Analysis Of Downlink Coverage For Multi-Tier Cellular Network Under Different Association Criteria Using Stochastic Geometry

The regularly rising of the information rates due to the huge usage of cellular applications implies that the legacy mobile network models comprising of macro-cell architecture do not fulfill the demand of the users. The only feasible solution to achieve the increasing demand is by adding small-scale BSs (pico cells, femto cells or both) in the legacy cellular network architecture of macro type BSs. The addition of small cells transforms the network into heterogeneous network. In this research, a heterogeneous network comprised of two-tiers of macro and pico BSs is evaluated for the downlink coverage probability of a user attached or associated to its macro or pico base station using stochastic geometry approach under two camping rules i.e., strongest instantaneous power and physically closet BS. Poisson point process (PPP) is utilized to model/represent the placement of BSs and users in the network. The analytical results of the SIR are presented, and the simulation model is developed accordingly to get the simulation results which are nicely matching with the analytical results. The results provide insights about the behavior of coverage (CCDF of SIR) under different assessed association criteria. It is observed on comparing all the coverage results for macro and pico tiers under both the studied associations that the coverage is highest for macro tier than the pico tier because of its high transmit power in the downlink as compared to pico BSs under both associations. Similarly, when compared the results of coverage for the two associations, the coverage under maximum strongest power association is slightly higher than the nearest association.