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Linear precoders have been shown to perform reasonably well at low SNR when the basestation of a MIMO downlink employs one-bit digital-to-analog converters to quantize the precoder outputs. However, at medium-to-high SNRs, an error floor is encountered due to the coarse quantization. This paper examines methods for slightly perturbing the transmitted signal prior to quantization in an effort to improve...
This paper investigates the impact of phase errors of beamforming networks on the performance of distributed transmit beamforming systems. Through multi-tone signal, wider band, models and the defined phase error percentage (PEP) of the beamforming networks, the distorted signal waveforms for different wider band occupying beamforming systems are presented. Furthermore, simulated bit error rates (BERs)...
In this paper, we have presented novel channel estimation technique of MIMO-OFDM system based on Extended Kalman filter. The proposed channel estimation method improves the bit error rate performance compare to conventional channel estimation method. We have also compared the proposed method with the conventional method. We have compared the Extended Kalman filter (EKF) method with the first order...
This paper proves the optimality of circular 8QAM in modulating 3 bits/symbol over an AWGN channel, using a parametrised constellation. Incorporating power amplifier's limitations, we move to a differential scheme that modulates 2 bits/symbol and analytically prove that maximum energy efficiency for this scheme can be achieved when 8PSK is the underlying constellation, and not circular 8QAM. We also...
We address the problem of learning an efficient and adaptive physical layer encoding to communicate binary information over an impaired channel. In contrast to traditional work, we treat the problem an unsupervised machine learning problem focusing on optimizing reconstruction loss through artificial impairment layers in an autoencoder (we term this a channel autoencoder) and introduce several new...
In this work, we carry out a exact performance analysis of dual-hop cooperative amplify-and-forward relaying systems in wireless body area networks over independent and nonidentically distributed Gamma fading channels. In particular, we derive new exact closed-form expressions for the end-to-end outage and symbol error probabilities at arbitrary signal-to-noise-ratios (SNRs) of these systems in terms...
IEEE 802.15.4 takes a center stage in IoT as Low-Rate Wireless Personal Area Networks(LR-WPANs). The standard specifies Offset Quadrature Phase Shift Keying Physical Layer (O-QPSK PHY) with half-sine pulse shaping which can be either categorized under the class of M-ary PSK signals (QPSK signal with offset) or as Minimum Shift Keying (MSK) signal. M-ary PSK demodulation requires perfect carrier synchronization...
The inter-carrier interference (ICI) caused by Doppler spread in mobile channels affects the OFDM orthogonality. This paper presents a comparative study of the performance of different low complexity methods to estimate the ICI power present in mobile reception. In addition, a new method based on experimental results is proposed. Several computer simulations based on OFDM systems with Log-likelihood...
Recently advanced time sharing scheme which is characterized as Variable Coding and Modulation (VCM) in satellite broadcasting system was adopted as a countermeasure for heavy rain fading in order to improve link availability in DVB-S2x (Digital Video Broadcasting — Satellite 2nd Generation eXtention) standard. Furthermore, we propose Layer Division Multiplexing (LDM) scheme to satellite broadcasting...
In this paper, a carrier phase estimation technique (CPE) based on 8-PSK partitioning and modified Viterbi-Viterbi for 32-QAM is proposed. The proposed algorithm shows 60% linewidth tolerance improvement compared to the already-existed CPE single stage techniques for 1-dB SNR penalty at BER of 1×10−2.
We have proposed waveguide-type optical circuits for recognition of optical QPSK symbols. The contrast ratio is theoretically discussed and the noise tolerance is numerically clarified.
The information efficiency assessment of high data rate IP-protocol based transmission systems is evaluated in this paper. In particular, systems based on the IEEE 802.11ac standard are analyzed.
We investigate the performance of dual-hop cooperative amplify-and-forward relaying systems in wireless body area networks over independent and non-identically distributed Gamma fading channels. In particular, tight lower bounds on the end-to-end outage and symbol error probabilities, for fixed gain and channel state information (CSI)-assisted relaying scenarios, are derived in closed-form for arbitrary...
We propose and experimentally demonstrate novel optical transceiver that enables accommodation of multiple services having diverse requirements within the bandwidth of the single transceiver by a holistic SNR optimization of signal assigned for each service.
We experimentally demonstrate the record SSMF transmission distance of 1200 km for dual polarization PAM-4 signal. By complex modulation of directly modulated lasers, OSNR sensitivity gap between QPSK and PAM-4 has shrunk to 5 dB.
We demonstrate error-free transmission over 1800 km with 1 dB Q2-margins using a commercially available real-time 200 Gb/s PDM-8QAM transponder (44.8 GBaud) in a super-channel with carriers spaced by 50 GHz using legacy 50GHz-mux-demux stages.
We demonstrate transmission of trellis-coded-modulated-12-spatial-and-polarization modes over 40km 6-LP-mode fiber with low differential mode group delay. By employing 8-PSK trellis coded modulation, an OSNR gain of 1.8dB is observed in comparison to QPSK.
Wavelength conversion of 32-Gbaud QPSK and 10-Gbaud 16-QAM is demonstrated using a 50-cm long low loss spiral Hydex-glass waveguide. BER < HD-FEC threshold is achieved over 10 nm bandwidth with OSNR penalty < 0.5 dB.
We show a spectral efficiency increase by combining constellation modulation and symbol mapping. The SE increases by 12.5% in theory and 6% in experiments for QPSK at a negligible SNR penalty for a BER=1×10−3.
A novel modulation format recognition algorithm based on connected component analysis in binary image processing is proposed and verified by both simulation and experiment. It shows high accuracy and much reduced complexity than conventional clustering-based method.
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