A comprehensive study on the variation of the carrier-to-noise-plus-interference ratio (CNIR) with different system parameters is of fundamental importance in the context of LTE planning. For cellular planning purposes, the UL and DL CNIRs from/at the mobile station are very important parameters, although we are only considering DL in this work. From a detailed analysis of its variation with the coverage and reuse distances for different modulation and coding schemes (MCS) and given empirical propagation models, an evaluation of the possible range for the reuse pattern is performed. By considering the CQI and reference CNIR requirements recommended by 3GPP. DL peak bit rates along with the Transport Block Size (TBS) assumed for single stream and bandwidth of 5 MHz, physical and supported throughputs are analysed. These formulations shows the clear decrease of the supported throughput for the longest coverage distances in the LTE 2.6 GHz band, a behaviour that is not so clear at 800 MHz, and gives hints to the optimization of the use of different frequency bands in the optimization of carrier aggregation between two different bands in LTE-A scenarios.