OFDMA子载波分配与子载波预留降低PAPR联合优化

综合研究正交频分多址(Orthogonal Frequency Division Multiple Access,OFDMA)系统中资源分配和峰值平均功率比(Peak to Average Power Ratio,PAPR)抑制问题,提出一种OFDMA子载波分配与子载波预留(Tone Reservation,TR)技术...     

一种基于多峰值搜索的PAR抑制算法

正交频分复用(OFDM)是高速数据传输中一项引人注目的调制技术。但是,较高的峰值平均功率比(Peak-to-Average Power Ratio,PAR)却是OFDM系统实际实现时主要的不利因素之一。Tellado和Cioffi提出了Tone Injection算法,可以有效地减少PAR。文章中提出对Tone Injection算法的一个改进,着眼于在时域内同时搜索和减少多个峰值。进一步,把改进后的算法应用到过采样的OFDM信号,以降低由带限滤波器而引入的PAR再生,更好地抑制模拟信号的峰均比。     

Automatic context induction for tone model integration in mandarin speech recognition

Tone model (TM) integration is an important task for mandarin speech recognition.It has been proved to be effective to use discriminatively trained scaling factors when integrating TM scores into multi...     

WDM系统中电监控信道方法的研究

波分复用(wavelength-Division Multiplexing,WDM)技术的发展大大提高了通信网络的传输容量,将成为下一代骨干网络的核心传输方式.在WM系统光网元设备之间的通信方法中,较多的是采用光监控信道(OSC)和调顶技术(Pilot Tone),但是这两种方法的固有缺陷在城域波分系统不可避免,从而引出电监控信道(ESC)一适用于城域波分系统的基于业务开销中现有的DCC字节来进行网元之间通信的一种实现方法.该方法易于实现、可靠性高,有效降低了系统成本,提高了系统资源利用率,有较好的应用前景.     

双音频DTMF技术在DSP系统中的实现

双音多频DTMF(Dual Tone Multi-Frequency)信令在全世界范围内得到广泛应用,将DTMF信令的产生与检测集成到含有数字信号处理器(DSP)的系统中,是一项较有价值的工程应用.本文给出一种成功的实现方案首先阐述DTMF信令的产生与检测的基本原理,然后给出在TI公司定点DSP芯片TMS320C54x系列中的实现方案,最后作了实现方案的性能分析.     

双音多频DTMF技术在DSP系统中的实现

双音多频DTMF(Dual Tone Multi—Frequency)信令在全世界范围内得到广泛应用，将DTMF信令的产生与检测集成到含有数字信号处理器(DSP)的系统中，是一项较有价值的工程应用。本文给出一种成功的实现方案：首先阐述DTMF信令的产生与检测的基本原理，然后给出在TI公司定点DSP芯片TMS320C54x系列中的实现方案，最后作了实现方案的性能分析。     

手机双音多频功能及其使用

当今数字手机一般都设有双音多频DTMF(Dual Tone Multi Freguency)功能,是手机普遍采用的拨号方式。手机用音频组合信号与交换机或相应终端设备联络,每个组合信号用两个音频频率,故称为双音(DT);不同的信号用不同的频率组合,因此称为多频(MF),总称便是双音多频(DTMF)。手机采用了国际电报电话咨询委员会(CCITT)推荐的8个不同的双音频电话机组合频率,1000Hz以     

基于EVM约束的预留子载波峰均比抑制

传统预留子载波(Tone Reservation, TR)技术要求预留的子载波与数据子载波正交,占据的带宽受限,因而其降低峰值平均功率比(Peak-to-Average Power Ratio, PAPR)能力有限。提出了一种基于误差适量幅度(Error Vector Magnitude, EVM)约束的TR算法,将传统的预留子载波扩展至数据子载波生成峰值消除信号,从而大幅度降低峰值功率。基于系统误码率的考虑,在优化问题中加入数据子载波上会出现的最大EVM约束,采用凹凸过程(Concave-convex Procedure, CCCP)优化算法求解提出的优化问题。仿真结果表明,所提算法在发送端峰均比改善5.6 dB的同时,接收端解调性能仅损失1 dB。     

猝发声发生器及其应用

一、概述猝发声通常指纯音猝发声(Tone Burst),是一种正弦波脉冲信号。它由一个或多个完整周期的正弦信号组成,往往要求其波形在零点交叉处起始和终止(图1)。猝发声主要用于声学和振动仪器的有效值检波特性、时间计权特性、脉冲特性、积分特性测试和扬声器瞬态特性的测试。因此,猝发声发生器是科研、生产、计量、鉴定工作必不可少的仪器。下面以HE5550型猝     

5G波束赋形优化的典型场景立体覆盖研究

5G波束赋形技术是5G NR满足增强移动宽带(eMBB)、超高可靠低时延(uRLLC)以及大规模机器类通信(mMTC)三大场景的核心技术之一.本研究采用大规模波束赋形增益计算方法对大规模波束赋形技术的实现原理、CSI反馈机制、波束扫描和波束管理的实现机制进行分析,研究发现波束赋形技术可以对水平和垂直方向进行扫描,增加了...     

Chromatic Dispersion Monitoring Technique Using Pilot Tone Carried by Broadband Light Source

We propose and demonstrate a simple chromatic dispersion monitoring technique based on the pilot tone generated by a broadband light source (BLS). Previously, the pilot tone has been obtained by directly modulating each transmitter laser with a small sinusoidal current. Thus, for use in the wavelength-division- multiplexed (WDM) network, each transmitter should be modulated with a unique pilot tone. However, we obtain the pilot tone by modulating an additional BLS such as a reflective semiconductor optical amplifier. Thus, there is no need to modulate each transmitter laser. We evaluate the performance of the proposed technique in an 8$, times ,$10 Gb/s WDM system. The result shows that, unlike the conventional pilot-tone-based monitoring technique, the performance of this technique is almost insensitive to the polarization-mode dispersion.      

Digital Video: A Buffer-Controlled Dither Processor for Animated Images

A new technique has been discovered which permits pseudo-gray tone video images to be played in real-time on bilevel, memory displays such as the ac plasma panel. The technique combines ordered dither processing, selective updating, and hysteretic thresholding to digitally transmit or store the video images. Only a 1 bit/pel frame memory plus a 0.3 bits/pel replenishment buffer are required. This technique makes possible the use of a single terminal to display both graphic-alphanumeric information as well as pseudo-gray tone video images.     

Dual-pilot tone calibration technique

Pilot-based calibration techniques are used to reduce the effects of multipath fading in mobile satellite receivers. One of the more recent of these techniques, namely the tone calibration technique (TCT), suggests transmitting double sideband modulation with the pilot tone located at the center of its spectrum where the amplitude and phase characteristics of the channel are most stable. To "make room" for the pilot in the presence of the Doppler shift, the equivalent low-pass data sidebands must be shaped so as to have zero response in the neighborhood of dc. Other techniques such as transparent tone-in-band (TTIB) similarly "notch out" a hole in the center of the data spectrum for location of the pilot. An alternate possibility which is at the same time much more bandwidth efficient than TCT is a dual-pilot tone calibration technique (DPTCT) that symmetrically locates a pair of pilots outside the data spectrum near the band edges of the channel. The operation and performance of DPTCT are analyzed, and its effectiveness is compared to that of the single tone TCT technique.     

Mobile digital communications via tone calibration

A new digital signaling technique that is particularly suited for channels impaired by multipath fading is presented. The proposed modulation scheme employs a continuous-wave (CW) tone to calibrate the mobile channel against the multipath-induced phase uncertainties. This technique is applicable to quaternary phase shift keying as well as to more complicated signal constellations such as M-ary phase shift keyed schemes. The advantages of tone calibration are: 1) robustness of the receiver and 2) elimination of the link dependent error floor. Furthermore, since the CW tone can also be used for coherent signal demodulation, carrier phase acquisition can be achieved within a bit time. This property is particularly attractive when a burst of data with a short burst length has to be detected. This radio technique is useful for both the terrestrial mobile and the newer satellite-aided mobile communication (SAMC) services.     

Progress Tones in PCM Switching Environment

This correspondence defines a new set of precision tone frequencies for digitally generating normal progress tones in a PCM switching environment. The technique of generating the progress tones is similar to the one described for digital multiple frequency (MF) tone senders in which the tone is generated by reading a memory store that contains the binary words representing a presynthesized waveform [1]. New frequency combinations are derived that minimize storage requirements by taking advantage of the allowable frequency tolerances to force waveform symmetry with respect to the sampling period.     

A single layer hydrogen silsesquioxane (HSQ) based lift-off process for germanium and platinum

Primarily used as etch mask, single layer hydrogen silsesquioxane has never been investigated for lift-off technique. In this article, we propose a new technique where a single layer of hydrogen silsesquioxane, a negative tone electron beam resist, is used to make lift-off of germanium and platinum. Removal of exposed hydrogen silsesquioxane is tested for various concentrations of hydrofluoric acid. Ultrasonic agitation is also used to reduce the formation of flakes due to accumulation of matter (evaporated metal in our case) along the sidewalls of the lift-off narrow slots. Results demonstrate potential in applying the hydrogen silsesquioxane as a negative tone lift-off resist to pattern nanometer scale features into germanium and platinum layers.     

Dispersion-Monitoring in WDM Systems by Injecting Modulated ASE

We demonstrate a technique for measuring the residual dispersion in wavelength-division-multiplexing links by injecting a low level of broadband amplified spontaneous emission that has been modulated with a radio-frequency (RF) tone into the start of the link to be monitored. The residual dispersion at the end of the link is then determined by measuring the RF phase shifts in this tone across different wavelengths. A benefit of this technique is that it does not require integration into the channel transponder and is not constrained to monitoring a fixed wavelength, but instead can be implemented as an independent unit capable of monitoring the link across the band irrespective of channel presence.     

First-order PMD monitoring for NRZ data using RF clock regeneration techniques

We propose and demonstrate two novel techniques for 10 Gb/s polarization-mode-dispersion (PMD) monitoring for NRZ signals that use a regenerated RF clock tone as a monitoring signal. Our techniques regenerate the RF clock tone that is usually absent after square-law detection in the electrical NRZ data spectrum (in the absence of dispersion). Our first technique uses a dispersive element in the monitoring tap-line to put the beat terms between the optical clock sidebands and the carrier in phase and thus regenerates the RF clock tone after detection. Our second technique involves the use of an optical filter that is centered at the bit rate frequency on either the upper or lower sideband of the optical spectrum, removing one of the sidebands and thus preventing the beating that normally cancels the RF clock tone. We show (theoretically, via simulation, and experimentally) the effect that PMD has on these regenerated RF clock tones. We also demonstrate PMD compensation at 10 Gb/s using these techniques for monitoring and show a 6-dB improvement in the 1% power penalty tail. Our techniques are simple, do not require modification at the transmitter, and can be applied to WDM systems via the use of a multichannel dispersive element or a tunable filter swept across all channels.     

奇异值分解抑制窄带干扰的非线性方法

提出了一种联合奇异值分解(SVD)和非线性滤波抑制直接序列扩频通信(DS/SS)中单音干扰的方法,建立了相应的系统模型。并对传统的线性双边滤波器的信噪比增进因子和误码率进行了比较。仿真结果表明,奇异值分解的非线性滤波方法对干扰有很强的抑制能力,较好地改善了系统的性能。     

Laboratory Measurements and a Theoretical Analysis of the TCT Fading Channel Radio System

This paper documents the laboratory and theoretical performance of a pilot-aided digital radio system. The technique considered transmits a midband pilot tone to improve the receiver data detection performance in a multipath fading channel and is referred to as the tone calibrated technique (TCT). We report on the performance of a 860 MHz prototype system carrying 2.4 kbit/s data under Rician fading conditions. Both experimental and analytical results show that the error floor experienced with nonpilot-aided transmission methods is effectively removed by the TCT scheme, resulting in significant performance gains at high signal-to-noise ratio (SNR) values. The paper also examines the TCT system performance under typical operating conditions and presents a new analysis of the TCT theoretical error probability.