In this paper, we propose an effective interference mitigation scheme to address the resource allocation problem in Heterogeneous networks (HetNets), where cognitive radio technology are employed to identify physical resource blocks (PRBs) that cause light interference to the users served by the macrocell. A stochastic scheduling algorithm is proposed to mitigate the cross-tier and the intra-tier interference by allocating different portions of the PRBs probabilistically, based on which an efficient algorithm is developed to work out the optimal resource allocation for un-planned femtocells with low computational load. Analysis and numerical results show our proposed scheduling scheme can keep the cross-tier and the intratier interference under control. Moreover, our proposed resource allocation algorithm for the femtocells achieves a significant capacity gain. Since the proposed interference mitigation scheme requires nonexistence of macro-femto backhaul coordination and no modifications of existing macrocells, it is promising for applications in the LTE-Advanced cellular systems that employ HetNets.
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