@conference {
	title = {Measurement and Simulation Based Effective Bandwidth Estimation},
	author = {Liu, Nelson X., Baras, John S.},
	year = {2004},
	month = {11/2004},
	abstract = {Effective bandwidth represents the resource demand for network traffic to achieve its QoS goal. However, so far, the estimation of the effective bandwidth for modern Internet traffic has been difficult and inaccurate. We present a novel scheme using measurement and simulation techniques to estimate the effective bandwidth. The advantages of the scheme lie in its accuracy, its applicability to various traffic environments, and its efficiency. We describe the simulation procedure, the efficient search algorithm to lock the effective bandwidth quickly, the sample size determination algorithm, and the performance judgment policy in the simulation to guarantee the estimation accuracy. We also examine the issue of estimating the effective bandwidth of aggregate traffic from sub-aggregates, and provide an empirical formula to achieve very good accuracy.},
	address = {Dallas, TX},
	booktitle = {GLOBECOM 04},
	pages = {pp. 2108-2112}
}
@conference {
	title = {Capability Assessment and Design Evaluation for the Hybrid Network of Space GiG and Terrestrial Sensor Nets: Global Monitoring, Tracking and Query},
	author = {Liu, Nelson X., Baras, John S.},
	year = {2004},
	month = {10/2004},
	abstract = {In this paper, we propose a hierarchical architecture for organizing the hybrid network of the LEO-satellite based space network and terrestrial sensor nets. The hybrid network has unique advantages in providing global monitoring, tracking, and query capabilities. We assess these three capabilities of the network, and seek the optimal design in terms of the cooperation of the MAC and routing protocols. We evaluate six combinations of the MAC and routing protocols, and identify the best solution. Extensive simulation results are provided, Application models and performance metrics for the three capabilities are developed. The work provides a reference framework for pursuing global monitoring, tracking, query capabilities with hybrid space-terrestrial networks.},
	address = {Monterey, California},
	booktitle = {MILCOM 2004},
	pages = {pp. 899-905}
}
@conference {
	title = {Adaptive Hierarchical Resource Management for the Hybrid network of MANET-Satellite Internet},
	author = {Liu, Nelson X., Zhou, Xiaoming., Baras, John S.},
	year = {2004},
	month = {09/2004},
	abstract = {MANETs are often deployed in an infrastructure-less or hostile region where the satellite provides the only link for the MANETs to communicate with the rest part of the world. It faces many challenges to support multiple serviced communications between MANETs and Internet through satellite. In this paper we propose an efficient resource management scheme called AHRM to dynamically allocate bandwidths among multiple MANET users and multiple priority and non-priority services sharing a multi-access satellite channel. It uses a flexible hierarchical structure to exploit the channel utility and resolve contention from two levels. A bandwidth adaptation algorithm is designed to adjust the allocation dynamically in response to traffic and link status changes. The algorithm turns out to be in line with reinforcement learning and is a customized version of it for the practical satellite network setting. Implementation issues are discussed. Simulation results are presented, showing that the scheme can guarantee fast delivery of critical messages in spite of channel contention, and significantly improve the performance of multiple services.},
	address = {Los Angeles, California},
	booktitle = {2004 IEEE Vehicular Technology Conference},
	pages = {pp. 4027-4031}
}
@conference {
	title = {Long-Run Performance Analysis of a Multi-Scale TCP Traffic Model},
	author = {Liu, Nelson X., Baras, John S.},
	year = {2004},
	month = {06/2004},
	abstract = {The long-run queueing performance of a multi-scale TCP traffic model, the HOO model, is analysed. Since the model links the multi-scale behaviour with practical traffic elements and approximates TCP traffic very well, the analysis is expected to provide insights into the physical interpretation of multi-scale traffic and to give useful results for performance prediction. To derive a meaningful solution and avoid the extreme difficulty of an exact analysis, the authors adopt several techniques to track the problem, among which are techniques to establish equivalent processes to the traffic process or the queue content process in two cases, the case of fast flows and the case of slow flows. Quantitative results for the queue tails are obtained in both cases, and a unified form is derived. It indicates that three levels of traffic elements in different time scales, i.e. the connection, the burst and the packet, all affect the asymptotic queueing performance. It shows quantitatively how the connection determines the index of the queue tail, and the burst and the packet contribute to the tail with their averages. Used with simple statistical inferences, the analytical result is shown to predict the queueing performance of real traffic well.},
	booktitle = {IEE Proceedings- Communications},
	pages = {pp. 251-257}
}
@conference {
	title = {Web Access Over a Multiple Access Channel: Evaluations and Improvements},
	author = {Zhou, Xiaoming., Liu, Nelson X., Baras, John S.},
	year = {2004},
	month = {06/2004},
	abstract = {We evaluate Web browsing performance over a multiple access satellite channel for three different MAC layer protocols. A Web user behavior model is used to generate realistic source traffic. A new transport layer protocol called RWBP is proposed to solve the TCP problems inside satellite networks. RWBP uses per-flow queuing, round robin scheduling and receiver window backpressure for congestion control. We compare its performance with TCP over the three multiple access protocols. Our simulation results show that RWBP can reduce the multiple access channel load and at the same time improve the Web page response time when driven by realistic Web traffic. For the MAC layer protocols, combined free demand assignment multiple access (CFDAMA) always performs better than the other two protocols.},
	address = {Paris, France},
	booktitle = {2004 IEEE International Conference on Communications},
	pages = {pp. 4392-4396}
}
@article {
	title = {Long-run Performance Analysis of a Multi-Scale TCP Traffic Model},
	author = {Liu, Nelson X., Baras, John S.},
	year = {2004},
	month = {06/2004},
	abstract = {The long-run queueing performance of a multi-scale TCP traffic model, the HOO model, is analyzed. Since the model links the multi-scale behavior with practical traffic elements and approximates TCP traffic very well, the analysis is expected to provide insights into the physical interpretation of multi-scale traffic and to give useful results for performance prediction. To derive a meaningful solution and avoid the extreme difficulty of an exact analysis, the authors adopt several techniques to track the problem, among which are techniques to establish equivalent processes to the traffic process or the queue content process in two cases, the case of fast flows and the case of slow flows. Quantitative results for the queue tails are obtained in both cases, and a unified form is derived. It indicates that three levels of traffic elements in different time scales, i.e. the connection, the burst and the packet, all affect the asymptotic queueing performance. It shows quantitatively how the connection determines the index of the queue tail, and the burst and the packet contribute to the tail with their averages. Used with simple statistical inferences, the analytical result is shown to predict the queueing performance of real traffic well.},
	pages = {pp. 251-257},
	volume = {Vol.  151},
	number = {No. 3},
	journal = {Communications \&ndash; IEEE Proceedings}
}
@conference {
	title = {Measurement and Simulation Based Effective Bandwidth Estimation MANETs},
	author = {Liu, Nelson X., Baras, John S.},
	year = {2004},
	month = {01/2004},
	abstract = {Effective bandwidth represents the resource demand for network traffic to achieve its QoS goal. However, the estimation of the effective bandwidth for modern Internet traffic is difficult and inaccurate so far. In this paper we present a novel scheme using the measurement and simulation techniques to estimate the effective bandwidth. The advantages of the schemelie in its accuracy, its applicability to various traffic environments, and its efficiency. We describe the simulation procedure, the efficient search algorithm to quickly lock the effective bandwidth, the sample size determination algorithm, and the performance judgment policy in the simulation to guarantee the estimation accuracy. We also examine the issue of estimating the effective bandwidth of aggregate traffic from sub-aggregates, and provide an empirical formula to achieve very good accuracy.},
	address = {Dallas, Texas},
	booktitle = {GLOBECOM 2004}
}
@conference {
	title = {Statistical modeling and performance analysis of multi-scale traffic},
	author = {Liu, Nelson X., Baras, John S.},
	year = {2003},
	month = {03/2003},
	abstract = {In this paper we propose a new statistical model for multi-scale traffic, and present an exact queueing analysis for the model. The model is based on the central moments and the marginal distributions of the cumulative traffic loads in different time scales. Only the first two moments are needed to characterize the traffic process, which greatly simplifies the representation and estimation. The queueing analysis uses a very general approach and can evaluate not only the steady state performance but also the transient queuing behavior. The analysis reveals that there exist two classes of packet losses, the absolute loss and the opportunistic loss, both of which can be examined exactly with the method. Based on the statistical model and the queueing analysis method, a compound model is constructed for the practical multiscale traffic, and its performance is evaluated from various aspects. This work provides a good basis for practical application of the multiscale traffic characterizations in network dimensioning and resource management.},
	address = {San Francisco, CA},
	booktitle = {22nd Annual Joint Conference of the IEEE Computer and Communications Societies, INFOCOM 2003},
	pages = {pp. 1837-1847}
}
@article {
	title = {Modeling Multi-Dimensional QoS: Some Fundamental Constraints},
	author = {Liu, Nelson X., Baras, John S.},
	year = {2004},
	month = {04/2004},
	abstract = {In this paper, we model multi-dimensional QoS in a unified framework and study some fundamental constraints from the network and the traffic on realizing multiple QoS goals. Multidimensional QoS requirements are quantitatively represented using a QoS region. Based on the theory of effective bandwidths, the framework connects the throughput, the delay, and the loss rate in a uniform formula. Important traffic and network factors, namely, the burst size and the link speed are involved. With this framework, it is found that the burst size sets a hard limit on the QoS region that can be achieved and that the matching between the link speed and the node processing power can greatly improve the limit. It is also made clear that while pure load imbalance among links does not affect the QoS region, the heterogeneities of burst size or link speed may severely degrade the QoS performance. Applying the theory to real-time services in differentiated services architecture, we show it provides a useful tool for QoS prediction and network dimensioning.},
	pages = {pp. 193-215},
	volume = {Vol. 17},
	journal = {International Journal of Communication Systems}
}
@techreport {
	title = {Web access over a multiple access channel: evaluations and improvements},
	author = {Zhou, Xiaoming., Liu, Nelson X.},
	year = {2004},
	month = {01/2004},
	abstract = {We evaluate web browsing performance over a multiple access satellite channel for three different MAC layer protocols. A web user behavior model is used to generate realistic source traffic. A new transport layer protocol called RWBP is proposed to solve the TCP problems inside satellite networks. RWBP uses per-flow queuing, round robin scheduling and receiver window backpressure for congestion control. We compare its performance with TCP over the three multiple access protocols. Our simulation results show that RWBP can reduce the multiple access channel load and at the same time improve the web page response time when driven by realistic web traffic. For the MAC layer protocols, combined free demand assignment multiple access (CFDAMA) always performs better than the other two protocols.},
	number = {Number: CSHCN TR 2004-10}
}
@techreport {
	title = {Dynamical Properties of TCP System with AQM Routers},
	author = {Chen, Huigang., Liu, Nelson X.},
	year = {2003},
	month = {01/2003},
	abstract = {In this report we discuss the dynamics of heterogeneous TCP systems with propagation delays. Instead of studying the local linearized TCP dynamics, we study the global stability conditions and obtain the stability regions. Also we provide proof of periodic behavior of a single TCP connection when stability conditions are not met.},
	number = {Number: CSHCN TR 2003-22}
}
@article {
	title = {On Scaling Property of Network Traffic in Small Scales},
	author = {Liu, Nelson X., Baras, John S.},
	journal = {Computer Networks Journal}
}
