Feng Wang 0049 Dingde Jiang Jiang Zhu Zuoliang Liu An Intelligent Relay Node Selection Scheme in Space-Air-Ground Integrated Networks. 157-167 2019 SimuTools https://doi.org/10.1007/978-3-030-32216-8_15 conf/simutools/2019 db/conf/simutools/simutools2019.html#WangJZL19