In this paper, it is proposed a model based on the truncated geometric distribution, which allows to characterize the available resources in an ad hoc network under a hierarchical architecture and then, estimate a growth factor which represents the appropriate relation between the available resources on two successive layers of the network, that guarantee an established quality level of communications. There were designed three simulation scenarios on ns-3 software for hierarchical architectures of two layers and it was shown that the growth of resources between the layers of an ad hoc network can be expressed using a linear model.