Convergence of Probability Measures. By P. Billingsley. Chichester, Sussex, Wiley, 1968. xii, 253 p. 9 1/4“. 117s.

Convergence of Probability Measures

"A Survey of Mobility Models for Ad Hoc Network Research," Wireless Comm. & Mobile Computing (WCMC) : Special issue on Mobile Ad Hoc Networking : Research

In the performance evaluation of a protocol for an ad hoc network, the protocol should be tested under realistic conditions including, but not limited to, a sensible transmission range, limited buffer space for the storage of messages, representative data traffic models, and realistic movements of the mobile users (i.e., a mobility model). This paper is a survey of mobility models that are used in the simulations of ad hoc networks. We describe several mobility models that represent mobile nodes whose movements are independent of each other (i.e., entity mobility models) and several mobility models that represent mobile nodes whose movements are dependent on each other (i.e., group mobility models). The goal of this paper is to present a number of mobility models in order to offer researchers more informed choices when they are deciding upon a mobility model to use in their performance evaluations. Lastly, we present simulation results that illustrate the importance of choosing a mobility model in the simulation of an ad hoc network protocol. Specifically, we illustrate how the performance results of an ad hoc network protocol drastically change as a result of changing the mobility model simulated.

/pdf/a-survey-of-mobility-models-for-ad-hoc-network-research-ygkxat400x.pdf

A survey of mobility models for ad hoc network research

Worst-case bounds on delay and backlog are derived for leaky bucket constrained sessions in arbitrary topology networks of generalized processor sharing (GPS) servers. The inherent flexibility of the service discipline is exploited to analyze broad classes of networks. When only a subset of the sessions are leaky bucket constrained, we give succinct per-session bounds that are independent of the behavior of the other sessions and also of the network topology. However, these bounds are only shown to hold for each session that is guaranteed a backlog clearing rate that exceeds the token arrival rate of its leaky bucket. A much broader class of networks, called consistent relative session treatment (CRST) networks is analyzed for the case in which all of the sessions are leaky bucket constrained. First, an algorithm is presented that characterizes the internal traffic in terms of average rate and burstiness, and it is shown that all CRST networks are stable. Next, a method is presented that yields bounds on session delay and backlog given this internal traffic characterization. The links of a route are treated collectively, yielding tighter bounds than those that result from adding the worst-case delays (backlogs) at each of the links in the route. The bounds on delay and backlog for each session are efficiently computed from a universal service curve, and it is shown that these bounds are achieved by "staggered" greedy regimes when an independent sessions relaxation holds. Propagation delay is also incorporated into the model. Finally, the analysis of arbitrary topology GPS networks is related to Packet GPS networks (PGPS). The PGPS scheme was first proposed by Demers, Shenker and Keshav (1991) under the name of weighted fair queueing. For small packet sizes, the behavior of the two schemes is seen to be virtually identical, and the effectiveness of PGPS in guaranteeing worst-case session delay is demonstrated under certain assignments. >

/pdf/a-generalized-processor-sharing-approach-to-flow-control-in-2dkaey9h9e.pdf

A generalized processor sharing approach to flow control in integrated services networks: the multiple node case

The stability of a queueing network with interdependent servers is considered. The dependency among the servers is described by the definition of their subsets that can be activated simultaneously. Multihop radio networks provide a motivation for the consideration of this system. The problem of scheduling the server activation under the constraints imposed by the dependency among servers is studied. The performance criterion of a scheduling policy is its throughput that is characterized by its stability region, that is, the set of vectors of arrival and service rates for which the system is stable. A policy is obtained which is optimal in the sense that its stability region is a superset of the stability region of every other scheduling policy, and this stability region is characterized. The behavior of the network is studied for arrival rates that lie outside the stability region. Implications of the results in certain types of concurrent database and parallel processing systems are discussed. >

/pdf/stability-properties-of-constrained-queueing-systems-and-1ejlpmfzvp.pdf

Stability properties of constrained queueing systems and scheduling policies for maximum throughput in multihop radio networks

Tracking strategies for mobile users in wireless networks are studied. In order to save the cost of using the wireless links mobile users should not update their location whenever they cross boundaries of adjacent cells. This paper focuses on three natural strategies in which the mobile users make the decisions when and where to update: the time-based strategy, the number of movements-based strategy, and the distance-based strategy. We consider both memoryless movement patterns and movements with Markovian memory along a topology of cells arranged as a ring. We analyze the performance of each one of the three strategies under such movements, and show the performance differences between the strategies.

Mobile users: to update or not to update?

Conflict-free access protocols aloha protocols carrier sensing protocols collision resolution protocols additional topics. Appendix: mathematical formulae and background.

Multiple Access Protocols: Performance and Analysis

A method and apparatus for testing a network having a plurality of nodes (24). The method includes sending commands to one or more traffic agents (60) connected to the network (20) and to at least one network management agent (70) coupled to a respective node (24) of the network (20), transmitting data from at least one of the traffic agents (60) over the network responsive to the commands, determining network information at the at least one network management agent (70) responsive to the commands and to transmission of the data through the respective node, and receiving and evaluating the network information to assess a state of the network.

Fault location and performance testing of communication networks

The cyclic polling model, its enhancement by customer routing, and the replacement of a fixed polling order by a random polling order are reviewed. Modeling of polling systems, performance improvement, and system optimization issues are discussed. Examples are given that include token rings, ARQ and time-sharing schemes, random-access protocols, robotics and manufacturing systems. Emphasis is not on the analytical derivations of polling systems but rather on the description of the capabilities and limitations of the different polling models. >

Polling systems: applications, modeling, and optimization

Tracking strategies for mobile users in wireless networks are studied. In order to save the cost of using the wireless links mobile users should not update their location whenever they cross boundaries of adjacent cells. The paper focuses on three natural strategies in which the mobile users make the decisions when and where to update: the time-based strategy, the number of movements-based strategy, and the distance-based strategy. The authors consider both memoryless movement patterns and movements with Markovian memory along a topology of cells arranged as a ring. They analyze the performance of each one of the three strategies under such movements, and show the performance differences between the strategies. >

http://delab.csd.auth.gr/~dimitris/courses/mpc_fall05/papers/location_management/ACM_WINET_1_2_95_update_or_not.pdf

Moshe Sidi

Papers

Mobile users: to update or not to update?

Multiple Access Protocols: Performance and Analysis

Fault location and performance testing of communication networks

Polling systems: applications, modeling, and optimization

Mobile users: to update or not to update?