Techniques are disclosed for modeling wireless system performance subject to limitations on shared system resources such as power amplifiers and spreading codes. In accordance with an aspect of the invention, a software modeling tool implemented on a computer or other processing device identifies two or more limited resources of the wireless system, models the wireless system utilizing a plurality of cascaded stochastic knapsack computations which collectively characterize the performance of the system subject to the two or more limited resources, and generates from the model a measure of the performance of the wireless system.