This paper presents a non-full interference analysis to derive the coverage probability when the shared spectrum allocation technique is applied to the homogeneous Poisson point process (PPP) network. Each cell is partitioned into two regions based on the strength of the signal to interference ratio (SINR): the cell center region if the SINR is more significant than a threshold and cell edge region otherwise. In our model, a given resource block (RB) is allocated to one user in a cell and cannot be shared by another user. The RB is hence divided into two sub-bands, which will be used exclusively according to whether the user is a cell center or cell edge user, letting a part of the RB unused in order to reduce the interference to the other cell. This scenario implies that the interfering set of base stations (BS) depends on the coverage probability of the typical user. We prove that the interfering BS set is a thinned version of the original PPP and is related to the probability of coverage of the cell center region. Results show that the scheme increases the network's global coverage probability.