在車載網路(VANETs)中,大部分的應用是基於I2V(infrastructure-to-vehicle)的傳遞方法下,傳送訊息給正在移動中的車輛。而現今也有許多的研究是針對I2V訊息傳遞及以車輛軌跡為基礎之通訊協定,這兩方面來進行相關探討。以車輛軌跡為基礎之通訊協定,主要運作是利用車輛未來的軌跡資訊來挑選出一個訊息及車輛之間的會合點(rendezvous point)。訊息將會在車輛經過會合點前傳送到,而之後只要車輛經過該會合點就能夠收取到訊息。然而,在大部分的方法當中並沒有考量到,在現實環境中,車輛在行徑過程有可能因為道路施工或是駕駛習慣等原因,而臨時更換原先所規劃的路徑軌跡的繞道(detour)行為。在本篇論文中,我們提出一個分析模組(analytic model)以遞迴式(recursive)的方法來推導,在車輛行徑過程中有可能發生繞道的考量之下,最後車輛能夠在會合點成功收到訊息的機率。此外,我們也額外發展一個模擬模組(simulation model)來驗證所提出的分析模組。而我們所提出的分析模組以及模擬模組兩者都可以提供給以車輛軌跡為基礎之通訊協定,來預測這些協定所挑選出的會合點,在考量車輛有可能繞道的情況下,最後還有多少的機率可以成功收到訊息。
In Vehicular Ad Hoc Networks (VANETs), there exist a variety of applications which rely on Infrastructure-to-vehicle (I2V) communication. A large number of studies have recently been conducted to investigate I2V data forwarding and trajectory-based delivery schemes to deliver the message. Trajectory-based I2V delivery schemes use the vehicle trajectory information to select a rendezvous point of the message and the vehicle. The message will be forwarded to the rendezvous point before the vehicle arrives. Since the vehicle passes through this point, it can thus receive the message. However, most trajectory-based delivery schemes do not consider the circumstances that the vehicle may detour because of the road construction or car accident in the real world. In this work, we propose an analytic model to recursively derive the probability which the vehicle can successfully receive the message at the selected rendezvous point considering the vehicle may detour during the movement. Besides, we also develop a simulation model to validate against our analytic model. Our analytic and simulation models both can provide for trajectory-based delivery schemes to estimate the message reception probability which the vehicle receives the message even under the vehicle detour.