Chronologically from the first generation of telephony (1G) that carried only analog voice data, to the current fourth generation (4G) of mobile technology, telecommunications have evolved over the years to cater for the growing networking demands of present day mobile communications users. Each generation has been developed building upon the previous technology to improve on it in order to deliver better services. The generations (G) specify the classes of technology, each having its own data rates and devices associated with it.
- EVOLUTION OF MOBILE COMMUNICATION NETWORKS
The 1G cellular networks started in the early 1980s and were designed mainly to carry analog voice communication with no data services in mind. The examples of the technologies based on this at that time included TACS, NMT, C-Nets and AMPS. In the early 1990s came the 2G networks which was digital unlike the analog 1G. This made up the first digital cellular network since the switches that were deployed supported digital calls using actual 1s and 0s. The technologies in this class included D-AMPS, Code Division Multiple Access One (CDMAOne) and Global System of Mobile Communication (GSM). The 2G technology offered higher capacity, improved voice quality and improved security over the 1G technology. The voice communication channel of 200 kHz bandwidth is broken down into 8 time slots that can carry voice or packet data at 14kbps. The evolution of the 2G network birthed the 2.5G network which is an enhanced version of 2G. In this category is found General Packet Radio Service (GPRS) technology and CDMA2000 1x. This technology provided the first always-on data services with data rates up to 144kbps.
Furthermore, the 3G networks aimed at improving the speed of the data services provided by the 2.5G evolution of mobile communication networks. The 3G networks delivered circuit-switched voice service and provided data rates of up to 384kbps. Examples of the 3G technologies include Unified Mobile Telecommunications Service (UMTS), WCDMA, EDGE, etc. Some technologies that also evolved from 3G, before the current 4G technology are the Long Term Evolution (LTE), WiMAX and High Speed Packet Access (HSPA). HSPA delivered data rates of up to 42Mbps uplink and 11Mbps downlink speeds.
4G technology, being the latest generation of mobile communication networks is still evolving, and yet to be finalized. But according to the International Telecommunications Union (ITU), before a network can qualify as 4G, it must possess some basic characteristics which include a single user downlink speed of 1Gbps and uplink speed of 500Mbps.
An examination of the basic features, nuances and modes of operation of both 3G and 4G are considered in subsequent sections of this paper.
- HOW 3G WORKS
3G networks have options for the Code Division Multiple Access (CDMA) or the Unified Mobile Telecommunications Service (UMTS). The UMTS is further sub-categorized as Wideband Code division Multiple Access (WCDMA), Time Division Synchronous CDMA (TD-SCDMA) and the HSPA. CDMA2000 1x uses 1.25MHz voice channels with each spreading code of the CDMA supporting voice communication or packet data up to 9.6Kbps. A total speed of up to 153Kbps can be obtained when up to 16 Codes are combined. In the CDMA2000 1xEV-DO however, one CDMA carrier is dedicated to packet data transmission. A peak data rate of 2.4Mbps is obtained when new Spreading Codes and Time Division techniques are combined.
For the 3G UMTS on the other hand, a 5MHz communication channel is used for data transmission. Spreading Codes of up to 94 can be used with new Spreading Codes combining to produce up to 2Mbps. 3G UMTS uses the same core network architecture as 2G and GPRS and is based on either circuit switching or packet switching. “The UMTS packet switch core network consists of SGSN and GGSN. The main function of the packet core is to provide packet routing, traffic management (e.g., load balancing), session authentication and application layer management, and traffic accounting for billing” (Dong, 2). The SGSNs (Serving GPRS Support Nodes) and GGSNs (Gateway GPRS Support Nodes), make up the core of the 3G technology and interconnects other network elements such as NodeBs and Radio Network Controllers (RNCs).
- HOW 4G WORKS
According to Marcin & Jinwoo (6), the Fourth-generation mobile networks 4G is a packet-switching network meant to provide a common point of mobile communication for all kinds of wireless networks through cellular wireless LANs using the IEEE 802.20 and WiMAX protocols. It used Orthogonal Frequency Division Multiplexing which gives it an improved spectral efficiency of 5bps/Hz downlink and 2.5bps/Hz uplink, and increased capacity. Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes are used for data transmission. A simultaneous transmission of the uplink and downlink data is done with FDD using different frequency bands while the transmission is done on the same frequency band but at different times in TDD mode. The evolved Node B (eNodeB) provides the radio access functionality in 4G networks. It performs admission control, schedules uplink and downlink, schedules and transmits paging and system broadcasts, performs dynamic resource allocation and IP header compression.
The requirement of single user peak data rates of 1Gbps downlink speed and 500Mbps uplink speed is achieved with the use of wider bandwidth of 100MHz. It makes use of multi-layer transmission technique (Advanced Adaptive MIMO) in a given bandwidth to increase data rates. In order to cater for the high bandwidth requirement of some real time applications like VOIP and multimedia streaming, 4G technology has introduced a significant delay over the air for data transmissions. It uses adaptive modulation and coding schemes, using QPSK, 16QAM and 64QAM for the uplink and downlink modulations. The 64QAM is optional for user Mobile Equipment (ME) in uplink modulation. A schematic of the working of the 4G technology is as shown below.
The 4G network is sub-divided into the Radio Access Network (RAN) and the Core Network (CN). The RAN provides users with access to the network while the CN performs the switching, billing and other management functions of the network.
In the diagram, users will access the network with their 4G-enabled mobile devices (UE) or via 4G modems on their PC terminals. The air interface uplink is based on Orthogonal Frequency Division Multiple Access (OFDMA) which provides improved capacity and spectral efficiency. The orthogonal FDM ensures there is no cross-talk between the signals and allowing the signals to overlap will save considerable bandwidth. The downlink is Single Carrier Frequency Division Multiple Access (SC-FDMA). The SC-FDMA is used for uplink because it consumes less battery power and thus will prolong the battery life of the mobile hand-held devices. The Radio uses adaptive modulation and coding, QPSK, 16QAM and 64QAM for downlink and uplink connection.
The 4G technology radio access point supports advanced MIMO spatial multiplexing which enables higher data rates to be obtained for a given bandwidth.. 4G's evolved NodeB (eNodeB) has replaced the 3G NodeB. The eNodeB has taken over the functionality provided by the Radio Network Controlers (RNCs) that were used in 3G networks.
The fixed backbone represents the Core Network of the 4G technology. The architecture of the core network is designed around a common IP base so as to support the data demands of applications that make use of heavy data, voice and video. The Evolved Packet Core (EPC) as the Core Network of 4G is called comprises the Mobility management Entity (MME), which performs some of the functions of the RNC in 3G, the Policy and Charging Rule Function (PCRF), Serving Gateway and the Packet Data Network (PDN) Gateway. This core of the network performs the switching, routing, billing and other management functions of the network. Only packet switching is supported in 4G technology.
The applications represent the different applications that will make use of the high speed data services provided for voice, data and video as provided by the 4G platform. Such applications include those that make use of live video streaming, maps and navigation software etc.
- DIFFERENCE BETWEEN 3G AND 4G
The differences in the 3G and 4G technology are most evident in the download and upload speeds available to users. The potential throughput obtainable in 3G is 3.1Mbps while a range of 100 – 300 Mbps is obtainable in 4G. The data switching technique used in 3G is packet switching and circuit switching, while packet switching as well as message switching is supported in 4G mobile telephony technologies. The network architecture of 3G is cell-based while it is an integration of wireless LAN and Wide area Networks in 4G. The eNodeB in 4G has replaced the RNC that were formally used alongside the NodeB in 3G networks.
- APPLICATIONS OF 4G
There is no doubt that the data demands of the mobile phone user continues to increase hence the need to advance the existing communications technologies and equipment to meet this growing demands. “Researchers see Digital Video Broadcasting-Handheld (DVB-H) and Digital Multimedia Broadcasting (DMB) as additional component of 4G providing video transmission to mobile devices” (Marcin and Jinwoo, 2). The high data rate offered by 4G will be able to meet users’ demand for live multimedia streaming and video conferencing at higher resolutions and improved picture quality. 4G networks will easily deliver maps and positioning services on demand to mobile devices.
“A 4G system will be able to provide a comprehensive IP solution where voice, data and streamed multimedia can be given to users on an 'Anytime, Anywhere' basis, and at higher data rates than previous generation networks” (Dhawan, 6).
- FUTURE OF MOBILE COMMUNICATIONS
For now, only LTE and WiMAX are the closest technologies in performance to 4G because they also both use OFDM technology. However, 4G is not yet fully developed and will still be ahead of all other existing technologies in the pack.
Going by the evolution of these various technologies starting from 1G to where we are now, it is evident that each generation was developed to improve the service delivery of the previous one. It is evident that the developments over the decades have lived up to the growing demands of users for access to larger data sizes at faster data rates.
I think the need for even faster mobile network access will not cease to grow, thus the continued quest to satisfy this need. The current 4G technology will evolve into newer generations to continue to build on the technological advancements attained in this generation. A Fifth-generation mobile network will obviously improve on the speed provided by 4G, a greater support for machine intelligence (Artificial Intelligence) and the capacity to support a growing population of users. This view is strongly supported by the growing migration of computing to mobile devices or better still, the electronic convergence of computing and mobile telecommunications.
- CONCLUSION
The 4G mobile technology is one that is not yet finalized and thus still evolving. Its deployment and commercial availability is still very limited. It is obvious that it is a technology that promises to deliver much better services than the existing obtainable services especially in terms of very high internet connection speeds for mobile devices. The implication of this however, will be increased cost of access to the network. I think by the time the network is more established, fewer users will be able to afford to pay for the use of 4G networks.
The 4G mobile networks will no doubt also see an increase in the development of applications that require very high data rates for functionality, thus increasing the derivable benefits to users.
Works Cited
Cheng, Yu et al. Efficient Resource Allocation for China's 3G/4G Wireless Networks. IEEE Communications Magazine, 2005. Print.
Dhawan, Mohan. I want my MTV! 4G: Content Distribution Re-defined. Department of Computer Science, Rutgers University. Print.
Dong, Wei, Zihui Ge and Seungjoon Lee. 3G Meets the Internet: Understanding the Performance of Hierarchical Routing in 3G Networks.
Lajos, Hanzo et al. Wireless Myths, Realities, and Futures: From 3G/4G to Optical and Quantum Wireless. Proceedings of the IEEE spec. Centennial Issue 100, 1853-36, 2012. Print.
Szczodrak, Marcin & Jinwoo Kim. 4G and MANET, Wireless Network of Future Battlefield. Department of Mathematics and Computer Science, John Jay College of Criminal Justice, The City Unversity of New York, New York, 2011. Print.
