Kenji Ohtsuka Shigeo Shioda Fumiaki Machihara A Finite Population Model and Product-Form Approximation for Cellular Mobile Systems with Traveling Users. 4664-4669 2007 GLOBECOM http://dx.doi.org/10.1109/GLOCOM.2007.885 conf/globecom/2007 db/conf/globecom/globecom2007.html#OhtsukaSM07