Dossier: the technical back of 4G

3.9 g or 4G?

Of course, it is possible to establish an ordinary phone call from a mobile 4G. The network then implements the process called CS Fallback (Circuit Switch Fallback), that is to say the switch to 3G. On some terminals this little sleight tower is visible: it displays 3G instead of 4G. Some American manufacturers have otherwise settled the issue by incorporating in the same housing two phones: one for voice and one for data communications. Obviously, this is all transparent to the user. It is the concerned phone module that takes the hand. The trouble is that the terminal is thicker and above all, the battery life is affected, since it must supply two modules at once.

A third method, called VoLTE (Voice over LTE), IP end to end, to be native in the next generation called LTE-Advanced and it is already possible to implement in 4G. But this requires the presence in the heart of the network, an IMS (IP Multimedia Subsystem), in order, to treat the specific signaling and voice packets, in the phone, a customer VoLTE (IMS layer ). In the opinion of French operators, their first concern does not lie there. They have much to do to deploy the 4G standard, which requires a new network.

The fact that the voice borrows the circuit mode did say the purists, the early experiments of 4G, that it was not for the LTE family, but should be normalized 3.9 g. As of the time of the GSM (Global System for Mobile Communications), GPRS (General Packet Radio Service) was considered 2.5G and 2.75G the Edge. Today, under the marketing pressure, both operators and manufacturers, the current 4G is indeed entered the LTE family. This “forgetting” the voice is that 4G is fruit of the cogitations of the computer, which did not take into account the specificities of the vote, while the 2G and 3G had been developed by operators and telecom manufacturers, whose core business was precisely the voice.