As the complexity of systems is rapidly growing, the designers are moving towards use system leve... more As the complexity of systems is rapidly growing, the designers are moving towards use system level design Languages (SLDL) such as SystemC and SpecC. In this paper we use SystemC and SpecC languages for modeling and simulation of wireless sensor networks (WSN). First we start on simple ECO model and add modular sections as increases as the complexity. In the next step, we add data encryption using DES algorithm for security reasons. The future steps include modeling the idel/active/work phases for nodes and we add attenuation-transmission-power checking model for estimation power dissipation among nodes. We also include IEEE 802.15.4 protocol module and buffer insertion module. We have simulated the proposed framework with simulation of 3, 7 and 11 nodes in 3000 ms. The fidelity of simulations with SpecC and SytemC meet with 9.8% error and RMSD 4%. Our preliminary results from deployment of the functional-proven SystemC models into SystemC synthesizers, urges that it may be directly used in early stages of WSN nodes synthesis.
We propose a technique for enhancing the achievable spectral efficiency of multiuser direct-seque... more We propose a technique for enhancing the achievable spectral efficiency of multiuser direct-sequence code-division multiple-access (DS-CDMA) channels in the presence of additive white Gaussian noise (AWGN) and multiple access interference (MAI). The proposed scheme is the joint optimization of outer loop power control and variable spreading factors (VSFs). The optimum SNR-target, the SNR that results in optimal spectral efficiency, is set in the outer loop. Accordingly, appropriate spreading factor is selected, and along with the transmit power adaptation in the inner loop, it leads to maximized spectral efficiency. Total and truncated channel inversion strategies are used in the inner loop. Analytical expressions are derived for the spectral efficiency of the joint optimization scheme for the conventional matched-filter and the multiuser decorrelating detectors. Average transmit power and instantaneous BER constraints are considered and the performance is evaluated over Nakagami-m flat fading channels. We show that our scheme achieves higher spectral efficiency than a system that uses VSF transmission but without outer loop optimal SNR-target. The gain is realized at no transmit power cost and without sacrificing the BER.
IEEE Transactions on Wireless Communications, 2009
Abstract We propose a technique for enhancing the achievable spectral efficiency of multiuser dir... more Abstract We propose a technique for enhancing the achievable spectral efficiency of multiuser direct-sequence code-division multiple-access (DS-CDMA) fading channels in the presence of additive white Gaussian noise (AWGN) and multiple access interference (MAI). The proposed scheme involves the joint optimization of outer loop power control (OLPC) and rate control using variable spreading factors (VSFs). The optimality is in the sense of average spectral efficiency maximization. The optimum outer loop target signal-to-noise ...
Abstract In this paper we provide an adaptive cross layer design in single input multiple output ... more Abstract In this paper we provide an adaptive cross layer design in single input multiple output systems which combines adaptive modulation at the physical layer with truncated automatic repeat request at the data link layer to maximize the spectral efficiency. The maximization is performed in the presence of imperfect channel state information at the receiver under prescribed quality of service such as delay and error rate constraints. Linear minimum mean square error filter with the aid of adaptive pilot symbols is used to facilitate ...
Abstract In this paper, we extend the phase noise suppression problem to single input multi outpu... more Abstract In this paper, we extend the phase noise suppression problem to single input multi output (SIMO) assisted orthogonal frequency division multiplexing (OFDM) systems, using the concept of Kullback-Leibler divergence (KL divergence) and under the context of variational inference approach. Using maximum ratio combining (MRC) receiver for SIMO system, we perform initial point detection improvement on joint estimation of common phase noise and random phase noise by minimizing the KL divergence, over desired unknown ...
A Pareto-efficient, goal-driven, and distributed power control scheme for wireless networks is pr... more A Pareto-efficient, goal-driven, and distributed power control scheme for wireless networks is presented. We use a noncooperative game-theoretic approach to propose a novel pricing scheme that is linearly proportional to the signal-to-interference ratio (SIR) and analytically show that with a proper choice of prices (proportionality constants), the outcome of the noncooperative power control game is a unique and Pareto-efficient Nash equilibrium (NE). This can be utilized for constrained-power control to satisfy specific goals (such as fairness, aggregate throughput optimization, or trading off between these two goals). For each one of the above goals, the dynamic price for each user is also analytically obtained. In a centralized (base station) price setting, users should inform the base station of their path gains and their maximum transmit-powers. In a distributed price setting, for each goal, an algorithm for users to update their transmit-powers is also presented that converges to a unique fixed-point in which the corresponding goal is satisfied. Simulation results confirm our analytical developments.
Existing multiuser detection techniques in wireless systems are based on the assumption that some... more Existing multiuser detection techniques in wireless systems are based on the assumption that some information on the parameters of the probability density function (pdf) of ambient noise is available. Such information may not be available in all cases, particularly for non-Gaussian and impulsive noises, or may change depending on circumstances. In this paper, we present a technique for multiuser detection that does not require any a priori knowledge about the noise parameters. This method is based on using pseudo norms for linear nonparametric regression. Analytical and simulation results show that the proposed method offers an improved, or at least comparable, performance over existing robust techniques in the absence of any information on the nature of noise in the environment. The increased computational complexity is marginal compared to existing parametric detectors. In addition, the proposed nonparametric detector is portable in the sense that it does not need to be tuned for different noise models without any considerable degradation of performance. We also show that in non-Gaussian noise, the performance of blind adaptive nonparametric multiuser detectors is better than that of robust multiuser detectors.
As the complexity of systems is rapidly growing, the designers are moving towards use system leve... more As the complexity of systems is rapidly growing, the designers are moving towards use system level design Languages (SLDL) such as SystemC and SpecC. In this paper we use SystemC and SpecC languages for modeling and simulation of wireless sensor networks (WSN). First we start on simple ECO model and add modular sections as increases as the complexity. In the next step, we add data encryption using DES algorithm for security reasons. The future steps include modeling the idel/active/work phases for nodes and we add attenuation-transmission-power checking model for estimation power dissipation among nodes. We also include IEEE 802.15.4 protocol module and buffer insertion module. We have simulated the proposed framework with simulation of 3, 7 and 11 nodes in 3000 ms. The fidelity of simulations with SpecC and SytemC meet with 9.8% error and RMSD 4%. Our preliminary results from deployment of the functional-proven SystemC models into SystemC synthesizers, urges that it may be directly used in early stages of WSN nodes synthesis.
We propose a technique for enhancing the achievable spectral efficiency of multiuser direct-seque... more We propose a technique for enhancing the achievable spectral efficiency of multiuser direct-sequence code-division multiple-access (DS-CDMA) channels in the presence of additive white Gaussian noise (AWGN) and multiple access interference (MAI). The proposed scheme is the joint optimization of outer loop power control and variable spreading factors (VSFs). The optimum SNR-target, the SNR that results in optimal spectral efficiency, is set in the outer loop. Accordingly, appropriate spreading factor is selected, and along with the transmit power adaptation in the inner loop, it leads to maximized spectral efficiency. Total and truncated channel inversion strategies are used in the inner loop. Analytical expressions are derived for the spectral efficiency of the joint optimization scheme for the conventional matched-filter and the multiuser decorrelating detectors. Average transmit power and instantaneous BER constraints are considered and the performance is evaluated over Nakagami-m flat fading channels. We show that our scheme achieves higher spectral efficiency than a system that uses VSF transmission but without outer loop optimal SNR-target. The gain is realized at no transmit power cost and without sacrificing the BER.
IEEE Transactions on Wireless Communications, 2009
Abstract We propose a technique for enhancing the achievable spectral efficiency of multiuser dir... more Abstract We propose a technique for enhancing the achievable spectral efficiency of multiuser direct-sequence code-division multiple-access (DS-CDMA) fading channels in the presence of additive white Gaussian noise (AWGN) and multiple access interference (MAI). The proposed scheme involves the joint optimization of outer loop power control (OLPC) and rate control using variable spreading factors (VSFs). The optimality is in the sense of average spectral efficiency maximization. The optimum outer loop target signal-to-noise ...
Abstract In this paper we provide an adaptive cross layer design in single input multiple output ... more Abstract In this paper we provide an adaptive cross layer design in single input multiple output systems which combines adaptive modulation at the physical layer with truncated automatic repeat request at the data link layer to maximize the spectral efficiency. The maximization is performed in the presence of imperfect channel state information at the receiver under prescribed quality of service such as delay and error rate constraints. Linear minimum mean square error filter with the aid of adaptive pilot symbols is used to facilitate ...
Abstract In this paper, we extend the phase noise suppression problem to single input multi outpu... more Abstract In this paper, we extend the phase noise suppression problem to single input multi output (SIMO) assisted orthogonal frequency division multiplexing (OFDM) systems, using the concept of Kullback-Leibler divergence (KL divergence) and under the context of variational inference approach. Using maximum ratio combining (MRC) receiver for SIMO system, we perform initial point detection improvement on joint estimation of common phase noise and random phase noise by minimizing the KL divergence, over desired unknown ...
A Pareto-efficient, goal-driven, and distributed power control scheme for wireless networks is pr... more A Pareto-efficient, goal-driven, and distributed power control scheme for wireless networks is presented. We use a noncooperative game-theoretic approach to propose a novel pricing scheme that is linearly proportional to the signal-to-interference ratio (SIR) and analytically show that with a proper choice of prices (proportionality constants), the outcome of the noncooperative power control game is a unique and Pareto-efficient Nash equilibrium (NE). This can be utilized for constrained-power control to satisfy specific goals (such as fairness, aggregate throughput optimization, or trading off between these two goals). For each one of the above goals, the dynamic price for each user is also analytically obtained. In a centralized (base station) price setting, users should inform the base station of their path gains and their maximum transmit-powers. In a distributed price setting, for each goal, an algorithm for users to update their transmit-powers is also presented that converges to a unique fixed-point in which the corresponding goal is satisfied. Simulation results confirm our analytical developments.
Existing multiuser detection techniques in wireless systems are based on the assumption that some... more Existing multiuser detection techniques in wireless systems are based on the assumption that some information on the parameters of the probability density function (pdf) of ambient noise is available. Such information may not be available in all cases, particularly for non-Gaussian and impulsive noises, or may change depending on circumstances. In this paper, we present a technique for multiuser detection that does not require any a priori knowledge about the noise parameters. This method is based on using pseudo norms for linear nonparametric regression. Analytical and simulation results show that the proposed method offers an improved, or at least comparable, performance over existing robust techniques in the absence of any information on the nature of noise in the environment. The increased computational complexity is marginal compared to existing parametric detectors. In addition, the proposed nonparametric detector is portable in the sense that it does not need to be tuned for different noise models without any considerable degradation of performance. We also show that in non-Gaussian noise, the performance of blind adaptive nonparametric multiuser detectors is better than that of robust multiuser detectors.
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Papers by Babak Seyfe