Uplink and downlink capacity analysis for two-tier CDMA cellular systems

The combination of macrocell and microcell in a two-tier cellular system is attractive because it provides a balance between maximizing the number of users per unit area and minimizing the network control associated with handoff. In this paper, we study system capacity of a two-tier cellular architecture employing 3 TDMA/CDMA strategies. Both the uplink and downlink are evaluated via mathematical analysis. It shows that system performance degrades for larger macrocell or microcell and the capacities are poor for users near the macrocells' boundary. It also shows that huge discrepancy between the results obtained for the center cell versus those obtained for the boundary cell.