The aim of this paper is to analyze downlink (DL) outage probability (OP) of femtocells deployed in 6-sector macrocells. When femtocells are used in co-channel deployment with macrocells, reducing that amount of received interference from macrocell network is an important issue. Macrocells with sectors can reduce the cross-tier interference. In this paper, at first we analyze the effect of interference from different sectors. Then according to the amount of received interferences, we propose an algorithm for channel allocation in femtocells. The closed-form equation for DL OP of femtocells is also calculated. Experimental results demonstrate the proposed hierarchical cellular network achieves lower DL OP of femtocell in comparison with other hierarchical cellular networks.