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Ensuring the passivity of macromodels obtained from tabulated data has become a critical issue for accurate signal integrity analysis. For delayed rational function based macromodels derived in the admittance domain, the issue of passivity has recently been addressed. In this paper, passivity verification and compensation algorithms for delayed rational function based macromodels derived in the scattering...
Nowadays, Internet congestion is indicated by dropping packets when the routers buffers are full, or by dropping packets according to an AQM mechanism such as RED. Many mechanisms have been proposed to eliminate or minimize the effect of packet loss and tackle the consequential inefficiency due the retransmission of the dropped packets. Fast congestion notification (FN), that has been evaluated through...
Bus signal priority at signalized intersections has demonstrated as an efficient and realizable approach to reduce bus delays. However the impact on passenger delays still needs to be analyzed after bus signal priority. This paper proposes a passenger delays reduction model by using the delay triangle. Taking a two-phase signalized intersection for example, it is found that the passenger delays reduction...
A novel time delay estimation (TDE) method is proposed based on the concept of mutual information (MI). The relative delay between two sensor output signals is estimated by maximizing the estimated MI of the two signals. In estimating the MI, it does not require any information about prior distribution of the source signal. Instead, the Parzen window estimator is used to estimate the density function...
In this paper, we highlight the impact of variable Push-To-Talk (PTT) delays on performance of a heterogeneous Land Mobile Radio (LMR) network. We first present the PTT delay values and distributions observed for some commonly used LMR nodes. An analytical model is then developed to estimate the asymmetric throughput problem. The results obtained using this model and simulations show that a LMR node...
In wireless networks, communication links may be subject to random fatal attacks: for example, sensor networks under sudden power losses or cognitive radio networks with unpredictable primary user spectrum occupancy. Under such circumstances, it is critical to quantify how fast and reliably information can be collected over attacked links. In our previous work, we studied such channels by considering...
This paper presents the ultra-wideband (UWB) channel measurement and modeling for an intra-vehicle environment. The measurement was conducted in time domain beneath a commercial vehicle chassis. Channel data were collected at the same locations for the car in stationary and in moving status. Stochastic tapped delay line model is used to characterize the channels in both cases. Slightly larger number...
In this paper, we study the network queuing effects on the VoIP delay and jitter. Two service polices, FIFO and Differentiated Service (DiffServ), are studied with repect to the queuing delays of VoIP packets. First, we present our assumptions for delay characterization. Then, we provide a model for the traffic flow. We create a ??Markovian+Deterministic (M+D)?? model in order to represent the traffic...
Ultra-wideband (UWB) has been considered a viable and an innovative solution for future short-range high-speed wireless communication systems. One of the big concerns for UWB devices to function properly is the narrow band interference (NBI) issue, which must be carefully studied. For this purpose, the performance of UWB communication system over indoor Lognormal fading channel in the presence of...
In this paper, an algorithm reprocessing of the power spectrum density (RPSD) is proposed to detect and estimate the PN code's period of the multipath direct sequence spread spectrum (DS/SS) signal in low SNR, which develops the previous processing method based on the single path environment. It can solve the difficult problem of PN code's period detection and estimation in multipath environment....
In this paper, we consider properties of the auto-ambiguity and cross-ambiguity functions of weighted pulse trains with Oppermann sequences. Several properties are examined and proved which in turn allows for reducing the design space for optimization of a particular design. The insights gained from these properties are consolidated in a formal framework leading to procedures that can be used for...
The effectiveness of queue management mechanisms relies on how good their control decisions will help in satisfying their goals regarding congestion avoidance and control. These decisions are implemented and compelled during the design of the packet mark probability and the mark activation functions. The design of fast congestion notification (FN) drop/mark probability function enables the two control...
A hard-deadline, opportunistic scheduling problem in which B bits must be transmitted within T time-slots over a time-varying channel is studied: the transmitter must decide how many bits to serve in each slot based on knowledge of the current channel but without knowledge of the channel in future slots, with the objective of minimizing expected transmission energy. In order to focus on the effects...
This paper presents a novel two-step approach for modeling forward and backward network delays in networked control systems (NCS). The first step is to build a colored Petri net (CPN) structural model for the simulation of Ethernet based networked control systems. The modular model captures the most important features of industrial networked control systems, such as client/server input/output scanning...
This paper deals with the problem of identifying a Petri net system given an observed sequence of events generated by it and an observed sequence of output vectors associated to the marking of the measurable places. The problem is not new in the literature. The original contribution of this work consists in the use of the timing information associated to the net so as to improve its identification...
The impact of parameter variations on components' and systems' characteristics, especially in the area of IC design, has been discussed for several years. To investigate the influence of parameter variations on system characteristics, standard Monte Carlo simulation is often used when exact results cannot be obtained using a deterministic algorithm. However, this procedure may require a huge number...
In this paper for MB-OFDM piconets the probabilities of symbol collision and symbol skipping are theoretically analyzed in the case that both the desired and interfering piconets employ Adaptive Symbol Skipping (ASS). In this scheme energy detection is employed and symbol transmission is skipped in order to avoid collision. Thermal noise is taken into account for analysis of the probabilities are...
Collaborative beamforming among a set of distributed terminals is studied, assuming a) no specialized RF hardware for carrier frequency synchronization, and b) zero feedback from destination (either in the form of pilot signals or explicit messages). A solution is provided for conventional radios in relevant critical applications, such as emergency radio. The proposed scheme simply exploits lack of...
Characterizing user churn has become an important topic in studying P2P networks, both in theoretical analysis and system design. Recent work has shown that direct sampling of user lifetimes may lead to certain bias (arising from missed peers and round-off inconsistencies) and proposed a technique that estimates lifetimes based on sampled residuals. In this paper, however, we show that under non-stationary...
We show that for a large class of scheduling algorithms, when the algorithm minimizes the drift of a Lyapunov function, the algorithm is optimal in maximizing the asymptotic decay-rate of the probability that the Lyapunov function value exceeds a large threshold. The result in this paper extends our prior results to the important and practically-useful case when the Lyapunov function is not linear...
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