This paper provides an algorithm to calculate SINR and throughput gain in a combined cell of LTE network based on Radio Frequency (RF) scanner measurement data containing RSRP of the serving cell and neighbor cells. The combined cell, a feature of 3GPP standard, is the combination of multiple physical cells which operate at the same frequency into one cell in LTE network system. The combined cell is able to improve the cell edge performance in terms of SINR. It is however noted that not all areas served by the combined cell get benefit from the combined cell feature. Some areas show a degraded performance in downlink throughput results from the higher traffic load due to shared resources. In this paper, combined cell performance is investigated to identify at what traffic level a combined cell becomes beneficial and at what traffic level it results in performance degradation. The investigation is made throughout the two steps, the simulation of combined cell SINR and calculation of new load condition. These two steps complement each other to provide better accuracy of network Downlink (DL) throughput evaluation of the combined cell in LTE network. This study reveals that in order to obtain the effective utilization of LTE combined cell feature, the feature needs to be implemented only when the average of component cell load is below 20-40% depending on the component cell overlapping level.