Introduction You might be reading this article on your mobile device within the comfort of your room or while travelling to your destination, but things were not like this earlier. The communication system was completely different and there were only point to point communication systems which were widely used even during the 1970s. The advent of the mobile phone has revolutionized our lives and we can communicate with others by just tapping on our devices. You might have seen the old Public Switched Telephone Network (PSTN) phones that were better known as land phones and might be using one at your home too.
Have you ever wondered how this communication system began? We all talk about 3G and 4G networks and 5G is on the cards, but it was only during the 1970s when the first mobile device was used for communication. Before the mobile phones, the wired landline telephone was the only way of communication and earlier, even possessing one landline phone was like a prized one.
Invention of the telephone "Mr Watson, come here, I want you". Alexander Graham Bell said these words over the telephone that he invented, to his assistant Thomas Augustus Watson and with these words the revolution began. It was in March 1876 and the telephone system was unidirectional that could cover a distance of around a hundred feet using twisted pair cables. After many changes to the design, it was commercialized and was used for long-distance communication. The Bell Telephone Company was formed in July 1877 to promote the telephone services and soon became popular. Within a few years, the company was restructured many times and AT&T is the descendant of the Bell Telephone Company which constructed the backbone of the telephone network throughout the USA. The dream of communicating with others while on the go was gaining some grounds and many new applications to transmit the voice signals over radio waves were experimented by scientists.
Modern mobile telephony The mobile phone, that we are using today, came into existence during 1973 when Motorola produced the first mobile phone. After that, the technology for mobile communications and designs of the handsets gone through major changes and now we are using some of the most sophisticated ones in terms of functionalities that were unthinkable when it was first invented.
History of mobile radiotelephony During the early 20th century, mobile radiotelephones were tried and put to use in different military and marine communications and it was in 1946, when a car-based phone system was used in St. Louis, USA, that deployed a large transmitter over a high rise building. It was developed by AT&T and was a single channel device that used the push-to-talk system to make a call. At that time both the speakers on two ends of the line couldn't speak simultaneously and had to wait until the other one finished speaking. These mobile telephones were mostly used in automobiles, consumed lots of power and were bulky. This communication standard, at that time, was known as Mobile Telephone Service (MTS) and was completely operator based where each call was routed through a mobile operator.
It was in the 1960s, when an improved version of MTS, Improved Mobile Telephone system (IMTS) developed. It was similar to the car-based phone system with a higher transmission power, around 200 Watt, where the transmitter was fitted atop a hill. In this system two frequencies were used, one for sending voice signals and the other for receiving voice signals, therefore, the push-to-talk system was not required anymore. IMTS used few more radio channels for communication and the role of the operator to set up calls was reduced to a great extent.
Things changed drastically when Advanced Mobile Phone System (AMPS), that was developed by Bell Labs came into existence. It was launched first in the USA in 1983 and a few other countries later on. From here the concept of cell developed and that's why mobile phones are also known as cell phones.
In this concept of the cell, the total geographical location where the mobile communications remain active is divided into cells which are 10 to 20 Km apart. Here when the user of the mobile phone is going beyond the limits of that particular cell, the communication channel, established between two mobile phones, is taken up by another cell in the new location automatically.
First generation (1G) networks It was launched during 1979 and continued till the arrival of 2G technology. At that time, the communication network was analogue, supporting only voice communication. Mind it, the facility to send text messages was not there. The voice quality was not so good and had no security features. Different communication systems were used at that time like AMPS, NMT and TACS. Commonly these systems are termed as first generation or 1G.
Second generation (2G) networks A marked improvement over 1G systems happened after the launch of Global System for Mobile communication (GSM) around 1991. The voice signals were digitally encrypted and Short Messaging Services, better known as SMS introduced at this time. Since it used digital signalling methods, the voice quality was absolutely clear. Few other technologies like, CDMA, FDMA, TDMA were also used during this time. At that time data transfer through mobile networks took place in a dial-up modem with a speed of around 64 Kbps. Picture and multimedia messages (MMS) could be sent through 2G networks and were popular at that time.
2.5G networks A technology to transfer data at a much higher speed was evolved known as General Packet Radio Service (GPRS) which completely changed the mobile data communication scenario. It used packet-based technology to transfer data at a maximum speed of 144 Kbps. Another technology known as Enhanced Data rates for GSM Evolution (EDGE) came into existence that offered data speed up to 384 Kbps.
3G networks The concept of mobile broadband came in this generation. It was introduced in 2001 that uses different frequencies and a larger spectrum for communication. This necessitated building of entirely new networks to support the wide range of frequencies. The Universal Mobile Telecommunication System (UMTS) is the standard followed in 3G networks that uses packet-based transmission of data. This technology is based on IP and uninterrupted mobile data transfer became possible at this time. Data rates of up to 2 Mbps became a reality with the use of different modulation techniques. Video calling, Mobile TV are a few of the significant features of 3G networks. A further enhancement in the data speed happened with the use of High-Speed Packet Access (HSPA) protocol, termed as 3.5G, where data transfer rate of up to 14 Mbps is achievable. This generation of networks is still in use in different parts of the world.
4G networks By the late 2000s, a new technology to transfer data at a higher speed was introduced. The Long Term Evolution (LTE) standard can theoretically provide data speed of up to 1 Gbps. This network cannot support the circuit-switched communications network and require a fully packet-switched based network. Here the modulation techniques are further modified to suit the enhanced speed and aim at providing ultra-broadband data access. Currently, 4G networks are implemented throughout the world with an aim to connect every corner. With this enhanced data speed, smartphone penetration has increased and the cost of internet access has reduced to a great extent.
Research on new standards With the aim of even higher data speed and more features, the research is in full swing for implementation of the 5G networks and is tested in few countries. It can provide a data transfer rate of 20 Gbps. It is expected to be launched by 2020. There are many exciting things to happen by this time when the Internet of Things (IOT) is expected to be used widely. With a 5G network, the expectation is to stay connected with the entire range of devices we use at all the time.
Conclusion It started with only voice communication and now we are using ultra-broadband mobile networks. Continuous research to improve the data transfer rate coupled with the implementation of various new technologies, mobile communication has changed the way we look at things. Many technologies, that were never imagined earlier, became reality and the development is going on even at a faster rate. After almost every 10 years a new generation, termed as G, of mobile network standards are introduced and now we are in the 4th generation. It's a continuous process and exciting too to stay connected with the latest features.