This article presents a strategy for channel assignment in Internet of Things (IoT) networks. The proposed strategy uses opportunistic spectrum access via cognitive radios. The originality of this work resides in the use of traffic history to guide the channel allocation in a distributed manner. The channel assignment algorithm mitigates the interference in links with higher traffic history. Our performance evaluation shows that using the historical network traffic as a decision criterion leads to better results when compared with the simple use of the network topology as a criterion.