近年來，車載自組織網絡中的移動數據流量呈爆炸式增長。許多研究都認為路邊單元 (RSU) 是卸載大量移動流量的有效方法，並且 RSU 快取內容的配置問題已得到廣泛討論，然而這些研究在配置RSU的快取內容時很少考慮下載截止時間的限制。在本文中，我們提出了一種在考慮下載期限的同時，提高下載快取內容的命中率的方法。我們設計了基於馬爾可夫聚類的快取內容配置算法，將 RSU 分組為集群，並將快取內容分發到集群中 RSU 的快取中。我們還研究了不同模擬參數對快取命中率的影響，例如快取大小、RSU 總數以及下載快取內容期間車輛訪問的 RSU 數量。根據我們的模擬實驗，我們的方法與現有方法相比，在感興趣區域（RoI）較小的情況下將快取命中率提高了至少 21.40％，在較大的 RoI 中也優於其他現有方法至少 26.16%到337.77%。這些結果表明，我們的方法顯著提高了 VANET 中快取內容配置的效率。

In recent years, mobile data traffic has grown explosively in vehicular ad hoc networks (VANETs). Many studies have considered roadside-units (RSUs) to be an effective way to offload large amounts of mobile traffic, and the issue of content placement for RSU caching has been widely discussed. However, download deadline constraints are rarely considered when caching content in RSU. In this paper, we proposed a method to maximize the hit ratio of downloading requested content from RSUs while considering download deadline constraints. We designed a content placement algorithm based on Markov clustering to group RSUs into clusters and distribute the content to the cache of RSUs in the cluster. We also investigated the effect of different simulation parameters on the cache hit rate, such as cache size, the total number of RSUs, and the number of RSUs accessed by vehicles during the download of cached content. On the basis of our simulation, our method improves the cache hit rate by at least 21.40% while a small region of interest (RoI), compared to the existing methods. Our method also outperforms other existing methods by at least 26.16% to 337.77% in a large RoI. These results demonstrate that our method significantly improves the efficiency of cache content placement in VANET.

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