Macrocell Resource Adaptation for Improved Femtocell Deployment and Interference Management

This paper studies the spectrum sharing of femtocell base station (FBS) and macrocell base station (MBS) in a heterogeneous network setting. We allow femtocell users (FUEs) to re-use the resource blocks of certain macrocell users (MUEs) who are categorized as outdoor users. We study the design tradeoff between MUE spectral diversity and the need to accommodate femtocells by intelligently determining when an MUE should be allowed to change resource allocation. Modeling the wireless channel state as a Markov chain, we formulate the decision as a Markov decision process (MDP). In the case of homogeneous channels environment, we reduce the MDP complexity, which enables the MBS to form the optimal decision matrix by solving only two equations. Our closed form expressions reveal the quantitative relationship among system parameters. Hence, we obtain an easy policy for the optimal channel switching. Our scheme is also robust to the uncertainties in the Markov models.