Optimum and Sub-Optimum Receivers for OFDM Signals with Strong Nonlinear Distortion Effects

Guerreiro, João; Dinis, Rui; Montezuma, Paulo

doi:10.1109/tcomm.2013.072913.120344

Cited by 44 publications

(42 citation statements)

References 20 publications

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“…Recently, another point of view was given to the nonlinear distortion. In [18][19][20] it was demonstrated that the nonlinear distortion has information on the transmitted signals and, instead of being regarded as noise, it can be considered to be useful information that can be harvested by optimum receivers. The optimum detection can provide two types of gain: an energy gain and a diversity gain that can be explored in frequency-selective channels.…”

Section: Optimum Performance Of Ce-ofdm Signalsmentioning

confidence: 99%

“…In order to do that, we focus our attention in the computation of an approximation of the pairwise error probability (PEP), that is related to the squared Euclidean distance between two CE-OFDM signals and can provide an insight to the optimum performance. In this section, we study the squared Euclidean distance between two CE-OFDM signals in both AWGN and frequency-selective channels, and present the correspondent asymptotic BER making use of the results of [19,20].…”

Section: Optimum Performance Of Ce-ofdm Signalsmentioning

confidence: 99%

“…In fact, recent results indicate that the nonlinear distortion component can have a positive effect on the BER performance, since it has information inherent to the transmitted symbols. In fact, by employing optimum or sub-optimum receivers the BER performance of OFDM schemes with strong nonlinear distortion effects can be as good or even better than the BER performance of linear OFDM schemes [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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CE-OFDM Schemes: Spectral Characterization and Optimum Performance

Guerreiro

Dinis

Montezuma

2017

Wireless Pers Commun

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Constant envelope orthogonal frequency division multiplexing (CE-OFDM) techniques have been recently proposed to allow the use of power-efficient saturated amplifiers, since those signals do not have the high peak-to-average ratio of OFDM signals, but maintain most of the OFDM advantages. However, the nonlinear nature of the phase modulation process inherent to CE-OFDM schemes gives rise to both theoretical challenges (analytical difficulties due to the nonlinear processes involved) and practical challenges (spectral widening and possible performance degradation due to nonlinear distortion effects). In this work, we present accurate expressions for the average power spectral density of CE-OFDM signals. Making use of recent results that indicate performance gains associated to the optimum detection of nonlinearly distorted multicarrier signals, we also investigate the optimum detection of CE-OFDM signals considering both additive white Gaussian noise channels and frequency-selective channels with Rayleigh fading, providing theoretical expressions for the asymptotic gains as well as the correspondent approximate bit-error-rate results.

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Section: Optimum Performance Of Ce-ofdm Signalsmentioning

confidence: 99%

Section: Optimum Performance Of Ce-ofdm Signalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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CE-OFDM Schemes: Spectral Characterization and Optimum Performance

Guerreiro

Dinis

Montezuma

2017

Wireless Pers Commun

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“…This approach is better than the SR. However, keeping in mind the fact that the distortions contain information about the transmitted signal, the best approach is to use the whole received signal, including distortions, in the receiver [7].…”

Section: Introductionmentioning

confidence: 99%

“…This approach is also known as the Maximum Likelihood (ML) receiver. A suboptimal solution to the above problem is given in [7]. In this paper we propose a suboptimal solution based on the idea of a class of global minima solutions coupled with a gradient minima search.…”

Section: Introductionmentioning

confidence: 99%

Maximum Likelihood Detection of Nonlinearly Distorted OFDM Signal

Regev¹,

Iofedov²,

Wulich³

2014

2015 IEEE Global Communications Conference (GLOBECOM)

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This paper deals with a Maximum Likelihood receiver for a nonlinearly distorted OFDM signal over a flat channel with AWGN. The nonlinearity destroys the orthogonality between subcarriers, consequently, a per subcarrier decision, used when the linear PA is considered, is no longer optimal. We propose a sub-optimal receiver based on the Maximum Likelihood (ML) criterion. The ML receiver has to find the minimum Euclidean distance between the received vector and a set of all possible OFDM symbols passed through the same nonlinearity. This approach has exponential complexity. To reduce the complexity, we propose a sub-optimal receiver that minimizes the Euclidean distance, seen as a cost function, by the gradient descent algorithm. Unfortunately, due to the nonlinearity, the cost function is non-convex. In order to overcome this obstacle, we propose a method to classify the solution, i.e., to decide if the achieved minimum is local or global. We modify the gradient descent algorithm to avoid convergence to a local minimum. It is shown that the proposed receiver outperforms the simple OFDM and iterative receivers in terms of symbol error rate (SER) performance.

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