System level performance of CoMP IR-HARQ over X2 interface in 3GPP LTE-Advanced system

In order to achieve higher data rates and more reliable QoS, coordinated multipoint transmission/ reception (CoMP) is raised in 3GPP release 10 and beyond. Cooperative transmission can effectively improve the performance of cell-edge users with the cost of exchange load between service eNodeB and cooperative eNodeB. Previous work of 3GPP release 11 has noticed the modeling of cooperative backhaul like X2, but research results are still under perfect assumptions during this release. In release 12, demand on modeling of imperfect backhaul has been launched to get a realistic result of CoMP. In this paper, we consider the delay of X2 interface in 3GPP LTE-Advanced systems, the influence of IR-HARQ under perfect and imperfect X2 modeling is given using our system level simulation platform. Simulation results shows that the delay in X2 will cause the delay in MAC layer and the HARQ process in CoMP mode need to be modified to match the feature of delay.