| 摘要: | 近幾年無線網路快速的成長，使得其應用與服務變得越來越普遍。車載資通訊有多樣應用服務，例如，行車安全、全球定位導航、多媒體、影音串流以及網路存取服務。隨著無線科技的成熟，各種無線網路需求的概念被提出；以Intelligent Transportation System 為例，許多交通設備皆配備車載裝置，以提供多樣化服務。然而IEEE 802.11 通訊協定的行為存在許多效能不彰的問題。由於每部車配備一組天線，欲使用頻道資源，則需在同一頻道競爭，造成效率降低，而又因為IEEE802.11p 頻道等週期切換機制，浪費一半頻道資源，使得存取網路的機會變得更少，因此需要有效使用頻道資源的方法提出。我們過去已經研讀車用無線網路及相關的規格與文獻。為了估算車用無線網路系統效能，我們將提出精確數研發學模型和利用模擬器（NS2/NCTUns），以及過去執行國科會計畫所開發的相關NS2 模組驗證分析IEEE 802.11p 系統效能。計畫目標將提出車用頻道存取協定（Vehicular Channel Access Scheme ，VCAS）、以分群為基礎車用頻道切換協定（Grouping based Channel Switching Protocol，GCSP），更延伸至多種傳送速率之車用頻道分群切換之協定（Multi-rate based Channel Switching Protocol，MCSP）。為了完成這項計畫，將此計劃分成兩年執行，第一年，我們將建立IEEE 802.11p 於多頻道之精確系統效能數學分析模型和車用頻道切換協定及其模擬器模組（NS2/NCTUns）以驗證分析系統。第二年將設計以多種傳輸速率應用於各種道路系統之車用頻道分群切換之協定，同時建立其系統效能數學模型並以模擬器驗證系統效能。 During the last few years, wireless networks have been rapidly growing and becoming more and more popular. In particular, telematics are receiving a lot of attentions due to wide variety of service which are safety, GPS navigation, multimedia, streaming, and other Internet applications. In telematics, there are many initiatives around the world in a near future. With the matured wireless transmission technology, the new demand on wireless applications is toward the concept of deploying wireless devices on transportation systems such as buses, trains and vehicles. Telematics services and entertainment are also important for users. That protocol behavior was described in IEEE 802.11 specification. Generally, each vehicle equips one antenna which can transmit and receive data over wireless medium. If vehicles would like to use channel resource, they shall contend each other on the same wireless channel. However, it usually suffers from packet collision, which decreases data throughput and increases delay as the number of vehicle increases. Moreover, the mandatory operation of channel switching between service channel and control channel will waste half channel resource. It is desired to have a smart channel access scheme for the vehicular networks. We have been studying relative vehicular based network technology such as IEEE 802.11p and specifications of IEEE1609 series. In order to evaluate the system performance, the popular NS-2 and NCTUns are adopted as the simulator platforms, and we will develop the related modules such as the proposed Vehicular Channel Access Scheme (VCAS), Grouping based Channel Switching Protocol (GCSP), and Multi-rate based Channel Switching Protocol (MCSP) in multi-channel operation environment. In order to successfully carry out the project, we plan a 2-year project, wherein the jobs of first year are to build precisely mathematical models for IEEE 802.11p multi-channel networks and to evaluate the proposed VCAS and GCSP schemes on the NS-2 and NCTUns simulators, and the jobs in the second year are to propose MCSP and to evaluate Grouping based Multi-Rate/Multi-channel Switching in vehicular wireless networks for different roadway systems to enhance the system performance in realistic environments. 研究期間：10008 ~ 10107 |
