Performance Modeling and Analysis of the LAA Category-4 LBT Procedure

This paper studies the modeling of an LTE LAA category-4 listen before talk (LBT) procedure for downlink data transmission in an unlicensed spectrum band, and analyzes the performance of the LTE LAA category-4 LBT procedure based on the modeling. A 3-D Markov model is first developed to describe the category-4 LBT procedure of an LAA eNodeB. The 3-D Markov model takes into account the GAP period and transmission priority in the category-4 LBT procedure, which are not considered in all existing models for LTE LAA LBT procedures. Based on the 3-D Markov model, a performance model is derived for analyzing the steady-state transmission probability, normalized throughput, and mean access delay of an LAA eNodeB, respectively. The derived performance models are justified through simulation results. The impacts of the GAP period and transmission priority on the system performance are investigated through numerical results, respectively.