車載網路模擬器之整合與閘道路由分析

近年來，結合無線網路通訊科技於交通工具，構成智慧型運輸系統（Intelligent Transportation Systems， ITS）已是各國矚目的研究焦點。為了研究車載資通訊，模擬器是不可缺少的工具，SUMO 和 NS2 是目前在此領域運用最廣的模擬器：SUMO 可以產生車流動態模擬，而 NS2 則可以模擬有線和有線節點的網路通訊過程。由於兩者都是公開軟體，其原始碼取得容易，適當加以結合即可以成為研究車載資通訊的利器。雖然 SUMO 支援彎道的敘述，然而以往將 SUMO 產生的車流動態轉成 NS2 所使用的節點移動描述檔的軟體，都只允許使用許多小段的直線道敘述來組成彎道，此對於建構拓樸上相當不方便。我們修改了 SUMO 軟體中的 NetExporter 工具使其直接對彎曲的道路做轉換。我們也修改了 NetExporter 的座標計算，使其能正好符合 NS2 的座標範圍。透過模擬器的整合，針對當前隨意網路中，單一路徑路由協定（DSDV、AODV）與多路徑路由協定（AOMDV）經由閘道連結網際網路之情況進行實驗分析比較，瞭解改變閘道數量與交通量之多寡，對於封包送達率之效能影響。

關鍵字

交通模擬器； SUMO ；單多路徑路由機制； NS2網路模擬器

並列摘要

Applying wireless communication technologies to vehicles to form intelligent transportation systems (ITS) is an important research topic in recent years. For verifying the protocols designed on vehicular communications, simulating tools are indispensable. SUMO and NS2 are two of the most popular simulators for this purpose. While Sumo can generate and simulate the traffic flows of vehicles, NS2 can simulate the network communication processes for both wired and wireless communications. Since both simulators are open software, researchers can obtain their source codes easily. By combining these two simulators, we can establish a very good environment for researches on vehicular communications. However, the current tools have a shortcoming: although crooked roads can be described in an XML statement in Sumo, but such statements are not allowed when they are transformed to a movement scenario of NS2 by current transformation tools. They enforce a crooked road being described with a several number of joined straight roads, which results in tedious jobs. To solve this problem, we modify the TraceExporter provided in SUMOso that it can support transformation of crooked-road statements directly. Moreover, we also remedy the coordinate translation problem of TraceExporter so that it can get a just-match boundary for NS2. With the integration of the simulation tools, extensive experiments are taken for the scenarios of accessing Internet via base stations or gateways by using the well-known ad hoc routing protocols, such as DSDV, AODV and AOMDV. We have made numerical comparisons among these protocols and investigate the effect on the performance measures, including packet arrival rate and delay, by varying the number of base stations and the amount of packet traffic.

並列關鍵字

SUMO ； NS2 ； TraceExporter ； network simulator ； vehicular ad hoc network

參考文獻

[1]D. Johnson and D. Maltz, "Dynamic SourceRouting in Ad Hoc Wireless Networks," in MobileComputing, 1996, pp. 153-181.

[2]C. E. Perkins and P. Bhagwat, "Highly dynamicDestination-Sequenced Distance-Vector routing(DSDV) for mobile computers," SIGCOMM Computer Community. 1994, pp. 234-244, 1994.

[3]C. E. Perkins and E. M. Royer, "Ad-hocOn-Demand Distance Vector Routing," presentedat the Proceedings of the Second IEEE Workshopon Mobile Computer Systems and Applications, 1999.

[4]Mahesh K. Marina and Samir R. Das, Ad hoc on-demand multipath distance vector routing, Wireless communications and mobile computing, DOI: 10.1002, 6(7), 969-988, 2006.

[6]鍾明志，智慧型運輸系統技術發展規劃之研究: 以台灣地區APTS 與ATIS 為例，國立成功大學交通管理科學研究所，中華民國九十五年五月二十六日

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車載網路模擬器之整合與閘道路由分析

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