基于Hermite函数的超宽带脉冲波形设计与性能分析

根据联邦通信委员会关于超宽带辐射功率谱的限制以及适用于多址方式的窄脉冲要求,设计了一组基于Hermite函数的超宽带脉冲波形。所设计的脉冲波形具有正交性和不随阶数变化的恒定脉宽两个重要特性,从而提供了良好的防时间抖动性能并有效降低符号间干扰;为了评估相关接收机的性能,对设计脉冲信号的自相关和互相关函数的闭合表达式进行了推导;分析了跳时脉位调制超宽带系统中脉冲波形在加性高斯白噪声、多址干扰、多径衰落信道等多种环境下的误码率性能,探讨了时间抖动对系统性能的影响,并将仿真结果与高斯单周期脉冲进行比较。分析结果表明该脉冲设计方案提供了一种灵活而系统的超宽带脉冲设计方法,所设计脉冲既满足辐射功率谱限制又提供良好的系统误码性能。     

Orthonormal pulses for high data rate communications in indoor UWB systems

In this letter, we propose novel pulses which not only meet the power spectral mask of the Federal Communications Commission (FCC) for indoor Ultra-wideband (UWB) systems but also preserve orthogonality at the correlation receiver. The proposed pulses are derived from a parametric closed-form solution. Thus, multiple orthonormal pulses that comply with the FCC mask without additional frequency shifting or bandpass filters can be generated for high data rate communications or multiple access schemes. Simulation results demonstrate that high data rate communication is achieved by the proposed orthonormal pulses via pulse shape modulation and pulse position modulation.     

Performance Evaluation of UWB Systems Exploiting Orthonormal Pulses

The novel pulses, which not only meet the power spectral mask of the Federal Communications Commission (FCC) but also preserve orthonormality at the correlation receiver, have been proposed by Kim for high data rate communications in indoor ultra-wideband (UWB) systems. The proposed multiple orthonormal pulses comply with the FCC spectral mask without additional frequency shifting or bandpass filters, and furthermore, provide enhanced bit-error rate (BER) performance, compared with a well-known Gaussian monocycle and modified Hermite pulses. This paper analyzes the impact of the proposed pulses' properties, such as their auto- and cross-correlations, on the correlation receiver of the UWB system based on the pulse position modulation. The performance of the proposed pulses are compared with different waveforms under various conditions, such as multipath fading, timing mismatch, and multiuser interference. We also discuss a modulation scheme using the multiple orthogonal pulses to achieve the enhancement of data rate and the impact of the correlation characteristics of the proposed waveforms on the BER performance. Simulation results demonstrate the effectiveness of the proposed orthonormal pulses in various conditions, comparing with different waveforms     

基于Polycycle信号的干扰抑制UWB自适应脉冲设计

 针对认知超宽带与现存窄带系统干扰问题,采用Polycycle信号作为超宽带原始脉冲,使用Hermite矩阵特征向量方法设计了认知超宽带自适应脉冲,实现了干扰抑制.仿真结果表明,提出的自适应脉冲功率谱密度分布符合FCC室内和室外频谱规范,实现了自适应频段陷波.基于PAM-TH UWB系统性能分析表明自适应脉冲具有较强的多用户干扰和窄带干扰抑制能力.     

Generation of orthogonal UWB shaping pulses based on compressed chirp signal

This study investigates a novel method to numerically generate orthogonal ultrawide band (UWB) shaping pulses based on compressed chirp signal. First, a pulse template with less than 1 ns duration time, which is used to construct a Hermitian matrix, is produced with a compressed chirp pulse. Sub-nanosecond orthogonal pulses are then generated for UWB by using the Hermitian matrix eigenvectors. The simulation results show that the power spectral density distribution of the UWB shaping pulses met the constraint of Federal communications commissions (FCC) spectral mask. The shaping pulses not only have higher spectrum utilization ratio and very short time duration but also have excellent autocorrelation and cross-correlation properties, which is an advantage to reduce the interference between multiusers. Especially, a method to produce sub-nanosecond orthogonal UWB shaping pulses by using a relatively longer duration chirp signal is presented.     

Novel Spectrally Efficient UWB Pulses Using Zinc and Frequency‐Domain Walsh Basis Functions

In this paper, two sets of spectrally efficient ultra‐wideband (UWB) pulses using zinc and frequency‐domain Walsh basis functions are proposed. These signals comply with the Federal Communications Commission (FCC) regulations for UWB indoor communications within the stipulated bandwidth of 3.1 GHz to 10.6 GHz. They also demonstrate high energy spectral efficiency by conforming more closely to the FCC mask than other UWB signals described in the literature. The performance of these pulses under various modulation techniques is discussed in this paper, and the proposed pulses are compared with Gaussian monocycles in terms of spectral efficiency, autocorrelation, crosscorrelation, and bit error rate performance.     

基于正交脉冲波形的高速超宽带通信系统

提出了基于小波函数的两个正交脉冲,其功率谱密度满足美国通信委员会(FCC)对UWB系统的频谱限制。在此基础上提出了使用脉冲波形的极性调制和正交脉冲波形的形状调制相结合的一种高速超宽带通信系统,可以同时传送多个比特信息提高传信率。     

满足FCC频谱限制的UWB脉冲设计算法研究

在超宽带通信系统中,满足FCC频谱限制的UWB脉冲波形设计是一个研究的热点.首先对高斯脉冲及其导函数的频谱形式进行理论推导及仿真实现,在此基础上提出了两种满足FCC频谱限制的UWB脉冲波形算法,并比较了各自的优缺点.     

Comparisons of various pulse shapes for DS-UWB signals over the UWB channel

In this paper, we first investigate the power spectral densities (PSD) of bipolar modulated Direct Sequence Ultra Wide Band (DS-UWB) signals using various pulse shapes under the FCC UWB emission mask. Considered pulse shapes are the first five derivatives of the Gauss pulse (p₁, p₂, p₃, p₄ and p₅), the first four orthogonal modified Hermite waveforms, and Daubechies wavelets (db-q). It is observed in the PSD results that p₄ and p₅ Gauss pulses, the Daubechies (db-q) for q>4 comply with the FCC UWB rule by selecting proper values for the pulse duration. Then, we derive the pulse shape dependent probability of error expression for bipolar DS-UWB signals over the standard UWB channel. The five pulse shapes (p₄, p₅, db-5, db-6 and db-7) complying with the FCC emission mask are numerically compared by using the derived probability of error expression over the CM1 model of the Standard UWB channel. Results reveal that the Daubechies have better performance than those of the two Gauss pulses.     

一种基于多频带PSWFs组合的CUWB自适应脉冲波形设计

本文简述了认知超宽带(CUWB)系统的工作原理,并从自适应频谱环境和兼容FCC频谱模板的角度出发,建立了基于频谱感知来动态构建CUWB系统自适应辐射掩蔽的机制。然后,利用PSWFs函数的特性,提出了一种基于多频带的回转椭球波函数(PSWFs)基的加权线性组合来设计CUWB自适应脉冲波形的算法。仿真结果表明,该算法所产生的脉冲波形不仅能满足CUWB系统频谱模板的要求,而且能自适应模板的动态变化。     

UWB pulse design using constraint convex sets method

In this paper, we propose a constrained convex sets–based method for designing ultra‐wideband (UWB) pulse. The UWB pulses designed using earlier proposed methods either do not fit well in UWB spectral mask or require extra processing circuitry for pulses to fit in the UWB spectral mask. The proposed constraint sets–based method is flexible and optimum for the UWB mask. The pulse designed by the proposed method is Federal Communication Commission compliant and has an autocorrelation function similar to the Gaussian pulse. The bit error rate performance of time hopping binary phase shift keying using the proposed method and some of the existing methods such as Norman and Lee pulses and sixth derivative Gaussian pulse is analyzed in additive white Gaussian noise and Saleh‐Valenzuela channels. Pulse designed using the proposed method outperforms existing pulse design, and the same is verified through simulations. The proposed algorithm is flexible and can also be used to mitigate narrow band interference, multiband UWB pulse generation and any other Federal Communication Commission (or other regulatory body) compliant spectrum mask by modifying the parameter of the proposed constraint set(s).     

基于高斯二阶导数组合的UWB脉冲波形设计

提出了一种基于高斯二阶导数组合的UWB脉冲波形设计方法.依据FCC对超宽带各频段带宽划分的不同及各频段辐射限制的差异来选取基函数,利用最小均方误差准则(LSE),以FCC室内辐射掩蔽为规范选取一组加权系数对基函数进行线性组合.再通过调整基函数参数脉冲形成因子和搬移因子,对波形进一步优化.仿真结果表明,文中设计脉冲实现了在全频段对辐射掩蔽的高效逼近,与基于随机系数选择的组合脉冲比较:方法简单,具有更高的频谱利用率.     

窄带干扰抑制的一种新型频率编码正交UWB脉冲设计

文中提出一种基于正交载波和伪随机序列的新型频谱编码正交UWB脉冲设计方法，该方法是在频域中利用PN序列对经过频移的子脉冲进行编码来产生正交脉冲．在IR-UWB（脉冲无线电超宽带）中引入了正交载波和PN序列，使其不仅具有传统IR—UWB和多频带CB-UWB（基于载波的超宽带）优点，而且提高了UWB信号发射的瞬时频谱和瞬时能量的效率．脉冲的自相关和互相关特性皆优于传统的脉冲。另外，借助于认知无线电技术，可保证发送信号满足FCC的UWB频谱规划，避免与其他传统窄带系统干扰。仿真结果表明该脉冲设计方法能够有效的抑制窄带干扰，并降低复杂度。     

一种新的UWB脉冲成形方案

本文基于美国联邦通讯委员会FCC对UWB信号的发射功率谱强制规定,提出了一种新的UWB脉冲成形方法-Gaussian-sinc函数波形脉冲.该方法通过方便灵活的参数调整,可以产生完全符合FCC频谱模板要求的极窄脉冲波形.仿真结果表明,该方法产生的UWB系统发射脉冲旁瓣小,频谱利用率高,不需降低整个频段的信号发射功率,就能有效解决共存通信环境下的同频干扰问题.     

基于高斯脉冲导数的正交UWB波形最优化设计

超宽带无线通信由于其在短距离高速率无线通信中的潜在应用已经引起了广泛的关注.超宽带信号要符合FCC发布的辐射掩蔽,并且要充分利用分配的频谱,这就要求合理的脉冲波形设计.本文分别采用4阶和5阶高斯脉冲导数,进行组合来合成用于UWB通信的脉冲波形,设计中采用归一化有效信号功率作为频谱利用的衡量标准,将波形设计问题转化成为线性规划问题,线性规划问题可以高效地求解,得到的波形具有很高的频谱利用率,并且4阶和5阶高斯脉冲导数合成的脉冲是相互正交的,可以进一步扩大通信的容量.     

Power controlled channel allocation for multiuser multiband UWB systems

Emerging ultra-wideband (UWB) technology offers a great potential for the design of high-speed short-range communications. However, in order for a UWB device to coexist with other devices, the transmitted power level of UWB is strictly limited by the FCC spectral mask. Such limitation poses a significant design challenge to any UWB system. An efficient management of the limited power is thus a key feature to fully exploit the advantages of UWB. In this paper, a cross layer multiuser multiband UWB scheme is proposed to obtain the optimal subband and power allocation strategy. Optimization criteria involve minimization of power consumption under the constraints on the packet error rate, the data rate, and the FCC limit. To ensure the system feasibility in variable channel conditions, an algorithm to jointly manage the rate assignment of UWB devices, subband allocation, and power control is proposed. A computationally inexpensive suboptimal approach is also developed to reduce the complexity of the problem, which is found to be NP hard. Simulation results under UWB channel model specified in the IEEE 802.15.3a standard show that the proposed algorithm achieves comparable performances to those of the complex optimal full search approach, and it can save up to 61% of transmit power compared to the current multiband scheme in the standard proposal. Moreover, the proposed algorithm can obtain the feasible solutions adaptively when the initial system is not feasible for the rate requirements of the users     

A CMOS UWB Pulse Generator for 6–10 GHz Applications

A CMOS ultra wideband (UWB) pulse generator with low energy dissipation and high peak amplitude is presented for 6–10 GHz applications. The pulse generator complies with the FCC spectral mask for indoor UWB systems. It consists of a glitch generator, a pulsed oscillator, and a pulse shaping filter. The pulsed oscillator is switched on by the glitch signal only for a short duration, so as to make a UWB pulse. For sub-nanosecond pulse generation, a pulsed oscillator with fast transient response is proposed. A pulse shaping filter makes the oscillator output fall into the FCC spectral mask. The pulse generator is fabricated using a 0.18 $mu$ m CMOS process. The core chip has a size of 0.11 mm $^{2}$. It shows pulse duration of about 500 ps with ${-}10$ dB bandwidth of 4.5 GHz from 5.9 to 10.4 GHz. The energy consumption is 27.6 pJ per pulse with a peak-to-peak amplitude of 673 mV on a 50 $Omega$ output load. The generated pulses are very coherent with 1.8 ps RMS jitter.      

基于遗传算法的超宽带波形设计

采用遗传算法(GA)进行了一种新颖的超宽带(UWB)脉冲波形的设计。从多带Chirp信号出发,将波形设计问题转化成有约束条件的逼近问题求解,然后通过遗传算法解决逼近问题。得到的波形不仅满足联邦通讯委员会(FCC)的频谱模板,而且具有88%的频谱利用率。仿真结果验证了采用遗传算法的波形设计具有低时间复杂度;提出的UWB脉冲波形具有较高的频谱利用率,优于其他的UWB脉冲例如B样条脉冲。     

干扰抑制的UWB脉冲设计与性能分析

提出了一种新的带内（窄带或宽带）干扰抑制的超宽带脉冲的设计方法。采用不同幅度和延迟的高斯脉冲的组合来拟合抽样函数脉冲,实现了超宽带频谱屏蔽的高效逼近,并能够和带内的其他通信系统更好地共存。在介绍设计原理的基础上,给出了设计时域波形的具体实现及波形所对应的功率谱密度图,使其满足FCC频谱屏蔽的要求。同时,对于假设存在的带内干扰对波形进行类似的设计,使其具备抑制干扰的能力。最后,分析了TH—PSKUWB系统的传输性能,并和最佳单周期高斯波形进行了详细的比较,结果表明：其误码性能远远优于最佳单周期高斯波形。     

Multiple ultra-wideband signal sources exploiting XPM in SFRL

A novel scheme for all-optical broadcast ultra-wideband (UWB) monocycle pulses generation based on cross-phase modulation (XPM) in semiconductor fiber ring laser (SFRL) is proposed, in which three UWB positive or negative monocycle pulses can be generated simultaneously. A comprehensive broad-band dynamic model for this kind of all-optical broadcast UWB monocycle sources is established, which is further applied to numerically analyze the impacts of injection current of semiconductor optical amplifier (SOA), the power and wavelength of the signal light on the performance of the UWB positive monocycle pulses with higher power spectral density. The results show that the spectra of the UWB positive and negative monocycle pulses generated by this scheme match the Federal Communications Commission (FCC) definition quite well. Three UWB positive monocycle pulses with better performance can be obtained when the power of signal light is at a high level, and three other UWB positive monocycle pulses with good tolerance to both the injection current of the SOA and the wavelength of the signal light can be obtained. In addition, the powers of the lasing light coupled into the SFRL should not be strong to obtain three UWB positive monocycle pulses with better performance.