Design and simulation of digital channelized receivers in fractional Fourier domain

An approach is proposed to realize a digital channelized receiver in the fractional Fourier domain （FRFD） for signal intercept applications. The presented architecture can be considered as a generalization of that in the traditional Fourier domain. Since the linear frequency modulation （LFM） signal has a good energy concentration in the FRFD, by choosing an appropriate fractional Fourier transform （FRFT） order, the presented architecture can concentrate the broadband LFM signal into only one sub-channel and that will prevent it from crossing several sub-channels. Thus the performance of the signal detection and parameter estimation after the sub-channel output will be improved significantly. The computational complexity is reduced enormously due to the implementation of the polyphase filter bank decomposition, thus the proposed architecture can be realized as efficiently as in the Fourier domain. The related simulation results are presented to verify the validity of the theories and methods involved in this paper.

Design and Implementation of Partial Shared Digital Channelized Receiver

A novel efficient partial sharing channelization structure with odd and even stacking is designed and implemented. There are two special designs in the proposed structure. Firstly, by the intensive channel overlap design, for non-cooperative wideband signals, the proposed structure can achieve good parameter estimation accuracy and high probability of complete interception.Secondly, based on the partial sharing design developed in this paper, the computation burden of the proposed structure can be greatly reduced compared with the traditional directly implemented structures. Experiments and numerical simulations are conducted to evaluate the proposed structure, which shows its improvements over traditional methods in terms of field programmable gate arrays(FPGA) resource consumption and parameter estimation accuracy.

A Fully Integrated 60GHz Four Channel CMOS Receiver with 7GHz Ultra-Wide Bandwidth for IEEE 802.11ad Standard

In this paper, a fully integrated CMOS receiver frontend for high-speed short range wireless applications centering at 60 GHz millimeter wave(mmW) band is designed and implemented in 90 nm CMOS technology. The 60 GHz receiver is designed based on the super-heterodyne architecture consisting of a low noise amplifier(LNA) with inter-stage peaking technique, a singlebalanced RF mixer, an IF amplifier, and a double-balanced I/Q down-conversion IF mixer. The proposed 60 GHz receiver frontend derives from the sliding-IF structure and is designed with 7GHz ultra-wide bandwidth around 60 GHz, supporting four 2.16 GHz receiving channels from IEEE 802.11 ad standard for next generation high speed WiFi applications. Measured results show that the entire receiver achieves a peak gain of 12 dB and an input 1-dB compression point of-14.5dBm, with a noise figure of lower than 7dB, while consumes a total DC current of only 60 mA from a 1.2V voltage supply.

Dual Channel SIS Receiver of Trao Telescope

We have developed the dual channel receiver with 100GHz and 150GHz band, which is used to make the simultaneous observation with two bands. The SIS mixers are used in both bands. The constructed dewar for receiver has the performance with the vacuum of 10 -8 Torr and the temperature of 4 2K. The receiver noise temperature is 50K (DSB) for 100GHz band and 80K (DSB) for 150GHz band ,respectively. In order to achieve the simultaneous observations, the quasioptical system is precisely designed, and also evaluated by the measurement in the laboratory. We have observed the various sources using this receiver since October 1998. The relative pointing offset between two bands is 3″.

A Receiver Structure for Frequency-Flat Time-Varying Rayleigh Channels and Performance Analysis

This paper proposes a wavelet based receiver structure for frequency-flat time-varying Rayleigh channels, consisting of a receiver front-end followed by a Maximum A-Posteriori (MAP) detector. Discretization of the received continuous time signal using filter banks is an essential stage in the front-end part, where the Fast Haar Transform (FHT) is used to reduce complexity. Analysis of our receiver over slow-fading channels shows that it is optimal for certain modulation schemes. By comparison with literature, it is shown that over such channels our receiver can achieve optimal performance for Time-Orthogonal modulation. Computed and Monte-Carlo simulated performance results over fast time-varying Rayleigh fading channels show that with Minimum Shift Keying (MSK), our receiver using four basis functions (filters) lowers the error floor by more than one order of magnitude with respect to other techniques of comparable complexity. Orthogonal Frequency Shift Keying (FSK) can achieve the same performance as Time-Orthogonal modulation for the slow-fading case, but suffers some degradation over fast-fading channels where it exhibits an error floor. Compared to MSK, however, Orthogonal FSK provides better performance.

ITERATIVE RECEIVER FOR OFDM SYSTEMS BASED ON SEMI-BLIND CHANNEL ESTIMATION

In this paper we propose two iterative algorithms of joint channel estimation and symbol detection for Orthogonal Frequency Division Multiplexing (OFDM) systems. In which, superimposed pilot scheme is adopted and an initial Channel State Information (CSI) is obtained by employing a first-order statistic. In each subsequent iteration, we propose two algorithms to update the CSI. The Mean Square Error (MSE) of channel estimation and Bit Error Rate (BER) performance are given and simulation results demonstrate that the iterative algorithm using method B has good perform-ance approaching the ideal condition.

A HIGH SENSITIVITY AND WIDE DYNAMIC RANGE ZERO-IF RF RECEIVER FOR COGNITIVE RADIO APPLICATION

This paper presents an RF receiver of zero-Intermediate Frequency(IF) architecture for Cognitive Radio(CR) communication systems.Zero-IF architecture reduce the image reject filter and IF filter,so it is excellent in low cost,compact volume,and low power dissipation.The receiver employs three digital attenuator and a high gain,high linearity low noise amplifier to achieve wide dynamic range of 70 dB and high receiving sensitivity of-81 dBm.A fully balanced I/Q demodulator and a differential Local Oscillator(LO) chips are used to minimize the negative effects caused by second-order distortion and LO leakage.In order to select an 8 MHz-channel from 14 continuous ones located in UHF band(694-806 MHz) accurately,approach of channel selectivity circuits is proposed.The RF receiver has been designed,fabricated,and test.The measured result shows that the noise figure is 3.4 dB,and the error vector magnitude is 7.5% when the input power is-81 dBm.

基于特征值的动态数字信道化子带检测算法

动态数字信道化接收结构通过检测所有子带,判断信号是否存在,为综合滤波器组处理提供依据,因此子带检测在接收结构中起着关键作用。针对传统检测算法存在低信噪比(signal-to-noise ratio,SNR)下检测性能不高的问题,依据随机矩阵理论,提出了基于最大最小特征值之差与平均特征值之比的检测算法,利用平均特征值和最小特征值的极限分布规律来推导算法的检测门限。其次,根据所有子带数据获取的特征值信息对所提算法进行了优化。最后,在动态数字信道化接收结构中,分析不同因素下算法的性能,表明了所提算法能够克服低SNR的影响,子带检测的性能更好。

一种面向112 Gb/s PAM4接收机的自适应均衡设计方案

提出了一种适用于超短距离(Very Short Reach,VSR)信道、面向112 Gb/s PAM4(Pulse Amplitude Modulation 4)接收机的自适应均衡设计方案。在该方案中,接收机前端利用3个连续时间线性均衡器(Continuous Time Linear Equalizer,CTLE)对信号分别在高频、中频和低频进行补偿,可变增益放大器(Variable Gain Amplifier,VGA)和饱和放大器(Saturation Amplifier,SatAmp)则用于对信号幅值的缩放。除了3个数据采样器外,引入4个辅助采样器用于进一步改善阈值自适应算法性能。同时,采用符号最小均方算法,利用接收端数据采样器和辅助采样器之间的偏移推动辅助参考电压收敛到信号星座电平,从而确保PAM4接收信号的眼图在垂直方向上3个眼睛具有相等的间隔和恒定的信噪比(Signal-to-Noise Ratio,SNR)。仿真结果表明,所提出的112 Gb/s PAM4接收机能够在损耗为15 dB的信道上实现小于10~(-12)的误码率,并且具有良好的眼图性能,其最差眼高为75 mV,眼宽为0.34 UI(Unit Interval),与传统方案相比具有显著的性能提升。

基于深度学习的高效矿井MIMO信号检测研究

针对智能接收机检测效率低的问题,提出了一种基于深度学习的高效矿井MIMO信号检测模型,该模型由非线性映射网络以及纠错网络共同组成。非线性映射网络实现接收信号到二进制比特信号的初步恢复,纠错网络用于纠正非线性映射网络恢复的错误信号,提升信号检测精度。通过搭建矿井MIMO通信系统对该模型的性能进行了验证,仿真结果表明,在模拟矿井MIMO通信环境中,在发射端调制方式,信道编码方式改变以及信道环境变化时其性能优于传统接收机。同时,相对于深度接收机模型,该模型具有更高的检测效率。这项研究为解决智能接收机译码效率低的问题提出了一个新的解决方案,并在复杂的矿井场景中证明了该模型的性能优势。

鬼波的受控因素及其对单道地震勘探的影响

鬼波影响地震勘探效果,其中较为典型的是震源鬼波。震源鬼波的变化主要由其相对一次有效反射地震波的延时决定。从鬼波的形成机理出发,借助二维海平面及水平海底模型建立海底反射震源鬼波延时、震源沉放深度、作业水深与炮检距间的数学公式,将确定的震源沉放深度和作业水深带入公式并实现可视化,分析炮检距及震源沉放深度对震源鬼波的影响。结合作业中震源沉放深度的变化状态,分析震源鬼波的间接控制因素的影响,并通过实测数据进行验证。研究表明:小炮检距作业有利于降低鬼波对地震勘探效果的破坏作用,但是炮检距对深部数据影响较小,在平面上大致限于作业水深小于炮检距的海域,在纵向上的影响深度约为炮检距与作业水深的差值;震源鬼波受震源沉放深度的影响要大大超过炮检距的影响,当作业水深<15 m时,震源鬼波延时变动范围对震源沉放深度变化响应约为对同尺度炮检距变化响应的5倍;海水面的起伏是导致震源鬼波变化的重要因素,选择较好的海况条件作业有利于提高海底及地层反射同相轴波形的一致性及地震波能量的均衡性。

一款0.16 mm^(2)基于180 nm CMOS采用全局去偏斜的半速率8×2.5 Gb/s时钟转发架构接收机

在时钟转发架构的高速有线通信接收机中,需要去偏斜电路实现时钟与数据之间的最佳采样关系,并保证多路数据的同步。本文提出了一种全局去偏斜方案,仅采用一路数据与时钟进行对齐,并通过时钟延时匹配与分布技术实现多路数据同步,减小了各通道独立去偏斜方案带来的功耗与面积开销。所提出的接收机由8路数据通道、1路半速率转发时钟通道与基于延迟锁定环路的全局去偏斜电路构成。基于180 nm CMOS工艺,在2.5 Gb/s数据率下,可去除输入时钟与数据任意偏斜,得到位于数据中心的采样相位,同时具有时钟占空比校准能力。在1.8 V电源电压下,所提出的接收机总功耗为187 mW,总面积为0.16 mm^(2),对比各通道独立去偏斜方案,功耗和面积开销分别节约了45.2%与62.8%。

多通道全频点并行接收技术研究

多通道并行接收适用于对大带宽信号的采集处理,针对大带宽高速跳频通信系统射频频率切换时间短、大射频带宽采集成本高等问题,提出了一种多通道全频点并行接收系统设计思路,提出了一种基于两级变频的多通道信号下变频处理方案。所提系统对频率切换响应时间要求小,工程实现难度低。

RSSI和PC-CSI加权融合的指纹定位方法

针对基于RSSI和CSI的指纹定位技术易受环境干扰、定位精度较低的问题,提出了一种基于RSSI指纹和相位修正信道状态信息(phase correct based channel state information,PC-CSI)指纹的加权融合指纹定位技术。基于PC-CSI的指纹定位在传统基于CSI幅值的指纹定位基础上增加相位信息对定位结果进行修正,之后对RSSI指纹和PC-CSI指纹的定位结果加权重定位。实验结果表明,提出的加权融合指纹定位算法与基于CSI的主动定位算法相比,平均定位误差(mean position error,MPE)降低了36.2%,能满足室内定位需求。

中国澳门轻轨延伸线横琴线隧道盾构区间施工关键技术研究

以中国澳门轻轨延伸线隧道盾构区间施工为研究背景,针对盾构隧道穿越建(构)筑物、盾构接收以及联络通道冷冻法施工3个方面的施工关键技术展开研究,盾构穿越建(构)筑物段,采用MJS工法桩加固隔离,并控制土压力、盾构推力等掘进参数,运用二次注浆控制地表变形;盾构接收段分5个阶段控制盾构推力、推进速度和刀盘转速等掘进参数;联络通道冷冻法施工段则从冻结范围、冻结孔布置、泄压孔布置以及制冷参数方面提出了相应的施工技术。结果表明:所提出的施工关键技术保证了隧道盾构区间的顺利贯通,该成果可为类似条件地铁盾构隧道提供参考。

UWB System Based on the Modified Gegenbauer Function in MISO Channel

In this paper, we propose a new multi-user Rake receiver, based on the interference mutualization with a matrix representation for Multiple Input Single Output MISO channel. The proposed system used the Modified Gegenbauer functions in order to generate the signal and to ensure the multi users transmission system. The new proposed receiver allows, using the temporal and special diversity, to avoid the interferences between symbols and to improve the system performances in terms of Bit Error Rate BER and interferences between users with a low algorithm complexity. The proposed solution is based on the classical Rake receiver associated with the equalizer receiver. In order to adapt the Rake approach, in single detection case and in multi users Ultra Wide Band environment, we propose a multi-user Rake receiver using the matrix form. Our proposed system is evaluated in terms of channel effects and multi users’ interferences.

Performance of terahertz channel with multiple input multiple output techniques

Terahertz(THz) communication is being considered as a potential solution to mitigate the demand for high bandwidth. The characteristic of THz band is relatively different from present wireless channel and imposes technical challenges in the design and development of communication systems. Due to the high path loss in THz band,wireless THz communication can be used for relatively short distances. Even,for a distance of few meters( > 5 m),the absorption coefficient is very high and hence the performance of the system is poor. The use of multiple antennas for wireless communication systems has gained overwhelming interest during the last two decades.Multiple Input Multiple Output( MIMO) Spatial diversity technique has been exploited in this paper to improve the performance in terahertz band. The results show that the Bit Error Rate( BER) is considerably improved for short distance( < 5 m) with MIMO. However,as the distance increases,the improvement in the error performance is not significant even with increase in the order of diversity. This is because,as distance increases,in some frequency bands the signal gets absorbed by water vapor and results in poor transmission. Adaptive modulation scheme is implemented to avoid these error prone frequencies. Adaptive modulation with receiver diversity is proposed in this work and has improved the BER performance of the channel for distance greater than 5 m.

ROBUST OPTIMIZATION OF TRANSMIT/RECEIVE BEAMFORMER FOR MIMO DOWNLINK WITH IMPERFECT CSI AT BASE STATION

A robust scheme is proposed to jointly optimize transmit/receive beamformers for Mul-tiple Input Multiple Output(MIMO) downlinks where the available Channel State Information(CSI) at Base Station(BS)(CSIBS) is imperfect.The criterion is to minimize the sum Mean Square Error(sum-MSE) over all users under a constraint on the total transmit power,which is a non-convex and non-linear problem.Observing from the first order optimization condition that the optimal trans-mit/receive beamformers are mutually dependent,the transmit/receive beamformers for each user are updated iteratively until the sum-MSE is minimized.Simulation results indicate that the proposed scheme can effectively mitigate the system performance loss induced by imperfect CSIBS.

一种基于MMF-FRM的低复杂度信道化接收机结构

为实现时域重叠信号的全概率接收和跨信道信号重构,降低窄过渡带信道化结构的复杂度,提出一种基于调制屏蔽滤波器频率响应屏蔽(Modulation Masking Filter Frequency Response Masking,MMF-FRM)技术的信道化接收机结构.通过对原型屏蔽滤波器进行调制得到两个分支屏蔽滤波器,给出了基于MMF-FRM的窄过渡带滤波器设计方法.推导出一种基于MMF-FRM的低复杂度信道化接收机结构,该信道化结构解决了多相分解受FRM(Frequency Response Masking)滤波器组限制的问题,并分析了该结构的有限字长性质和纹波系数.用Xilinx System Generator进行了硬件实现与仿真,在采样速率为1 GHz,信道数为8的条件下,提出的信道化接收机结构比多相信道化结构节省74.1%的乘法器资源,比FRM信道化结构节省13.5%的乘法器资源.