Performance Evaluation of Heterogeneous Cellular Networks Using Stochastic Petri Nets

Heterogeneous cellular network (Het-Net) is an overlay of multiple cellular communication networks including low- power small cells within the coverage area of a macro-cell and can effectively increase system capacity and enhance network coverage. However, owing to different attributes of cells, such as coverage range, transmission power, and radio propagation, handovers usually occur between macro and small cells. Therefore, it is significant to investigate the impact of handover on system performance. In this paper, we model a two-tier Het-Net using spatial stochastic geometry and analyze the association method of user equipment (UE) with cells and the handover of UE in the two-tier Het-Net based on the A2-A4 (reference signal received quality) RSRQ handover algorithm. For the system performance evaluation, we describe the overall system behavior using a composite stochastic Petri net (SPN), aiming to calculate the transaction loss probability of the UE and use a continuous-time Markov chain to analyze the assumptions of the SPN model. In particular, we compare the system performance with and without handover to investigate the impact of handover on the system.