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 OFDM PAPR reduction for image transmission using improved tone reservation

2021 ◽  
Vol 11 (1) ◽  
pp. 416
Author(s):  
Zainab Noori Ghanim ◽  
Buthaina M. Omran
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Image Transmission ◽  
Low Complexity ◽  
Papr Reduction ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm System ◽  
Tone Reservation ◽  
The Cost

High peak to average power ration (PAPR) in orthogonal frequency division multiplexing (OFDM) is an important problem, which increase the cost and complexity of high power amplifiers. One of the techniques used to reduce the PAPR in OFDM system is the tone reservation method (TR). In our work we propose a modified tone reservation method to decrease the PAPR with low complexity compared with the conventional TR method by process the high and low amplitudes at the same time. An image of size 128×128 is used as a source of data that transmitted using OFDM system. The proposed method decrease the PAPR by 2dB compared with conventional method with keeping the performance unchanged. The performance of the proposed method is tested with several numbers of subcarriers; we found that the PAPR is reduced as the number of subcarriers decreased.

scholarly journals A REVIEW OF NOVEL APPROACH FOR REDUCTION IN SUB CARRIER PEAK TO AVERAGE POWER RATIO IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING

2020 ◽  
Vol 5 (2) ◽  
pp. 114-122
Author(s):  
Manju Sangar ◽  
Professor Brijendra Mishra ◽  
Professor Bhupendra Verma
Keyword(s):  
High Power ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
High Mobility ◽  
Low Complexity ◽  
Multimedia Data ◽  
Papr Reduction ◽  
Frequency Division Multiplexing ◽  
Power Ratio ◽  
Frequency Division

In last few decades the demand for multimedia data services has grown up fastly. One of the most promising multicarrier system, Orthogonal Frequency Division Multiplexing (OFDM) allow large number of capacity the number of subcarriers, high data rates and ubiquitous coverage with high mobility. But OFDM is extensively affected by peak to average power ratio (PAPR). Unfortunately, the high PAPR inherent to OFDM signal envelopes will frequently drive high power amplifiers (HPAs) which are operate in the nonlinear region. The nonlinearity of the High Power Amplifier exhibits phase and amplitude distortions, which causes loss of orthogonality between the subcarriers; also (ICI) is introduced in the source signal. This dissertation is basically focused on PAPR reduction in OFDM system and measuring BER in different Modulation Technique. In PAPR reduction Signal companding methods have low complication, high distortion and spectral properties; however, we have limited PAPR reduction capabilities. Partial transmit sequences (PTS) and selected mapping (SLM), have also been considered for PAPR reduction. Such kind of techniques are very efficient and distortion less, Also the SLM is very good technique to the PAPR problem in single carrier system. This method has low complexity as well as it is data independent. In this paper, we are describing a combine technique of SLM and PTS to minimize the PAPR. In PTS scheme, number of sub blocks increases; the IFFT block to be performed for sub blocks also increases. Simulation results have shown that the reductions of PAPR of proposed scheme is more than PTS and SLM methods as well as the difficulty reduced considerably.

scholarly journals Architecture Optimization for Filtered Multicarrier Waveforms in 5G

2021 ◽  
Author(s):  
Muhammad Abid ◽  
Farman Ali ◽  
Ammar Armghan ◽  
Fayadh Alenezi ◽  
Sharoz Khan ◽  
...  
Keyword(s):  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Clean Energy ◽  
Low Complexity ◽  
Smart Devices ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Data Traffic ◽  
Wireless Communication Network

Abstract Wireless communication network is the backbone of each and every organization of today modern globe. The rapid emergence of smart devices, smart homes, internet of things and clean energy become key sources in today society. In result the data traffic, emerging of new service and application are increase every year. Hence, there is a growing demand for 5G technology in all above mentioned fields. Therefore, better waveform types for 5G technology is needed, which has ability of high spectral efficiency, lower latency and less complexity. It is predicted that the data traffic will arise 1000x in near future. In this work filtered orthogonal frequency division multiplexing (F-OFDM) and universal filtered orthogonal frequency division multiplexing (UF-OFDM) techniques will be discussed to degrade key issues such as computational complexity, peak average power ratio (PAPR), lower spectral efficiency, and higher latency. The suggested work will clearly overcome the drawbacks faced by previous work like limited capacity and complexity. We also analyze algorithms and simplification for F-OFDM and UF-OFDM waveforms from an implementation perspective towards low complexity and efficient transceiver
design. Moreover, F-OFDM and UF-OFDM will be mainly based on multicarrier modulation and will be enabled to reduce to out-of-band power leakage (OOBPL) of OFDM.

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