Interference forwarding for D2D based heterogeneous cellular networks

For extended cell coverage and green communication, various small-cell networks, such as femtocells and picocells, are applied to cellular networks. This leads to the reduction of shadow areas and an increase of spectral efficiency with higher cell-edge capacity. Due to increasing heterogeneity, however, small cells cause co-tier and cross-tier interferences which are the critical issue that aggravates the signal-to-interference-plus-noise ratio (SINR) of macro user equipment (MUE). Especially, a MUE in the cell-edge area can be a victim owing to a nearby small-cell access point despite its low transmit power. We propose an interference forwarding (IF) scheme in a dual link for enhancing the SINR at victim MUE, considering a two-tier network where a macrocell and underlaid closed-access small cells coexist, along with device-to-device (D2D) communication between close-by peer MUEs supported. Numerical results with 3-dimensional plot demonstrates that our proposed IF scheme notably improves the achievable spectral efficiency at victim MUE.