Precise interference estimation for the uplink of LTE heterogeneous networks

Link adaptation mechanism is introduced in long term evolution (LTE) networks. With link adaptation, a base station (BS) selects a modulation and coding scheme (MCS) for each transmission based on signal to interference and noise ratio (SINR) estimation of the link. In the uplink, MCS is selected in advance of actual data transmission, which means a BS need to predict the SINR level. However, interference level may change drastically along with time as different sets of user equipments (UE) can be scheduled in neighbor cells every ms. The fluctuation of interference level poses serious challenge to SINR prediction and the effectiveness of link adaptation, especially for heterogeneous networks (HetNet). To solve the problem it has been proposed to exchange resource allocation information among neighbor BSs via backhaul so that the interference level can be predictable. However, such schemes are sensitive to backhaul delays. In this paper, a novel technique, i.e. precise interference estimation (PIE), is proposed to enhance the efficiency of link adaptation. The proposed scheme doesn´t rely on backhaul for resource allocation information exchanging. Extensive system level simulations are carried out to evaluate the performance of the proposed scheme and significant gains can be observed.