For two-tier cellular network design, resource management between tiers is an important issue to be studied. In this paper, in order to use the network resources preciously, we considered sharing of the available spectrum between the tiers. We evaluate this sharing for two network architectures. In the first architecture, called System I, DS-CDMA is deployed in both tiers. In the second architecture, called System II, TDMA is deployed for users in the microcell tier and CDMA for macrocell users. Using analytically evaluated intercell interference for a two-tier cellular system, we will show the performance and the allowable system capacity for the above systems.