Shadow chasing enhancement in resource allocation for heterogeneous networks

In this paper1, we propose an enhancement to a resource allocation scheme known as shadow chasing for interference mitigation in heterogeneous networks composed of Macrocell User Equipments (MUEs) and Home User Equipments (HUEs). In shadow chasing, the Home eNB (HeNB) uses Downlink Control Information (DCI) together with the overheard ACK/NAK feedback and CQI reports to assign its HUEs the Physical Resource Blocks (PRBs) that are assigned to outdoor MUEs. Since the HeNB receives an outdated DCI due to backhaul delay, our solution is to derive a likelihood metric for each PRB being either empty or assigned to an outdoor MUE by using a MC model for the state of each PRB. By dynamically separating the MUE and HUE PRB assignments, enhanced shadow chasing can better constrain the downlink interference to the MUE. Our results show effective reduction of probability of PRB assignment collision and MUE interference compared to schemes that do not integrate the delay effect or exploit user feedbacks.