Routing protocols for vehicular ad hoc networks resort to clustering in order to optimize network performance. Concerning the optimized link state routing protocol and the plethora of its derivatives, the multipoint relaying (MPR) technique has proven its efficiency as an accurate clustering scheme over the last two decades. However, it has been emphasized recently that the MPR technique, which was originally designed for open areas, does not benefit from the particular configuration of road sections, which are intrinsically spatially constrained. A clustering scheme exploiting this particularity, namely chain-branch-leaf (CBL), has been introduced in order to enhance the flooding of broadcast traffic, including that related to routing operations. In this paper, both MPR and CBL are evaluated through MATLAB simulation over several scenarios based on realistic road configurations and traffic generated with SUMO simulator. The results show that CBL actually reduces the number of nodes acting as relays (cluster-heads) in the network, thus decreasing the routing traffic related to creation and retransmission of topology control messages. Also, they show that, with CBL, the nodes chosen as relays remain longer in this role, thus favoring the overall network stability, and that most of the nodes remain attached longer to the same relay than with the MPR technique.

中文翻译：

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基于优化链路状态路由的车载 Ad Hoc 网络中的多点中继与 Chain-Branch-Leaf 聚类性能

车载自组织网络的路由协议诉诸集群以优化网络性能。关于优化的链路状态路由协议及其众多衍生协议，多点中继 (MPR) 技术在过去的二十年中已经证明了其作为一种精确聚类方案的效率。然而，最近有人强调，最初为开放区域设计的 MPR 技术并没有受益于路段的特定配置，这些路段在本质上是空间受限的。已经引入了利用这种特殊性的集群方案，即链-分支-叶 (CBL)，以增强广播流量的泛滥，包括与路由操作相关的流量。在本文中，MPR 和 CBL 都通过 MATLAB 仿真在多个场景中进行评估，这些场景基于真实的道路配置和使用 SUMO 模拟器生成的交通。结果表明，CBL 实际上减少了网络中充当中继（簇头）的节点数量，从而减少了与拓扑控制消息的创建和重传相关的路由流量。此外，他们表明，使用 CBL，选择作为中继的节点在此角色中保持更长的时间，从而有利于整体网络稳定性，并且与 MPR 技术相比，大多数节点与同一中继保持连接的时间更长。从而减少与拓扑控制消息的创建和重传相关的路由流量。此外，他们表明，使用 CBL，选择作为中继的节点在此角色中保持更长的时间，从而有利于整体网络稳定性，并且与 MPR 技术相比，大多数节点与同一中继保持连接的时间更长。从而减少与拓扑控制消息的创建和重传相关的路由流量。此外，他们表明，使用 CBL，选择作为中继的节点在此角色中保持更长的时间，从而有利于整体网络稳定性，并且与 MPR 技术相比，大多数节点与同一中继保持连接的时间更长。