Associate Professor, Dept. of ECE, SVIET, Pedana, Krishna District, Andhra Pradesh, India **
Abstract:
Usage of Mobile communication technology developing day to day very fastly. Some countries switch from existed technology to new technology in that span of time a new advanced technology is invented. Like that the mobile revolution is taken place from 1st generation to 7th generation. Some countries like of India 3G technology also not installed successfully in entire country. In some countries like of U.S.A. and Japan etc., switch from 4g to 5G technology. Depend on the economical and personal problems in their countries the mobile communication revolution takes place. Now in this paper we review about the entire mobile communication generations.
First generation wireless systems provide analog speech and inefficient, low-rate, data transmission between the base station and the mobile user. However, the speech signals are usually digitized using a standard, time division multiplexing format for transmission between the base station and the MSC (Mobile Switching Center) and are always digitized for distribution from MSC to the PSTN (Public switched telephone network).It uses a narrow band FM with a usable audio frequency band of 300-3KHz and maximum frequency deviation of 12KHz for 100 percent modulation [7]. AMPS called autonomous registration. AMPS is process by which a mobile notifies a serving MSC of its presence and location.
Fig: 1.1 Operation of cellular System
The mobile accomplishes this by periodically keying up and transmitting its identity information, which allows the MSC to constantly update its customer list. The MSC (Mobile Switching Center) is able to distinguish home users from roaming users based on each active user, and maintains a real time user list in the home location register (HLR) and Visitor location register (VLR) allows the MSC neighboring systems to automatically handle the registration and location validation of roamers so that users no longer need to manually register as they travel. Voice calls only possible through the network. Messages are transmitted as paging (numbers).
2). 2nd Generation:
The drawbacks of first generation cellular systems are analog voice signal transmission and limited service performance. To improve the signal transmissions and service area and additional application purpose the analog systems are upgraded to digital cellular systems. Second generation cellular systems also called digital cellular systems. Compare to of first generation the applications of like SMS (Short message Service), MMS (Multimedia Service) are developed in second generation. The frequency range assigned for this is 800MHz onwards. For forward channel 25MHz and Reverse channel 25MHz slot is assigned [7]. The various types of 2nd generation cellular systems are shown below.
Fig: 2.1 Block diagram of 2nd generation
The above figure represents the structure of the 2generation cellular systems. Let we discuss about each one briefly .The TDMA (Time Division Multiple Access) is a technique the data or information transmit based on the time slots. Based on logic the three systems were designed. CDMA (Coded Divisional Multiple Access) is a technique which transmits data based on the code assigned for the channel.
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GSM: Global System for Mobile Communication)
For this technique the channel contains 200 KHz frequency band and 8 users are accessed that available channel. In this GMSK modulation technique is used for encoding. The data rate speed for speech signal transmission is 13kbps maximum. And the data transmission speed is 270.83 kbps [8].
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IS-136 (Interim Standard) or NADC (North American digital Cellular system):
For this technique the channel contains 30 KHz frequency band and 3 users are accessed that available channel. In these 45 degrees of DPSK modulation technique is used for encoding. The data rate speed for speech signal transmission is 7.95kbps maximum. And the data transmission speed is 48.6 kbps [7][8].
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PDC (Pacific Digital Cellular System):
For this technique the channel contains 25 KHz frequency band and 3 users are accessed that available channel. In these 45 degrees of DPSK modulation technique is used for encoding [7]. The data rate speed for speech signal transmission is 7.95kbps maximum. And the data transmission speed is 48.6 kbps [8]. The IS-136 and PDC have almost same technical specifications.
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CDMA1: (Coded Divisional Multiple Accessing)
For this technique the channel contains 1.25MHz frequency band and 64 users are accessed that available channel. In this BPSK modulation technique is used for encoding [7]. The data rate speed for speech signal transmission is 8kbps maximum. And the data transmission speed is 1.28Mega chips/sec. CDMA technology codes are designed based on the pseudo random noise code.
3). 2.5 Generation:
In the second generation the data rate speed (Internet speed) is limited means very slow. So to increase the data rate without changing the equipment which has supported for 2G voice transmission this 2.5G technology is developed. In this generation also various types are developed those are discussed as below [7].
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HSCSD (High Speed Circuit Switched Data):
This technology is developed for GSM data rates. The speed is increased from 9.6Kbps to 14.4kbps.After that the speed is increased to 57.6Kbps i.e. at a time 4 timeslots of data is transmitted (4*14.4Kbps) [7].
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GPRS (General Packet Radio System):
This technology is developed for GSM data rates. Which has also same of HSCSD [7].
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CDPD (Cellular Digital Packet Data):
This technology is developed for data rate is increased up to 171.2 Kbps and the number of time slots transmitted at a time is 8 [7].
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EDGE (Enhanced data Rates for GSM):
This Technology also called as Enhanced GPRS. For Which 8PSK (Phase Shift Keying) modulation technique is used and the data rate is increased up to 547.2Kbps.This method also developed for the essence of GSM [7].
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IS-95B:
This technology is developed for CDMA data rates. speed is increased from 8 Kbps to 14.4kbps.It has the speed of medium data rates. The speed of this one is 115.2Kbps.At a time 8 timeslots are transmitted (8*14.4Kbps) [6][7] [8].
4). 3rd Generation: (HSDPA-High Speed Data Packet Access)
To facilitate the video calling rate this generation is developed. Which means for establishing of video call the data rate of EDGE is not finite. So the revolution is come to increase the data rate more. For that sake this generation is developed. In this the maximum data rate are increased up to 8Mbps.For mobile first it is developed up to 3.6Mbps later it will extend up to 8Mbps around. And the data rates are from as low as 8kbps.If the user wants voice calls transmission only lower data rates are assigned. If the user wants to establish video call higher data rate channel is assigned. The five alternatives reflect the evolution from the second generation. Two of the specifications grow out of the work at European Telecommunications standards Institute (ETSI) to develop a UMTS (Universal Mobile Telecommunication System) as Europe’s 3G wireless standard. UMTS includes two standards. One of this is known as wideband CDMA or W-CDMA. This scheme fully exploits CDMA technology to provide high data rates with efficient use of bandwidth. The other European effort under UMTS is known as IMT-TC or TD-CDMA. This approach is a combination of W-CDMA and TDMA technology. IMT-TC is intended to provide an upgrade path for the TDMA based GSM Systems. Another CDMA based system known as CDMA-2000, has a North American origin. This scheme is similar to, but incompatible with W-CDMA, in part because the standards use different chip rates.CDMA-2000 uses a technique known as multicarrier, not used with W-CDMA.IMT-FT used by both TDMA and FDMA carriers to provide some 3G services, It is an outgrowth of the digital European cordless telecommunication standard [7][8].
Fig: 2.2 Block Diagram of 3rd Generation
The Frequency range is used for this network is 2500MHz onwards. The modulation technique used for this one is in forward channel QPSK and for reverse channel BPSK are used. Data is sent to packet switching and voice calls are interpreted through circuit switching.
4). 3.5 Generation:
This development is based on higher through-put and speed at packet data rates of 14.4Mbps, supporting higher data rates for customers [4].
5). 4th Generation: (LTE-Long Term Evolution)
4th generation systems are being designed to support 5 to 10 times of 3G data rates and gives enhansively video data transmission. Higher spectral efficiency and lower cost per bit than 3G network systems and Air interface optimized for IP traffic like OFDM, MIMO. OFDM (Orthogonal Frequency Division Multiplexing) was used into fixed access either as a replacement for other access technologies like ADSL or cable or to provide service in regions where the other access technologies where not deployed. OFDM simple architecture overcomes noise, signal to noise ratio challenges, multipath fading, adjacent channel, interference, non-adjacent channel interference OFDM also provides a frequency diversity gain, improving the physical layer performance. It is also compatible with other enhancement technologies such as smart antennas and MIMO. The infrastructure for 4G is only packet-based (all-IP) [2].
6). 5th Generation: (WISDOM-wireless Innovative System for Dynamic Operating Mega communications concept)
The twenty first century is surely the century of speed and achieves a high evolution in all the possible domains, especially in communication: a very large variety of services software, equipments, possibilities etc. But this huge and colored offer also brings a complicated lifestyle and waste of time for the human beings and needs to be integrated and achievable in a simple manner. A new technology started to be delineated that will provide all the possible applications by using only one universal device and interconnecting the already existing communication infrastructures i.e. fifth generation mobile communication. Cognitive radio and 5G are considered to be the future technologies.CR offers the possibility to significantly increase the spectrum efficiency, by smart secondary users (CR) using the free licensed users’ spectrum holes [1].CR integrated technology and networking is to provide efficient use of radio spectrum, a natural resource and advanced user services. The data rate for 5G technology is almost 1Gbps.This system is innovative manner. Where the spectrum is had holes through that signals are transmitted. It need system has interface between software and hardware i.e. software in the sense cloud computing like that and hardware in the sense IP address matching to network interface systems [1].
7). 6th Generation: (Very High Data Rates Quality of Service (QoS) and Service application)
6G will integrate all wireless mobile networks with satellites to get global coverage [1]. The data rate for this technology is almost 100Gbps.
Fig: 2.3 Block diagram of 6th generation mobile coverage
8). 7th Generation: (Space Roaming)
7G wireless mobile networks are going to unite the four GPS systems available in space roaming in addition to 6G systems. The data rates for 7G technology is almost 1Tbps [1].The 6G mobile networks will support local voice coverage and other services. The 7G will be the most advance generation in mobile communication but there will be some research on demanding issues like the use of mobile phone during moving condition from one country to another country, because satellite is also moving in constant speed and in specific orbit, the standards and protocols for cellular to satellite system and for satellite to satellite communication system. The dream of 7G can only be true when all standards and protocols are defined. May be this is possible in next generation after 7G and can be named as 7.5G.
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Conclusion:
In this paper we are discussed existing and future mobile communication technologies. In each generation we focused mainly about data rates and bandwidth or spectrum allocations. The key source behind in mobile communication is relation to spectrum to data rate speed. Now a days in maximum of countries the technology existed is 3G,It will switch to future generations like of 6g or 7g the cost of pulse rate need to decrease and delay between pulse to pulse is decrease with increase of data rate through satellite space roaming technology. And with development of mobile technology the voice and data are propagates very fastly with the technique of VOIP (Voice over Internet Protocol) through WWWW (Wireless World Wide Web) gives efficient result.
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Authors:
*Mr. B. Anil Kumar pursued B.Tech from VYCET, Chirala in Dept., of ECE. After that he pursued M.Tech in Systems and Signal Processing at LBRCE, Vijayawada. Working as a Assistant Professor from past 4 years. Now Pursuing Ph.D at GITAM University, Hyderabad in Dept., of ECE with Specialization of Wireless communications & Signal Processing.
E-mail:anilbudati@gmail.com
**Dr. K. Naga Prakash Completed his Ph.D in JNTUK, Andhra Pradesh. He published
various national and international journals. He worked as a Assistant and Associate Professor in Various engineering colleges in Andhra Pradesh. Now he works as a Head. of the Department in Sri Vasavi engineering college, pedana, Krishna District.