利用小世界性質達成群體協調以維持車隊叢集機制

Abstract

在此篇論文中，我們在VANET網路上提出一個以車隊為主的應用，其目的是要發展一個分散式維持車隊叢集的策略。因為車隊在VANET網路常會受到路況、交通號誌、道路的速度上限不同等因素影響，導致車隊分散成許多無法溝通的子車隊。我們的策略就是要來解決這樣時常分散的情形。首先我們將每台車分成 Pseudo-leader與Follower，在每個分散的子車隊中，車輛間透過短距離的通訊方式(V2V)彼此協調速度以及位置等資訊。另外，為了要能在分散的子車隊中交換資訊，Pseudo-leaders 透過遠距離的通訊方式(V2I)來達成，而這樣的通訊方式就如同小世界現象中的Shortcuts一般，建立起一個快速資訊交換的網路。因此每個 Pseudo-leader 便可以得知本身在整體車隊中的相對位置，進而決定加速與減速的行為。能讓車隊在出遊時每台車能夠密集而不失散並且彼此保持相同的速率前進，如同動物界中群體協調的特性。

A car fleet is a group of cars that should travel close together with a common speed. Due to dynamic road conditions, traffic signals, road speed limits and other factors, a car fleet may suffer from frequent partition. This paper proposes a distributed cohesive car fleet maintenance scheme by employing a swarming model complemented by a small world phenomenon. Vehicles within a car fleet are classified into the roles of pseudo-leader and follower. Within each partition, cars form a cohesive swarm by coordinating their speed and position via short-distance V2V communications. To exchange information between partitions of a dispersed cat fleet, pseudo-leaders communicate via long-distance V2I communications, which resembles the shortcuts of the small world phenomenon. Pseudo-leaders then determine their relative positions within the car fleet, and decide to speed up or slow down so as to achieve a cohesive swarming behavior of the entire car fleet. Merits of the distributed scheme are demonstrated through simulations.