scholarly journals Constant Envelope Modulation Techniques for Limited Power Millimeter Wave Links

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1521
Author(s):  
Yael Balal ◽  
Monika Pinchas ◽  
Yosef Pinhasi
Keyword(s):  
Millimeter Wave ◽  
Mobile Communications ◽  
Orthogonal Frequency Division Multiplexing ◽  
Power Transmission ◽  
Average Power ◽  
Symbol Error Rate ◽  
High Energy ◽  
Constant Envelope ◽  
Modulation Techniques ◽  
Link Availability

The demand for increased capacity and link availability for mobile communications requires the utilization of higher frequencies, such as millimeter waves at extremely high frequencies (EHFs) above 30 GHz. In this regime of frequencies, the waves are subjected to high atmospheric attenuation and dispersion effects that lead to a degradation in communication reliability. The fact that solid-state millimeter and sub-millimeter wave sources are producing low power calls for effective signaling utilizing waveforms with a low peak to average power ratio (PAPR), such as constant envelope (CE) modulation. The CE techniques present a PAPR of 0 dB resulting in peak power transmission with high energy efficiency. The study of the performances of constant envelope orthogonal modulation techniques in the presence of co-channel interference is presented. The performance is evaluated in terms of the average symbol error rate (SER) using analytical results and simulations. The theory is carried out for the CE-M-ary time orthogonal (CE-MTO) and CE-orthogonal frequency division multiplexing (CE-OFDM), demonstrating comparable performances while leading to a simpler implementation than that of the CE-OFDM.

scholarly journals Forward Transformation from Reactive Near-Field to Near and Far-Field at Millimeter-Wave Frequencies

2020 ◽  
Vol 10 (14) ◽  
pp. 4780
Author(s):  
Serge Pfeifer ◽  
Arya Fallahi ◽  
Jingtian Xi ◽  
Esra Neufeld ◽  
Niels Kuster
Keyword(s):  
Electric Field ◽  
Power Density ◽  
Millimeter Wave ◽  
Mobile Communications ◽  
Average Power ◽  
Spatial Average ◽  
Far Field ◽  
Phase Reconstruction ◽  
Noise Levels ◽  
Wide Range

With the advent of 5G mobile communications at millimeter-wave frequencies, the assessment of the maximum averaged power density on numerous surfaces close to the transmitter will become a requirement. This makes phasor knowledge about the electric and magnetic fields an inevitable requirement. To avoid the burdensome measurement of these field quantities in the entire volume of interest, phase reconstruction algorithms from measurements over a plane in the far-field region are being extensively developed. In this paper, we extended the previously developed method of phase reconstruction to evaluate the near and far-field of sources with bounded uncertainty, which is robust with respect to noisy data and optimized for a minimal number of measurement points at a distance as close as λ /5 from the source. The proposed procedure takes advantage of field integral equations and electric field measurements with the EUmmWVx probe to evaluate the field phasors close to the radiation source and subsequently obtain the field values in the whole region of interest with minimal computation and measurement costs. The main constraints are the maximal noise level regarding the peak electric field and measurement plane size with respect to the percentage of transmitted power content. The measurement of a third plane overcomes some of the noise issues. The method was evaluated by simulations of a wide range of antennas at different noise levels and at different distances and by measurements of four different antennas. A successful reconstruction in the near and far-field was achieved both qualitatively and quantitatively for distances between 2.5–150 mm from the antenna and noise levels of −24 dB from the peak. The deviation of reconstruction from the simulation reference for the peak spatial-average power density with an averaging area of 1 cm 2 was, in all cases, well within the uncertainty budget of 0.6 dB, if the reconstruction planes captured >95% of the total radiated power. The proposed new method is very promising for compliance assessment and can reduce test time considerably.

New Tone Reservation Technique for Peak to Average Power Ratio Reduction

Frequenz ◽  
2014 ◽  
Vol 68 (9-10) ◽  
Author(s):  
Joachim Wilharm ◽  
Hermann Rohling
Keyword(s):  
Computational Complexity ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Peak Position ◽  
High Power Amplifier ◽  
Constant Envelope ◽  
Tone Reservation ◽  
Power Ratio Reduction ◽  
Ratio Reduction ◽  
High Computational Complexity

AbstractIn Orthogonal Frequency Division Multiplexing (OFDM) the transmit signals have a highly fluctuating, non-constant envelope which is a technical challenge for the High Power Amplifier (HPA). Without any signal processing procedures the amplitude peaks of the transmit signal will be clipped by the HPA resulting in out-ofband radiation and in bit error rate (BER) performance degradation. The classical Tone Reservation (TR) technique calculates a correction signal in an iterative way to reduce the amplitude peaks. However this step leads to a high computational complexity. Therefore, in this paper an alternative TR technique is proposed. In this case a predefined signal pattern is shifted to any peak position inside the transmit signal and reduces thereby all amplitude peaks. This new procedure is able to outperform the classical TR technique and has a much lower computational complexity.

Applying an FSK Based Transmission Scheme to Broadband Channels Using Frequency Domain Equalization

Frequenz ◽  
2012 ◽  
Vol 66 (5-6) ◽  
Author(s):  
Dr. Sebastian Georgi ◽  
Prof. Dr. Jürgen Peissig
Keyword(s):  
Energy Efficiency ◽  
Frequency Domain ◽  
Power Amplifier ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal Transmission ◽  
Average Power ◽  
Cyclic Prefix ◽  
Transmission Scheme ◽  
Constant Envelope ◽  
Ber Performance

AbstractEqualization of broadband signals can be efficiently realized in frequency domain. One prominent example is the orthogonal frequency division multiplexing (OFDM) transmission technique. With the introduction of a cyclic prefix and a modulation onto orthogonal subcarriers the equalization can be performed in frequency domain with one tap only. However the extremely high peak to average power ratio of OFDM modulated transmit signals and the demand of linearity inside the signal transmission chain results in a poor energy efficiency at the power amplifier. This paper claims, that as long as a cyclic prefix exists, any receive signal can be equalized in frequency domain.In this paper a transmission scheme with constant envelope is chosen for energy efficiency reasons. Therefore an FSK modulation and gaussian pulse shaping is used to create the transmit signal. Equalization at the receiver is done in frequency domain as known in OFDM. To simplify the equalization, a cyclic prefix is added to the transmit signal as well.This transmission scheme is introduced and evaluated in terms of spectral efficiency and bit error rate (BER) performance in this paper. The comparison is done with a typical OFDM system. In particular the characteristics of a nonlinear power amplifier are considered. It will be shown, that signals with constant envelope such as FSK modulated signals can also make use of an OFDM like equalization procedure with comparable BER performance and spectral requirements.

Performance Comparison of MDFT Filter Bank with OFDM in Multi-Carrier Systems

2014 ◽  
Vol 926-930 ◽  
pp. 1822-1826
Author(s):  
Ling Zhuang ◽  
Ju Ge ◽  
Guang Yu Wang ◽  
Kai Shao
Keyword(s):  
Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Filter Bank ◽  
Average Power ◽  
Symbol Error Rate ◽  
Performance Comparison ◽  
Frequency Division ◽  
System Prototype ◽  
Detailed Derivation ◽  
Carrier Systems

Based on the filter bank, the theory of multi-carrier modulation using Orthogonal Frequency Division Multiplexing (OFDM) and Modified Discrete Fourier Transform (MDFT) filter bank has been discussed and the detailed derivation process has been given. Following these discussions, the actual implementation of MDFT filter bank in multi-carrier modulation systems has been discussed, and then the comparison of their prototype functions, Peak to Average Power Ratio (PAPR) and Symbol Error Rate (SER) are drawn. Experimental results demonstrate that compared with the OFDM system, prototype functions of MDFT have obvious advantage in spectrum leakage. In terms of PAPR, they have similar performance. Whether using QPSK or 16QAM modulation, MDFT is superior to OFDM in symbol error rate as a whole and with increasing of filter length L, the advantage becomes more and more apparent.

scholarly journals Data-Aided Frequency Offset Estimation for CE-OFDM Broadband Satellite Systems

2019 ◽  
Vol 9 (11) ◽  
pp. 2310 ◽  
Author(s):  
Wang Cheng ◽  
Cao Yushi ◽  
Wang Weidong
Keyword(s):  
Network Architecture ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Average Power ◽  
Frequency Offset ◽  
Satellite Systems ◽  
Constant Envelope ◽  
Pilot Symbols ◽  
Estimation Scheme ◽  
Cramer Rao Bound

In recent years, the constant-envelope orthogonal frequency-division multiplexing (CE-OFDM) has been considered as a candidate waveform in broadband satellite systems as it has a 0-dB peak-to-average power ratio (PAPR). However, the carrier frequency offset (CFO) estimation scheme for CE-OFDM broadband satellite systems directly affects system performance. In this paper, we analyze the network architecture and the propagation environment of CE-OFDM broadband satellite systems, and we propose a data-aided CFO estimation strategy based on the frequency domain pilot symbols. The Cramer–Rao bound (CRB) of our CFO estimator is given by mathematical analysis, and the effect of the number of pilot symbols on the estimation performance is analyzed. The pilot symbol-based CFO estimator is composed of a phase demodulator and a discrete Fourier transform (DFT) module, and it can obtain a large estimation range under a small pilot overhead. The simulation results show that the CE-OFDM broadband satellite systems can achieve a good bit error rate (BER) performance by using the proposed strategy to estimate and compensate the CFO.

scholarly journals Algorithm for Decreasing the Large Peak to Average Power Ratio in Mimo-Ofdm

2020 ◽  
Vol 8 (6) ◽  
pp. 2272-2276
Keyword(s):  
Error Rate ◽  
Communication System ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Symbol Error Rate ◽  
Power Ratio ◽  
Mapping Algorithm ◽  
Mimo Ofdm ◽  
Large Maximum

Every personal want to use high speed communication system but bandwidth is limited and users are unlimited in that case some of technologies are use for improving speed. One of the best technology called multiple inputs multiple outputs orthogonal frequency division multiplexing. Which provides very fast communication system but drawback of this technique is large maximum to average power ratio, these reduce efficiency of power amplifier. In this article developed new algorithm, for reduction of large maximum to average power ratio and improve bit or symbol error rate in MIMO-OFDM system. Proposed technique, called filter companding selected mapping algorithm technique (FC-SLM) to reduce PAPR using filtering and companding concept. In this techniques, after modulation of input data are converted into serial to parallel steam, phase mapping of all data from 0 to 360 degrees and perform IFFT operation, calculate PAPR and pass through desire range of filter and select minimum PAPR then perform companding and transmitted through an antenna. This scheme is reduce 2.3 dB PAPR and improve bit or symbol error rate. This is one of the most excellent promising techniques for next generation (5-G) communication system.

scholarly journals Two-Step Multiuser Equalization for Hybrid mmWave Massive MIMO GFDM Systems

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1220 ◽  
Author(s):  
Joumana Kassam ◽  
Manar Miri ◽  
Roberto Magueta ◽  
Daniel Castanheira ◽  
Pedro Pedrosa ◽  
...  
Keyword(s):  
Mobile Communications ◽  
Orthogonal Frequency Division Multiplexing ◽  
Analytical Approach ◽  
Hybrid Approach ◽  
Average Power ◽  
Low Complexity ◽  
Base Station ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Digital Architecture

Although millimeter-wave (mmWave) and massive multiple input multiple output (mMIMO) can be considered as promising technologies for future mobile communications (beyond 5G or 6G), some hardware limitations limit their applicability. The hybrid analog-digital architecture has been introduced as a possible solution to avoid such issues. In this paper, we propose a two-step hybrid multi-user (MU) equalizer combined with low complexity hybrid precoder for wideband mmWave mMIMO systems, as well as a semi-analytical approach to evaluate its performance. The new digital non-orthogonal multi carrier modulation scheme generalized frequency division multiplexing (GFDM) is considered owing to its efficient performance in terms of achieving higher spectral efficiency, better control of out-of-band (OOB) emissions, and lower peak to average power ratio (PAPR) when compared with the orthogonal frequency division multiplexing (OFDM) access technique. First, a low complexity analog precoder is applied on the transmitter side. Then, at the base station (BS), the analog coefficients of the hybrid equalizer are obtained by minimizing the mean square error (MSE) between the hybrid approach and the full digital counterpart. For the digital part, zero-forcing (ZF) is used to cancel the MU interference not mitigated by the analog part. The performance results show that the performance gap of the proposed hybrid scheme to the full digital counterpart reduces as the number of radio frequency (RF) chains increases. Moreover, the theoretical curves almost overlap with the simulated ones, which show that the semi-analytical approach is quite accurate.

scholarly journals Enhanced Next Generation Millimeter-Wave Multicarrier System with Generalized Frequency Division Multiplexing

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Hidekazu Shimodaira ◽  
Joongheon Kim ◽  
Ali S. Sadri
Keyword(s):  
Millimeter Wave ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Papr Reduction ◽  
Frequency Division Multiplexing ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Performance Improvements ◽  
Multicarrier System ◽  
Ieee 802.11Ad

Orthogonal Frequency Division Multiplexing (OFDM) is a popular multicarrier technique used to attain high spectral efficiencies. It also has other advantages such as multipath tolerance and ease of implementation. However, OFDM based systems suffer from high Peak-to-Average Power Ratio (PAPR) problem. Because of the nonlinearity of the power amplifiers, the high PAPR causes significant distortion in the transmitted signal for millimeter-wave (mmWave) systems. To alleviate the high PAPR problem, this paper utilizes Generalized Frequency Division Multiplexing (GFDM) which can achieve high spectral efficiency as well as low PAPR. In this paper, we show the performance of GFDM using the IEEE 802.11ad multicarrier frame structures. IEEE 802.11ad is considered one of the most successful industry standards utilizing unlicensed mmWave frequency band. In addition, this paper indicates the feasibility of using GFDM for the future standards such as IEEE 802.11ay. This paper studies the performance improvements in terms of PAPR reduction for GFDM. Based on the performance results, the optimal numbers of subcarriers and subsymbols are calculated for PAPR reduction while minimizing the Bit Error Rate (BER) performance degradation. Moreover, transmitter side ICI (Intercarrier Interference) reduction is introduced to reduce the receiver load.

Compensation of Non-linear Distortion Effects in MIMO-OFDM Systems Using Constant Envelope OFDM for 5G Applications

2020 ◽  
Vol 29 (16) ◽  
pp. 2050257
Author(s):  
M. El Ghzaoui ◽  
A. Hmamou ◽  
J. Foshi ◽  
J. Mestoui
Keyword(s):  
Power Consumption ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Channel Model ◽  
Average Power ◽  
Base Stations ◽  
Mimo Channel ◽  
Multicarrier Transmission ◽  
Constant Envelope ◽  
Mimo Ofdm

Orthogonal frequency division multiplexing (OFDM) is a multicarrier transmission system that can achieve high data rate over wireless channels. At the same time, multiple input multiple output OFDM (MIMO-OFDM) in wireless communication systems has been exposed to offer significant improvement over wireless technology by providing transmit diversity. It has become a promising technique for high-performance 5G broadband wireless communications. However, the main problem associated with MIMO-OFDM is that its signal exhibits high peak-to-average power ratio (PAPR), which causes nonlinear distortion and consequently performance degradation. Besides, PAPR carries weaknesses such as an increase in power consumption of high power amplifier (HPA) and analog to digital converter (ADC). Thus, 5G base stations will push up power requirements because energy consumption grows with the number of transceiver elements. So, mobile operators must find the right compromise that, on the one hand, guarantees a certain level of performance to a data flow, and, on the other hand, the energy cost generated for the deployment of the network. For this, as part of the management of power consumption, we propose MIMO constant envelope OFDM (MIMO-CE-OFDM) technique. In this work, we used MIMO-CE-OFDM to mitigate the nonlinear effect of HPA and ADC. To perform practical simulations, we have used COST 2100 MIMO channel model. In this paper, a MIMO-CE-OFDM system has been presented and analyzed under COST 2100 channel model conditions. Simulation results are given to illustrate the performance of [Formula: see text] MIMO-CE-OFDM in the presence of both HPA and ADC nonlinearity. This work shows that the effect of nonlinearity is shown to be negligible on MIMO-CE-OFDM signal.

Improving Space-Time-Frequency MIMO-OFDM with ICI Self-Cancellation Scheme using Least Square Error Estimator

2015 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Nur Farahiah Ibrahim ◽  
Zahari Abu Bakar ◽  
Azlina Idris
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Symbol Error Rate ◽  
Space Time ◽  
Least Square ◽  
Error Estimator ◽  
Frequency Diversity ◽  
Time Frequency ◽  
Mimo Ofdm ◽  
Subcarrier Mapping

Channel estimation techniques for Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) based on comb type pilot arrangement with least-square error (LSE) estimator was investigated with space-time-frequency (STF) diversity implementation. The frequency offset in OFDM effected its performance. This was mitigated with the implementation of the presented inter-carrier interference self-cancellation (ICI-SC) techniques and different space-time subcarrier mapping. STF block coding in the system exploits the spatial, temporal and frequency diversity to improve performance. Estimated channel was fed into a decoder which combined the STF decoding together with the estimated channel coefficients using LSE estimator for equalization. The performance of the system was compared by measuring the symbol error rate with a PSK-16 and PSK-32. The results show that subcarrier mapping together with ICI-SC were able to increase the system performance. Introduction of channel estimation was also able to estimate the channel coefficient at only 5dB difference with a perfectly known channel.

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