Spectral analysis of GFDM modulated signal under nonlinear behavior of power amplifier
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Spectral analysis of GFDM modulated signal under nonlinear behavior of power amplifier Amirhossein Mohammadian1
•
Abbas Mohammadi1 • Abdolali Abdipour1 • Mina Baghani2
Ó Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Generalized frequency division multiplexing (GFDM) is a flexible non-orthogonal waveform candidate for 5G which can offer some advantages such as low out-of-band emission and high spectral efficiency. This paper investigates the effects of nonlinear behavior of practical power amplifier (PA) on the GFDM spectrum. A closed form expression for power spectral density (PSD) of GFDM signal is extracted. Then, PSD at the output of PA as a function of input power and the coefficients of nonlinear polynomial PA model is derived. In addition, the adjacent channel power (ACP) and ACP ratio, as two important performance metrics, are evaluated. The simulation results confirm the accuracy of derived analytical expressions. Moreover, to validate the performance of GFDM modulation after nonlinear PA, it is compared with orthogonal frequency division multiplexing modulation. Keywords 5G GFDM modulation Power amplifier nonlinearity Power spectral density Adjacent channel interference Saturation and 1 dB compression points
1 Introduction Wide range of applications such as internet of things (IoT), machine-to-machine (M2M) communication, vehicle-tovehicle (V2V) communication, tactile internet and cognitive radio are turning points in emergence of next generation wireless cellular networks (5G) [1]. For accomplishing these applications implementation, the next generation of the wireless systems must overcome the challenges such as
& Amirhossein Mohammadian [email protected]; [email protected] Abbas Mohammadi [email protected] Abdolali Abdipour [email protected] Mina Baghani [email protected] 1
Microwave/Millimeter-Wave and Wireless Communications Research Laboratory, Electrical Engineering Department, Amirkabir University of Technology, Tehran, Iran
2
Faculty of Technical and Engineering, Imam Khomeini International University, Qazvin, Iran
lower power consumption, higher spectral efficiency, lower out-of-band (OOB) emission and lower latency compared to the previous generation of wireless communication systems [2–4]. Indispensable role of modulation technique in addressing these requirements is undeniable. Orthogonal frequency division multiplexing (OFDM) scheme is a common multi-carrier modulation which is used in physical layer of the modern cellular communication system. In spite of its simple implementation, it cannot deal with all vital requirements of 5G. Solid synchronization requirement in order to keep the orthogonality of OFDM subcarriers impose higher power consumption [5]. Moreover, by adding cyclic prefix to each OFDM symbol, obtaining high throughput is not easily achievable [6]. In addition, high OOB emission of OFDM [7] is absolutely inefficient for cognitive radio networks and multip
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