As a mobile phone user, you may occasionally come across situations where you, for whatever reason, need to know the difference between digital and analogue (or analog) mobile networks. This situation can be a more frequent occurrence if you are an electrical, electronics, or telecommunications engineering student. While you may find tens if not hundreds of videos and tutorials that may show you pictures of clocks or old telephone systems with sine or square waves popping out of them, this post uses no such examples and is specific to mobile networks.
Digital mobile networks are the 2G, 3G, 4G and 5G networks that exist today and use technologies like GSM, UMTS, IS-95, CDMA2000, LTE and NR. Analog mobile networks are the first-generation (1G) networks that are now obsolete and were based on FDMA. Digital mobile networks use TDMA, CDMA and OFDMA.
|Generation||Cellular Technologies||Digital or Analog|
|1G||AMPS, NMT, TACS, JTACS, C-Netz||Analog|
|2G||GSM, D-AMPS, IS-95||Digital|
|3G||UMTS and CDMA2000||Digital|
The mobile networks that exist today are primarily on the GSM track or the CDMA track. Both of these tracks are digital, but it is important to know that they still have and will always have analogue network components that enable radio communication.
Which mobile networks are analogue?
The first generation of mobile networks (1G) represents the analogue mobile networks that employed analogue cellular technologies including AMPS, NMT, C-Netz and TACS across Europe and America. These technologies were based on the Frequency Division Multiple Access (FDMA) radio access technique.
Analogue mobile networks are the first generation (1G) networks introduced in the early 1980s. 1G mobile networks used Frequency Division Multiple Access (FDMA) for the radio access part of the network. With FDMA, the available frequency spectrum is broken down into individual frequency channels of a specific bandwidth to enable communication between a base station and the mobile phone.
1G mobile networks employed various analogue technology standards to launch mobile services in different parts of the world. One of the most popular technology standards for the first-generation mobile networks is the Advanced Mobile Phone System (AMPS). AMPS started its journey in the American region (United States) and was adopted as the 1G analogue standard by various other countries.
The United Kingdom (UK) and some other European countries adopted a variant of AMPS called Total Access Communications System (TACS). In Japan, NTT (Nippon Telegraph and Telephone) introduced 1G in 1979, which was the first commercial launch of a mobile cellular network in the world. Later Japan introduced a slightly modified version of TACS called the Japanese Total Access Communication System (JTACS).
Germany introduced 1G through a technology called Funktelefonnetz-C (C-Netz for short and Radio Telephone Network C in English). The specific name for the technology standard was C-450. The Nordic countries (Sweden, Finland, Denmark, Norway and Iceland) that are well known in the world of mobile communications employed a different 1G technology NMT or Nordisk Mobil Telefoni (Nordic Mobile Telephone in English).
Some other European countries and Russia later adopted NMT. 1G network offered low capacity, and the communication was not very secure. 1G handsets were hefty in size and offered only a talk time of around 30 minutes. The first generation mobile networks are now obsolete, and they have been replaced by 2G, 3G, 4G and 5G.
Which mobile networks are digital?
The second (2G), third (3G), fourth (4G), and fifth (5G) generations of mobile networks are digital mobile networks that employ digital cellular technologies, including GSM, D-AMPS, IS-95, UMTS, CDMA2000, LTE and NR. Digital mobile networks use TDMA, CDMA and OFDMA radio access techniques.
The digital era of mobile communications began in the early 1990s with the introduction of the Global System for Mobile Communications (GSM), which would later become the most widely deployed 2G technology standard in the world. Another key technology of that era is D-AMPS which is the Digital version of AMPS. Both GSM and D-AMPS use a combination of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) for radio communication.
D-AMPS is also referred to as TDMA because it used the existing frequency bands in the FDMA-based AMPS technology and applied TDMA to create timeslots in the existing frequency channels. Another prominent 2G standard is IS-95 (proprietary name: cdmaOne), which uses Code Division Multiple Access (CDMA) for its air interface. IS-95 is the world’s first CDMA-based mobile communications technology standard which later evolved to CDMA2000 for third-generation (3G) cellular services.
The 2G GSM networks migrated to 3G using UMTS (Universal Mobile Telecommunication System). Both CDMA2000 and UMTS use the LTE technology for 4G migration and New Radio (NR) technology for 5G migration. All of these cellular technology standards are digital. The reason why these technologies are digital is not that anything different happens in air interface (radio) but because the information they carry is digitised. Digital mobile networks are secure and efficient, and they enable voice, text messages (SMS) and mobile data services.
What makes a mobile network analog or digital?
A digital mobile network handles data in a digital format using digital modulation techniques such as QPSK (Quadrature Phase Shift Keying) and QAM (Quadrature Amplitude Modulation). However, when the data travels through the air interface, it is in the form of analogue signals.
Today, the latest mobile networks are the fifth-generation (5G) mobile networks that use the New Radio (NR) technology. The second most recent technology is LTE (Long Term Evolution), enabling fourth-generation (4G) mobile communications. These mobile network technologies use advanced digital modulation techniques that ensure the efficient use of radio network resources to provide the highest possible data rates.
All the information carried by the mobile networks, including our messages, voice calls, YouTube videos, etc., are handled in a digital format and therefore require digital modulation, making the 4G and 5G networks digital. However, when a mobile signal leaves the antennas of a radio base station and enters the antennas of our mobile phones, it is always an analogue signal.
That is because the world we live in is analogue, and radio signals are electromagnetic radiations that have to comply with that. Therefore, the cellular base stations and mobile phones have DAC (Digital to Analogue Converter) and ADC (Analogue to Digital Converter) that perform the digital-to-analogue and analogue-to-digital conversions.
I have written a detailed post on modulation techniques for 4G LTE networks that dives into the details of OFDMA to provide an end-to-end picture of how digital data is handled by mobile networks. If you are a student, I would recommend reading that post.
Here are some helpful downloads
Thank you for reading this post. I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need extra support, especially when preparing for a new job, studying a new topic, or buying a new phone. Whatever you are trying to do, here are some downloads that can help you:
Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.
Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.