Dynamic spectrum sharing for hybrid access in OFDMA-based cognitive femtocell networks

Cognitive femtocell has emerged as one of the promising ways to solve the indoor coverage and spectrum shortage problems in cellular networks. However, it is a challenge to motivate both macro base station and femtocell access points {FAPs} to adopt this hybrid access policy. In this paper, we propose a systematic dynamic spectrum sharing framework for hybrid access in orthogonal frequency-division multiple-access-based cognitive macro-femtocell networks. In this framework, the {MBS} offloads some macro user equipments {MUEs} to {FAP} to improve the transmission performance and save energy. In return, the MBS leases a portion of its spectrum to {FAP}. Then, the {FAP} can use a part of spectrum for its own transmission and use another part to serve {MUEs}. We design an auction-based approach where each {FAP} receives additional {MUE} as bidders, while MBS acts as auctioneer. We formulate the dynamic resource sharing as a sum utility maximization problem. Numerical results demonstrate that both the macro and femtocell could get benefit from our framework.