Interference alignment in heterogeneous networks with macro-to-picocell offloaded users

This work proposes a symbol-spreading-based interference alignment technique to reduce the interference suffered by a user that has been offloaded from a macrocell to a picocell in a heterogeneous network scenario. The proposed precoding and decoding technique uses the time dimension on the OFDM symbol basis to improve the effective signal-to-interference-and-noise ratio (SINR) at the affected user, without requiring coordination between the macro and pico base stations. Our simulation results demonstrate improvements w.r.t. the performance of current interference coordination techniques used in the latest releases of LTE-Advanced, with the added feature of avoiding compromising the resources of the interfering macrocell.