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A 2D Markov-Chain analysis is used to model channel occupancy within a high mobility picocell based network including handover and outage events. Single-cell performance is evaluated by the Grade of Service and by the call dropping probability. The relations between different picocellular network parameters are analyzed and guidelines for proper MAC protocol design are given.
Many studies have shown that Vegas TCP has a better throughput and stability than Reno TCP in homogeneous networks with a single TCP flavor, but performs less well in heterogeneous networks in which two TCP flavors coexist. The progressive behavior of Reno TCP and the conservative behavior of Vegas TCP cause a bias when they are used simultaneously, and thus Vegas TCP fails to obtain a fair share...
End-to-end QoS is a challenge for future Internet. A per flow resource reservation can be carried out among heterogeneous domains on the communication path using signaling protocols. When one or both communicating terminals are mobile there is additional complexity. Signaling delays and resource lacking on future paths can dramatically impact user experience. In this paper, a rational future path...
We study the impact of time-correlated arrivals on the performance of backpressure policy for stochastic network control. The arrival process considered in this work is fairly general in the sense that it may exhibit short/long-range dependence depending on the asymptotic shape of the autocorrelation function. In this paper, we show that that the backpressure policy stabilizes the network whenever...
We consider the downlink of an OFDM system for supporting a large number of delay-sensitive users. The OFDM scheduling problem can be modeled as a discrete-time multi-source multi-server queuing system with time-varying connectivity. For such a system, the Max-Weight policy is known to be throughput-optimal and the Server-Side Greedy (SSG) policy has been recently shown to achieve small queue lengths...
We consider the problem of joint service rate control and load balancing of a network of servers. The system incurs holding cost, effort cost, and a routing cost whenever a demand is routed to other servers. This formulation is motivated by recent interest on energy efficiency in IT systems where effort cost models power consumption and holding cost represents performance in terms of delay. The aim...
In this work, we study the effects of finite buffers on the throughput and delay of line networks with erasure links. We identify the calculation of performance parameters such as throughput and delay to be equivalent to determining the stationary distribution of an irreducible Markov chain. We note that the number of states in the Markov chain grows exponentially in the size of the buffers with the...
Increasing demands of ubiquitous services in wireless networks and evolution towards heterogeneous solutions has driven the necessity of developing efficient QoS aware vertical handoff (handoff between different networks) mechanisms. This paper proposes a QoS aware fuzzy rule based vertical handoff mechanism that makes a multi-criteria based decision, found to be effective for meeting the requirements...
In this paper, we consider a simple two-relay wireless sensor network with packet retransmission where transmission energy and network geometry can be adjusted to improve the energy efficiency of the whole network. We model the energy states of the system as a Markov chain. With both analytical and numerical methods, we investigate how total energy consumption per packet and system throughput are...
We propose an event driven semi-Markov chain model for dual radio node architecture. The performance of proposed architecture in terms of energy-latency tradeoff is compared with that of schedule based dual radio architecture. Numerical results show the usefulness of event driven dual radio architecture for delay sensitive data transmission.
In this paper performance modeling for a mobile stations operating according to CSMA/CA with binary exponential back-off (BEB) is discussed. Unlike the previous studies we concentrate on delay and loss performance metrics experienced by individual stations. To obtain delay distribution of an arbitrary packet we use Geo(i)/G(i)/1/K queuing system representing the number of stations having a frame for...
Modern logic synthesis systems apply a sequence of loosely-related function-preserving transformations to gradually improve the circuit with respect to certain criteria such as area, performance, power, etc. For the quality of a complete synthesis run, the application order of the transformations for the individual steps are critical as they can produce vastly different outcomes. In practice, the...
We explore the spatio-temporal congestion dynamics of wireless networks with backlog-based random-access mechanisms. While relatively simple and inherently distributed in nature, suitably designed backlog-based access schemes provide the striking capability to match the optimal throughput performance of centralized scheduling algorithms in a wide range of scenarios. In the present paper, we show that...
We consider a saturated tree network with flow control. The network consists of two layers of polling stations, all of which use the random polling service discipline. We obtain the equilibrium distribution of the network using a Markov chain approach. This equilibrium distribution can be used to efficiently compute the division of throughput over packets from different sources. Our study shows that...
Analysis of IEEE 802.15.4 CSMA/CA scheme with homogeneous or saturated traffic has received considerable attention recently since a great convenience is offered to applications of low-power and low-rate wireless sensor networks (WSNs) which almost touch upon all aspects of our life. In this paper, we propose a stochastic analysis approach to evaluate the delay performance of CSMA/CA scheme with heterogeneous...
Network coding can significantly improve the throughput and power efficiency of wireless networks by mixing packets from different flows into a single packet. However, forcing packets to be coded may induce large delay and packet-loss rate which is intolerable to some services such as real-time communications. Considering the diversity of traffic flows and the stochastic nature of the packet arrival...
For the congestion problems in high-speed networks, a genetic based fuzzy Markov game flow controller (GFMC) is proposed. Because of the uncertainties and highly time-varying, it is not easy to accurately obtain the complete information for high-speed networks. In this case, the fuzzy Markov game, which is independent of mathematic model, and prior-knowledge, has good performance. It offers a promising...
Optical packet switching is an emerging technology, which provides enormous bandwidth for Internet traffic. In this paper, we investigate the performance of hybrid buffering optical packet switch with fixed-length packets under self-similar Pareto traffic, for a more realistic traffic. The performance is evaluated in terms of packet loss rate and average delay by means of simulation experiments. Usually,...
This paper studies the stability and stabilization problems for networked control systems with partly unknown transition probabilities by using time-varying sampling period method where the main focus is the packet-loss issue,packet-loss process is the Markovian packet-loss process and the transition probabilities does not require completely known. A developed packet dropouts dependent Lyapunov functional...
False and nuisance alarms are major problems in the process industry. Techniques like deadbands, delay-timers, and filtering can significantly reduce these false and nuisance alarms. The down-side, however, is that using these techniques introduces some delay in raising the alarm (detection delay). In this paper, detection delays caused by deadband and delay-timer techniques are calculated using Markov...
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