共查询到20条相似文献,搜索用时 15 毫秒
1.
Dirk K. Neumann Michael W. Hoffman Sina Balkır 《Circuits, Systems, and Signal Processing》2008,27(3):381-390
Many ultra-wideband (UWB) systems are challenged by strong jammers and narrowband interferers. Using two antennas, we demonstrate
a robust UWB radio frequency (RF) front-end design in a 0.25 μm mixed-signal complementary metal oxide semiconductor (CMOS)
technology. The proposed realization is capable of adaptively removing a high-power, narrowband interferer early in the receiver
chain avoiding front-end saturation and preserving UWB signal power. The early interferer removal resulting in interferer-free
demodulation is based on the least mean squares (LMS) algorithm and achieved through a novel combiner low-noise amplifier
and noise optimized filtering. Circuit level RF simulations of the proposed circuitry indicate a maximum improvement in signal-to-interference
ratio of 39.6 dB. 相似文献
2.
ZHENG Sheng-hua XU Da-zhuan JIN Xue-ming 《中国电子科技》2007,5(1):33-37
The developments of the high speed analog to digital converters (ADC) and advanced digital signal processors (DSP) make the smart antenna with digital beamforming (DBF) a reality. In conventional M-elements array antenna system, each element has its own receiving channel and ADCs. In this paper, a novel smart antenna receiver with digital beamforming is proposed. The essential idea is to realize the digital beamforming receiver based on bandpass sampling of multiple distinct intermediate frequency (IF) signals. The proposed system reduces receiver hardware from M IF channels and 2M ADCs to one IF channel and one ADC using a heterodyne radio frequency (RF) circuitry and a multiple bandpass sampling digital receiver. In this scheme, the sampling rate of the ADC is much higher than the summation of the M times of the signal bandwidth. The local oscillator produces different local frequency for each RF channel The receiver architecture is presented in detail, and the simulation of bandpass sampling of multiple signals and digital down conversion to baseband is given. The principle analysis and simulation results indicate the effectiveness of the new proposed receiver. 相似文献
3.
A Percival coil connected between the photodetector and amplifier in the receiver of an optical communication system offers the possibility of improved signal-to-noise ratios (SNR's). When the photodetector is an avalanche diode, the modified receiver requires a lower value of avalanche gain for optimum performance. 相似文献
4.
本文提出了一种用于多入多出(MIMO)比特交织编码调制(BICM)系统的低复杂度迭代接收机方案.该方案在第一次迭代中采用线性最小均方误差(MMSE)滤波,而在随后的迭代中采用一种低复杂度MMSE结合软干扰消除(SIC)的算法来抑制残余干扰和噪声.该算法通过将软干扰消除后的残余干扰和噪声的各分量近似为不相关的随机变量,使得在MMSE滤波时不必矩阵求逆,从而大大降低了计算复杂度.仿真证实该方案可以获得和传统的基于MMSE结合SIC的方案几乎相同的性能。 相似文献
5.
Manstretta D. Laurenti N. Castello R. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(4):324-328
This paper presents an analysis on the receiver front-end architectures for multiband orthogonal frequency-division multiplexing ultra-wide-band (UWB) terminals. An interference analysis is carried out in order to derive the main linearity specifications of the receiver front-end. A reconfigurable narrow-band architecture is introduced that can best cope with the main challenges of the UWB receivers: broadband impedance matching and high out-of-band linearity. Simulation results show that linearity requirements can be achieved with sizeable margin. 相似文献
6.
IBM's Systems Network Architecture (SNA) is formally defined by a meta-implementation program written in the Format and Protocol Language (FAPL). This paper describes the structure of the SNA meta-implementation and the development of FAPL. The most interesting aspect of the meta-implementation is that the architecture specification of SNA is itself machine executable. This property leads to a number of applications in software technology, such as automated protocol validation and direct Implementation from the formal specification. 相似文献
7.
针对WCDMAFDD下行链路,提出了一种接收机结构。与传统接收机不同,该结构是根据多径来拉动(延时)输入信号,即根据多径把各径的信号延时对齐,而本地码的相位只需一个,来对多径支路解扩,并直接合并输出。该结构可进一步通过串行方法实现,大大减少硬件资源。由于采用全硬件技术,因此,便于ASIC集成。 相似文献
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A beamspace-time (BT) RAKE receiver is proposed for multiple accessinterference (MAI) suppression and multipath diversity reception insectored wireless CDMA communications. The scheme involves three stages.First, a set of adaptive beamformers encompassing a prescribed angular sectoris constructed on an antenna array, each providing effective suppression ofout-of-sector MAI and reception of in-sector signal. Second, a set of adaptivecorrelators is attached to each beam to combat in-sector MAI. Finally, thebeamspace correlator output data are combined to capture the signal multipathscoherently.The above three-stage operation is performed in a blind mode inthat no training signal is needed. The only information required is the signature,timing and a rough estimate of the angle of arrival (AOA) of the desired signal. 相似文献
10.
A Percival coil connected between the photodetector and amplifier in the receiver of a digital optical communication system offers the possibility of a reduced signal power requirement for a given bit error rate. When the photodetector is an avalanche diode, the modified receiver requires a lower value of avalanche gain for optimum performance. 相似文献
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Rivet F. Deval Y. Begueret J.-B. Dallet D. Cathelin P. Belot D. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(4):344-348
The next generation of mobile terminals is faced with the emergence of the software-defined radio (SDR) concept. The communication devices tend to provide various wireless services through a multi-functional, multi-mode and multi-standard terminal. The SDR concept aims at designing a re-configurable radio architecture accepting all cellular or noncellular standards working in the 0-5-GHz frequency range. Some technical challenges have to be solved in order to address this concept. Working in the digital domain may be a solution but the analog-to-digital conversion cannot be done at Radio Frequencies, at an acceptable resolution and at an acceptable level of power consumption. The idea proposed here was to interface an analog pre-processing circuit between the antenna and a digital signal processor to pre-condition the RF signal. It uses the principle of a fast Fourier transform to carry out basic functions with high accuracy in a low-cost technology like CMOS. This paper presents the design and the behavioral simulations of this analog discrete-time device which gives the hardware flexibility required for a cognitive radio component. 相似文献
13.
Electronic switching systems were introduced in the mid1960's, and have since undergone constant modifications to provide new features, expand into new applications, and adapt to new hardware technologies. The increasing costs of software development have led to the need to reexamine the design concepts of present systems and define more cost-effective architectures. The specifications and derivation of a new modular switching system architecture which addresses the problems of constant change are discussed. 相似文献
14.
Madde R. Morley T. Lanucara M. Abello R. Mercolino M. De Vicente J. Sessler G.M.A. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2007,95(11):2215-2223
The need to support radio science experiments and enhance navigation accuracy for the currently flying deep-space missions of the European Space Agency (ESA) has triggered the development of suitable tools in the agency's deep-space stations. This paper describes the modifications implemented in the ESA standard receiver, the Intermediate Frequency and Modem System (IFMS), for the above goals. These modifications were possible due to the highly flexible architecture of the IFMS. Results obtained in the area of radio science research and delta differential one-way ranging tracking are also presented. 相似文献
15.
An optimum receiver structure for optical PPM systemics is considered and from this a simple sub-optimum receiver is proposed which offers significant SNR improvement relative to existing design approaches and yet requires few circuit changes. Receivers incorporating either p-i-n or avalanche photodiodes and FET or BJT preamplifiers are analyzed. The optimization technique relies on matching the frequency response of the receiver to that of the incident optical pulse and setting the avalanche gain and threshold detector at optimum levels. For a FET preamplifier the SNR improvement is 10.8 dB with a p-i-n photodiode and 4.7 dB with an avalanche photodiode. For a BJT preamplifier the SNR improvement is 3.1 dB and 2.3 dB with the p-i-n and avalanche diodes, respectively. 相似文献
16.
该文针对在密集多径室内环境中超宽带(UWB)信道的延迟扩展时间长,脉冲超宽带(IR-UWB)系统在高速数据传输时码间干扰(ISI)严重致使误码率(BER)增加以至于系统无法工作的问题,基于ISI的成因,提出了一种分数间隔判决反馈居中均衡(FS-DFME)均衡接收机,该均衡接收机能够联合实现匹配滤波和信道均衡,从而能够有效地收集多径信号能量和抑制ISI影响。研究结果表明均衡接收机的观察窗口长度是影响ISI消除效果的重要参数;与线性均衡(LE)和分数间隔判决反馈非居中均衡(FS-DFNME)均衡接收机相比,FS-DFME均衡接收机能够更加有效地消除ISI,提高系统的BER性能。 相似文献
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本文提出了一种应用于MIMO系统的新型低复杂度迭代接收机.接收端采用基于QR分解的干扰抵消,对不同层分组并进行部分并行干扰抵消,组内采用MAP联合检测输出软信息.通过交织解交织器将软入软出检测器与turbo迭代译码器级联起来,经过迭代有效的消除了多天线问的干扰.文中采用三维外信息转移图分析了接收机迭代过程.与传统基于QR分解的串行干扰抵消迭代接收机相比性能有了极大提高,并且受信噪比估计误差的影响较小。 相似文献
19.
Fantacci Romano Mancini Leonardo Marini Mauro Tarchi Daniele 《Wireless Personal Communications》2003,27(3):195-213
The Universal Mobile Telecommunications System (UMTS) which is based on Wideband-Code Division Multiple Access (W-CDMA) techniques
is one of the most important broadband wireless communication systems. Adaptive Blind Multiuser Detection was widely considered
for mobile receivers. The main drawback of this approach is that it achieves the optimum solution after a certain number of
bit times. This paper deals with a new neural network approach in order to reduce the convergence time in different application
environments. In particular, a modified Kennedy-Chua neural network, based on the Hopfield model is proposed. The neural network
stability was investigated by means of a suitable analytical approach, while the performance of the proposed receiver scheme
was derived by means of computer simulations. The numerical results shown in this paper highlight a fast convergence behavior
of the proposed scheme, in particular under multipath-fading conditions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献