Event-synchronization protocol for parallel simulation of large-scale wireless networks

Abstract

An event synchronization protocol called time-based synchronization (TBS) is employed to control operation of a network simulation. In TBS, processors in the simulated network execute events based on comparisons between timestamps for each event and a value generated by a time tracking device in the processor. In this manner, event execution is not dependent on other processes in the network and the simulation can actually be carried out at speeds faster than real time. A multiprocessor network is specially designed to execute TBS-based simulations.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority under 35 U.S.C. 11 9(e) on U.S. Provisional Application No. 60 / 568,259, which was filed on May 6, 2004, and is hereby incorporated by reference.[0002]This application is also related to a U.S. patent application entitled Sensor-Network Processors Using Event-Driven Architecture, which is being filed concurrently herewith on May 6, 2005.GOVERNMENT SPONSORSHIP STATEMENT[0003]This invention arose out of research sponsored by a United States Government Agency, the Office of Naval Research (ONR), under ONR Contract No. N00014-00-1-0564. The Government has certain rights in the invention.BACKGROUND OF THE INVENTION[0004]1. Field of the Invention[0005]The present invention relates in general to a conservative event-synchronization protocol, time-based synchronization, which is particularly suited for parallel discrete event simulation of mobile ad hoc wireless networks.[0006]2. Description of the Background Art[0...

AI Technical Summary

Benefits of technology

[0014]The present invention relates in general to new conservative event synchronization protocol called time-based synchronization (TBS). In TBS, a time scale is employed to control operation of a network simulation such that the size of the network to be simulated is no longer a factor in determining the speed at which the simulation will run. Furthermore, the use of a TBS-based protocol enables the simulation to be carried out at speeds many times faster than real time, depending on the processor architecture used to run the simulation. With this protocol, very large MANETs, for example, can be simulated quickly.

[0015]The manner in which the TBS protocol works is as follows. An LP in a simulation using TBS becomes sure that it can execute an event when a timestamp of the event is less than the elapsed real time (or scaled version thereof) since the simulation began. In other words, if the simulation has been executing for time t, then an LP can execute the event when the event's timestamp T is less than the elapsed real time (or, in the case of scaled time, less than the elapsed real time multiplied by the time scale of the simulation). Note that, unlike an LP in a simulation using the null message protocol, an LP in a TBS-based simulation does not need to know which other LPs can send it messages. Moreover, an LP in a TBS-based simulation can determine whether an event is executable without waiting for information from other LPs. The ability of an LP to make this determination on its own is what allows TBS-based simulations to scale well and be unaffected by the number of LPs in the network being simulated.

Problems solved by technology

A drawback to know MANET simulation protocols, such as the null-message protocol, is that the speed at which an LP can execute an event depends on the rate at which the LP receives messages from other LPs in the network.

However, for very large networks with hundreds or even thousands of nodes, such limitations can dramatically increase the amount of time necessary to run a network simulation.

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