結論

In this work, we first describe a tool MOVE which is based on an open source micro-traffic simulator SUMO. MOVE allows user to quickly generate realistic mobility models for vehicular network simulations. We show that the details of a mobility model such as the existence of traffic lights, driver route choice and car overtaking behavior can have a significant impact on the simulation results. Care should be taken if simple mobility models are used for evaluation of VANET as the results might not be as close to reality as expected. Our next step is to use MOVE to understand the effect of user travel plan (such as path selection, means of transportation, etc) on VANET simulations. We first evaluated congestion significant effect in VANET. The results depicted congestion can increase network performance.

We have made MOVE publicly available and can be downloaded via the following URL- http://lens1.csie.ncku.edu.tw/MOVE/. In our current implementation, the movements of vehicles are based on static configurations predefined in the Vehicle Movement Editor. In other words, the mobility model is first generated off-line and then used by a network simulator like ns-2. In the next version of our software, because an accident can change mobility model in any time, we plan to build an interface to tightly integrate SUMO and ns-2. Such an interface will allow that vehicle state information (such as location, speed, direction, etc) can be fed into ns-2 in real time. Hence, during the simulation the vehicles can dynamically adjust their routes based on different traffic scenarios and communication techniques employed.

參考資料

[8] J. Heidemann, N. Bulusu, J. Elson, C. Intanagonwiwat, K. chan Lan, Y. Xu, W.

Ye,D.Estrin,and R.Govindan,“Effectsofdetailin wirelessnetwork simulation,”in CNDS 2002, Jan. 2001.

[Online]. Available: http://www.isi.edu/~johnh/PAPERS/Heidemann00d.html

[9]S.S.ofUrban MObility,“http://sumo.sourceforge.net/.”

[10] TIGER (Topologically Integrated GEographic Encoding and Referencing),

“http://www.census.gov/geo/www/tiger/.”

[11]S.Floyd and V.Paxson,“Difficultiesin simulating theInternet,”ACM/IEEE Transactions on Networking, vol. 9, no. 4, pp.

392–403, Feb. 2001. [Online]. Available: http://www.icir.org/vern/papers.html [12]K.tutorial,“http://www.keyhole.com/kml/kmltut.html.” Vehicular Ad Hoc Networks (VANET), Cologne, Germany, Sep. 2005.

[Online]. Available: http://www.aqualab.cs.northwestern.edu/publications/DChoffnes05vanet.html in Mobile Computing, vol. 35, Kluwer Academic, 1996, pp. 153–181.

[19]S.R.Das,C.E.Perkins,and E.M.Royer,“Performancecomparison oftwo

on-demand routing protocolsforad hocnetworks,”in Proc. IEEE Infocom, 2000.

[20]G.Holland and N.H.Vaidya,“Proc.mobicom,acm intern.conf.on mobile computing and networking,”in Proc. IEEE Infocom, Aug. 1999.

[21]C.E.Perkinsand E.M.Royer,“Ad-hoc on-demand distancevectorrouting,”in Proc. IEEE Workshop on Mobile Computing Systems and Applications, Feb. 1999.

[22] P. Johansson, T. Larsson, N. Hedman, B. Mielczarek, and M. Degermark,

“Routing protocols for mobile ad-hoc networks - a comparative performance

Special issue on Mobile Ad Hoc Networking: Research, Trends and Applications, vol.

2, no. 5, 2002, pp. 483–502.

[26]F.Bai,N.Sadagopan,and A.Helmy,“Important:aframework to systematically analyze the impact of mobility on performance of routing protocols for ad hoc networks,”in The 22th IEEE Annual Joint Conference on Computer Communications and Networking INFOCOM 2003, 2003, pp. 825–835.

[27]F.Bai,N.Sadagopan,and A.Helmy,“The importantframework foranalyzing the impact of mobility on performance of routing for ad hoc networks,” AdHoc Networks Journal - Elsevier Science, vol. 1, no. 4, pp. 383–403, Nov. 2003.

[28] A. P. Jardosh, E. M, Belding-Royer,K.C.Almeroth,and S.Suri,“Real-world environmentmodelsformobilenetwork evaluation,”Mar.2005.

[29] I. Stepanov, P.-J.Marron,and K.Rothermel,“Mobility modeling ofoutdoor scenarios for manets,” in Proc. of the 38th annual Symposium on Simulation ANSS ’05,Apr. 2005, pp. 312–322.

[30]M.B.Sven Jaap and L.Wolf,“Evaluation ofrouting protocolsforvehicularad hocnetworksin city trafficscenarios,”in Proc. of the 5th International Conference on Intelligent Transportation Systems Telecommunications (ITST), 2005.

[31]M.Treiber,A.Hennecke,and D.Helbing,“Congested trafficstatesin empirical observationsand microscopicsimulations,”IPhys. Rev., vol. 62, no. 2, Aug. 2000.

[32] H.-M.Zimmermann,I.Gruber,and C.Roman,“A voronoi-based mobility model forurban environments,” in Proc. of the European Wireless 2005 (EW05), Apr. 2005.

[33]A.Mahajan,N.Potnis,K.Gopalan,and A.A.Wang,“Urban mobility models forvanets,”in Proc. of the IEEE Workshop on Next Generation Wireless Networks (WoNGeN), Dec. 2006.

[34] N. Potnis and A. Mahajan, “Mobility models for vehicular ad hoc network simulations,”in proc. of the 44th annual Southeast regional conference, ACM, 2006, pp. 746–747.

[35]G.Marfia,G.Pau,E.Giordano,E.D.Sena,and M.Gerla,“Evaluating vehicle network strategies for downtown portland: Opportunistic infrastructure and importanceofrealisticmobility models,”in proc. of MoBiOpp 2007, co-located with ACM/USENIX International Conference on Mobile Systems, Applications, and Services (MobiSys 2007), Jun. 2007.

[36]TRANSIMS:,“http://transims.tsasa.lanl.gov/.”

[37]R.Baumann,S.Heimlicher,and M.May,“Towardsrealisticmobility modelsfor vehicular ad-hocnetworks,”in 2007 Mobile Networking for Vehicular Environments, May 2007, pp. 73–78.

[38]B.Raney,N.Cetin,A.Vollmy,M.Vrtic,K.Axhausen,and K.Nagel,“Towards a microscopic traffic simulation of all of switzerland,” in ICCS 2002, 2002, pp.

371–380.

[39] J.-Y.L.Boudecand M.Vojnovic,“Perfectsimulation and stationarity ofaclass ofmobility models,”in IEEE Infocom, 2005.

[40] R. Mangharam, D. S. Weller, D. D. Stancil, R. Rajkumar, and J. S. Parikh,

“GrooveSim: A topography-accurate simulator for geographic routing in vehicular network,”in Proc. of the 2nd ACM International Workshop on Vehicular Ad Hoc Networks (VANET), Cologne, Germany, Sep. 2005.

[Online]. Available: http://www.andrew.cmu.edu/