The high peak-to-average power ratio (PAR) in orthogonal frequency division multiplexing (OFDM) modulation systems can significantly reduce efficiency and performance. Methods exist which alter or introduce new signal constellations to combat large peaks. We present a PAR-reduction method that dynamically extends outer constellation points active (data-carrying) channels, within margin-preserving constraints, order minimize the peak magnitude. This scheme simultaneously decreases bit error...

We present an optimal, computationally efficient, integer-bit power allocation algorithm for discrete multitone modulation. Using efficient lookup table searches and a Lagrange-multiplier bisection search, our converges faster to the optimal solution than existing techniques can replace use of suboptimal methods because its low computational complexity. Fast algorithms are developed data rate performance margin maximization problems.

Common to all orthogonal frequency division multiplexing (OFDM) systems is a large peak-to-average-power ratio (PAR), which can lead low power efficiency and nonlinear distortion at the transmit amplifier. Tone reservation uses other unused or reserved tones design peak-cancelling signal that lowers PAR of OFDM block. In contrast previous methods, new active-set method proposed here converges very quickly toward minimum-PAR solution lower computational cost. An efficient real-baseband...

We study the transmission performance of recently proposed multiband discrete-Fourier-transform spread orthogonal frequency-division multiplexing (MB-DFT-S-OFDM) format in which each subband is essence a single-carrier signal with Nyquist bandwidth. have found that optimal bandwidth for 428-Gb/s MB-DFT-S-OFDM 15 and 3 GHz inline dispersion compensated (IDC) nondispersion (NDC) fiber links, respectively. The optimized outperforms coherent by 1 dB (0.8 dB) after 1000-km over IDC links.

This paper investigates the performance of some recently proposed optical orthogonal frequency-division multiplexing (OFDM) transmission techniques in a short-range intensity-modulated, direct-detected (IM/DD) channel. Due to unipolarity IM/DD channel, asymmetric clipping and associated nonlinear distortion is inevitable, resulting an unfavorable dc power significant penalty. Using detailed analysis clipped signal, our recent work focused on reducing this clipping-resulted via both...

This paper looks at the problem of theoretically characterizing nonlinear biasing and clipping (BAC) effects on an optical Orthogonal Frequency-Division Multiplexing (OFDM) signal in intensity-modulated, direct-detected (IM/DD) systems. Due to unipolarity IM/DD channel, a large DC bias associated distortion (NLCD) is inevitable, resulting significant performance penalty. NLCD can be well modelled as linear deterministic attenuation plus uncorrelated random additive noise time domain. In...

We present an optimal, efficient power allocation algorithm for discrete multitone modulation (DMT). Using lookup table searches and a Lagrange multiplier bisection search, our converges much faster to the optimal solution than existing techniques can replace use of suboptimal methods because its low computational complexity. A fast is developed pseudocode provided.

This paper looks at the problem of performance enhancement for orthogonal frequency-division multiplexing (OFDM) transmission in intensity modulated, direct detected (IM/DD) optical systems. Due to unipolarity IM/DD channel, asymmetric clipping and associated biasing is inevitable, which results a significant signal degradation. ACO-OFDM has been previously proposed avoid this detrimental distortion with cost lower spectral efficiency. In paper, help detailed analysis such distortion, simple...

Polarization-switched quadrature phase-shift keying (PS-QPSK) is a recently introduced 4-D signal constellation that has power efficiency (and sensitivity) advantage over polarization-division multiplexed QPSK (PDM-QPSK). Using polarization-rotated form of PS-QPSK, we show it equivalent to short block code, and assert basic information theory explains its PDM-QPSK. We consider the practicality PS-QPSK by considering performance after forward error correction (FEC) applied, as this true...

In cognitive radio networks, compressive sensing has the potential to allow a secondary user efficiently monitor wideband spectrum at sub-Nyquist sampling rate without complex hardware. general, techniques leverage assumption of sparsity recover by solving set ill-posed linear equations. this paper, we adopt framework generative adversarial neural network (GAN) in deep learning and propose GAN (DCSS-GAN), where two networks are trained compete with each other from undersampled samples time...

The high peak-to-average power ratio (PAR) in orthogonal frequency division multiplexing (OFDM) modulation systems can significantly limit performance. Methods exist which alter or introduce new signal constellations to combat large peaks. We present an improved PAR-reduction method that dynamically extends outer constellation points active (data-carrying) channels, within margin-preserving constraints, order minimize the peak magnitude. This scheme simultaneously decreases bit error rate...

This paper investigates Orthogonal Frequency- Division Multiplexing (OFDM) transmission in intensity modulated, direct-detected (IM/DD) optical systems. Due to the unipolarity of IM/DD channel, DC biasing and associated nonlinear clipping distortion (NLCD) is inevitable, unless an anti-periodic signal created by limiting bit loading only half available bandwidth. To generalize this idea, we first provide a class such signals generated with different subchannel combinations. Using theoretical...

Wireless sensor networks (WSNs) are the foundation of Internet Things (IoT), and in era fifth generation wireless communication networks, they envisioned to be truly biquitous, reliable, scalable, energy efficient. To this end, topology control is an important mechanism realize self-organized WSNs that capable adapting dynamics environment. Topology optimization combinatorial nature, generally NP-hard solve. Most existing algorithms leverage heuristic rules reduce number search candidates so...

We consider Active Constellation Extension to reduce the PAPR in CO-OFDM systems. find that nonlinearity threshold is improved by 1.5 dB at a reach of 400 km SSMF fiber.

The high peak-to-average power ratio (PAR) in OFDM systems can significantly limit performance. Tone reservation techniques use unavailable or reserved tones to design a peak-cancelling signal that lowers the PAR of transmit data block. These have been shown reduce for real-baseband signals, such as ADSL. Our fast-converging tone-reservation approach based upon active-set methods is extended complex-baseband signals. This new technique converges very quickly toward minimum-PAR solution at low cost.

We propose DFT-spread (DFT-S) OFDM within each sub-band of multiband-CO-OFDM to mitigate fiber nonlinearity. For 1000-km standard-single-mode-fiber transmission at 420-Gb/s, 32-band DFT-S CO-OFDM outperforms conventional and coherent single-carrier by 1.1 0.8 dB, respectively.

We demonstrate transmission of 1.63-Tb/s PDM-16QAM unique-word DFT-spread OFDM signal over 1,010-km SSMF with 80-km span length and EDFA-only amplification. find a 20 % reach improvement conventional OFDM.

This paper investigates the effects of nonlinear biasing and clipping (BAC) on a random optical orthogonal frequency-division multiplexing (OFDM) signal with direct detection. We look at problem theoretical performance evaluation such system. Specifically, we derive an approximation for symbol error rate (SER). The BAC process is modeled as linear deterministic gain plus additive noise. total effective SNR presented function power, modulation constellation receiver SNR. Analytical results...

We propose DFT-spread OFDM (DFT-S-OFDM) to mitigate fiber nonlinearity in long-haul transmission systems. For 1000-km standard-single-mode-fiber at 420-Gb/s, 32-band DFT-S-OFDM outperforms conventional coherent optical-OFDM (CO-OFDM) and single-carrier by 1.1 0.8 dB, respectively.

This paper considers the use of full-duplex technology in cognitive radio networks to allow secondary users sense presence primary and transmit data simultaneously. is main advantage over half-duplex radios. In such networks, so-called sensing-throughput trade-off exists due fact that while a higher power results network throughput, sensing performance degraded by self-interference at transceiver. presents novel deep reinforcement learning-based joint spectrum control algorithm for downlink...

Small formed elements and gas bubbles in flowing blood, called microemboli, can be detected using Doppler ultrasound. In this application, a pulsed constant-frequency ultrasound signal insonates volume of blood the middle cerebral artery, microemboli moving through its sample produce Doppler-shifted transient reflection. Current detection methods include searching for these transients short-time Fourier transform (STFT) reflected signal. However, since embolus transit time is inversely...

We present a computationally efficient, integer-bit power allocation algorithm for discrete multitone modulation (DMT) which optimally maximizes the performance margin. Using efficient lookup table searches and Lagrange multiplier bisection search, our converges faster to optimal solution than existing techniques can replace use of suboptimal methods because its low computational complexity. A fast is developed pseudocode given as well numerical qualitative comparisons methods.

Interference suppression in spread spectrum communication systems is often essential for achieving maximum system performance. Existing interference methods do not perform well most types of nonstationary interference. We first consider schemes based on adaptive orthogonal time-frequency decompositions, such as wavelet packet and arbitrary dyadic tilings. These reduce substantially, but their performance can vary dramatically with minor changes characteristics the center frequency. To...

This paper derives the optimal power allocation for a coordinated orthogonal frequency-division multiplexing (OFDM) transmission system in which $K$ points (CTPs) coherently transmit and allocate across $N$ subchannels under both total individual constraints. In maximizing capacity, previous works showed that, constraint, strategy is maximum-ratio (MRT) CTPs with waterfilling type of solution subchannels. For constraints, we derive new co-phasing following property: any given subchannel, if...