An IP Passing Protocol for Vehicular Ad Hoc Networks with Network Fragmentations
An IP Passing Protocol for Vehicular Ad Hoc Networks with Network Fragmentations
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DOI：
10.1016/j.camwa.2011.07.062
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发表时间：
2011-06
期刊：
影响因子：
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通讯作者：
Yuh-Shyan Chen;Chih-Shun Hsu;Wei-Han Yi
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文献类型：
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作者：
Yuh-Shyan Chen;Chih-Shun Hsu;Wei-Han Yi
当车辆在高速公路上快速行驶时，如何有效地减少切换延迟，保持车辆与互联网的连接是一个重要的问题。现有的IP通过协议可能能够减少切换延迟，并在所有车辆都连接到互联网时保持车辆与互联网的连接。然而，当车辆密度低或车辆速度变化时，由于网络碎片，车辆可能无法直接或通过多跳中继与预期车辆通信。因此，当发生网络分片时，车辆无法通过现有的IP传递协议将其IP地址传递给预期的车辆，从而导致更长的切换时延和更高的丢包率，这将降低网络的吞吐量。为了改进现有的IP传递协议，我们提出了一种适用于具有网络分片的车载网络的IP传递协议。该协议可以推迟向DHCP服务器释放IP地址的时间(延长IP寿命)，并选择一种更快的方式来获取车辆的新IP地址。在延长的IP寿命期间，车辆可以通过多跳中继从同方向或相反方向的车道上的车辆获取IP地址，从而减少切换延迟并保持与互联网的连接。仿真结果表明，该方案能够减少IP获取时间、切换时延、丢包率，延长IP生命周期。
When a vehicle is moving fast in a highway, how to effectively reduce the handoff delay and maintain the connectivity of the vehicle to the Internet is an important issue. The existing IP passing protocol may be able to reduce the handoff delay and maintain the connectivity of the vehicle to the Internet when all the vehicles are connected. However, when the vehicle density is low or the speeds of vehicles are varied, the vehicle may not be able to communicate with the intended vehicle either directly or through multi-hop relays because of network fragmentation. Hence, when network fragmentation occurs, a vehicle cannot pass its IP address to the intended vehicle through existing IP passing protocols and thus incurs longer handoff latency and higher packet loss rate, and these would lower down the throughput of the network. To improve existing IP passing protocols, we propose an IP passing protocol for VANETs with network fragmentation. The proposed protocol can postpone the time to release IP addresses to the DHCP server (extend IP lifetime) and select a faster way to get the vehicle’s new IP address. During the extended IP lifetime, the vehicle can acquire an IP address through multi-hop relays from the vehicles on the lanes of the same or opposite direction, and thus reduces handoff delay and maintain the connectivity to the Internet. Simulation results have shown that the proposed scheme is able to reduce IP acquisition time, handoff latency, packet loss rate, and extend IP lifetime.