The main aim of this research is to find out the technical causes of the degradation of LTE (Long Term Evolution) service using the band of 700MHz with the simulator ns-3. We analyze how the QoS (Quality of Service) parameters change when more devices are aggregated to the base station and the scheduler allocates radio resources for each user. In this scenario, the QoS depends on the type of CQI Feedback (Channel Quality Indicator) configured to estimate the physical channel. The QoS can be modified according to the QCI (QoS Class Identifier), that identifies each transmission per TTI (Transmit Time Interval), but also the different CQI feedback types can cause the degradation of the performance for some services.