无间隙的车联网协助下载方法

doi:10.11959/j.issn.1000-436x.2016022

摘要/Abstract

摘要：

车辆通过AP(access points)接入Internet具有低费用、高带宽以及低时延等优点，然而AP间的通信盲区(DA, dark area)使车辆只能间歇式接入Internet，造成网络的QoS难以得到保障。为了解决这一问题，提出一种面向高速公路场景的无间隙协助下载方法(NICDM,non-intermittent cooperative downloading method)。在NICDM中，目标车辆未完成的下载任务依据车速、任务大小以及DA距离等信息进行分解，并分别委托行驶方向上的最近2个AP 协助下载；一组经过优化选择的协助车辆从AP获得数据，并在DA区转交给相遇的目标车辆；同时针对传输冲突提出了N-副本的冲突解决策略，进一步提高协助下载的稳定性。仿真结果表明，NICDM实现了目标车辆在整个DA区无间隙地获得数据，与相类似的方法相比，进一步提高了系统的QoS与吞吐量。

关键词: 车联网, 协助下载方法, 间歇式接入, 冲突处理, 车辆选择策略

Abstract:

Internet access through access points (AP) for vehicles has the advantages of low cost, high-bandwidth and low latency. However,because of dark area (DA) around AP, vehicles have to take interm tent linking to Internet, result-ing in the QoS of network is difficult to be guaranteed.A non-intermittent cooperative downloading method (NICDM)for highway was proposed. The unfinished download task of target vehicular in current AP was decomposed into several parts according to vehicle's speed, the size of unfinished task and distance of DA, then commissioned to two nearest APs. A group of cooperative vehicles selected under selection strategy would get data from the APs and forward it to the target vehicle when theymeet in DA.And an N -replicaconflict resolution strategy was used to improve the stability of coopera-tive downloading. Simulation results show that compared with similar cooperative methods, NICDM can uninterruptedly get cooperative download data through DAs and improve system's QoS and throughput.

Key words: vehicular network, cooperative downloading approach, intermittent access, conflict resolution, vehicle selec-tion strategy

谢永,吴黎兵,何炎祥,范静,刘冰艺. 无间隙的车联网协助下载方法[J]. 通信学报, 2016, 37(1): 180-190.

Yong XIE,bing WULi,xiang HEYan,Jing FAN,yi LIUBing. Non-intermittent cooperative downloading approach for VANET[J]. Journal on Communications, 2016, 37(1): 180-190.

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DA区	DA长度
	8 km		12 km		16 km
	D	P	D	P	D	P
FDA	6 281	785.06	9 239	769.92	11 382	711.35
LDA	6 534	816.75	9 540	795.00	12 647	790.43

阶段	DA=8 km			DA=12 km			DA=16 km
阶段	ra-co	DSRelay	NICDM	ra-co	DSRelay	NICDM	ra-co	DSRelay	NICDM
DA的前半程	144.0	132.1	5.7	219.1	200.8	10.1	293.5	269.2	21.2
DA的后半程	38.5	2.5	2.3	62.6	3.7	3.8	96.4	5.3	4.7