A comparative study on scheduling restriction schemes for LTE-Advanced networks

In a heterogeneous network (HetNet) in Long-Term Evolution (LTE)-Advanced, a cell range expansion (CRE) bias can be applied in cell selection so that macrocell users are offloaded to picocells even if the received signals from the picocells are weaker than those of macrocells by up to the bias value. Macrocells stop transmission for a specific resource (“protected resource”) and transmit only in the other type of resource (“non-protected resource”), so that the range expanded (or offloaded) picocell users can be scheduled in the protected resource to avoid the strong macrocell interference. Scheduling of the other picocell users can be either subject to no restriction, or restricted to the non-protected resource. We compare, in terms of performance and channel quality feedback, such CRE-based scheduling restriction schemes with the proportional fair resource allocation (PFRA)-based scheme, where the restricted scheduling resource is determined by the PFRA derived from a simplified static channel over a period. We show, by system level simulation of LTE-Advanced downlink, that PRFA-based scheduling restriction scheme strikes better tradeoff between the performance and the channel feedback overhead.