Accurate analysis of spectral regrowth of nonlinear power amplifier driven by cyclostationary modulated signals

Majidi, Mahdi; Mohammadi, Abbas; Abdipour, Abdolali

doi:10.1007/s10470-012-9986-5

Cited by 12 publications

(10 citation statements)

References 17 publications

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“…Also, we consider only the odd-order terms in (6) since the even-order terms cause a further decrease in the spectral regrowth [43]. Similar to [12,13,44], we assume that the order of non-linearity is three, that is K = 1 and neglect the effect of high order terms.By plugging ( 5) into (6), we get…”

Section: System Modelmentioning

confidence: 99%

Analysis of spectral efficiency for OFDM cooperative cognitive networks with non‐linear relay

2021

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This paper analyzes the downlink achievable spectral efficiency of an orthogonal frequency-division multiplexing (OFDM) cooperative cognitive network with a non-linear relay. The analysis is carried out subject to the power amplifier's (PA) non-linear effect on the relay node which operates in the amplify-and-forward (AF) mode. Specifically, an analytical expression for the power spectral density (PSD) of relay output in terms of its source power is derived. By using the obtained PSD, the power of relay's PA output is derived for each subcarrier and the 1 dB compression point is determined. Then, the adjacent channel power (ACP) of each subcarrier is analytically derived in terms of secondary user (SU) source input power. Next, the signal to interference and noise ratio (SINR) of each subcarrier at destination (SU receiver) is calculated by considering the non-linear effect of PA at the relay. Having the SINRs of all subcarriers, a constrained optimization problem on the source's input power is formulated in which the achievable spectral efficiency is the objective function and all ACPs being less than the interference temperature limit are its constraints. Finally, we perform some simulations and show that the numerical results are consistent with the analytical findings.

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Section: System Modelmentioning

confidence: 99%

Analysis of spectral efficiency for OFDM cooperative cognitive networks with non‐linear relay

2021

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“…By considering a third‐order polynomial model for the PA, the maximum spectral regrowth is up to 3 B as illustrated also in Figure B. The exact out‐of‐band power at right or left adjacent subcarrier of n th subcarrier because of the nonlinear PA of k th user, can be expressed as

P_{A C} false(p_{k, n} false) = E_{n} μ p_{k, n}^{3},

where μ is a function of nonlinear PA coefficients. The auxiliary variable E n is 1 when n th subcarrier is not used by any of the PUs (or is used by SUs) and is 0 otherwise.…”

Section: System Modelmentioning

confidence: 99%

“…One common way to model a nonlinear PA is a polynomial function. The exact expressions for inband and out‐of‐band power of a nonlinear amplifier are derived in the previous study . Accordingly, the results of nonlinearity analysis are used for power allocation of a single user cognitive radio in another reference in which instantaneous and average signal‐to‐noise ratio are maximized.…”

Section: Introductionmentioning

confidence: 99%

“…The exact expressions for inband and out-of-band power of a nonlinear amplifier are derived in the previous study. 24 Accordingly, the results of nonlinearity analysis are used for power allocation of a single user cognitive radio in another reference 25 in which instantaneous and average signal-to-noise ratio are maximized. In the work of Baghani et al, 26 the rate of a SU in an OFDM-based cognitive radio system is optimized.…”

Section: Introductionmentioning

confidence: 99%

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Uplink resource allocation in multiuser multicarrier cognitive radio networks under power amplifier nonlinearity

Baghani

Mohammadi

Majidi

et al. 2017

Trans. Emerging Tel. Tech.

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In this paper, the nonlinear distortion effects of power amplifiers are studied, in particular from uplink subcarrier and power allocation perspectives in multiuser multicarrier cognitive networks. The out‐of‐band emissions of a nonlinear power amplifier create interference to the other users. The target is then to maximize the achievable uplink rate in a multiuser multicarrier cognitive network where a cognitive user should not introduce interference to the other users more than a specified threshold level, called interference power constraint. This task is formulated as a convex optimization problem with interference power constraints. Obtaining a closed‐form solution for this problem is, however, not feasible due to its nonlinear nature. Accordingly, the problem is solved numerically, and extensive simulations are conducted to obtain performance results. The obtained results are also compared with a more simple heuristic approach. The results show that the proposed scheme provides a maximum rate while at the same time also guaranteeing that the interference levels are lower than the specified interference power constraint. The results also indicate that the maximum rate can be closely approximated by using the assisted or optimization‐directed heuristic approach.

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“…In general, for a closed-form expression for the autocovariance function of the PA output, its Fourier transform yields the output power spectral density function. Usual nonlinear effects on the transmitted OFDM signal are spectral spreading of the OFDM signal and warping of the signal constellation in each signal [20, 21]. We believe that our proposed scheme is generalized enough to incorporate with the nonlinear PA spectral models.…”

Section: The Proposed Ga-based Interference Control Schemementioning

confidence: 99%

Dynamic Interference Control in OFDM-Based Cognitive Radio Network Using Genetic Algorithm

Khan

Yoo

2015

International Journal of Distributed Sensor Networks

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In OFDM-based cognitive radio networks, minimizing the interference caused to the primary user (PU) by the substantial amount of out-of-band (OOB) emission is a great challenge. In this paper, we propose a dynamic interference control method using the additive signal side lobe reduction technique and genetic algorithm (GA) in CR-OFDM systems. Additive signal side lobe reduction technique is based on adding a complex array to modulated data symbols in the constellation plane for side lobe reduction in OFDM system. In the proposed method, GA generates optimum additive signal which can effectively reduce the OOB signal interference to the primary system. The GA also strives to keep the interference below a predefined tolerable limit and at the same time it maximizes secondary user's transmission opportunity. The results show that the side lobes of the OFDM-based secondary user signal can be reduced by up to 38 dB and the PU interference tolerable limit can be satisfied at the cost of a minor addition in bit error rate (BER). The results further show that the proposed method delivers better performance as compared to non-GA additive signal method in terms of side lobe reduction as well as BER.

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Accurate analysis of spectral regrowth of nonlinear power amplifier driven by cyclostationary modulated signals

Cited by 12 publications

References 17 publications

Analysis of spectral efficiency for OFDM cooperative cognitive networks with non‐linear relay

Analysis of spectral efficiency for OFDM cooperative cognitive networks with non‐linear relay

Uplink resource allocation in multiuser multicarrier cognitive radio networks under power amplifier nonlinearity

Dynamic Interference Control in OFDM-Based Cognitive Radio Network Using Genetic Algorithm

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