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This mobility of the so called mobile rigs, would consequently give way to the evolvement of the generations of mobile phone that we have today. Originally, mobile phones were permanently installed in the vehicles, but as time went on, it gained more mobility when the later versions came out with equipment with a cigarette lighter plug, for the 12 volt power that it required to operate. This made this mobile set to be unplugged and taken away to be used as mobile or as portable phones.
The idea of patching the vehicle mounted phones, incorporating certain modifications, to the telephone network was evolved and tested by the Swedish police in 1946 for use in police cruisers. It was found that the car battery would run out after half a dozen calls were made. Towards the end of 1940s, the so called radio-telephones began to be available publicly in the United States. Since the switching technology was not as advanced as it is today, these phones had to be manually patched into telephone network for the purpose of a meaningful communication.
Erricsson first developed the first fully automatic mobile phone system, which was called Mobile Telephone system A (MTA). This was released commercially in Sweden in 1956. This was the first time that a mobile phone operated without any manual intervention, but the disadvantage was that it weighed 40Kg. The next version, Mobile Telephone system B (MTB), an upgraded version with transistors, used dual-tone multi-frequency signaling, weighing only 9kg and was introduced in 1965. The product closed down in 1983 while it has 600 subscribers using it.
The first fully successful and commercial mobile phone networks were the Address Resolution Protocol (ARP) network in Finland, launched in 1971. ARP is sometimes viewed as the 0G version of the cellular network, being considered to be slightly above the previous proprietary and limited coverage networks.
First Generation Mobile IG
Mobile technology and the growth in mobile telephony were built on the concept of communication networks that would provide for voice and data communication throughout a wide geographic area. The system would divide large geographic areas into small radio cell areas that are interconnected with each other. Each cell coverage area would have one or several transmitters and receivers that communicate with mobile telephones within that cell. It is this cellular concept that has given the name – cellular technology. This architecture, would allow you to maintain a continuous communication as you move from one cell to the other, and as you leave one cell and move into the next, the previous transmitter/receiver would hand over the call to the cell where you presently are, maintaining a seamless communication while you are moving.
When the true mobile telephony evolved commercially, it was the first generation systems (1G). These were analog systems, circuit-switched. The primary disadvantages were that the voice quality was bad, hand-off operation was not reliable, the capacity of accommodating enough simultaneous calls was low and there was no security. Mobile technology as we know today, started to evolve during 1970s, which was put under trial at Chicago in 1973. The system used a technology called Advanced Mobile Phone Service (AMPS), operating in the 800MHz band. For several reasons, the break-up of AT&T being one, the system could not be launched commercially before 1983. That launch occurred in Chicago in 1983, with other cities following rapidly. Japan launched the AMPS system in 1979 and the Europeans, being active in the field of their own mobile technology, launched their system in 1981. This was launched in Sweden, Norway, Denmark, and Finland. The Europeans had a different technology and they called it Nordic Mobile Telephony (NMT), operating in the 450-MHz band. Later the NMT was developed to work on 900MHz bandwidth and became known as NMT900. Consequently the British came out with their own technology in 1985 which they called Total Access Communications System (TACS), which operated in the 900MHz bandwidth. TACS is, in reality, a modified version of AMPS.
Motorola DynaTAC 8000X was the first hand-held mobile phone that was commercially introduced in the year 1983 after receiving due approvals. Consequently mobile phones started to take shape through the 1980s with the introduction of the cellular concept in mobile phones, and the creation of multiple base stations relatively close to each other with the protocols to switch between the cells, when a mobile phone moved from one cell to the other. The technology was completely based on analog transmission systems. The mobile phones were larger than what we have today and were designed to be permanently installed in the cars, getting the name ‘car phone’.
The first mobile phone service with roaming was started in Saudi Arabia in the year 1981. The system was called Nordic Mobile Telephony (NMT) and was manufactured by Svenska Radio Aktiebolaget (SRA). It was after one month of the introduction that SRA started country based roaming. Soon mobile communication became a necessity with many other countries, and the world ventured into the technology. Although many technologies were developed during this time, particularly in Europe, AMPS, NMT, and TACS remained the most successful of them all. These are known to be the first generation (IG) mobile systems and it is said that they are still in service today. The success of the first generation of mobile telephony experienced success but remained with the disadvantage of not having adequate capacity to accommodate handling of substantial subscriber calls. The system had the capability to handle the capacity of large numbers of subscribers, but when the subscribers started to grow in millions, deficiency in handling of the calls appeared in the design of the system, mainly in the densely populated urban areas. Limitation of handling subscribers was not the only problem. The other major problem which came up was fraud which became a major concern. Steps were taken and the 2G technology began to evolve.
Second Generation Mobile2G
This saw the evolvement of the Global System for Mobile Communications (GSM), the original acronym of which is Groupe Spécial Mobile. GSM is a global digital radio system that uses Time Division Multiple Access (TDMA) technology. This technology in GSM, enabled subscribers to operate on the same radio channel simultaneously by sharing time slots on full duplex mode, where both can talk at once. Half duplex mode is used in a walkie-talkie, where one person can transmit one at a time.
GSM is a digital cellular technology that was initially created to provide a single-standard pan-European cellular system. The development of GSM was started in 1982 and the first commercial GSM digital cellular system was activated in 1991. Being the most popular standard, GSM is used by over 2 billion people across more than 212 countries and territories. This technology has made international roaming very much possible, enabling the subscribers to use their phones in many parts of the world. GSM is completely based on digital signalling, which meant more clarity in speech transmission. With the evolvement of this technology the second generation (2G) of mobile telephony came into existence.
The GSM mobile phone works on various frequency bands, which are allocated differently to the countries throughout the world. These frequency bands are as follows-
850 MHz (824.2 – 848.8 MHz Tx; 869.2 – 893.8 MHz Rx)
900 MHz (880-2 – 914.8 MHz Tx; 925.2 – 959.8 MHz Rx)
1800 MHz (1710.2 – 1784.8 MHz Tx; 1805.2 – 1879.8 MH Rx)
1900 MHz (1850.2 – 1909.8 MHz Tx; 1930.2 – 1989.8 MHz Rx)
Rx represents receive mode while Tx is the transmit mode.
The GSM phones in North America and Canada operates on 850MHz and 1900MHz bands which are different from the frequency bands in Europe, with a result that North America is set apart from the rest of the world. This is the reason that if you live in the United States and even if you have a GSM phone, it becomes doubtful if it will work outside North America and Canada, though in some countries you may find one of the frequency bands matching one of the operating frequency.
As GSM evolved, the backward compatibility was retained, for example packet data capabilities was added to the consequent releases by means of General Packet Radio Service (GPRS), featuring data speeds up-to 177kilobits/second. High speed data transmission has also been introduced with Enhanced Data rates for GSM Evolution (EDGE) providing enhanced GPRS capability. EDGE provides a greater speed of up-to 470 kilobits/second, although the consumers could only realise a speed of 100 kilobits/second on average.
The idea of ‘roaming’ provided the foundation of GSM, which allowed subscribers from other networks and countries to call cell phones anywhere in the world. Behind this simple sounding process, there are some 600+ GSM network that exist in this world, and it is estimated that more than 30,000 agreements, concerning roaming, is in place between the operators, with more being added everyday. Therefore a complex process of information gathering of all the roaming calls and its subscriber details are constantly being updated in the relevant database, which takes a standard approach to the charges being incurred for each individual roaming connection being set up.
The 2G system brought in various applications in mobile telephony. Besides voice, it supports messaging and high speed data, with advanced services such as voice mail and paging, which are often bundled into a basic service program and ofcourse the web service.
Third Generation Mobile 3G
Shortly after the introduction of the 2G networks, the development of the third generation (3G) network was started, where many of the contenders with many different standards were pushing their own technology. 3G is the generic name for a set of mobile technologies, which used a whole lot of high tech infrastructure networks, handsets, base stations, switches and other equipment, which enabled subscribers to attain higher mode of applications through their phone. These are typically high-speed Internet access, data, video and CD-quality music services.
Quite different to the 2G systems, the 3G systems have been defined and specified in the International Mobile Telecommunications-2000 (IMT-2000) standarisation process. IMT-2000 project, which is the 3G systems, have been developed by the International Telecommunication Union (ITU). The project specifically specified the requirement of the 3G system rather than standarising on a technology. For example, 2Mbit/s maximum data rate indoors, 384kbit/s outdoors. But somehow the concept of a unified standard broke down and several different standards have been introduced.
3G digital cellular systems uses radio channels that have a wider bandwidth and uses Wideband Code Division Multiple Access (WCDMA), which has a wider bandwidth than 2G digital cellular systems using CDMA, such as, GSM or IS-95 CDMA. WCDMA is normally deployed in a 5MHz channel plan. CDMA is a digital wireless technology which enables multiple subscribers to share radio frequencies without interfering with each other. GSM is a 2G technology and uses TDMA, providing data speed of 9.6kbps/14.4kbps. GPRS was brought in as an interim technology towards 3G, which provided a speed of up-to 177kilobits/second. This then came to be known as 2.5G system. The use of 2G systems may fade away in 10 to 15 years time, with the use of a newer and better Universal Mobile Telephony System (UMTS) technology. In Europe, 3G Wide Band CDMA (W-CDMA) networks are known as UMTS, which is another name for (W-CDMA)/3G services.
Key features of IMT-2000 are:
High degree of commonality of design worldwide.
Compatibility of services within IMT-2000 and with the fixed networks.
Small terminal for worldwide use.
Worldwide roaming capability.
Capability for multimedia applications, and a wide range of services and terminals.
3G networks are not upgrades of 2G systems, but are entirely different technology network, providing a whole lot of enhanced features than the 2G and 2.5G systems. 2.5G network is an enhancement of 2G system, towards 3G. Japan was the first country to introduce 3G networks in a large commercial scale, with 40% of the mobile telephony subscribers using 3G, pushing 2G on the way out. The year 2006 saw the transition from 2G to 3G network in Japan, with upgrades to the next 3.5G stage with 3Mbit/s data rates being underway.
write by Dempsey