What do 2G, 3G, or 4G mean? That’s what we’ll look at in this video. The concept of dividing the territory into cells, each cell being covered by a base station was defined in the 70s in the United States. The first networks in Europe appeared in the Nordic countries in the 80s. We speak of first generation, because these were the first networks and the transmission was analog. The principle is to transmit a communication on a frequency. It’s what we call FDMA, Frequency Division Multiple Access. The life of these networks was approximately from 1980 to 1995. A huge innovation was the deployment of a network based on digital transmission: GSM or “Groupe Spécial Mobile” in the beginning, when it was in French, and now, Global System for Mobile Communications, now that it’s global. GSM is still used frequently today. The principle is to use one frequency to transmit several communications by dividing the time into slots, each slot supporting one communication. This is called TDMA, Time Division Multiple Access. These networks are called second generation: they only enabled telephony and the exchange of SMS, Short Message Services. With the development of the Internet in the 90s, there was a,, need to have mobile access to the Internet. This was managed by adding procedures and equipment to the GSM network. This is called GPRS, Global Packet Radio Service. With an evolution called EDGE, Enhanced Data Rate for the GSM Evolution, the throughput was increased in comparison with what was initially possible with GPRS. The principle of GPRS is to supply a service of packet transmission and to use packet access and new modulations on the radio channel. IP access is possible, at best, at 100 kilobits per second in a network with a low load. This throughput is therefore relatively low. Starting in the 90s, the specification of a new system was created which permitted higher throughputs: it’s UMTS, Universal Mobile Telecommunication System. The technology used by UMTS is based on spread spectrum. This technology is called CDMA, Code Division Multiple Access. The first networks were deployed starting in 2002-2003 and are still operational. It’s possible to access an IP network at typically one megabit per second. So, it’s still relatively limited, even if it’s better than for second generation networks. The third generation was completed by what is sometimes called the 3. 9 generation, with HSDPA, High Speed Data Packet Access. Throughputs were increased using a new modulation, going up to 10 megabits per second. HSDPA was deployed starting in 2008. Fourth generation has a different approach. Up ‘till now, a lot of services ware specified in mobile networks. The principle of fourth generation is to say, Now, we have a lot of services available on IP, voice over IP, videophone, web browsing, social networks, and so on; Therefore, it’s not useful to define services specific to a mobile network. What a 4G network provides is “just” the transmission of IP packets from a mobile terminal to a fixed or mobile server or the other way around. Therefore, the only service provided in 4G is high throughput IP access: it can go up to100 megabits per second. The technology in Europe and throughout the world corresponding to 4G is called LTE for Long Term Evolution. The term “Evolution” is poorly chosen, because It’s not an evolution, it’s really a different system to 3G or 3. 9G. Transmission on the radio interface is based on OFDMA, Orthogonal Frequency Division Multiple Access. It’s the type of transmission used in a large number of systems, such as digital television, ADSL, and many others. The benefit of OFDMA is that, by using mathematical processing, it enables parallel transmissions. So, we have the possibility of having high throughput. Because we’re making a large number of transmissions in parallel, each transmission is actually done with medium throughput. LTE networks have been deployed since 2010 and now the coverage of this type of network is very large in Europe and throughout the world. This is the technology that we’re going to look at in this course. But a certain number of principles, even if the system is completely new, have been picked up from preceding generations. The 4G system is relatively well designed and well structured. For that reason, this course can also be used as an introductory course to the mobile network, independently of the generation.
