The present document applies to the following equipment types: 1) An Onboard Base Transceiver System (OBTS) supporting GSM, UMTS or LTE communication protocols including specific functions for restricting the transmit power of the MSs or UEs, respectively associated with the OBTS. 2) Network Control Unit (NCU) preventing direct connection of the onboard mobile terminals with mobile networks on the ground by raising the noise floor in the cabin. These Base stations are capable of operating in all or any part of the frequency bands given in table 1-1. Table 1-1: Base station operating bands Band designation Direction of transmission Base Station operating bands UTRA I BS Transmit 2 110 MHz to 2 170 MHz (UMTS) BS Receive 1 920 MHz to 1 980 MHz (UMTS) E-UTRA 3 BS Transmit 1 805 MHz to 1 880 MHz (LTE) BS Receive 1 710 MHz to 1 785 MHz (LTE) DCS 1800 BS Transmit 1 805 MHz to 1 880 MHz (GSM) BS Receive 1 710 MHz to 1 785 MHz (GSM) These NCU is capable of operating in all of the frequency bands given in table 1-2.Table 1-2: NCU operating bands NCU operating bands Comment 460 MHz to 470 MHz 791 MHz to 821 MHz LTE 921 MHz to 960 MHz GSM 1 805 MHz to 1 880 MHz GSM / LTE 2 110 MHz to 2 170 MHz UMTS 2 570 MHz to 2 620 MHz LTE 2 620 MHz to 2 690 MHz LTE It applies to equipment for continuous and discontinuous transmission of data and digital speech. The present document applies only to radio equipment using a dedicated transmitting antenna that is designed as an indispensable part of the system for usage on board an aircraft. The system covered by the present document operates in accordance with the operational requirements as outlined in the Commission Decision 2013/654/EU [i.3]. The present document contain requirements to demonstrate that Radio equipment both effectively uses and supports the efficient use of radio spectrum in order to avoid harmful interference. In addition to the present document, other ENs that specifie technical requirements in respect of essential requirements under other parts of Article 3 of the Radio Equipment Directive may apply to equipment within the scope of the present document.