Hierarchical approach to interference mitigation in multi-cell downlink orthogonal frequency-division multiple-access networks with low feedback

A low-complexity and low-feedback interference mitigation scheme is developed for multi-cell orthogonal frequency-division multiple-access (OFDMA) cellular systems. The problem is formulated as a weighted sum-rate maximisation problem for all users in the network. The centralised solution assuming full feedback of interfering base stations (BSs) from each mobile on each subchannel is prohibitively expensive in terms of computational complexity and feedback overhead. A hierarchical solution is proposed where the BSs solve only localised resource allocation problems, whereas a centralised controller arbitrates the conflicts of interest among different cells. Moreover, the mobiles apply simple threshold rules to reduce the feedback to the BSs. The simulation results show significant savings in the BS-mobile signalling as well as the signalling between the radio network controller (RNC) and the BSs, while maintaining comparable performance to the case of full feedback.