Integration of Spatial Reuse and Allocation for Downlink Broadcast in LTE-Advanced and WiMAX Relay Networks

Downlink broadcast in LTE-Advanced-(LTE-A) and WiMAX-based relay networks is a crucial service for multimedia delivery. Currently, most research effort goes into devising efficient resource allocation mechanisms to achieve more efficient resource utilization. However, spatial reuse, which is an important technique in improving transmission capacity, has received little attention in the literature. Thus, in this work, we investigate ways of achieving more efficient resource allocation in wireless relay networks via spatial reuse. We first formulate a joint spatial reuse and resource allocation problem as an integer linear programming (ILP) model. We then consider a grouping mechanism in which relay stations (RSs) are grouped together if they do not interfere with each other's transmission signal. RSs in the same group can thus utilize spatial reuse by using the same set of resources to broadcast data. Because of the high computational complexity of the ILP model, we propose a two-phase heuristic solution. In the first phase, the enhanced-resource diminishing principle approach is employed to determine the number of resources required by the base station and a set of selected RSs. In the second phase, a max-coloring algorithm is employed to organize the selected RSs into broadcast groups and then assign the required resources to each group by exploring the maximum advantage of spatial reuse. The simulation results show that the proposed solution improves system performance up to 61%, as compared with two existing mechanisms.