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10th International ITG Conference on Systems, Communications and Coding, SCC 2015

作者： Munir, Jawad Mezghani, Amine Khawar, Haris Slim, Israa Nossek, Josef A. Institute for Circuit Theory and Signal Processing Technical University Munich Germany

ISBN: (纸本)9783800736591

A long-haul transmission of 100 Gb/s without optical chromatic-dispersion (CD) compensation provides a range of benefits regarding cost effectiveness, power budget, and nonlinearity tolerance. The channel memory is largely dominated by CD in this case with an intersymbol-interference spread of more than 100 symbol durations. In this paper, we propose CD equalization technique based on nonmaximally decimated discrete Fourier transform (NMDFT) filter bank (FB) with non-trivial prototype filter and complex-valued infinite impulse response (IIR) all-pass filter per sub-band. The design of the sub-band IIR all-pass filter is based on minimizing the mean square error (MSE) in group delay and phase cost functions in an optimization framework. Necessary conditions are derived and incorporated in a multi-step and multi-band optimization framework to ensure the stability of the resulting IIR filter. It is shown that the complexity of the proposed method grows logarithmically with the channel memory, therefore, larger CD values can be tolerated with this approach. © VDE VERLAG GMBH · Berlin · Offenbach.

关键词： All-pass filters

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On physical limits of massive MISO systems 20

On physical limits of massive MISO systems

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20th International ITG Workshop on Smart Antennas, WSA 2016

作者： Ivrlač, Michel T. Nossek, Josef A. Institute for Circuit Theory and Signal Processing Technische Universität München MunichD-80333 Germany

ISBN: (纸本)9783800741779

We analyze the performance of a fixed-size uniform circular array which is used to transmit information to a single antenna receiver as a function of the number of transmit side antennas. We find that the minimum necessary energy to transfer one information bit stops decreasing once the number of antennas grows over a certain bound. We relate this bound to the diameter of the array and show that there is an optimum and finite number of antennas for every such array. For large array diameters this optimum number grows linearly with the diameter, the factor of proportionality primarily depending on whether the receiver is inside or outside of the transmit uniform circular array. © VDE VERLAG GMBH · Berlin · Offenbach, Germany.

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Channel capacity comparison of different system concepts for mmWave 20

Channel capacity comparison of different system concepts for...

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20th International ITG Workshop on Smart Antennas, WSA 2016

作者： Roth, Kilian Garcia, Javier Munir, Jawad Faerber, Michael Nossek, Josef A. Next Generation and Standards Intel Deutschland GmbH Neubiberg Germany Institute for Circuit Theory and Signal Processing Technical University Munich Munich Germany

ISBN: (纸本)9783800741779

For 5G it will be important to leverage the available millimeter wave spectrum. Communication at high carrier frequencies requires antenna arrays at both the base and mobile station. A 1-bit analog to digital converter can effectively reduce the complexity and power consumption of the analog receiver frontend. This is especially interesting in the context of large antenna arrays with a sizable signal bandwidth. The RF receiver frontend power consumption of analog beamforming, full resolution ADC digital beamforming, and 1-bit quantized digital beamforming are compared. This power model consists of components designed for the 60 GHz band. With this power model systems with equal power consumption, and therefore different numbers of antennas, are compared in terms of channel capacity. In the low SNR regime the performance of the system with 1-bit quantization outperforms the ones with full resolution ADC digital beamforming and analog beamforming. © VDE VERLAG GMBH · Berlin · Offenbach, Germany.

关键词： Beamforming

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Tensor-based approach for time-delay estimation 20

Tensor-based approach for time-delay estimation

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20th International ITG Workshop on Smart Antennas, WSA 2016

作者： Hammoud, Bilal Antreich, Felix Nossek, Josef A. Da Costa, João Paulo C.L. De Almeida, André L.F. Institute for Communications and Navigation Wessling Germany Institute for Circuit Theory and Signal Processing Technical University Munich Munich Germany Brasília Distrito Federal Brazil Fortaleza Brazil

ISBN: (纸本)9783800741779

Multipath (ML) signals reflected from the surrounding objects of a Global Navigation Satellite Systems (GNSS) receiver lead to a bias in the time-delay estimation of the line-of-sight (LOS) signal. In several cases, this bias is reflected as errors in the pseudo-range estimation of the receiver. In this paper, we derive a tensor-based filtering approach using an antenna array and a compression method based on canonical components (CC) with a bank of signal matched correlators in order to mitigate multipath and to estimate the time-delay of the LOS signal of a GNSS satellite. First, we resort to multidimensional filtering based on the principal singular vectors of the multi-dimensional data. In order to separate highly correlated signal components in the multi-dimensional signal subspace methods like forward-backward averaging (FBA), spatial smoothing (SPS), and the recently developed expanded spatial smoothing (SPS-EXP) are applied. Afterwards, time-delay estimation of the LOS signal is performed with a simple interpolation based on the multi-dimensional filtered cross-correlation values of the bank of correlators. An advantage of such an approach is that no multidimensional nonlinear problems need to be solved and also no model order estimation is required. © VDE VERLAG GMBH · Berlin · Offenbach, Germany.

关键词： Time delay

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Orthogonal frequency division multiplexing for spectrally efficient Nyquist WDM systems 18

Orthogonal frequency division multiplexing for spectrally ef...

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18th International OFDM Workshop 2014, InOWo 2014

作者： Slim, Israa Xie, Changsong Nossek, Josef A. Institute for Circuit Theory and Signal Processing Technische Universität München Munich Germany European Research Center Huawei Technologies Duesseldorf GmbH Munich Germany

ISBN: (纸本)9783800735891

In order to meet the increasing demand on high data rate in the backbone optical networks, we choose offset QAM Nyquist Wavelength Division Multiplexing (OQAM N-WDM) as the technique to increase the spectral efficiency (SE) of fiber-optic WDM transmission systems. To get intersymbol interference (ISI)-free transmission, root-raised-cosine (RRC) pulses are used in the transmitter. To get interchannel interference (ICI) free transmission, OQAM is employed as modulation scheme enabling the multiplexing of the users' channels with a spacing equal to the symbol rate and thus achieving the highest SE. The performance is evaluated for this system propagating over a linear chromatic dispersion (CD) channel. Simulation results show that the required optical SNR (ROSNR) at BER of 10−3 for back-to-back connection of the transmitter and receiver meets the theoretical value of OSNR for QPSK transmission i.e. ROSNR = 13.3 dB. © VDE VERLAG GMBH ∙ Berlin ∙ Offenbach

关键词： Quadrature amplitude modulation

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Weighted sum rate maximization for multi-user MISO systems with low resolution digital to analog converters 20

Weighted sum rate maximization for multi-user MISO systems w...

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20th International ITG Workshop on Smart Antennas, WSA 2016

作者： Kakkavas, Anastasios Munir, Jawad Mezghani, Amine Brunner, Hans Nossek, Josef A. Institute for Circuit Theory and Signal Processing Technical University of Munich Munich80290 Germany Huawei Technologies Duesseldorf GmbH European Research Center Munich80992 Germany Technical University of Munich Germany

ISBN: (纸本)9783800741779

We study the problem of downlink beamforming for the Weighted Sum Rate maximization (WSR) of Multi-User Multiple-Input-Single-Output systems with low-resolution Digital-to-Analog Converters (DACs) in a single-cell setup. The DACs, modeled as quantizers, are performing a nonlinear operation on the signals and are linearized using Bussgang decomposition and a linear approximation of the covariance of quantized signals. For the maximization of the WSR of the linearized system, we propose a gradient-based solution and a lower-complexity heuristic solution, based on the structure of the globally optimal solution. Through numerical simulations, we show that taking quantization into account in the filter design results in significant performance improvement when the number of transmit antennas is comparable to the number of users. When the number of transmit antennas becomes much larger than the number of users, it is found that the heuristic solution achieves near-optimal performance and that a quantization-aware design becomes less important. © VDE VERLAG GMBH · Berlin · Offenbach, Germany.

关键词： Linearization

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Downlink precoder and equalizer designs for multi-user MIMO FBMC/OQAM 20

Downlink precoder and equalizer designs for multi-user MIMO ...

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20th International ITG Workshop on Smart Antennas, WSA 2016

作者： De Candido, Oliver Cheema, Sher Ali Baltar, Leonardo G. Haardt, Martin Nossek, Josef A. Institute for Circuit Theory and Signal Processing Technische Universität München Munich80290 Germany Communications Research Laboratory Ilmenau University of Technology P.O. Box 100565 IlmenauD-98684 Germany Next Generation and Standards Intel Deutschland GmbH Am Campeon 10-12 Neubiberg85579 Germany

ISBN: (纸本)9783800741779

In this contribution we propose two new iterative precoder and equalizer designs for the Downlink (DL) scenario of Multi-User (MU)-MIMO systems which employ Filter Bank based Multi-Carrier (FBMC) with Offset-Quadrature Amplitude Modulation (O-QAM). In a MU-MIMO DL scenario, we must design our per-subcarrier filters to compensate the inter-symbol and inter-carrier interference (ISI and ICI) present in an FBMC/OQAM system in addition to multi-user interference (MUI). The first method presented takes advantage of the Mean Squared Error (MSE)-duality to design Minimum MSE (MMSE)-based precoders and equalizers. The second method looks at maximizing the signal-to-Leakage Ratio (SLR) in the transmitter and the signal-to-Interference plus Noise Ratio (SINR) in the receiver. Through numerical simulations we will evaluate the performance of these methods and compare them to recent approaches found in the literature. © VDE VERLAG GMBH · Berlin · Offenbach, Germany.

关键词： Equalizers

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Power- and spectral efficient communication system design using 1-bit quantization

arXiv

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arXiv 2017年

作者： Jedda, Hela Ayub, Muhammad Mudussir Munir, Jawad Mezghani, Amine Nossek, Josef A. Institute for Circuit Theory and Signal Processing Munich University of Technology Munich80290 Germany

Improving the power efficiency and spectral efficiency of communication systems has been one of the major research goals over the recent years. However, there is a tradeoff in achieving both goals at the same time. In this work, we consider the joint optimization of the power amplifier and a pulse shaping filter over a single-input single-output (SISO) additive white Gaussian noise (AWGN) channel using 1-bit analog-to-digital (ADC) and digital-to-analog (DAC) converters. The goal of the optimization is the selection of the optimal system parameters in order to maximize the desired figure-of-merit (FOM) which is the product of power efficiency and spectral efficiency. Simulation results give an insight in choosing the optimal parameters of the pulse shaping filter and power amplifier to maximize the desired FOM. Copyright © 2017, The Authors. All rights reserved.

关键词： Power amplifiers

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Mmse precoder for massive mimo using 1-bit quantization

arXiv

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arXiv 2017年

作者： Bin Usman, Ovais Jedda, Hela Mezghani, Amine Nossek, Josef A. Institute for Circuit Theory and Signal Processing Technische Universität München Munich80290 Germany

We propose a novel linear minimum-mean-squared-error (MMSE) precoder design for a downlink (DL) massive multiple-input-multiple-output (MIMO) scenario. For economical and computational efficiency reasons low resolution 1-bit digital-to-analog (DAC) and analog-to-digital (ADC) converters are used. This comes at the cost of performance gain that can be recovered by the large number of antennas deployed at the base station (BS) and an appropiate precoder design to mitigate the distortions due to the coarse quantization. The proposed precoder takes the quantization non-linearities into account and is split into a digital precoder and an analog precoder. We formulate the two-stage precoding problem such that the MSE of the users is minimized under the 1-bit constraint. In the simulations, we compare the new optimized precoding scheme with previously proposed linear precoders in terms of uncoded bit error ratio (BER). Copyright © 2017, The Authors. All rights reserved.

关键词： MIMO systems

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DFE/THP duality for FBMC with highly frequency selective channels

arXiv

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arXiv 2017年

作者： Jedda, Hela Baltar, Leonardo G. de Candido, Oliver Mezghani, Amine Nossek, Josef A. Institute for Circuit Theory and Signal Processing Technische Universität München Munich80290 Germany

Filter bank based multicarrier with Offset-QAM systems (FBMC/OQAM) are strong candidates for the waveform of future 5-th generation (5G) wireless standards. These systems can achieve maximum spectral efficiency compared to other multicarrier schemes, particularly in highly frequency selective propagation conditions. In this case a multi-tap, fractionally spaced equalizer or precoder needs to be inserted in each subcarrier at the receiver or transmitter side to compensate inter-symbol interference (ISI) and inter-carrier interference (ICI). In this paper we propose a new Tomlinson-Harashima precoder (THP) design for FBMC/OQAM based on the mean squared error (MSE) duality from a minimum MSE (MMSE) designed decision feedback equalizer (DFE). Copyright © 2017, The Authors. All rights reserved.

关键词： Mean square error

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