DIRECT CONNECTION ON THE MOVE: CHARACTERIZATION OF USER MOBILITY IN CELLULAR-ASSISTED D2D SYSTEMS ArticleOrsino A., Moltchanov D., Gapeyenko M., Samuylov A., Andreev S., Militano L., Araniti G., Koucheryavy Y.IEEE Vehicular Technology Magazine. Vol. Vol 11 Issue 3. 2016. P.. 38-48