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1.1 Generation network
 0G Networks
0G Represents the 1st Generation of mobile telephony, where satellite phones were developed and deployed for boats mainly – but anyone could get one in one’s car in the beginning of the 90s for several thousand dollars. Networks such as Iridium, Global Star and Eutelsat were truly worldwide.
 1G Network
It Provided the facilities of making voice calls and sending text messages. (NMT, AMPS, TACS) are considered to be the first analog cellular systems, which started in early 1980s. The greatest disadvantage 1G had was that it only allowed to contact within the premises of that particular nation, NO CROSS OPERATOR ROAMING FACILITIES were provided.
 2G Network
2g Represents the 2nd Generation of mobile telecommunications and is still the most widespread technology in the world; also known as GSM (GSM stands for Groupe Spécial Mobile in French, renamed in Global System for Mobility). Delivered data at the slow rate of 9.6 Kbytes/sec.
 2.5G Network
This mid generation was introduced mainly for involving latest bandwidth technology with addition to the existing 2G generation. This offered a higher data rate than 2G technology and enabled the delivery of basic data services like text messaging. Still the data rates were not enough to download an image or browse a website from a PDA. 2.5 G could provide data rate upto 144 kbps. GPRS, EDGE and CDMA 2000 were 2.5 technologies.
 2.75G Network (a.k.a EDGE)
To be able to watch streaming video and download mp3 files faster – that’s precisely what EDGE stands for where data packets can effectively reach 180kbps. EDGE is now widely being deployed in India.
 3G Network
it Represents the 3rd Generation designed to overcome all the limitations of above technologies. In this, 3G Wide Brand Wireless Network is used to increase the clarity giving the perfection like that of a real conversation. GSM 3G networks are termed UMTS, or the universal mobile telecommunications service, in the United States, while wideband CDMA (WCDMA) is an effectively synonymous term for UMTS used elsewhere in the world. One of the major positive points of UMTS is its global roaming capabilities. The speed is 3 times that of a GSM, so its called a 3GSM service.
 3.5G or 3G+ NETWORK:
HSDPA (3.5G) standard today offers anywhere between 7.2 and 14.4 Mbps on cell phones, Practically speaking, this would mean downloading an mp3 file would take about some seconds instead of something like 2 minutes.
 4G Networks
Pre-4G technologies such as mobile WiMAX and first-release 3G Long term evolution (LTE) have been on the market since 2006 and 2009 respectively, and are often branded as 4G. The current versions of these technologies did not fulfill the original ITU-R requirements of data rates approximately up to 1 Gbit/s for 4G systems. Marketing materials use 4G as a description for Mobile-WiMAX and LTE in their current forms.
IMT-Advanced compliant versions of the above two standards are under development and called “LTE Advanced” and “WirelessMAN-Advanced” respectively. ITU has decided that “LTE Advanced” and “WirelessMAN-Advanced” should be accorded the official designation of IMT-Advanced.
 5GNetworks (Real wireless world) (completed WWWW: World Wide Wireless Web) .
The idea of WWWW, World Wide Wireless Web, emerged from 4G technologies. The following evolution will be based on 4G that will boost the dream of having a REAL wireless world. Thus, 5G should make an important difference and add more services and benefit to the world over 4G; 5G should be a more intelligent technology that interconnects the entire world without limits.
Before compiling this article I had spoken to a few telecoms experts in France, and the future is blurry, to say the least. 4G LTE technology is bringing CDMA and GSM technologies closer as possible, and unification of formerly in-war standards is in order for 5G or 6G the latest, and what Verizon and AT&T are bringing in 2011 should be worth waiting
1.2 1G vs 2G vs 3G vs 4G vs 5G
2.1 INTRODUCTION
The approaching 4G (fourth generation) mobile communication systems are projected to solve still-remaining problems of 3G (third generation) systems and to provide a wide variety of new services, from high-quality voice to high-definition video to high-data-rate wireless channels. The term 4G is used broadly to include several types of broadband wireless access communication systems, not only cellular telephone systems. One of the terms used to describe 4G is MAGIC—Mobile multimedia, anytime anywhere, Global mobility support,integrated wireless solution, and customized personal service. As a promise for the future, 4G systems, that is, cellular broadband wireless access systems, have been attracting much interest in the mobile communication arena. The 4G systems not only will support the next generation of mobile service, but also will support the fixed wireless networks. The features of 4G systems might be summarized with one word- Integration.The 4G systems are about seamlessly integrating terminals, networks, and applications to satisfy increasing user demands. The continuous expansion of mobile communication and wireless networks shows evidence of exceptional growth in the areas of mobile subscriber, wireless network access, mobile services, and applications. An estimate of1 billion users by the end of 2003 justifies the study and research for 4G systems. In telecommunications, 4G is the fourth generation of cellular wireless standards. It is a successor to the 3G and 2G families of standards. In 2008, the ITU-R organization specified the IMT-Advanced(International Mobile Telecommunications Advanced) requirements for 4G standards, setting peak speed requirements for 4G service at 100 Megabits per second for high mobility communication (such as from trains and cars) and 1 Gbps for low mobility ommunication (such as pedestrians and stationary users A 4G system is expected to provide a comprehensive and secure all-IP based mobile broadband solution to laptop computer wireless modems, smartphones, and other mobile devices. Facilities such as ultra-broadband Internet access, IP telephony, gaming services, and streamed multimedia may be provided to users.
Pre-4G technologies such as mobile WiMAX and first-release 3G Long term evolution (LTE) have been on the market since 2006 and 2009 respectively, and are often branded as 4G. The current versions of these technologies did not fulfill the original ITU-R requirements of data rates approximately up to 1 Gbit/s for 4G systems. Marketing materials use 4G as a description for Mobile-WiMAX and LTE in their current forms.
IMT-Advanced compliant versions of the above two standards are under development and called “LTE Advanced” and “WirelessMAN-Advanced” respectively. ITU has decided that “LTE Advanced” and “WirelessMAN-Advanced” should be accorded the official designation of IMT-Advanced. On December 6, 2010, ITU announced that current versions of LTE, WiMax and other evolved 3G technologies that do not fulfill "IMT-Advanced" requirements could be considered "4G", provided they represent forerunners to IMT-Advanced and "a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed
2.2 HISTORY
In February 2007, the Japanese company NTT DoCoMo tested a 4G communication system prototype with 4x4 MIMO called VSF-OFCDM at 100 Mbit/s while moving, and 1 Gbit/s while stationary. NTT DoCoMo completed a trial in which they reached a maximum packet Transmission rate of approximately 5 Gbit/s in the downlink with 12x12 MIMO using a 100 MHz frequency bandwidth while moving at 10 km/h, and is planning on releasing the first commercial network in 2010 On 12 November 2008, HTC announced the first WiMAX-enabled mobile phone, the Max 4G.On 3 March 2009, Lithuania's LRTC announcing the first operational "4G" mobile WiMAX network in Baltic states.In December 2009, Sprint began advertising "4G" service in selected cities in the United States, despite average download speeds of only 3– 6 Mbit/s with peak speeds of 10 Mbit/s (not available in all markets). On 6 December 2010, at the ITU World Radiocommunication Seminar 2010, the ITU stated that LTE, WiMax and similar "evolved 3G technologies" could be considered "4G" The history and evolution of mobile service from the 1G to 5G are discussed in this section.. This process began with the designs in the 1970s that have become known as 1G. The earliest systems were implemented based on analog technology and the basic cellular structure of mobile communication. Many fundamental problems were solved by these early systems. Numerous incompatible analog systems were placed in service around the world during the 1980s.The 2G (second generation) systems designed in the 1980s were still used mainly for voice applications but were based on digital technology, including digital signal processing techniques. These 2G systems provided circuit-switched data communication services at a low speed. The competitive rush to design and implement digital systems led again to a variety of different and incompatible standards such as GSM (global system mobile), mainly in Europe; TDMA (time division multiple access) (IS-54/IS- 136) in the U.S.; PDC (personal digital cellular) in Japan; and CDMA (code division multiple access) (IS-95), another U.S. system. These systems operate nationwide or internationally and are today's mainstream systems, although the data rate for users in these system is very limited. During the 1990s, two organizations worked to define the next, or 3G, mobile system, which would eliminate previous incompatibilities and become a truly global system. The 3G system would have higher quality voice channels, as well as broadband data capabilities, up to 2 Mbps. Unfortunately, the two groups could not reconcile their differences, and this decade will see the introduction of two mobile standards for 3G. In addition, China is on the verge of implementing a third 3G system. An interim step is being taken between 2G and 3G, the 2.5G. It is basically an enhancement of the two major 2G technologies to provide increased capacity on the 2G RF (radio frequency) channels and to introduce higher throughput for data service, up to 384 kbps. A very important aspect of 2.5G is that the data channels are optimized for packet data, which introduces access to the Internet from mobile devices, whether telephone, PDA (personal digital assistant), or laptop. However, the demand for higher access speed multimedia communication in today's society, which greatly depends on computer communication in digital format, seems unlimited. According to the historical indication of a generation revolution occurring once a decade, the present appears to be the right time to begin the research on a 4G mobile communication system. The nomenclature of the generations generally refers to a change in the fundamental nature of the service, non-backwards compatible transmission technology, and new frequency bands. New generations have appeared about every ten years since the first move from 1981 analog (1G) to digital (2G) transmission in 1992. This was followed, in 2001, by 3G multi-media support, spread spectrum transmission and at least 200 kbit/s, in 2011 expected to be followed by 4G, which refers to all-IP packet-switched networks, mobile ultra-broadband (gigabit speed) access and multi-carriertransmission
The fastest 3G based standard in the WCDMA family is the HSPA+ standard, which was commercially available in 2009 and offers 28 Mbit/s downstreams without MIMO, i.e. only with one antenna (it would offer 56 Mbit/s with 2x2 MIMO), and 22 Mbit/s upstreams. The fastest 3G based standard in the CDMA2000 family is the EV-DO Rev. B, which was available in 2010 and offers 15.67 Mbit/s downstreams
In mid 1990s, the ITU-R organization specified the IMT-2000 specifications for what standards that should be considered 3G systems. However, the cell phone market only brands some of the IMT-2000 standards as 3G (e.g. WCDMA and CDMA2000), but not all (3GPP EDGE, DECT and mobile-WiMAX all fulfil the IMT-2000 requirements and are formally accepted as 3G standards, but are typically not branded as 3G). In 2008, ITU-R specified the IMT-Advanced (International Mobile Telecommunications Advanced) requirements for 4G systems