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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...
This paper considers the problem of routing packets across a multi-hop wireless network while ensuring throughput optimality. One of the main challenges in the design of throughput optimal routing policies is identifying appropriate and universal Lyapunov functions with negative expected drift. The few well-known throughput optimal routing policies in the literature are constructed using simple quadratic...
We consider a wireless downlink shared by a dynamic population of flows. The flows of random size (bits) arrive at the base station at random times, and leave when they have been completely transmitted. The transmission rate supported by the wireless channel of each flow while the flow awaits transmission varies randomly over time and is independent of that of the other flows. The scheduling problem...
We consider the problem of event detection in wireless sensor networks (WSNs) that are large in the sense that an event affects the statistics of the observations of a small number of sensors in the vicinity of where it occurs. An event occurs at a random time at a random location in the region (called the region of interest, ROI) covered by the WSN. We consider a distance based sensing model in which...
Most of the existing scheduling algorithms in OFDMA and TDMA systems assume the availability of perfect channel quality indicator (CQI) at the transmitter. Unfortunately, this is unrealistic since the receiver (e.g. mobile users) estimates the CQI at time t - ?? and feed back this CQI estimate to the transmitter (e.g. base station). The scheduler uses then this outdated CQI at time t to make the allocation...
We present a novel scalable call admission control for VoIP based on blocking probability calculation (BPC). Blocking probabilities were measured carrying VoIP for every router across the source-destination path. Ingress router selects the optimal path for the new request by calculating blocking probabilities across all source-destination paths. A simple algorithm design and evaluation results show...
Network calculus is widely used in network analysis and quality of service research, but till now the main work of the network calculus theory focuses on the time invariant field, and little work on the case that arrival curve and service curve are time varying functions. We propose a time varying network calculus theory, define the concept of time varying arrival curve and time varying service curve,...
Modelling of practical situations in which spikes do appear leads to the use of delta generalized functions. Many of them are properly handled by means of the symbolic character of Mathematica. In this note we will point out how these functions are properly handled when are involved as inputs in some practical modelizations of dynamic systems.
In present paper, we investigate a class of stochastic differential delay equations with Poisson jump and Markovian switching. Constructing discrete approximate solution and continuous approximate solution by means of Euler-Maruyama scheme, we show the numerical solution converges to the true solution of stochastic differential delay equations with Poisson jump and Markovian switching in the sense...
We investigate a form of logic decomposition that generates a 2SPP-P-circuit, which includes two blocks representing the projected subfunctions obtained by Shannon cofactoring with respect to a chosen variable, and a block representing the intersection of the projections. The three blocks are implemented as minimal 2-SPP forms (XOR-ANDOR with XOR restricted to two inputs). The minimization is performed...
Componentised systems, in particular those with fault confinement through address spaces, are currently emerging as a hot topic in embedded systems research. This paper extends the unified rate-based scheduling framework RBED in several dimensions to fit the requirements of such systems: we have removed the requirement that the deadline of a task is equal to its period. The introduction of inter-process...
Traffic measurements from communication networks have shown that network traffic is exhibiting self similar as well as long range dependence properties. In telecommunication networks, congestion events tend to persist, producing large delays and packet loss resulting in performance degradation. In order to guarantee quality of service to diverse Internet services, congestion prediction became a fundamental...
This paper analyzes Monte Carlo simulation procedures to estimate the impact of process intradie variations on the delay variability of digital circuits. The traditional approach based on the separate evaluation of intradie and interdie variations is shown to be incorrect. Indeed, Monte Carlo simulations on a 65-nm CMOS technology show that this approach can lead to underestimation by up to 35% in...
This paper examines a new method for sequential detection of a sudden and unobservable change in a sequence of independent observations with completely unspecified distribution functions. A nonparametric detection rule is proposed which relies on the concept of a moving vertically trimmed box called V-Box Chart. Its implementation requires merely to count the number of data points which fall into...
In this paper, the ground-to-air channel model is studied and the simulation results of the model are provided. Then, we implement it in the improved single carrier frequency domain equalization (SC-FDE) system and compare the transmission characteristics in different conditions. Theoretical analysis and simulation results show that the BER performance of the proposed system can reach 10-7 or even...
The non-coherent time-of-arrival (TOA) estimations are applied in impulse location for its simplicity. However, the multipath propagation of the narrow pulse results in complicated performance analysis. By fitting the output envelope of energy detection into a exponential decay, we approximately deduce the closed-form Cramer-Rao low bound (CRLB) of TOA estimation. Simulations with non-coherent TOA...
We propose a novel, passive, nonintrusive method to measure the one-way delay of all the packets flowing between customer sites connected by a provider backbone. Our approach does not sample traffic and requires the injection of a negligible amount of control packets, possibly none. This is obtained by deploying a Measurement Agent in each customer site and exploiting a covert channel to carry information...
Using data communication networks for telephony services has evolved the telecommunication industry. The basic requirement in this field is achieving confidence about the quality of the telephony service. In this paper, a practical approach based on the quantitative and qualitative analysis is presented in order to evaluate the readiness of an Ethernet network for telephony service. The aim is to...
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