Many of us fly by plane, this is the fastest and most convenient way to travel between remote cities. Most often, before takeoff, we hear the phrase "please turn off your phones and other electronic devices." Although it has already been proven that interference from gadgets cannot cause harm, air carriers, out of habit, prohibit their use. A modern person cannot imagine life without a tablet, smartphone and, most importantly, without the Internet, so an increasing number of airlines provide access to the Internet for an additional fee. Most often, this is the usual Wi-Fi, but the Internet reaches the router not by wire, but with the help of a satellite or a special cellular base station. And to ensure a comfortable access speed, the Internet operator uses modern Deep Packet Inspection (DPI) systems on the ground.
For an airplane, the Internet can be provided in two ways:
1) Air-to-Ground (ATG) - "Air - ground"
On the ground, existing base stations (BS) are built or used, the antennas of which are directed upwards. The aircraft equipment is a 3G router, which switches during the flight from one BS to another without breaking the connection and distributes the Internet to passengers. The advantages of this method include the use of a ready-made cellular network infrastructure, it is enough just to install special antennas and make sure that there are trunk optical communication lines between the BS throughout the entire territory of the echelons. Moreover, the flight routes are always known in advance, and the number of required antennas is significantly less than when providing Internet access from mobile devices on the ground: one BS covers up to 100 square kilometers of the flight area due to the height of the aircraft above ground level. This method has one limitation - when the aircraft is over a large body of water, the connection with the BS is lost, which means the Internet is lost. This limits the use of the technology for transcontinental flights. In this case, the second method comes to the rescue.
1) Satellite communication
A repeater appears between the ground Internet and the aircraft – a satellite that is in geostationary orbit and retransmits the signal from the ground to an area of up to several hundred thousand square kilometers. The Internet operator rents capacity from a satellite operator and transmits its traffic to aircraft. Different ranges are used for transmission. Low-frequency (several GHz) are currently outdated, and most operators use the K-band (short, over 10 GHz) and Ku-band (from 12 to 18 GHz) – they provide low cost and fairly high speed (up to 50 Mbit/s). Even higher speed can be provided by satellites equipped with Ka-transponders (30/20 GHz range), they are currently used by Eutelsat, Viasat and Hughes, providing broadband Internet access in North America.
Deep Packet Inspection organizes an air channel
Installing a DPI system in front of a satellite operator's equipment allows traffic management for several airlines with a fleet of thousands of aircraft that transport passengers to any point in the world. DPI allows you to identify traffic in real time and apply policies based on specified priorities, block and shape certain types of content. Deep analysis allows you to compile detailed reports on the protocols and applications used, and evaluate the most visited resources. The DPI system is able to protect users' mobile devices during the flight from network attacks. Using deep traffic analysis (DPI) systems is useful not only for providing Internet access on board an aircraft, but also in any place where there is a physical limitation of channel width.
OFiSS engineer
Inagamova N.S.
