Abstract. Visible light communication (VLC) has the ability to provide a high data rate up to Mbp... more Abstract. Visible light communication (VLC) has the ability to provide a high data rate up to Mbps in underwater environments for real-time communication systems. In underwater VLC (UWVLC), two major impairments are the turbulence-induced fading due to variation of salt and temperature of seawater and incremental path loss with distance due to absorption and scattering. We consider these two impairments and derive the closed form expressions for average symbol error probability (ASEP), asymptotic relative diversity order, and ergodic capacity for UWVLC dual-hop cooperative communication system. We consider multiple receiver branches with selection combining to combat the effect of fading. The impact of temperature on the fading parameters and system performance is highlighted. We conduct a comparative analysis of ASEP for four-pulse amplitude modulation and four-square quadrature amplitude modulation schemes and draw useful insights. We prove the accuracy of the derived analytical expression using Monte Carlo simulations.
In this paper, we consider Mt×M system (Mt > M), where Mt and M are the numbers of antennas at... more In this paper, we consider Mt×M system (Mt > M), where Mt and M are the numbers of antennas at the transmitter and receiver, respectively. We select M out of Mt transmit antennas using two different antenna selection schemes. In scheme 1, we select the subset of M antennas out of total $$(\begin{array}{l}{M_{t}} \\{M}\end{array})$$ subsets. In the selected subset, the minimum SNR is maximum compared to minimum SNR of all the remaining subsets. In scheme 2, Mt available transmit antennas are divided into Mtg disjoint groups of successive antennas, where Mtg = Mt/N. It means that there are N antennas in each group, where N ≤ M. Further both Mt and M are divisible by N and the total possible combinations of available groups are given $$(\begin{array}{l}{M_{tg}} \\{C}\end{array})$$ Then we select the subset of M antennas out of total $$(\begin{array}{l}{M_{tg}} \\{C}\end{array})$$ subsets. In the selected subset, the minimum SNR is maximum compared to minimum SNR of all the remaining subsets. In this scheme, N and C are chosen to meet the requirements of M selected antennas for transmission. After antenna selection, the resulting system will be M×M. We use Minimum Mean Square Error (MMSE) Vertical Bell Laboratories Layered Space Time (VBLAST) detection at the receiver for both the antenna selection schemes. We present MIMO Symbol Error Rate (SER) versus MIMO Symbol SNR using simulations for M-QAM constellations with Rayleigh fading channels. We have compared the performance of the considered systems with prevailing high complexity schemes ML and MMSE Improved VBLAST. The considered scheme 1 with MMSE VBLAST outperforms the prevailing schemes while scheme 2 with MMSE VBLAST provides similar performance in a wide range of SNR compared to prevailing schemes. However, the number of feedback bits used in scheme 2 is less as compared to scheme 1. There is a tradeoff between the SER performance and the number of required feedback bits. As N decreases, scheme 2 performance starts moving towards the performance of scheme 1. Both the systems provide the diversity gain in the fading channel.
Non-parametric sensing algorithms are preferred in cognitive radio. In this paper, spectrum sensi... more Non-parametric sensing algorithms are preferred in cognitive radio. In this paper, spectrum sensing method based on censored observations is proposed. We evaluate the performance of Censored Anderson-Darling (CAD) sensing method in time-varying and flat-fading channel using Monte Carlo simulations. We have shown the performance of the CAD sensing in terms of receiver operating characteristic (ROC). The considered channel is modeled by Gaussian variables and characterized by a first ordered autoregressive process (AR1). It is shown that the proposed method outperforms prevailing techniques such as the Energy detection (ED) sensing and Order-statistic (OS) based sensing in time-varying channel at lower signal to noise ratio.
A novel goodness-of-fit-based non-parametric spectrum sensing scheme in a non-Gaussian noise envi... more A novel goodness-of-fit-based non-parametric spectrum sensing scheme in a non-Gaussian noise environment, modelled by Middleton class A distribution, is proposed. The sampling distribution of the proposed test statistic is derived and the detection performance is shown using Monte Carlo simulations. Results are presented and it is concluded that the performance is degraded if the Gaussian component in the Middleton noise is higher than the non-Gaussian component.
2010 National Conference On Communications (NCC), 2010
ABSTRACT We consider a Multiple Input Single Output (MISO) system equipped with Lt transmit anten... more ABSTRACT We consider a Multiple Input Single Output (MISO) system equipped with Lt transmit antennas in spatially uncorrelated Rayleigh fading channels. We consider a sub-optimum Antenna Selection (AS) scheme, wherein all the Lt antennas are divided into two groups with L1 and L2 antennas such that L1+L2 = Lt. Assuming perfect CSI, the best single antenna within each group is selected. For the well known Alamouti transmit diversity, we derive exact closed-form expressions for the pdf of received SNR, probability of outage and SER for MPSK and MQAM constellations.
2011 International Conference on Devices and Communications (ICDeCom), 2011
In this paper, we propose a simple technique for the reduction of high Peak to Average Power Rati... more In this paper, we propose a simple technique for the reduction of high Peak to Average Power Ratio (PAPR), based on Clipping and Differential Scaling, in Orthogonal Frequency Division Multiplexing (OFDM) systems. In this technique, the amplitude of complex OFDM signal is clipped and then scaled in such a way so that the PAPR is reduced without causing much degradation
ABSTRACT In cognitive radio, spectrum sensing is a challenging task. In this paper, a spectrum se... more ABSTRACT In cognitive radio, spectrum sensing is a challenging task. In this paper, a spectrum sensing method based on censored observations is proposed. We call it as Censored Anderson Darling (CAD) sensing. We present the performance of the CAD sensing method with receiver operating characteristics (ROC) in fading channels using simulations. It is observed that the proposed method outperforms the conventional energy detection (ED) at lower signal to noise ratio. It also provides better detection performance compared to Ordered Statistics (OS) based sensing method. We also use the CAD sensing method assuming noise uncertainty. It means noise variance at secondary user(SU) is unknown. We call it as Blind CAD sensing (B-CAD). We also show that the B-CAD outperforms the energy detection.
AEU - International Journal of Electronics and Communications, 2013
ABSTRACT We consider orthogonal frequency division multiplexing (OFDM) in a multiple input single... more ABSTRACT We consider orthogonal frequency division multiplexing (OFDM) in a multiple input single output (MISO) system. In the presence of spatially uncorrelated time-varying frequency selective channel, we use subcarrier by subcarrier antenna selection using delayed feedback. We derive closed-form expressions for the pdf of the received SNR and BER for MQAM constellation. The expressions have been obtained as a function of the correlation (ρ) between perfect channel state information (CSI) and delayed CSI, where 0 ≤ ρ ≤ 1. We have verified our analytical expressions by comparing them with simulation results. We have also reduced the BER expression for some special cases and compared them with the results available in the literature. We conclude that the diversity gain of the considered system is reduced to one for ρ < 1, i.e. not having perfect antenna selection for each subcarrier. However, we get some coding gain compared to single input single output system, the coding gain reduces with decreasing the correlation.
... JM Chakravarti Department of E & C Institute of Technology Nirma University Ahmedabad... more ... JM Chakravarti Department of E & C Institute of Technology Nirma University Ahmedabad-382481, INDIA Email: jatin.chakravarti@gmail.com YN Trivedi Department of E & C Institute of Technology Nirma University Ahmedabad-382481, INDIA Email: yogesh.trivedi@nirmauni.ac ...
Abstract. Visible light communication (VLC) has the ability to provide a high data rate up to Mbp... more Abstract. Visible light communication (VLC) has the ability to provide a high data rate up to Mbps in underwater environments for real-time communication systems. In underwater VLC (UWVLC), two major impairments are the turbulence-induced fading due to variation of salt and temperature of seawater and incremental path loss with distance due to absorption and scattering. We consider these two impairments and derive the closed form expressions for average symbol error probability (ASEP), asymptotic relative diversity order, and ergodic capacity for UWVLC dual-hop cooperative communication system. We consider multiple receiver branches with selection combining to combat the effect of fading. The impact of temperature on the fading parameters and system performance is highlighted. We conduct a comparative analysis of ASEP for four-pulse amplitude modulation and four-square quadrature amplitude modulation schemes and draw useful insights. We prove the accuracy of the derived analytical expression using Monte Carlo simulations.
In this paper, we consider Mt×M system (Mt > M), where Mt and M are the numbers of antennas at... more In this paper, we consider Mt×M system (Mt > M), where Mt and M are the numbers of antennas at the transmitter and receiver, respectively. We select M out of Mt transmit antennas using two different antenna selection schemes. In scheme 1, we select the subset of M antennas out of total $$(\begin{array}{l}{M_{t}} \\{M}\end{array})$$ subsets. In the selected subset, the minimum SNR is maximum compared to minimum SNR of all the remaining subsets. In scheme 2, Mt available transmit antennas are divided into Mtg disjoint groups of successive antennas, where Mtg = Mt/N. It means that there are N antennas in each group, where N ≤ M. Further both Mt and M are divisible by N and the total possible combinations of available groups are given $$(\begin{array}{l}{M_{tg}} \\{C}\end{array})$$ Then we select the subset of M antennas out of total $$(\begin{array}{l}{M_{tg}} \\{C}\end{array})$$ subsets. In the selected subset, the minimum SNR is maximum compared to minimum SNR of all the remaining subsets. In this scheme, N and C are chosen to meet the requirements of M selected antennas for transmission. After antenna selection, the resulting system will be M×M. We use Minimum Mean Square Error (MMSE) Vertical Bell Laboratories Layered Space Time (VBLAST) detection at the receiver for both the antenna selection schemes. We present MIMO Symbol Error Rate (SER) versus MIMO Symbol SNR using simulations for M-QAM constellations with Rayleigh fading channels. We have compared the performance of the considered systems with prevailing high complexity schemes ML and MMSE Improved VBLAST. The considered scheme 1 with MMSE VBLAST outperforms the prevailing schemes while scheme 2 with MMSE VBLAST provides similar performance in a wide range of SNR compared to prevailing schemes. However, the number of feedback bits used in scheme 2 is less as compared to scheme 1. There is a tradeoff between the SER performance and the number of required feedback bits. As N decreases, scheme 2 performance starts moving towards the performance of scheme 1. Both the systems provide the diversity gain in the fading channel.
Non-parametric sensing algorithms are preferred in cognitive radio. In this paper, spectrum sensi... more Non-parametric sensing algorithms are preferred in cognitive radio. In this paper, spectrum sensing method based on censored observations is proposed. We evaluate the performance of Censored Anderson-Darling (CAD) sensing method in time-varying and flat-fading channel using Monte Carlo simulations. We have shown the performance of the CAD sensing in terms of receiver operating characteristic (ROC). The considered channel is modeled by Gaussian variables and characterized by a first ordered autoregressive process (AR1). It is shown that the proposed method outperforms prevailing techniques such as the Energy detection (ED) sensing and Order-statistic (OS) based sensing in time-varying channel at lower signal to noise ratio.
A novel goodness-of-fit-based non-parametric spectrum sensing scheme in a non-Gaussian noise envi... more A novel goodness-of-fit-based non-parametric spectrum sensing scheme in a non-Gaussian noise environment, modelled by Middleton class A distribution, is proposed. The sampling distribution of the proposed test statistic is derived and the detection performance is shown using Monte Carlo simulations. Results are presented and it is concluded that the performance is degraded if the Gaussian component in the Middleton noise is higher than the non-Gaussian component.
2010 National Conference On Communications (NCC), 2010
ABSTRACT We consider a Multiple Input Single Output (MISO) system equipped with Lt transmit anten... more ABSTRACT We consider a Multiple Input Single Output (MISO) system equipped with Lt transmit antennas in spatially uncorrelated Rayleigh fading channels. We consider a sub-optimum Antenna Selection (AS) scheme, wherein all the Lt antennas are divided into two groups with L1 and L2 antennas such that L1+L2 = Lt. Assuming perfect CSI, the best single antenna within each group is selected. For the well known Alamouti transmit diversity, we derive exact closed-form expressions for the pdf of received SNR, probability of outage and SER for MPSK and MQAM constellations.
2011 International Conference on Devices and Communications (ICDeCom), 2011
In this paper, we propose a simple technique for the reduction of high Peak to Average Power Rati... more In this paper, we propose a simple technique for the reduction of high Peak to Average Power Ratio (PAPR), based on Clipping and Differential Scaling, in Orthogonal Frequency Division Multiplexing (OFDM) systems. In this technique, the amplitude of complex OFDM signal is clipped and then scaled in such a way so that the PAPR is reduced without causing much degradation
ABSTRACT In cognitive radio, spectrum sensing is a challenging task. In this paper, a spectrum se... more ABSTRACT In cognitive radio, spectrum sensing is a challenging task. In this paper, a spectrum sensing method based on censored observations is proposed. We call it as Censored Anderson Darling (CAD) sensing. We present the performance of the CAD sensing method with receiver operating characteristics (ROC) in fading channels using simulations. It is observed that the proposed method outperforms the conventional energy detection (ED) at lower signal to noise ratio. It also provides better detection performance compared to Ordered Statistics (OS) based sensing method. We also use the CAD sensing method assuming noise uncertainty. It means noise variance at secondary user(SU) is unknown. We call it as Blind CAD sensing (B-CAD). We also show that the B-CAD outperforms the energy detection.
AEU - International Journal of Electronics and Communications, 2013
ABSTRACT We consider orthogonal frequency division multiplexing (OFDM) in a multiple input single... more ABSTRACT We consider orthogonal frequency division multiplexing (OFDM) in a multiple input single output (MISO) system. In the presence of spatially uncorrelated time-varying frequency selective channel, we use subcarrier by subcarrier antenna selection using delayed feedback. We derive closed-form expressions for the pdf of the received SNR and BER for MQAM constellation. The expressions have been obtained as a function of the correlation (ρ) between perfect channel state information (CSI) and delayed CSI, where 0 ≤ ρ ≤ 1. We have verified our analytical expressions by comparing them with simulation results. We have also reduced the BER expression for some special cases and compared them with the results available in the literature. We conclude that the diversity gain of the considered system is reduced to one for ρ < 1, i.e. not having perfect antenna selection for each subcarrier. However, we get some coding gain compared to single input single output system, the coding gain reduces with decreasing the correlation.
... JM Chakravarti Department of E & C Institute of Technology Nirma University Ahmedabad... more ... JM Chakravarti Department of E & C Institute of Technology Nirma University Ahmedabad-382481, INDIA Email: jatin.chakravarti@gmail.com YN Trivedi Department of E & C Institute of Technology Nirma University Ahmedabad-382481, INDIA Email: yogesh.trivedi@nirmauni.ac ...
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