Inter-cell interference in multi-tier heterogeneous cellular networks: modeling and constraints

Interference is the main source of capacity limitation in wireless networks. In some medium access technologies in cellular networks, such as OFDMA, the allocation of frequency subbands is such that interference between cells occurs. This article focuses on preventing harmful interference by properly allocating cells and wireless resources such as subbands to users. In this way, at any time, a set of connections is established that there is no harmful interference between them. In this study, we model inter-cell interference using the protocol interference model and describe interference graph. The proposed model is also applicable to heterogeneous cellular networks. This study provides several types of constraints for the feasibility of a set of connections; each uses a specific component in the network. All constraints are linear; thus, including them in the optimization programs does not increase their structural complexity. A network utility maximization program with joint cell association and interference management is presented, and the effect of applying such interference constraints on simplifying and linearizing the problem structure is described. The presented constraints are discussed in terms of necessary and sufficient conditions for the feasibility of connection, as well as the possibility of distributed construction and verification in cellular network. Two network scenarios are considered, and by using the proposed interference model and appropriate interference constraint, the problem of subband and cell allocation is formulated and solved. The simulation results strongly confirm the performance of the proposed model in practice.