Abstract
Formulas are derived for the congestion in single-cell mobile radio systems in which there are both land-to-mobile and mobile-to-mobile calls and in which mobile-to-mobile calls go via the base station. Two approaches are used. The first yields modified forms of the familiar Erlang and Engset formulas. The second gives more complicated but more accurate formulas. The results of computer simulations to establish the accuracy of the formulas are described.