An Optimized IR-UWB Communication System with Interference Reduction on a Narrowband System Using Genetic Algorithm

This paper proposed a new impulse radio ultra wideband (IR-UWB) signal to reduce interference on narrowband systems at high usage 5.2 GHz frequency. The combination of 4th and 5th order derivatives of Gaussian pulses were employed to generate the signal so that satisfy the US Federal Communications Commission (FCC) mask. The genetic algorithm technique was used to find the pulse optimized parameters. In this paper, spectrum was optimized by changing the shape factor (sigma) and amplitude of Gaussian pulses so that the transmitted power spectrum density was minimized at a frequency of 5.2 GHz and maximized at the other frequencies from 3.1 to 10.6 GHz according to the FCC mask. The signal was applied in an IR-UWB transceiver system with binary-phase shift keying modulation. The IR-UWB waveform is generated by a programmable digital to analog based circuit. The proposed system was compared with conventional IR-UWB systems at the same condition. The simulation results in multipath channel showed that the proposed system not only reduced interference with the narrowband system, but also this was robust against narrowband interference at 5.2 GHz frequency.

     

基于压缩感知的脉冲超宽带信号检测

传统的信号检测算法基于奈奎斯特采样定理来实现,这对于带宽极宽的超宽带(ultra-wideband,UWB)信号而言由于要求采样速率过高而很难用硬件去实现。为此,本文研究了基于压缩感知(compressive sensing,CS)的脉冲超宽带(impulse radio UWB, IR-UWB)信号检测问题,利用IR鄄UWB 信号在时域上的稀疏特性,设计了一种基于压缩感知的IR鄄UWB 信号检测框架,在此基础上提出了一种自适应加权正交匹配追踪检测算法。仿真结果表明,新算法不仅能够通过远少于奈奎斯特定理所要求的采样速率检测出IR-UWB 信号,而且与基于匹配追踪的压缩感知检测算法相比,新算法在低信噪比的情况下对IR-UWB 信号的检测效果更佳。     

Joint estimation of TOA and DOA in IR-UWB system using a successive propagator method

Impulse radio ultra-wideband (IR-UWB) ranging and positioning require accurate estimation of time-of-arrival (TOA) and direction-of-arrival (DOA). With receiver of two antennas, both of the TOA and DOA parameters can be estimated via two-dimensional (2D) propagator method (PM), in which the 2D spectral peak searching, however, renders much higher computational complexity. This paper proposes a successive PM algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak searching. The proposed algorithm firstly gets the initial TOA estimates in the two antennas from the propagation matrix, then utilises successively one-dimensional (1D) local searches to achieve the estimation of TOAs in the two antennas, and finally obtains the DOA estimates via the difference in the TOAs between the two antennas. The proposed algorithm, which only requires 1D local searches, can avoid the high computational cost in 2D-PM algorithm. Furthermore, the proposed algorithm can obtain automatically paired parameters and has better joint TOA and DOA estimation performance than conventional PM algorithm, estimation of signal parameters via rotational invariance techniques algorithm and matrix pencil algorithm. Meanwhile, it has very close parameter estimation to that of 2D-PM algorithm. We have also derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer-Rao bound of TOA and DOA estimation in this paper. The simulation results verify the usefulness of the proposed algorithm.     

An efficient method for nonlinear distortion calculation of the AM and PM noise spectra of FMCW radar transmitters

The demand for autonomous cruise control and collision warning/avoidance systems has increased in recent years. Many systems based on frequency-modulated continuous-wave (FMCW) radar have emerged and are still in development. Due to the high complexity of such systems, the accurate evaluation of the noise spectra in the transmitter chain driven by complex modulated signals is today a severe drawback due to the limitation of simulation tools. In this paper, a method is proposed to compute easily with any commercially available nonlinear simulator, the amplitude and phase modulated signal distortion introduced by the nonlinearities of the transmitter on an FMCW signal. First, the amplitude modulation (AM) and phase modulation (PM) noise spectra of the driving FMCW signal is derived from the knowledge of the continuous wave (CW) AM and PM noise spectra of the voltage-controlled oscillator (VCO), and the modulating saw-tooth signal applied. Using the narrow band envelope concept and a first-order expansion of the nonlinear transfer function of the transmitter, the transfer of the AM and PM noise spectra of the driving FMCW signal through the nonlinear transmitter chain and the resulting output distortion are then computed. This novel approach allows to compute with reduced computation time and very good accuracy the AM/AM, AM/PM, PM/PM, and PM/AM conversion terms in any nonlinear system driven by CW or FMCW signals. This new method has been applied to the characterization of a whole car radar transmitter operating at 77 GHz driven by an FMCW signal issuing from a VCO. A successful comparison between measured and simulated PM-to-AM conversion coefficients of this transmitter is shown, validating the proposed method.     

基于FP-LD实现副载波信号产生

采用一种基于法布里-珀罗腔激光二极管(FP-LD)的副载波信号的产生方案,此方案主要包括一个FP-LD和一个电光相位调制器(PM)。首先利用可调谐激光器、电光PM及微波源产生光正弦相位调制信号,将该信号注入到FP-LD中,通过FP-LD的注入锁定将该信号转换为副载波信号。在实验中,分别以2、3、4和5 GHz的调制频率注入到FP-LD中,相应得到22、21、24和25 GHz的副载波信号。     

脉冲超宽带技术在航天测控系统中的应用

针对当前航天测控系统安全性不足的问题,将脉冲超宽带技术应用于航天测控系统中,构建了一种新的脉冲超宽带测控体制。建立了基本的脉冲超宽带测控信号模型,对脉冲超宽带测控系统的性能和传输链路进行了分析。给出了脉冲超宽带测控系统结构框图,介绍了系统工作过程。针对并行信号捕获方法资源消耗大的不足,提出了两步并行捕获方法。分析表明,脉冲超宽带技术可用于航天测控系统中,完成测距测速和数据传输任务。脉冲超宽带测控系统可有效提高测控系统的隐蔽性和抗干扰能力,同时提高测距精度。在信号捕获方面,与并行捕获方法相比,两步并行捕获方法的硬件资源消耗得到大大降低,同时还可保证较快的捕获速度,但会产生一定的信噪比损失。     

Multisideband Detection Radio-Over-Fiber Link With Phase Modulation and Fiber Demodulation for Vector Signal Transmission

We propose and demonstrate a multisideband detection (MSD) radio-over-fiber (RoF) link with optical phase modulation (PM) and fiber demodulation to transmit vector signals. In the scheme, the optical PM signal is demodulated by the fiber dispersion. The fading effect can be almost entirely overcome thanks to the MSD. In case of 50-Msymbols/s vector signal with frequencies of subcarrier ranging from 2 to 12 GHz over 25-, 50-, and 100-km single-mode fibers, respectively, the RoF-link's error vector magnitude of better than 4.5% and spurious-free dynamic range of more than 97 ${hbox {dB}}cdot hbox{Hz}^{2/3}$ are obtained experimentally.      

脉冲超宽带测控信号时延精密跟踪方法

脉冲超宽带测控新体制可有效提高测控系统的安全性能,且具有潜在的高精度测距能力.为了实现其高精度测距功能,提出了一种基于延迟锁定环路的脉冲超宽带测控信号时延精密跟踪方法.该方法在传统伪码跟踪环的基础上进行改进,利用基于非相干积分的非线性反馈环路对接收信号的脉冲相位进行精密跟踪.理论分析和仿真结果表明,该延迟锁定环路可以完成对脉冲超宽带测控信号的时延精密跟踪.与直扩测控信号相比,在相同条件下,脉冲超宽带测控信号的时延跟踪相对误差更大,但由于脉冲宽度很窄,在一定载噪比条件下,其测量精度仍可达厘米量级甚至更高.     

采用单个相位调制器产生毫米波

实验研究了采用单个相位调制器(PM)产生毫米波的方案。该方案采用电混频器将射频(RF)信号与基带信号混频后再利用相位调制器产生双边带调制(DSB)信号,经光纤传输到基站后用一个光交叉复用器(IL)分离一阶边带和中心载波,一阶边带经过光电(O/E)检测器拍频产生两倍频于射频频率的毫米波,而中心载波可以作为上行链路载波重新利用。理论分析了该毫米波的传输性能,研究发现由于色散导致两个一阶边带时延不同,码元的占空比会随着传输距离的增加而减小,将限制毫米波的最大传输距离;实验中采用频率为20 GHz射频信号产生频率为40 GHz的毫米波,速率为2.5 Gbit/s的非归零(NRZ)码作为下行链路数据,经过20 km色散光纤传输后下行链路的功率代价为0.2 dBm。     

Alternate Test of LNAs Through Ensemble Learning of On-Chip Digital Envelope Signatures

This paper presents a novel and low-cost methodology for testing embedded Low Noise Amplifiers (LNAs). It is based on the detection and analysis of the response envelope of the Device Under Test (DUT) to a two-tone input signal. The envelope signal is processed to obtain a digital signature sensitive to key specifications of the DUT. An optimized regression model based on ensemble learning is used to relate the digital signatures to the target specifications. A new Figure of Merit (FOM) is proposed to evaluate the prediction accuracy of the statistical model, and a demonstrator has been developed to prove the feasibility of the approach. This demonstrator features a 2.445 GHz low-power LNA and a simple envelope detector, and has been developed in a 90 nm CMOS technology. Post-layout simulations are provided to verify the functionality of the proposed test technique.     

Chirp Pulse Compression in Non-Coherent Impulse-Radio Ultra-Wideband Communications

The paper investigates chirp pulse compression as a signal dimension reduction technique in non-coherent impulse-radio ultra-wideband (IR-UWB) communications. Two common types of non-coherent IR-UWB detection are considered, energy detection of IR-UWB pulse position modulated (PPM) symbols and sample-wise differential detection of differential phase shift keying (DPSK) IR-UWB symbols, as well as a newly introduced sample-wise differential detection of IR-UWB PPM symbols. A common problem with these low-complexity IR-UWB detection schemes is poor performance when the dimension of the symbol in detection is high, which is usually the case at low data rates and is especially pronounced in interference environments. Chirp pulse compression mitigates this problem by reducing the dimension of the symbol in detection along with very small fading factor, which also lowers the computational complexity in the case of digital implementation. In the analytic part of the paper, we develop a closed-form expression for the bandwidth and dimension of the signal after the chirp pulse compression, which was lacking before. Furthermore, a closed-form expression of the bit error probability in white noise with the above detection schemes is also given. In the numerical part of the paper, we compare the performance with and without chirp pulse compression of the above modulation/detection pairs in noise and interference environments.     

基于训练序列进行系统优化的60GHz正交频分复用-光载无线通信系统

分析了60 GHz正交频分复用-光载无线通信(OFDM-RoF)系统中OFDM信号经光纤传输后在光电检测时存在的子载波间互拍干扰(SSBI)现象。提出使用交叉型训练序列结构的OFDM信号来降低SSBI的影响。实验证明,在无色散补偿的情况下,2.5 Gb/s交叉型训练序列结构的基带OFDM信号在58 GHz毫米波系统中经光纤传输20 km后,在误码率为10-3时,其功率代价仅为0.5 dB,而连续型训练序列结构OFDM的功率代价为2 dB。说明基于交叉型训练序列结构的OFDM信号的传输性能在抵抗SSBI方面要明显优于连续型训练序列结构OFDM信号。     

基于相位调制器倍频技术产生56GHz毫米波的光载无线通信系统

提出并实验研究了一种基于光相位调制器(PM)倍频技术产生56GHz毫米波的光载无线通信(RoF)系统。在中心站,通过28GHz射频(RF)信号驱动PM产生了56GHz光毫米波,并将下行的2.8Gb/s开关键控(OOK)信号调制到该光载波上,然后经过20km标准单模光纤(SSMF)传输至基站,最后由天线进行发射。用户终端接收后,采用相干解调恢复出基带信号。实验结果表明,56GHz光载毫米波信号经SSMF传输20km后其功率代价小于1dB,通过无线方式传输1.1m后其功率代价小于2.5dB。     

基于高频微波技术的分布式光纤传感器布里渊散射信号检测

分析了布里渊分布式光纤传感技术原理,采用自行研制的光纤单纵模分布反馈(DFB)激光器结合电光调制技术,利用相干检测技术,对布里渊微弱后向散射信号进行检测。通过改进滤波放大技术,对微弱后向散射光信号进行有效放大,再用扰偏技术及信号采样平均处理,实现对光纤传感器后向布里渊散射信号在11 GHz高频段直接采集显示。结果表明,探测所得布里渊散射信号峰值功率可达50 mV,能有效降低解调系统信号检测难度,改善了系统信噪比(SNR)。初步实验结果证明了该方案的可行性。     

60 GHz OCS mm-wave generation for ROF system based on saturated parametric amplification effect in HNLF

A novel approach to generate 60 GHz optical carrier suppression (OCS) millimeter-wave (mm-wave) signal based on the saturated optical parametric amplification (OPA) effect in high non-linear fiber (HNLF) is investigated. In the proposed system, the OPA effect occurs when the signal and pump with 30 GHz frequency interval are set into the high non-linear fiber. By controlling the length of HNLF, OPA effect saturates, and the pump power is delivered in a large extent to the signal and idler light, so a 60 GHz OCS mm-wave is generated. The system does not need high-speed external modulator, high-frequency vibration source or narrow-band filter, which greatly reduces the cost and improves the stability of the radio over fiber (ROF) system. Results show that the 10 Gb/s downstream signal can be transmitted with negligible power penalty.     

128 Gbit/s high speed optical interconnection networks in data centers by a 30 GHz Mach-Zehnder modulator

A decision feedback equalization (DFE) algorithm is proposed by simplifying Volterra structure. The simplification principle and process of the proposed Volterra-based equalization algorithm are presented. With the support of this algorithm, the signal damage for four-level pulse amplitude modulation signal (PAM-4) is compensated, which is caused by device bandwidth limitation and dispersion during transmission in C-band intensity modulation direct detection (IM-DD) fiber system. Experiments have been carried out to demonstrate that PAM-4 signals can transmit over 2 km in standard single-mode fiber (SSMF) based on a 30 GHz Mach-Zehnder modulator (MZM). The bit error rate (BER) can reach the threshold of hard decision-forward error correction (HD-FEC) (BER=3.8×10-3) and its sensitivity is reduced by 2 dBm compared with traditional feedforward equalization (FFE). Meanwhile, the algorithm complexity is greatly reduced by 55%, which provides an effective theoretical support for the commercial application of the algorithm.     

低功耗IR-UWB接收机和LNA设计研究

在分析各种超宽带(UWB)接收机系统结构的基础上,提出了一种低功耗IR-UWB接收机结构.该结构基于非相干通信机制,使用自混频技术和脉冲宽度调制方式(PPM).在该结构中,低噪声放大器(LNA)的低功耗优化是系统低功耗实现的关键.综合分析各种宽带LNA结构,提出了一种低功耗LNA设计.该LNA采用65 nmCMOS标准...     

A New Transceiver Scheme for OFDMA System Based on Discrete Cosine Transform and Phase Modulation

A high peak-to-average power ratio of the transmit signal is a major drawback of multicarrier transmissions, such as orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA). An alternative approach to mitigate the peak-to-average power ratio (PAPR) problem is based on signal transformation using phase modulation (PM). A phase modulation based systems have the advantage of constant envelope (CE) signals and the ability to improve the diversity of multipath channels. In this paper, a different implementation of discrete Fourier transform DFT-OFDMA system which is based on discrete cosine transform (DCT) is proposed. The DCT-OFDMA system is then used to develop a new transceiver system called DCT-OFDMA-PM which refers to discrete cosine OFDMA with phase modulation. The PM input signal to be modulated must be real which can be produced using DCT-OFDMA with pulse amplitude modulation (M-PAM). The new system involves a signal transformation prior to amplification. This gives the advantage of CE (i.e. 0 dB PAPR). The proposed system is implemented with frequency domain equalization (FDE) to obtain high diversity gains over the frequency multipath channel. Simulation the PM-based systems with multipath fading can outperform that with single path fading.     

UWB for multi-gigabit/s communications beyond 60 GHz

The recently allocated 71–76 GHz and 81–86 GHz bands provide an opportunity for realizing Line Of Sight (LOS) links for directional point-to-point “last mile” applications. An efficient use of this spectrum may allow wireless to finally “catch up” with wires, leading to systems such as “multi-Gigabit wireless Ethernet,” and “wireless fiber.” However, the transmission at such a frequency range is characterized by several additional challenges compared to lower frequency bands, from both technological and propagation point of view, which makes difficult to use them efficiently. In this scenario, IR (Impulse Radio) UWB (Ultra Wide Band) technology might offer some more degrees of freedom for the design of a highly integrated and low cost transceiver. This work has at its core the design and BER (Bit Error Rate) performance evaluation of an IR-UWB architecture based on an 85 GHz up-conversion stage of train of Gaussian pulses having duration lower than 1 ns. Finally, we compare performance of this architecture with the ones of a more traditional continuous wave communications system with FSK (Frequency Shift Keying) modulation. Simulation results show that BER performance, in presence of RF non-linearities, for an IR-UWB transceiver architecture operating at 85 GHz (with same data rate and bandwidth) are better than a coherent BFSK scheme working in a similar scenario. Finally, some conclusions are reported, pointing out the UWB antenna design and the future works related to the modeling of the channel at frequencies beyond 60 GHz and the implementation of the test bed.     

基于光纤XPM光学生成UWB信号的方法

提出了一种基于色散位移光纤(DSF)的交叉相位调制(XPM)效应的超宽带(UWB)光学生成方法。该方法首先利用DSF的XPM效应实现高功率的高斯泵浦光对低功率的直流探测光的交叉相位调制,然后利用光纤布拉格光栅(FBG)对探测光进行鉴频,实现相位调制到强度调制的转换,从而获得单周期UWB信号。利用光子仿真软件对方案进行了仿真实验,得到了中心频率分别为7GHz和6.95GHz、相对带宽分别为143%和145%的UWB信号,验证了所提方法的可行性。同时,研究了输入信号脉冲宽度、FBG的反射率、鉴频器的类型对产生的单周期UWB脉冲信号波形和频谱的影响。仿真实验的结果表明,该方案对输入信号脉冲宽度不是过宽的情况下具有良好的容忍度,光学高斯带通滤波器、波分复用器和FBG等光滤波器均可作为鉴频器,采用FBG优点是可通过改变反射率灵活地调整产生的UWB脉冲信号的波形。