Introduction
Access to information is among the most important aspects of contemporary life. The popularity of portable devices capable of Internet connection has created a strong demand for network systems that provide fast and reliable data transfer. The following paper is a literature review on the evolution of network systems from 1G to 4G, focusing on key aspects of each generation.
Generation Definition
A generation of network systems refers to a fundamental change in the technology behind the concept that provides enhancements in performance, reliability, and scalability. Each generation is incompatible with its predecessors. For this reason, subsequent upgrades of existing technology are usually clustered under a single generation as its versions. It should also be understood that this loose definition was introduced relatively late in the course of evolution and has been applied retrospectively to the first generations.
1G
The first generation of network systems was developed in Japan in the late seventies and deployed in several European countries several years later. The main goal of the solution was to ensure the possibility to maintain the connection as the user moved from one location to the other. This was achieved by transferring calls from one entry point (referred to as a cell) to the other. The technology became commercially available in 1983, with the deployment of the Advanced Mobile Phone System (AMPS) in the U.S., Israel, and Australia (Agrawal and Zeng 208). The system contained several major limitations.
First, the analog signal required a broad transmission spectrum in order to operate efficiently. Consequently, it required a large frequency gap between users to decrease interference. Second, it supported one user per channel, severely limiting its usage. Third, it was prohibitively expensive and energy-consuming. Finally, it contained several security flaws – specifically, the data was not encrypted and could be intercepted relatively easily. Despite these issues, 1G has introduced several important aspects of network systems. For instance, it relied on base stations for providing coverage, with different frequencies used by neighboring cells to avoid interference, and used automated means of coordination to ensure a seamless connection.
2G
The second generation was introduced in the early nineties through two competing technologies, GSM and CDMA. Two main aspects signified the fundamental change required for the system to qualify as 2G. First, the analog AMPS system was superseded by its digital counterpart, D-AMPS. Second, the addition of an out-of-band channel ensured faster phone-to-network signaling (Penttinen 277).
The switch to a digital format provided several crucial advantages for the technology. First, it allowed using digital encryption, which significantly improved the safety and security of the data. Second, it optimized the use of the frequency spectrum, ensuring greater penetration levels. Third, it broadened the scope of data transferring by introducing text messaging through short messaging service (SMS). The latter was especially important since it can be argued that the diversity of data has remained the defining feature of mobile networking in the modern setting.
Unlike its predecessor, 2G saw several major upgrades. The first one, commonly referred to as 2.5G, was General Packet Radio Service (GPRS). The technology was based on GSM service, with the respective upgrade of CDMA200 networks in Europe. The main difference of GPRS was the enhancement of the circuit-switched domain with a packet-switched one. This shift allowed charging users based on the volume of transferred data instead of time allocated for network usage. In addition to greater affordability, it allowed for a more efficient network usage by removing the restrictions on channel usage and permitting multiple users to transfer data via the same channel (Penttinen 372).
The second improvement, known as 2.75G, was the Enhanced Data rates for GSM Evolution (EDGE). The technology relied on advanced encryption and transmission mechanisms, known as 8PSK encoding, which permitted a threefold increase in the volume of data per symbol (Abdullah and Al-Hindawi 2). Importantly, EDGE was a backward-compatible technology, which allowed for a seamless implementation in GSM networks and, in some instances, D-AMPS generation. Due to its technological superiority, EDGE was eventually adopted for 3G standards. Overall, the switch to 2G contributed to its commercial availability and thus ensured mainstream adoption.
3G
The rising popularity of portable devices capable of network connectivity created strong demand for faster data transfer rates and greater scalability. Thus, a new generation of networks was developed. The packet switching principle was adopted from 2.5G in order to maintain the high transfer capacity of the carrier wave. Two main competitors were responsible for the establishment of a 3G standard. The first was Evolution-Data Optimized (EV-DO), which decreased connection establishment time, enabled several devices to share a slot, and increased the maximum burst rate to 3.1 Mbit/s (Attar et al. 49).
The second was WCDMA, which relied on a GSM network and used a 5Mz carrier. The latter enjoyed greater adoption due to its capacity for high-speed, reliable network connection. Eventually, a number of improvements were developed and deployed under the umbrella term High-Speed Packet Access (HSPA). The upgraded version of the network system (sometimes referred to as 3.5G) uses the W-CDMA frequencies of 2100, 1900, 850, and 900 MHz, is backward-compatible with earlier 3G versions and offers significantly increased data transfer speed (14.4 Mbit/s in the uplink and 5.76 Mbit/s in the uplink) (Penttinen 884).
The next upgrade of HSPA, known as HSPA+ or 3.75G, increased the rate to 42.2 Mbit/s and 22 Mbit/s., respectively, with up to 168 Mbit/s possible in theory. The technologies responsible for the improvement include beamforming and multiple-input, multiple-output communications (MIMO). The former provides a stronger signal by focusing the beam in the direction of a user, whereas the latter uses several antennas for greater stability. The HSPA upgrades ensured compliance with consumer expectations and lowered hardware requirements, allowing for greater reliability and lower power consumption.
4G
The growing popularity of data-demanding services such as video and audio streaming, coupled with the growing popularity of smartphones, eventually rendered 3G insufficient for widespread use. In response, several technologies were proposed that offered up to a 10-fold increase in data transfer rate over 3G. Currently, 4G is in the early stage of implementation, with several competitors available in different regions.
The first candidate is WiMAX, an IEEE-based standard initially capable of 40 Mbit/s data rate, with the eventual improvement of up to 1 Gbit/s (Penttinen 897). WiMAX is also notable for its flexibility, being used either as a replacement or an enhancement of the networks of existing generations. This aspect of technology greatly enhances its suitability for developing countries. The second candidate is Long-Term Evolution (LTE), a standard based on GSM technology and incorporating many of its features, including HSPA.
Importantly, LTE was initially considered incompatible with the definition of 4G due to the use of legacy technologies but was eventually recognized as such for marketing reasons. Both technologies are still in the active stage of development and have not been deployed consistently on a global scale.
Conclusion
As can be seen, each of the generations has contributed to the evolution of the current state of mobile network technology. The current approach adopted by the researchers prioritizes increased capacity, reliability, and scalability, with additional focus on efficiency and accessibility. Considering the progress demonstrated by the pioneering projects in the field, it is possible to expect further improvements in the technological aspect of the systems and, by extension, a more even implementation on a global scale.
Works Cited
Abdullah, Osama Ali, and Asaad M. Jassim Al-Hindawi. “Analysis and Modeling of GSM/EDGE Mobile Communication System.” IOSR Journal of Engineering, vol. 4, no. 12, 2014, pp. 1-14.
Agrawal, Dharma Prakash, and Qing-An Zeng. Introduction to Wireless and Mobile Systems. 4th ed., Cengage learning, 2015.
Attar, Rashid, et al. “Evolution of CDMA2000 Cellular Networks: Multicarrier EV-DO.” IEEE Communications Magazine, vol. 44, no. 3, 2006, pp. 46-53.
Penttinen, Jyrki T. J., editor. The Telecommunications Handbook: Engineering Guidelines for Fixed, Mobile and Satellite Systems. John Wiley & Sons, 2015.