sharing the same channel and bandwidth. The performance degrades in...     

On the MAC-BC duality of multiuser non-regenerative MIMO relay systems

Multiple input multiple output(MIMO) relaying techniques can greatly improve the spectral efficiency and extend network coverage for future wireless systems.This article investigates a multiuser MIMO relay channel,where a base station(BS) with multiple antennas communicates with multiple mobile stations(MS) via a relay station(RS) with multiple antennas.The RS applies linear processing to the received signal and then forwards the processed signal.The dual channel conditions between MIMO relay multiple access channel(MAC) and broadcast channel(BC) are first developed for single-relay scenario with white Gaussian noise.Then the MAC-BC duality for MIMO relay systems is established by proving that the capacity region of MIMO relay MAC is equal to that of dual MIMO relay BC under the same total network transmit power constraint.In addition,the duality is also extended to multi-relay scenario with arbitrary noise.Finally,several simple general numerical examples are provided to better illustrate the effectiveness of the MIMO relay MAC-BC duality.