IEEE 802.15.4 defines three frequency bands − 868 MHz, 915 MHz, 2.4 GHz and each one contains several channels except 868 MHz band that contains only one channel[1]. Communication in adjacent or alternate channel simultaneously may lead to interference to the desired network. In this paper effect of interference in adjacent and alternate channel has been quantified in terms of packet drop ratio by varying different parameters such as transmission power, time interval between two consecutive transmission and packet size[2].