Semianalytic BER evaluation by simulation for noisy nonlinearbandpass channels

The bit error rate (BER) of channels including a memoryless bandpass nonlinearity is evaluated by simulation. This would typically be an onboard travelling wave tube (TWT) amplifier in a satellite repeater, when the noise at the input of such a nonlinear element is non-negligible. The usual evaluation technique, error counting, requires a large amount of computer time if small error probabilities are to be estimated. It is shown that faster semianalytic procedures can be used, provided that a proper model for the nonlinear element is adopted. The output process is decomposed into a signal component plus an additional term representing an equivalent noise component, and an equivalent nonlinear transformation, relating the input useful signal to the output signal component, is derived. In addition, several modes for the probability density function (PDF) of the uplink noise component at the output of the transmission chain are discussed and compared. The procedure has been tested on a transparent satellite link using 4-CPSK modulation format. The results compare well with those of the error-counting technique if a composite rectangular PDF with exponential tails as adopted     

Comments on 'Signal design for a class of clutter channels' by Balakrishnan, A. V.

When scatterers introduce Doppler shifts distributed uniformly over a frequency band more than twice as wide as that of the signal, the maximum echo SNR for detection in the clutter and white noise is independent of the shape of the transmitted signal.     

Comments on `A novel bandpass filter using the amplifier pole'

In a recent correspondence by Anandamohan (see ibid., vol.SC-14, p.649, 1979), the author fails to see any new circuit. The author suggests that the proposed circuit is a particular case of a circuit reported earlier by Mitra and Aatre (1976).     

Parametric bandpass filters for simulation with generalized immittance converters

Methods proposed for the simulation of LC ladder band-pass filters with generalized immittance converters (GIC's) are reviewed, and the advantages of a recently proposed approach are emphasized. An alternative to an inexact approximation used to reduce element value spread is found in the design methods for parametric bandpass filters, and pertinent references are given.     

BER performance evaluation for MC-CDMA systems in Nakagami-m fading

Based on the approximation of the sum of several Nakagami-m variables and an alternative expression of the Q-function, an efficient bit error rate (BER) expression is described. The closed BER form is applicable to multicarrier code-division multiple-access (MC-CDMA) systems with equal gain combining (EGC) in frequency selective Nakagami (1960) fading channels.     

BER evaluation for general QAM in Nakagami-m fading channels

Evaluation of the bit error rate for general M-ary quadrature amplitude modulation (M-QAM) in Nakagami-m fading channels is presented. The analysis considers real values of the Nakagami fading parameter m, and bit-to-symbol mapping that is not necessarily Gray. Analytical and simulation results are compared to illustrate the accuracy of the analysis, taking as examples non-Gray mapped 16-QAM and 32-cross-QAM constellations.     

A novel analytical method for the BER evaluation in optical systemsaffected by parametric gain

A novel analytical method to evaluate the bit-error rate in optical links where the amplified spontaneous emission (ASE) noise at the receiver is a nonwhite random process is presented. The technique is used to estimate the impact of the nonlinear phenomenon called parametric gain on the performance of a wavelength-division-multiplexed (WDM) system. It is also compared with the Q-factor approximation, showing how this method may lead to significant errors     

Comments, with reply, on 'Another algorithm for converting a low-pass function into bandpass form' by K. Metzger

The commenter points out that the recursive algorithm described by K. Metzger in the above-titled letter (ibid., vol.76, no.5, p.634-5, May 1988) was published by him in the September 1980 issue of the IEEE Circuits and Systems Magaz (vol.2, no.3, p.3-5). He notes that the recursive technique is very useful not only for the low-pass to bandpass transformation, but also for performing the bilinear transformation used in digital filter design. The author replies that he was unaware of the earlier paper and thanks the commenter for calling it to his attention.<>     

Switched-capacitor bandpass filter based on simulation of canonical reactance sections

A design method is described for switched-capacitor filters. It is based on the simulation of doubly terminated reactance filters in a canonical tandem section configuration and using the bilinear s-to-z transformation between the frequency planes of the continuous-time reference filter and the discrete-time switched-capacitor filter. The switched-capacitor circuits are completely insensitive to parasitic capacitances. The method permits the switched-capacitor realization of the whole class of lossless two-ports.     

交叉耦合带通滤波器的优化研究及仿真

第五代移动通信技术对系统的滤波性能有着更高的要求,所以滤波器的优化是保障系统性能的关键所在。首先通过对滤波器函数多项式的损耗分析,推导出各项滤波指标与谐振器无载Q值之间的函数关系,并在一定的拓扑结构中进行仿真验证。然后对每个谐振器无载Q值进行补偿仿真,通过采用高Q值谐振器的方法,使通带边频点的损耗及响应曲线得到改善,最终实现滤波器优化设计的目标。     

超高频带通滤波器的设计与仿真

介绍一种在理论计算的基础上,采用ADS软件对射频滤波器进行优化及仿真的方法,重点阐述射频滤波器设计过程中的优化设计、器件仿真以及矩量法分析等相关内容。射频滤波器的测试结果表明其通带内波纹小于3dB,带内输入输出端口反射系数小于-20 dB,阻带衰减大于40 dB,相比于传统设计方法,此方法具有可行性和有效性。     

BER performance evaluation for CPFSK phase and polarizationdiversity coherent optical receivers

The following methods of continuous phase frequency shift keying (CPFSK) signal demodulation are compared for phase and polarization diversity receivers: single filter, dual filter, delay and multiply. Bit error rate (BER) values are obtained in each case showing that for negligible laser linewidths the delay demodulation method outperforms the dual-filter method by approximately 3 dB, and the single-filter method by 6 dB. Since the noise bandwidth for minimum-shift keying (MSK) and delay demodulation is approximately twice as small as for the other methods, one should add another 3 dB to get the gain for that modulation/demodulation method. The influences of nonzero laser linewidth, noise correlation, and the nonGaussian character of the probability density functions of the noise at the sampler are taken into account     

BER evaluation and rate matching attribute selection for QoS support on the UMTS downlink

In UMTS technology, Coded Composite Transport Channels (CCTrCh-s) are used to carry multiple Transport Channels (TrCh-s) in parallel on (usually) one physical layer connection. Rate Matching Attributes (RMA-s) are used to share the CCTrCh resources among the transport channels. We consider I transport channels on the downlink of a UMTS network, with RMA values RMA ₁,RMA ₂,…,RMA _I . The QoS experienced by the multiplexed connections depends on the RMA values used. We derive analytical expressions for the Bit Error Probabilities (BER-s) seen by each uncoded TrCh in the multiplex when transmitted over an AWGN and a multipath channel. Simulations indicate that the expressions are very accurate. Next, we derive analytical expressions for bounds on the per-channel bit error probabilities seen when convolutional coding is employed by each channel and the multiplex is transmitted over an AWGN and a multipath channel, respectively. The derivation of these analytical expressions is the main contribution of this paper. Further, we use the expressions to obtain simple procedures that provide the RMA values required to achieve a target set of BER-s for a specified signal-to-noise ratio. The results of this paper indicate how differentiated QoS may be provided while maintaining high spectral efficiency. R. M. Karthik is currently a Ph.D. candidate in the Centre for Electronics Design and Technology, Indian Institute of Science, Bangalore, India. He received his B. E. (Electronics and Communication Engineering) from Government College of Technology, Coimbatore, India in 1998 and M. E. (Applied Electronics) from College of Engineering, Guindy, Anna University, India in 2000. His current research interests include communication networks and QoS in UMTS Networks. Joy Kuri has a B.E. in Electronics and Telecommunication engineering from Jadavpur University, Kolkata. After a year in the industry, he joined the M.E. program in the Department of Electrical Communication Engineering at the Indian Institute of Science. He went on to receive a Ph.D. from the same department at IISc in 1995. Subsequently, he spent two years at Ecole Polytechnique, University of Montreal, Canada and one and a half years in INRS-Telecommunications, University of Quebec, Canada as a Research Associate. Since 1999 he has been with the Centre for Electronics Design and Technology, Indian Institute of Science, where he is currently Associate Professor. His research and teaching interests are in the areas of modelling, analysis and control of communication networks and stochastic systems. He is co-author of the book Communication Networking: An Analytical Approach by Kumar, Manjunath and Kuri, published by Morgan Kaufman/Elsevier.     

BER estimation for all-optical regenerators influenced by patterneffects

An efficient method is presented for the estimation of the bit-error rate (BER) of a system employing all-optical regenerators influenced by pattern effects. We theoretically study noise accumulation and noise redistribution in long distance transmission systems employing a delayed interference signal wavelength converter for all-optical regeneration. The BER is studied for return-to-zero signals at bit rates of 2.5 Gb/s (no patterning) up to 40 Gb/s (strong patterning). The calculation of the BER is based on pattern dependent transfer functions, which may be obtained numerically or measured     

WDM网络中波长信道的误码率估计

本文建立了完整的WDM光网络节点的同频串扰理论分析模型，考虑光放大器ASE噪声的影响，采用重要性采样技术进行数值仿真，得出某一波长信道中串扰导致的误码率，讨论波长个数、同源串扰数及消光比等因素对系统性能的影响，并与高斯近似法的结果进行了比较。     

Semianalytic BER for PSK

Semianalytic bit error rate (BER) estimation is a well-known method for evaluating the BER of a digital communication system. The main utility of the method is the significant time savings in computation relative to Monte Carlo simulation. Despite this advantage, no known reference defines the procedure for computing exact BER for M-ary phase shift keying (PSK) with ISI and AWGN using the semianalytic method. This letter defines an efficient procedure for computing exact semianalytic BER for modulation formats with circular constellations when the noise component of the decision variable has a circularly symmetric Gaussian distribution. The technique is demonstrated for 8PSK over the Digital Video Broadcasting-Satellite-Second Generation (DVB-S2) channel.     

平行耦合微带线带通滤波器的设计仿真与测试

在ADS软件的辅助下,设计出了一种应用于1IGHz频段数字微波传榆系统室外单元,中心频率为11GHz,带宽为1．5GHz的平行耦合微带线带通滤波器,并进行了实物测试,测试的S参数与仿真优化结果及指标要求吻合较好。     

Comments on "Effect of system imperfections on BER performance of a CDMA receiver with multipath diversity combining"

For original paper see Panicker, J. and Kumar, S., ibid., vol.45, p.622-30 (1996). In Panicker and Kumar's paper, a direct-sequence (DS) code-division multiple-access (CDMA) system with imperfections in power control, channel parameter, and spreading code-phase estimation was analyzed. The received signal power was modeled by a log-normally distributed random variable and the estimation errors were assumed to be zero-mean Gaussian-random variables. With Gaussian approximation, the bit error rate (BER) performance for such a multipath combining receiver was obtained. However, several errors (apparently due to incomplete proofreading) have been found in the performance analysis. These are noted and corrected.     

Universal curves for bandpass filters

Universal curves are presented which permit the determination of bandpass poles when band-edge frequencies and low-pass poles are known. These curves are also useful for band-reject filters.     

BER evaluation for phase and polarization diversity opticalhomodyne receivers using noncoherent ASK and DPSK demodulation

An analysis of the performance of phase diversity receivers using amplitude-shift keying (ASK) and differential phase-shift keying (DPSK) is presented. Both {2×2} and {3×3} multiport receivers are investigated. Asymptotic methods are used to estimate the bit error rate (BER) and signal-to-noise power ratio (SNR) dependence for each type of the receiver. The analysis favors the squarers as the demodulators for ASK whose performance approaches that of the ideal heterodyne detector in the limit of large SNR. A modification of the ASK ({3×3}) receiver which cancels the local oscillator intensity noise is proposed. Receivers which comprise polarization and phase diversity techniques are also investigated for both ASK and DPSK. Their performance is independent of the polarization state of the received signal, and the value of SNR required to obtain the BER of 10^-9 is only a few tenths of a decibel greater than that needed by the phase diversity receivers