The first generation was analog. From 2G onwards, the generations have used different protocols for increasing the amount of digital traffic that can be carried on analog radio waves. This means that standards are necessary so that transmission equipment and handsets from different manufacturers can all be used in the carriers’ networks. Thus, the criteria for classifying mobile systems by generation are the international standards being used.
The key elements of these standards are the frequencies specified for the radio communications and the multiple-access schemes. The latter refers to the modulation and multiplexing methods that prevent interference between multiple users in the same cell – that is, in the area served by one antenna. Since the “1G” analog generation, there has been continuous work on more efficient coding and multiple access schemes to achieve faster transmission rates and to carry more traffic.
This work has resulted in more than four digital standards. Some of these standards are enhancements that allow inter-operability with equipment developed under an earlier standard or an earlier version. On the other hand, some have different frequencies and multiplexing techniques, requiring all new equipment. This is the basis for calling them “generations,” and identifying four main digital generations – 2G through 5G.
The names of standards come from the committees, abbreviations for the multiplexing schemes, or other references. The widely used name for the first digital standard was “GSM,” which initially stood for the Europe-based committee, Groupe Speciale Mobile, and then later for Global System for Mobile communications. The abbreviation has since been trademarked by the GSM Association. The most widely used 4G standard is LTE, which stands for Long-Term Evolution. Other standards referred to as 4G include WiMax and LTE-Advanced.
Some of the standards have been referred to with expressions such as “2.5G,” 2.75G,”, “3.5G,” “3.9G,”: “pre-5G,” and other designations. The table shows these digital mobile standards from the last 30 years grouped into the four main generations. The 3G designation, for example, refers to a group of standards including W-CDMA, CDMA-2000, TD-SCDMA, EDGE, and DECT. All of these meet the requirements defined by the International Telecommunications Union (ITU) to be classified under the broader 3G designation.
The table’s row labelled “Initial deployments” has the years highlighted in red. These are the years when carriers first offered commercial services, with customers paying monthly fees. Prior to this, the carriers often have had two or more phases of trials, including both laboratory and field trials. Some of the field trials have had limited coverage areas – just one antenna serving a confined area, such as a corporate campus. Larger field trials may include entire cities.
With 5G trials, laboratory trials were underway in 2015, and field trials were underway in 2017. The field trials with 5G have included some of the new application concepts, such as driverless vehicles and high-speed transportation. Many carriers have had field trials underway in 2018 or scheduled for 2019, but only a few carriers are planning to launch commercial service this year.
Since the earliest 5G trials at a few key laboratories in 2015, there has been a rapid progression with more than 100 carriers announcing new trials in about two years. The Global Mobile Suppliers Association (GSA) reported in August that it had “identified 154 operators in 66 countries that have demonstrated, are testing or trialing, or have been licensed to conduct, field trials of 5G-enabling and candidate technologies.” Further, the GSA says that this number is up from 81 operators in 42 countries in September of 2017 – a big increase in less than a year.
In late 2010, the GSA was reporting on early 4G developments as it is reporting on 5G now. In August 2010, for example, GSA said that three 4G networks were in commercial service. At that time, another 101 carriers in in 41 countries were in trials or had committed to deployments. Now, three US carriers, AT&T, T-Mobile, and Verizon, have announced plans to launch commercial 5G services before the end of 2018. Thus, 5G technology seems to have about the same amount of carrier activity now as 4G did in the Fall of 2010.
The GSA’s August 2018 report said that 681 operators in 208 countries currently offer 4G network services. Another 84 carriers have trials underway or have committed to deploy 4G, but construction is still pending. This means that 4G has not “run its course,” and will certainly be operating concurrently with 5G for many years. In fact, 2G, 3G and 4G mobile networks have been operating concurrently for 18 years and will continue to do so for several more years. Some carriers have turned off 2G networks, but we are not aware of any carriers that have plans to turn off 3G networks. This means that 3G, 4G, and 5G will be operating concurrently well into the 2020s.
Another industry trade association, the GSM Association (GSMA), has published a forecast of 1.2 billion 5G subscribers worldwide in 2025. Ericsson’s forecast is 1.0 billion subscribers by 2023. Another equipment company, Juniper, forecasts 1.5 billion by 2025. All these forecasts have 5G progressing more rapidly than 3G but less rapidly than 4G in terms of the number of subscribers signing on in the initial years. Considering the number of systems in service, the number of 5G subscribers is likely to be less than 100 million until after 2020.