The Modeling and Cross-Layer Optimization of 802.11p VANET Unicast
The Modeling and Cross-Layer Optimization of 802.11p VANET Unicast
复制标题
802.11p VANET单播建模与跨层优化
DOI：
10.1109/access.2017.2761788
复制
发表时间：
2018-01-01
期刊：
影响因子：
3.9
通讯作者：
Magsino, Elmer R.
中科院分区：
文献类型：
--
作者：
Xie, Yu;Ho, Ivan Wang-Hei;Magsino, Elmer R.
车载自组织网络（VANESTs）在智能交通系统中的车辆之间的无处不在的通信和连接中发挥着重要作用。在VANET中可以传输各种消息，以提高道路安全性并提供多种类型的应用服务。因此，VANET的性能评估和优化是必须考虑的问题。先前关于VANET建模的常规考虑仅仅包括一般的均匀道路交通场景。此外，先前的研究工作主要集中在VAN中的广播性能，因为安全信标分组是在周期性广播中传输的。然而，车辆之间的一些重要数据的交换通过使用单播而不是具有重传机制的广播来更好地完成。另一方面，在VANET优化的上下文中，大多数常规方案需要通过测量相邻节点的数量来配置传输功率或相应地调整传输速率来连续监测网络。这种恒定跟踪导致大的传输开销和测量延迟。在本文中，我们提出了一套802.11p单播建模和优化方法，以确定最佳的网络参数，而无需连续监控附近的车辆。这是通过在分析中集成随机城市流量模型，然后对每个网络节点进行跨层优化以减少数据包冲突来实现的。最佳的传输范围和竞争窗口大小在不同的位置推导出的时空速度分布的基础上，并进入车辆。这些有助于车辆在进入路段时相应地配置其传输功率和速率。我们评估所提出的系统的网络延迟和吞吐量性能。大量的仿真运行，以验证所提出的模型和优化方法的可行性。我们的研究结果表明，延迟（吞吐量）平均提高了约53%（120%）的均匀流量和45%（104%）的平均异构流量。
Vehicular ad-hoc networks (VANETs) play an important role in enabling ubiquitous communications and connectivity among vehicles in intelligent transportation systems. Various messages can be transmitted in a VANET to improve road safety and furnish multiple types of application services. Therefore, the evaluation of VANET performance and its optimization should be considered. Previous conventional considerations regarding VANET modeling merely incorporated a general homogeneous road traffic scenario. Furthermore, prior research works primarily focused on the broadcasting performance in VANETs, since the safety beacon packets are transmitted in periodic broadcast. However, the exchange of some important data between vehicles is better accomplished by using unicast instead of broadcast with the retransmission mechanism. On the other hand, in the context of VANET optimization, most conventional schemes required continuous monitoring of the network by measuring the number of neighboring nodes to configure the transmission power or adjusting the transmission rate accordingly. Such constant tracking leads to large transmission overheads and measurement delay. In this paper, we propose a set of 802.11p unicast modeling and optimization methodologies to determine the optimal network parameters without continuously monitoring the vehicles in vicinity. This is accomplished by integrating a stochastic urban traffic model in the analysis then performing a cross-layer optimization for each network node to reduce packet collisions. The optimal transmission range and contention window size at different locations are derived based on the spatio-temporal velocity profile and are made known to entering vehicles. These aid the vehicles to configure their transmission power and rate accordingly upon entering a road segment. We evaluate the proposed system in terms of the network delay and throughput performance. Considerable simulation runs to verify the feasibility of the proposed model and optimization methods. Our results indicate that delay (throughput) is improved by about 53% (120%) on average for homogeneous traffic and 45% (104%) on average for heterogeneous traffic.