Mitigation of Macro-Femto Co-Channel Interference by Spatial Channel Separation

Interference mitigation between macro-cell and femto-cells are studied in this paper. Via demonstrating the communications between various transmitter-receiver pairs on different spatial channels could be insulated via proper channel de-correlation at receivers, we propose to separate the transmissions of macro-cell and of femto-cell in spatial domain. Induced challenges such as spatial channel estimation and codeword-to channel mappings are investigated, and we further adopt the Gibbs sampler to achieve co-channel selection of femto-cells. The proposed solutions can be realized without macro-femto coordinations and additional feedback, and are demonstrated aligned with current 3GPP LTE standardization status. We evaluate the proposed schemes by sophisticated simulations based on the dual-strip model in 3GPP femto-cell evaluation scenarios. It has been shown the SINR of users attached to macro-cell can be improved 60 dB while the SINR of users attached to femto-cells can be maintained about 10 dB. Both the significant performance improvements and backward compatibility implies the proposed scheme is valuable and could be contributed to 3GPP instantly.