This document summarizes a research paper that proposes a Markov model to analyze the performance of two low layers (picocell and femtocell) of a hierarchical cellular network with a FIFO queue. It describes modeling the femtocell layer with and without a queue, and the picocell layer without a queue. The blocking probabilities of new and handoff calls are calculated for different configurations. Results show that having a queue in the femtocell layer increases blocking probability compared to configurations without queues, since it introduces additional queuing delays. The paper contributes to understanding the impact of queues on performance in multi-layer cellular networks.