System Overview

The Onboard Mobile Telephony System (OMTS) is part of a multi-program cabin connectivity system, which extends the availability of common mobile/cellular telephony services into the aircraft. It can be based on a number of different technical standards (e.g.: GSM1800, GSM1900, GPRS, EDGE, CDMA). The general system architecture includes two segments.

The Airborne Segment is made up of all functionalities on the aircraft needed to provide radio access to passenger’s cell phones or laptops, in this case our focus is strictly on cell phones.  The Airborne Segment also includes all functionalities that are required to gain power control over all digital mobile devices onboard the aircraft.  As noted in the introductory section, control of the RF environment is required to limit the cell phone interaction with the ground stations and limit the power out of the cell phone.

The Ground Segment interfaces to the satellite or air-to-ground networks and transmits/receives the data stream from/to the off board communication system inside the aircraft.
The Bearer Network link connects the Airborne Segment and Ground Segment, providing the transport and interconnection between terrestrial service providers/backbone networks, and the aircraft cell phones.

The OMTS is usually only active during cruise phase above 10,000 ft. (3000 m) and if allowed by local authorities. 

The aircraft integrated mobile telephony system will allow passengers to use their own cell phone voice and data services on board and during flight. In that way, the system design enables the operation of a worldwide commercial mobile radio service. The system is designed to cope with the electromagnetic constraints due to usage of cell phones in the aircraft. The system ensures that:
- The transmitted radio signals by the cell phones are fully controlled by the OMTS system.
- The cell phone in the controlled mode will transmit at power levels far lower than in typical          terrestrial environments.
- The emissions from controlled cell phones should not interfere with aircraft equipment.
- Cell phones are prevented from registering to terrestrial networks.
The OMTS system is intended to work independently of the bearer system (i.e. satellite or air to ground system) used. The system provides an IP (Internet Protocol) interface for interconnection with the bearer system. In this way, co-existence of the OMTS voice services with other IP services can be achieved.

Besides the airborne and bearer system, a ground segment needs to be available for typical back end functionalities such as authentication, authorization, and accounting.