[论文解读] A Methodology for Studying VANET Performance with Practical Vehicle Distribution in Urban Environment

Ivan Wang‐Hei Ho, Kin K. Leung+1 more|arXiv (Cornell University)|Nov 27, 2012

Vehicular Ad Hoc Networks (VANETs)参考文献 11被引用 5

一句话总结

本文提出一种随机交通模型，用于分析在城市环境中非均匀车辆分布下的VANET性能。通过建模车辆密度动态和传输概率，该方法能够准确分析不同路由策略和信道协议下的吞吐量与传输进度，表明最优传输概率随空间位置变化，且可由路边单元广播以实现网络优化。

ABSTRACT

In a Vehicular Ad-hoc Network (VANET), the amount of interference from neighboring nodes to a communication link is governed by the vehicle density dynamics in vicinity and transmission probabilities of terminals. It is obvious that vehicles are distributed non-homogeneously along a road segment due to traffic controls and speed limits at different portions of the road. The common assumption of homogeneous node distribution in the network in most of the previous work in mobile ad-hoc networks thus appears to be inappropriate in VANETs. In light of the inadequacy, we present in this paper an original methodology to study the performance of VANETs with practical vehicle distribution in urban environment. Specifically, we introduce the stochastic traffic model to characterize the general vehicular traffic flow as well as the randomness of individual vehicles, from which we can acquire the mean dynamics and the probability distribution of vehicular density. As illustrative examples, we demonstrate how the density knowledge from the stochastic traffic model can be utilized to derive the throughput and progress performance of three routing strategies in different channel access protocols. We confirm the accuracy of the analytical results through extensive simulations. Our results demonstrate the applicability of the proposed methodology on modeling protocol performance, and shed insight into the performance analysis of other transmission protocols and network configurations in vehicular networks. Furthermore, we illustrate that the optimal transmission probability for optimized network performance can be obtained as a function of the location space from our results. Such information can be computed by road-side nodes and then broadcasted to road users for optimized multi-hop packet transmission in the communication network.

研究动机与目标

• 解决以往VANET研究中同质节点分布假设的局限性。
• 在城市道路网络中对真实、非均匀的车辆密度动态进行建模。
• 开发一种方法，用于在实际交通条件下分析VANET的吞吐量与传输进度。
• 推导与位置相关的最优传输概率，以提升网络性能。
• 通过大量仿真验证分析框架。

提出的方法

• 开发一种随机交通模型，以捕捉城市环境中的一般车辆流和个体车辆的随机性。
• 利用该模型推导车辆平均密度的动态及其在空间和时间上的概率分布。
• 将密度模型应用于评估不同信道访问协议下三种路由策略的性能。
• 在性能分析中将传输概率作为空间可变参数进行整合。
• 采用解析推导方法计算吞吐量与传输进度，并通过仿真进行验证。
• 使路边单元能够基于位置计算并广播最优传输概率。

实验结果

研究问题

• RQ1 城市环境中非均匀车辆分布如何影响VANET性能？
• RQ2 随机交通动态对VANET吞吐量与传输进度有何影响？
• RQ3 能否将最优传输概率作为VANET中空间位置的函数推导出来？
• RQ4 基于真实车辆密度分布的解析性能模型准确度如何？
• RQ5 路边单元在多跳传输中，多大程度上可利用空间可变的传输概率来提升性能？

主要发现

• 所提出的随机交通模型能准确捕捉城市环境中车辆密度的动态特性。
• 由于车辆分布不均，吞吐量与传输进度性能在不同空间位置上存在显著差异。
• 为提升网络性能而设定的最优传输概率是空间位置的函数，而非固定值。
• 吞吐量与传输进度的解析结果与仿真结果高度吻合，验证了该方法的可靠性。
• 路边单元可计算并广播基于位置的最优传输概率，从而提升多跳传输效率。
• 该方法为分析车辆网络中其他协议与网络配置提供了基础。