基于出租车轨迹数据的车联网通信机会间隔模型

针对车联网中车辆间相遇机会间隔的统计分布模型及其参数估计问题，基于北京市出租车轨迹大数据，提出了基于栅格划分和地理哈希值索引的过滤查找方法和轨迹内插方法以高效提取车辆间的相遇机会时刻，进而对机会间隔进行统计建模、参数估计和假设检验.模型呈现分段分布，在小尺度时间间隔上呈指数分布，在大尺度间隔上呈对数正态分布，并具有重尾特征.

Modeling the Statistical Distribution of the Inter-Contact Times for Communication Opportunities in Vehicle Networks

As a kind of opportunistic networks, the vehicle network, in which vehicles communicate instantaneously with each other only when they meet opportunely, attracts more and more attentions. The inter-contact times of communication opportunities depend on the factors such as the vehicle moving model and the vehicle density. Based on the data of the taxi traces in Beijing city, an efficient method which combines the GeoHash-based filter and the trace interpolation is proposed to extract all the instants of the communication opportunities to model the statistical distribution. It is concluded that the inter-contact times obey an exponential distribution if the interval is small while a log-normal one if the interval is large. Such a piecewise heavy-tailed distribution will affect the design of the vehicle networks to some extent.