Interference Evaluation in LTE Heterogeneous Networks

This document evaluates the interferences generated due to the insertion of the femtocells in a LTE network using ICS Designer software simulations. Due to interferences, there are coverage problems and a decrease in the SINR (Signal to Interference plus Noise Ratio) and RSRQ (Reference Signal Received Quality) levels. These indicators are important to guarantee the user's connection, as seen below. Interferences cause the decrease of the quality of service, create dead spots, prevent user access to a macrocell or a femtocell and causes missed calls or signaling errors. At evaluating them, inteference reduction algorithms could be develop from the results of this paper. The downlink interference scenarios, with FDD (Frecuency Division Duplexy) duplexing model in a heterogeneous LTE network, were based on the technical report developed by the 3GPP Release 8 working group called 3GPP TR 25.820. One of the most critical cases is when interference is generated when a mobile user connected to a femtocell is located in the limit of the cell macrocell coverage area, causing the quality of offered services to diminish or to prevent any type of access. The interferences are evaluated according to the following parameters: SINR of the data traffic channel PDSCH (Physical Downlink Shared Channel), RSSI (Received Signal Strength Indicator) and RSRQ. These parameters allow the analysis of the quality of the signal in the receiver and they are measured in three different scenarios.