Measuring peak and average power of digitally modulated advancedtelevision systems

The author reviews why it is that the peak power of the NTSC visual signal is measured, noting that its average power varies inversely with scene brightness. The average power of a digital TV signal is independent of scene content, motion, and other variables and is, therefore, the parameter to be measured and used to compute interference, coverage, and the utility cost to provide that coverage. Transient peak power varies with the data stream, and for this reason it is a statistical quantity. A method to determine the transient peak power is described. Thermocouple power sensors and the limitations of square law power sensors are also discussed     

降低OFDM系统高峰均功率比的方法研究

针对OFDM技术具有较高的峰均功率比（peak to average power ration,PAPR）这一主要缺点,提出一种控制OFDM载波信号衍生频谱的迭代算法,在降低系统高峰均功率比的同时,也降低系统的误码率.利用该算法对数据序列长度为64的OFDM信号进行仿真验证,随着迭代次数的增加,衍生频谱系数增大,系统平均功率增加,OFDM信号的峰值功率比得到一定的降低.     

一种新的降低MIMO-OFDM信号峰均比的方法

一、引言 在未来宽带无线通信系统中，面临的两个最大的困难：多径衰落和带宽利用效率。多入多出正交频分复用系统（MIMO-OFDM）以其高效的频谱利用率和良好的抗多径衰落性能成为4G宽带无线通信系统的热门候选传输方案。但是，与OFDM系统一样，MIMO-OFDM系统本质上也是多载波结构，仍然存在高峰均功率比（PAPR）的问题。     

A phase scrambling scheme for suppression of peak to average power ratio for OFDM

The complex-valued modulating vectors for the subcarrlers consist of two kinds of components: One is the information-bearing components superposed with pseudo-randomized phases and the other is the suppression components with specified scrambling phases. The pseudorandomized phases are generated according to the predefined polynomial and mapping function whereas the scrambling phases are from a gradient algorithm. The simulation results verify the rationality and validity of the phase scrambling.     

一种基于格雷互补序列抑制峰均功率比的方法

正交频分复用(0FDM)信号调制中存在的高峰均功率比(PAPR)，为其实用化设置了障碍。具体分析了采用格雷互补序列和雷德密勒码来降低PAPR的算法，并用MATLAB进行了仿真，验证了当采用PSK调制时该编码方法可将PAPR降至3dB以下。     

Use of data permutation to reduce the peak‐to‐average power ratio of an OFDM signal

A set of fixed permutations is used in this paper to reduce the peak‐to‐average power ratio (PAR) of an orthogonal frequency division multiplexing (OFDM) signal. For this technique, K − 1 interleavers are used to produce K − 1 permuted sequences from the same information sequence. The peak powers of the permuted sequences and the original information sequence are computed using K inverse discrete Fourier transforms; the sequence with the lowest PAR is chosen for transmission. Before the optimization process begins the identity of each interleaver is embedded into the data frame as side information (SI). SI which is critical to the receiver operation, is coded using a simple forward error correction code in order to increase its reliability. An adaptive approach is proposed for the reduction of this technique's complexity. Furthermore, theoretical expressions are derived for the complementary cumulative distribution function of the PAR and for the average number of permutations required by the adaptive approach. Computer simulations are performed for finding the PAR reduction capability of several types of interleavers. It is subsequently found that random interleavers and odd–even symmetric interleavers are performing equally well in reducing the PAR. Results are also presented for the out of band radiation and the bit error rate performance of interleaved OFDM (IOFDM) and conventional OFDM in an additive white Gaussian noise channel. IOFDM also has less adjacent channel interference than that of conventional OFDM. Copyright © 2002 John Wiley & Sons, Ltd.     

A low complexity selected mapping scheme for peak to average power ratio reduction with digital predistortion in OFDM systems

One of the effective methods used for reducing peak‐to‐average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems is selected mapping (SLM). In this paper, a new SLM scheme called DSI‐SLM, which is a combination of dummy sequence insertion (DSI) and conventional selected mapping (C‐SLM) is proposed. Previous techniques have had some drawbacks. In DSI, increasing the number of dummy sequences to have better PAPR degrades transmission efficiency, and in C‐SLM, the complexity rises dramatically when the number of sub‐blocks increases. The proposed DSI‐SLM scheme significantly reduces the complexity because of the reduction in the number of sub‐blocks compared with the C‐SLM technique while its PAPR performance is even better. To enhance the efficiency of the OFDM system and suppress the out‐of‐band distortion from the power amplifier nonlinearity, a digital predistortion technique is applied to the DSI‐SLM scheme. Simulations are carried out with the actual power amplifier model and the OFDM signal based on the worldwide interoperability for microwave access standard and quadrature phase‐shift keying modulation. The simulation results show improvement in PAPR reduction and complexity, whereas the BER performance is slightly worse. Copyright © 2011 John Wiley & Sons, Ltd.     

Breakup of AT&T and liberalization of the telecommunicationsbusiness

The author argues that the present status and future direction of liberalization of the telecommunications business in the wake of the breakup of AT&T must be considered from two viewpoints. One viewpoint approaches the telecommunications business as a public business; the other approaches it as a means to promote, in various countries, advancement and diversification of universal telecommunications. In this context he evaluates the impact of the breakup on communication policy worldwide     

Estimate of local average power of a mobile radio signal

The procedure for obtaining the local average power (also called local mean) of a mobile radio signal is described. The measured length of a mobile radio signal necessary to obtain the local average power is determined to be in the range of 20 to 40 wavelengths. It is based on the Rayleigh distribution. The sufficient number of samples for estimating the local average power values is about 36. It is based on a 90 percent confidence interval and less than 1 dB error in estimate. This procedure of estimate can be treated as a standard procedure.     

Realization of a Signaling System No. 7 Network for AT&T

Transition of the AT&T Communications Common Channel Interoffice Signaling (CCIS) Network, currently the world's largest, to a more powerful and flexible network with Common Channel Signaling System No. 7 capability has begun with the introduction of a more powerful signaling transfer point system and high-speed data links. The evolving AT&T network will be a key element in supporting an Integrated Services Digital Network (ISDN) capability. This paper describes the status of the existing AT&T CCIS network and how it will evolve toward a new network employing Signaling System No. 7 utilizing the ISDN User part (ISDN-UP). It also considers Signaling System No. 7 ISDN-UP implementation and the flexibility of the ISDNUP protocol in support of future customer needs.     

Assessment of radiation-induced loss for AT&T fiber-optictransmission systems in the terrestrial environment

Environmental radiation dose rate estimates are provided for both outdoor terrestrial and indoor environments. Laboratory radiation sensitivity measurements are reported for the AT&T standard single-mode fiber and standard and radiation-hardened multimode fibers. These are used to estimate typical system losses for long-haul, trunk, feeder, local area network, and optical data environments. It is reported that radiation-induced loss is unusually harsh environments can be minimized by using the radiation hardened 62.5/125-μm multimode fiber, which has sensitivities roughly an order of magnitude lower than the standard product at 0.85 μm and almost two orders of magnitude lower at 1.3 μm     

频谱仪测量邻道功率比动态范围的研究

频谱分析仪几乎是目前测量邻道功率比（ＡＣＰＲ）的唯一有效工具。ＡＣＰＲ是影响通信系统容量及电磁兼容性的重要技术指标，也一直是各级无线电管理机构进行无线电发射设备管理及检测的一个重要内容。怎样利用频谱仪固有的参数并结合被测信号的特点从理论上确定频谱仪对应的ＡＣＰＲ最大测试动态范围，对各级无线电管理机构来说有一定的技术指导意义。由于涉及到的理论较多，限于篇幅，本文不做太多的理论推导而直接给出结果。一、频谱仪测量ＡＣＰＲ的原理探讨频谱仪测量ＡＣＰＲ的原理，主要是弄清有关ＡＣＰＲ的概念。ＡＣＰＲ（Ａｄｊ…     

Peak‐to‐average power ratio reduction of a hidden training sequence‐aided precoding scheme for MIMO‐OFDM

We analyze a peak‐to‐average power ratio (PAPR) reduction property based on a hidden training sequence‐aided precoding scheme for MIMO‐OFDM systems. In addition to the benefits of a hidden training sequence‐aided precoding scheme such as improvement in bandwidth efficiency and frequency diversity gain, we address that power amplifier efficiency can be improved without any additional complexity burden. By mathematically analyzing PAPR of the precoded MIMO‐OFDM signal with a hidden training sequence, we demonstrate that PAPR reduction can be obtained by varying the allocated power to the hidden training sequence. Because of the low PAPR property of this scheme, it is possible to utilize a low‐cost power amplifier, resulting in the reduction in the total cost for hardware implementation. Copyright © 2014 John Wiley & Sons, Ltd.     

利用功率谱最大最小平均比的频谱感知算法

由于载波频偏未知和噪声不确定性影响,信号功率谱的最大值和最小值不能根据单个频点来准确估计。该文提出利用功率谱最大最小平均比的频谱感知算法。利用基频附近一段功率谱的平均值作为功率谱最大值估计,利用功率谱中点频率附近一段的平均值作为功率谱最小值估计,将此二者之比作为检测统计量。推导了算法的虚警概率,得到了判决门限。加性高斯白噪声信道和瑞利衰落信道下的仿真结果表明:该算法性能优于基于功率谱分段对消频谱感知算法（PSC）和基于功率谱的平均比值算法（PSRA）,降低了载波频偏未知和噪声不确定性对频谱感知算法性能的影响。      

A large volume copper vapor +HCI--H/sub 2/ laser with a high average power

A copper vapor laser tube with a large volume (15.1 L) has been built for the study of extrapolation in power of the Cu-Ne-HCl-H/sub 2/ laser medium. A high-power (77 kW) all-solid-state high-voltage power supply has been also used for this purpose. Results show an improvement of the optical power after the HCl-H/sub 2/ mixture injection. An optical power of 312 W has been extracted from this laser head in oscillator configuration.     

Realization of GaAs/AlGaAs quantum-cascade lasers with high average optical power

Quasi-continuous-wave operation of GaAs/AlGaAs quantum-cascade lasers with high average optical power is demonstrated. Double X-ray diffraction has been used to investigate the quality of the epitaxial material. The compositional gradients and the interface quality are controlled effectively. The corrected average power of per facet about 17 mW and temperature tuning coefficient of the gain peak about 0.91 nm/K from 83 K to 140 K is achieved in pulse operation. Best value of threshold current density is less than 3.0 kA/cm² at 83 K.     

Maximisation of signal/noise ratio in array with broadened zero

A technique for synthesising a maximally-flat zero in antenna array while maximising the signal/noise ratio is described. It is shown that the optimum radiation pattern consists of a main beam, a cancellation beam and its pattern derivatives. The properties and characteristics of the pattern are also discussed.     

Peak‐to‐average power ratio reduction of orthogonal frequency division multiplexing systems using modified tone reservation techniques

This paper proposed a modified tone reservation (TR) technique that can reduce the peak‐to‐average power ratio (PAPR) of the orthogonal frequency division multiplexing (OFDM) system and is able to correct errors to avoid channel interference. The TR technique is a widely used PAPR reduction technique, which divides subcarriers of the OFDM system into two sets to generate peak‐canceling signals and transmit modulated data. The subcarriers used to reduce the PAPR are called the peak reduction tone sets. The mechanism of peak‐canceling signal generation is a primary factor in determining the quality of the PAPR reduction performance of the TR technique. Currently, two signal generation mechanisms exist: TR‐gradient‐based and TR‐clipping‐based techniques. Although TR techniques can effectively reduce the high PAPR in the OFDM system, TR techniques lack the ability to correct errors. Therefore, this paper combined block coded modulation codes and TR techniques to provide the modified TR techniques with error correction abilities. From the simulation results, the modified TR techniques had a superior effect on PAPR reduction performance compared with the conventional TR technique. The modified TR technique also possessed the ability to correct errors during signal transmission. Copyright © 2015 John Wiley & Sons, Ltd.     

Optical architecture and interface lightguide unit forfiber-to-the-home feature of the AT&T SLC Series 5 carrier system

The subscriber loop has evolved from analog transmission on passive copper through digital carrier on copper to initial applications of fiber to customer premises. In planning its initial deployment of fiber to customer premises, AT&T analyzed a variety of optical devices and transmission techniques. It was decided to employ 1300-nm laser-based baseband duplex transmission employing fused fiber splitter devices. An optical interface lightguide unit was designed to house the optical components and protect them during assembly to a transceiver circuit board. This unit has proved compatible with a mass production factory environment. The optical transceivers have been deployed to sites throughout the US and have been performing reliably since the fall of 1988. The author discusses the choice of media, source, and wavelength; the lightguide unit; and the system characteristics     

Techniques for reducing the peak power of a switching transistor with p-i-n diode load

Describes techniques for reducing the peak power of switching transistor that reverse biases a p-i-n diode load. Particular emphasis is placed on a parallel combination of a Zener diode and an inductor and it is shown that, for an experimental p-i-n driver, the peak power is reduced from 252 to 90 W.