scholarly journals Practical Evaluations of SEFDM: Timing Offset and Multipath Impairments

2018 ◽  
pp. 2-9
Author(s):  
Tongyang Xu ◽  
Hedaia Ghannam ◽  
Izzat Darwazeh
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Additive White Gaussian Noise ◽  
Joint Effect ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Timing Offset ◽  
Channel Conditions ◽  
Selective Channel ◽  
Frequency Selective ◽  
The Cost

The non-orthogonal signal waveform spectrally efficient frequency division multiplexing (SEFDM) improves spectral efficiency at the cost of self-created inter carrier interference (ICI). As the orthogonal property, similar to orthogonal frequency division multiplexing (OFDM), no longer exists, the robustness of SEFDM in realistic wireless environments might be weakened. This work aims to evaluate the sensitivity of SEFDM to practical channel distortions using a professional experiment testbed. First, timing offset is studied in a bypass channel to locate the imperfection of the testbed and its impact on SEFDM signals. Then, the joint effect of a multipath frequency selective channel and additive white Gaussian noise (AWGN) is investigated in the testbed. Through practical experiments, we demonstrate the performance of SEFDM in realistic radio frequency (RF) environments and verify two compensation methods for SEFDM. Our results show first frequency-domain compensation works well in frequency non-selective channel conditions while time-domain compensation method is suitable for frequency selective channel conditions. This work paves the way for the application of SEFDM in different channel scenarios.

The Diversity Gains of Amplify-and-Forward Relay System with Frequency Selective Channels

2014 ◽  
Vol 644-650 ◽  
pp. 4297-4302
Author(s):  
Y.H. Ding ◽  
R.J. Tian ◽  
K. Xue ◽  
Y. Tian ◽  
X.C. Wang ◽  
...  
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Amplify And Forward ◽  
Relay System ◽  
Relay Systems ◽  
Frequency Selective ◽  
Multiple Relay ◽  
Frequency Selective Channels ◽  
Diversity Gains

The diversity gains of amplify-and-forward (AF) relay system with frequency selective channels are discussed. The orthogonal frequency division multiplexing (OFDM) is applied to overcome the inter-symbol interference. The diversity gains are presented for single and multiple relay systems with detailed derivations.

PHYSICAL LAYER OF A BASE-BAND OFDM MODEM: ALGORITHMS AND PERFORMANCE

2005 ◽  
Vol 14 (03) ◽  
pp. 631-651
Author(s):  
ARISTODEMOS PNEVMATIKAKIS ◽  
SPYROS BLIONAS ◽  
DIMITRIS TRIANTIS
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Wireless Networking ◽  
Physical Layer ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Channel Conditions ◽  
Digital Broadcasting ◽  
And Performance ◽  
Base Band

The base-band section of a modem employing Orthogonal Frequency Division Multiplexing (OFDM) is described in this paper. It utilizes the necessary algorithms to combat distortion due to the channel conditions and imperfect synchronization. A model describing these distortions is used to derive the algorithms. The system is realized in a prototype platform for the HIPERLAN/2 standard, but modifications for compliance to other broadband digital broadcasting and wireless networking OFDM systems are proposed. The performance of the prototype base-band modem is described.

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 Novel GFDM Waveform Design Based on Cascaded WHT-LWT Transform for the Beyond 5G Wireless Communications

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1831
Author(s):  
Meryem Maraş ◽  
Elif Nur Ayvaz ◽  
Meltem Gömeç ◽  
Asuman Savaşcıhabeş ◽  
Ali Özen
Keyword(s):  
Fading Channels ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Additive White Gaussian Noise ◽  
Average Power ◽  
Hadamard Transform ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Simulation Results ◽  
Walsh Hadamard Transform

In this paper, a new WHT-LWT-GFDM waveform obtained by combining Walsh–Hadamard Transform (WHT), Lifting Wavelet Transform (LWT), and Generalized Frequency Division Multiplexing (GFDM) is presented for use in next-generation wireless communication systems. The proposed approach meets the requirement of 5th-generation (5G) and beyond communication schemes in terms of low latency, low peak-to-average-power ratio (PAPR), and low bit-error rate (BER). To verify the performance of the presented waveform, PAPR and BER simulation results were obtained in additive white Gaussian noise (AWGN) and flat Rayleigh fading channels, and the performance of the proposed system was compared with conventional Orthogonal Frequency Division Multiplexing (OFDM), GFDM, and Walsh–Hadamard transform-based GFDM (WHT-GFDM). Simulation results show that the proposed waveform achieves the best BER and PAPR performances and it provides considerable performance gains over the conventional waveforms.

scholarly journals Characterization of GFDM Signal with Timing Offset, CFO, Non-Linearity, and PN

2021 ◽  
Author(s):  
Fereshteh Yazdani ◽  
Abbas Mohammadi ◽  
Abdolali Abdipour ◽  
Mohammad Kazemi
Keyword(s):  
Power Amplifier ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Matched Filter ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Synchronization Errors ◽  
Timing Offset ◽  
Nonlinear Power Amplifier

Abstract In this paper, we study the joint effects of timing offset (TO), carrier frequency offset (CFO), nonlinear power amplifier distortion, and phase noise (PN) on generalized frequency division multiplexing (GFDM) system. Closed form expressions for signal-to-interference ratio (SIR) at GFDM receiver with synchronization errors and PN using a nonlinear power amplifier is derived. Then, we have been conducted simulation studies to compare the performance of GFDM systems with orthogonal frequency division multiplexing (OFDM) systems using matched filter (MF) and zero forcing (ZF), in presence of these impairments. The results show that GFDM systems are more robust against TO and PN while they are more sensitive to CFO and nonlinear distortion compared to OFDM systems.

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