Wednesday, 15 June 2016

The G’s: Past, Present & Future!!!
Considering the recent developments in the wireless field, mobile communications is not a new topic. It all started since 1946 with massive two-way car radio equipment installation called “radio telephone” by Motorola. The extremely bulky equipment provided the operations of a modern Walky-Talky with the PTT (Push to Talk) feature. This pre-cellular system was commonly called as the 0G system.
The cellular systems became prevalent during 1980’s. Such systems opened the door to frequency reuse among geographical cells to optimize frequency usage. In 1973, Motorola demonstrated the world’s first portable cellular telephone using its DynaTAC (DYNamic Adaptive Total Area Coverage) technology. It was after 10 years (in 1983) that the US FCC (Federal Communications Commission) approved Motorola’s DynaTAC 8000X phone. Thus, world’s first commercial portable cellular phone that weighed 794 g phone was publicly available in 1984. Some features of the world’s first mobile phone were: A full charge took roughly 10 hours, offered 30 minutes of talk time and had an LED display for dialing one of 30 phone numbers. The equipment price was $3995 (about 50,000) and if calculated today, would be $10000( 67,000 approx). The 1G (1st generation) of cellular communication used FM (Frequency Modulation) for analog transmission where the voice signals being transmitted through RF (radio frequencies) over a specific geographical area. The first cellular network, NTT (Nippon Telegraph & Telephone), commercialized in 1979 in Tokyo soon expanded to cover Japan within 5 years, and became the world’s first 1G network. This was later replaced by NTACS (Narrowband Total Access Communications System) and JTACS (Japanese Total Access Communications System). The US followed up with its AMPS (Advance Mobile Phone Service). Countries like Denmark, Finland, Norway and Sweden, during the same period (1981), saw the growth of NMT (Nordic Mobile Telephone) system that offered international roaming feature. These systems lacked data privacy (encryption) as they used analog modulation. Another drawback was higher interference due to the cellular characteristic of the network that allowed for the development process for 2G (2nd Generation) of cellular mobile systems.
The evolved 2G mobile systems, based on the digital transmission, came with a number of various standards of which GSM (Global System for Mobile) has been the most popular one even now. First deployed in 1990’s, the GSM system incorporates digital transmission and has a SIM (Subscriber Identity Module) to authenticate a user for identification and other purposes, and provides the facility for data encryption. To increase the network capacity, the transmission uses TDMA (Time Division Multiple Access) and CDMA One (Code Division Multiple Access One) techniques. The communication range is better than in 1G systems, but prohibits seamless roaming across heterogeneous access networks. A GSM system has a typical data transmission rate of 9.6 kbps and includes services such as SMS (Short Messaging Service). To enable connectivity to the internet, that started its growth during the same period, the GSM system evolved to include Packet Data for transfer of MMS (Multimedia Messaging Service) and images with mobiles. The radio technology enabling this packet feature over GSM architecture led to the growth of 2.5G systems having a data rate of up to 115 kbps. The data rate was further increased to up to 384 kbps by using EDGE (Enhanced Data Rate for GSM Evolution) technology and the systems called as 2.75G systems. The inherent limitation of seamless roaming (handover) between heterogeneous networks and the need to increase data transmission rates to enable features like GPS (Global Positioning System), video conferencing/calling and mobile television, justified further evolution of mobile systems to the 3G (3rd Generation) systems.
The world saw its 1st 3G network deployed by NTT DoCoMo in Japan (2001), and we got our first 3G network in late 2008. The differentiating feature of 3G from 2G is the increased data rate of the order of up to 2 Mbps and simultaneous transmission of voice and data at high-speed. 3G networks need WCDMA (Wideband CDMA) along with 3G enabled handsets, and the emphasis is towards packet data in 3G against voice data in 2G. The target feature of 3G networks was to offer robust connectivity for streaming videos, web browsing and turn by turn GPS navigation. To further increase the data rate and to allow for the seamless movement of mobile users within heterogeneous networks, the 4G (4th Generation) networks emerged through 3.5G, 3.75G, and 3.9G. HSUPA (High-Speed Uplink Packet Access) & HSDPA (High-Speed Downlink Packet Access) are features of 3.5G and give theoretical data rates of 5.8 and 14 Mbps, respectively. HSPA+ (High-Speed Packet Access enhanced), a feature of 3.75G further increased the data rate to up to 28 Mbps. The HSOPA (High-Speed OFDM Packet Access) is a key feature of 3.9G that was (mis)interpreted as 4G.  Facilities like IP (Internet Protocol) telephony, Interactive Gaming Services, HD (High Definition) TV, Live TV etc are the add-ons for the real 4th Generation (4G) networks that offer a theoretical data rate of up to 100 Mbps.
The 5G (5th generation) represents the next phase of the mobile standard that is highly reconfigurable and expected to hit the markets by 2020. 5G, envisaged as the real wireless network, has features supporting wwww (Wireless World Wide Web) applications and PAN (Personal Area Networks) including human body interface called BAN (Body Area Networks). The advanced technologies suggested for 5G are - an all IP-based system, nano-devices using cellular pico-nets, intelligent antennas working on millimeter wavelengths, flexible modulation schemes, and AI (Artificial Intelligence) inclusion in the devices. Google has already developed a driverless car that is in the testing phase now, and the trend is to meet higher data rate and enhanced connectivity between the devices.
The RoF (Radio over Fiber) systems offer coverage to areas where no wireless connectivity is found, are deployed in US and China to provide wireless access in such “tough regions”. These systems drop the need for separate antennas for different wireless access techniques and make use of a single antenna and for use in the next generation networks. The 6th Generation (6G) further suggests integrating satellite networks with 5G, to offer global coverage. The integration of 5G with satellite networks, point to the absence of a unified standard, as the satellite network may be a telecom satellite network, a GPS satellite network, an imaging satellite network or a navigational satellite network.
Maybe the 6G communication would altogether change the communication scenario, visualized with the application of recently developed technologies such as Li-Fi (Light Fidelity). The Li-Fi has about 10,000 times more frequency spectrum available to use than in contemporary mobile communication, and almost zero interference.  This, in turn, would motivate the research to be carried out for a common unified standard under the 7G (7th Generation) of networks.
Concluding, as the trend of increasing cellular capacity, extreme advancements have been observed within last 2-3 decades. As a rule of thumb, the capacity has also been increasing to 10 times of the previous mobile network generation. The upcoming 5G aims a real wireless world with no limitations while 6G integrates 5G with satellite networks. The 6G roaming issue drives 7G wireless networks, which aim to acquire space roaming. The world is trying to become completely wireless, demanding uninterrupted access to information anytime and anywhere with better quality, high-speed, increased data rate and a reduction in cost.
By
Mr. SAURABH SRIVASTAVA
Asst. Prof.

Department of Electronics and Communication Engineering.

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