Effects of SINR estimation errors on the DL cell throughput of an LTE system in different environments

In this paper we analyze the influence of errors in SINR estimation on the system level performance of an LTE system. Additionally we investigate the effect of the selection of the SINR/CQI mapping curve on the cell throughput and error resistance. We focus on downlink scenarios in a macro-cell (57 cells deployed in a hexagonal grid) and a micro-cell environment (Manhattan grid deployment with 72 cells). Up to 20 users are simultaneously active in the observed cell. For that we use a Best CQI scheduling algorithm. Our investigations are done using a simulation environment based on two tools with different modeling accuracy. With that approach the simulation runtime can be kept short enough in order to produce results efficiently. Simulations have shown that the LTE system is very resistant to SINR estimation errors, but it does not always achieve the best cell throughput performance when operating with the parameters for the SINR-to-modulation-and-coding curves recommended in the LTE-standard documents [1]. However, by increasing cell throughput performance, the resistance to SINR estimation errors decreases.