The neuron’s membrane potential build-up allows for refractoriness. In this context, the refractory effect is often the primary reason spike trains are not accurately described by traditional counting distributions. Inspired by this biological phenomenon, this paper introduces a counting distribution that includes a parameter specifying the length of the refractory period in neural spike generation. Specifically, the paper considers a lower bound on the intervals between any two spikes that follow an exponential or Gamma distribution. The proposed distribution is a generalized form of standard counting distributions, such as the Poisson distribution, and is named the refractory Poisson distribution. This study aims to provide estimation methods for the proposed distribution. Additionally, it introduces a novel estimation approach called “one-shot” maximum likelihood estimation. The research also provides guidance on the maximum amount of information that can be reliably transferred through a single neuron due to refractoriness. The optimality conditions for the capacity-achieving distribution in the capacity per unit cost problem are presented, which, to the best of our knowledge, have not been reported in the literature. The proposed counting distribution can be used for numbering any random phenomena where a refractory period exists between occurrences. Additionally, the distribution can be applied in various scenarios. For example, it can replace the Poisson distribution in the Generalized Linear Model as an alternative counting distribution.

Along with the growth of the Internet comes a competitive environment among Internet service providers. In this regard, quality of service (QoS) and customer’s quality of experience (QoE) are introduced as the two main criteria of satisfaction for network users/regulators. In this paper, we evaluate these two criteria for one of the largest Internet service communication networks in Iran. By providing a predictive model, we propose a solution to improve the quality of the communication. Our model predicts the quality of experience from the quality-of-service parameters with an accuracy of roughly 90%. Next, we reverse-engineer the relationship between the quality of experience and quality of service to develop a service level agreement (SLA) contract. The relationship between quality of experience and quality of service is then compiled into a set of if-then rules. By using a decision tree classifier, we were able to set the quality-of-service parameter thresholds for the gold, silver, and bronze SLAs.

Maximizing the information per the expected unit energy cost in biological neurons is vital in understanding the functionality of our nervous system and improving the bio-inspired nano-networks. Hence, toward a better comprehension of neuronal information processing and communication from an information-energy standpoint, this paper presents the following novel results on the capacity-achieving distribution: 1) For the first time, the paper presents the probability mass function of the number of spikes observed in a given time window where inter-spike intervals follow the Inverse Gaussian distribution. To extend this result, the first and second moments of the underlying probability mass function will be determined. 2) The paper proves that the relationship between the underlying probability mass function and the marginal distribution of the intensity parameter is one-to-one when the parameter is a random variable. 3) Proof that a unique capacity-achieving distribution for the stimulus intensity exists in a discrete form with a finite number of mass points that varies with the energy budget. Then, the paper presents an algorithm that numerically computes a trade-off between the maximum transmit bits and the coding-duration energy expenditure. Subsequently, the optimal multiplier along with the optimal distribution and the corresponding capacity will be obtained.

This study, for the first time, presents an exact expression for the symbol error floor (SEF) of M ‐ary phase shift keying in the presence of phase noise, in‐phase/quadrature (I/Q) gain and phase imbalances, and DC‐offsets altogether. Accurate calculation of symbol error probability, and also the SEF, in the presence of transmitter and receiver impairments is usually a cumbersome task. In this study, the symbol decision boundaries are moved from the demodulator output to the demodulator input as a means to simplify the SEF calculation. In other words, the effect of the receiver I/Q imbalance and DC‐offset is applied on the symbol decision boundaries. Using the decision boundaries at the demodulator input facilitates the exact SEF calculation. The proposed exact expression consists of single integrals. These integrals can be accurately approximated by Gaussian one‐dimensional Q ‐functions assuming a Gaussian distribution for the phase noise. Computer simulations with Gaussian phase noise validate the exactness of the proposed analysis.

We consider the problem of joint routing, scheduling and power control in multi-hop wireless networks. We use a linear relation between link capacity and signal to interference noise ratio in our formulation. In a previous work, using a duality approach, the optimal link scheduling and power control that minimizes the total average transmission power is found. We formulate this problem as a linear programming problem with exponential number of constraints. To cope with the exponential number of constraints, we propose an iterative algorithm based on the cutting plane method. The separation oracle for the cutting plane algorithm turns out to be an element-wise concave optimization problem that can be effectively solved using branch and bound algorithm. We extend the same method to find the optimal routing scheduling and power control. Simulation results show that this methodology is more efficient and scalable compare to the previously proposed algorithm.

We consider J transmitter units each equipped with N transmit antennas over wireless Rayleigh fading channels. Previously in [1], it was proved that when each transmitter unit has TV transmit antennas, using (J - 1)N + r receive antennas for any r ges 1, the receiver can completely separate the signals of J users. The provided diversity to each user was shown to be Nr if the units employ space-time trellis codes even if the units transmit asynchronously. Here, we consider the case when all units are synchronized and employ quasi-orthogonal space-time block codes (N > 2). It is proved that in this case a receiver with J + r - 1 antennas with r ges 1 can separate the transmitted signals of all units and provide each unit with a diversity order of Nr. Based on our interference cancellation technique, we then offer an array processing scheme which provides trade-off between diversity and spatial multiplexing. It is shown via simulations that this array processing scheme performs better than well-known modulation schemes, e.g. space-time block codes and BLAST, for a moderate number of receive antennas.

We study the effects of physical layer parameters on the connectivity of fading ad-hoc networks. Relying on a symbol error rate connectivity metric for such networks, we assume a pair of nodes are connected if their bi-directional measure of connectivity satisfies a given threshold. We investigate the effects of three parameters on the connectivity phenomenon. First and assuming the nodes are distributed over a fixed finite area, we study the effects of the changes in nodes' density. Next, we measure the connectivity effects of the interference coefficients, i.e., the portion of power an interfering node contributes to other links. Finally, we experiment with the threshold of link quality for connectedness. For each parameter, we also provide an intuitive explanation of the phenomena observed in our experiments. Our simulation results show that (1) depending on the value of interference coefficient, an increase in node density may increase or decrease, and (2) increasing the interference coefficients and thresholds of link quality will decrease the connectivity of fading ad-hoc networks.

We consider J transmitter units each equipped with N transmit antennas over a wireless Rayleigh fading channel. Previously, it was proved that when each transmitter unit has N transmit antennas, using JN receive antennas, the receiver can completely separate the signals of J users. The provided diversity to each user was shown to be N. Here, we consider the case when all units are synchronized and employ quasi-orthogonal space-time block codes with N = 4 transmit antennas. It is proved that in this case a receiver with J receive antennas can separate the transmitted signals of all units and provide each unit with the same diversity order of N = 4

We study the problem of connectivity in MIMO fading ad-hoc networks. Based on a probabilistic analysis of achievable capacity on individual links of a random topology, we introduce a novel connectivity metric for wireless ad-hoc networks. We assume a pair of nodes are connected if their bi-directional capacity is more than a given threshold. Our metric is more sophisticated compared to previously proposed metrics of connectivity as it captures the effects of time-varying fading channel, power, and multiple antennas. Our results show that employing mobile nodes with multiple antennas enhances the connectivity of fading wireless ad-hoc networks