Telecom, 5G, 6G and the internet

The first principle

Every wireless link carries information by changing a radio wave, and the amount of information a link can carry depends on two things: the width of the band of frequencies it uses and how strong the signal is compared with the noise. This is the Shannon limit, which says that capacity equals bandwidth multiplied by the base two logarithm of one plus the signal to noise ratio. Spectrum is therefore the raw material of all wireless communication, and because the same frequency cannot be used by two transmitters in the same place without interference, it is scarce. Every generation of mobile technology, every auction and every quarrel about satellites follows from this one idea.

The core

How a mobile network works

• The cell is the trick that multiplies spectrum. A mobile operator divides an area into small cells, each served by a base station, and reuses the same frequencies in cells far enough apart not to interfere, so a limited band can serve millions of people.
• A network has three parts. The radio access network links the phone to the nearest base station, the backhaul carries traffic from base stations to the operator's centre, mostly over optical fibre or microwave links, and the core network routes calls and data, checks who the user is and connects to the internet.
• Frequency decides reach and capacity. Low frequencies such as the 700 megahertz (MHz) band travel far and pass through walls, so they give wide coverage, while high frequencies such as the 26 gigahertz (GHz) millimetre wave band carry much more data but reach only a few hundred metres and are blocked by walls, trees and even rain. The mid band around 3.3 to 3.6 GHz is the main 5G band in India because it balances the two.

From 1G to 6G

• Each generation solved one problem. The first generation (1G) was analogue voice; 2G made voice digital and added text messages; 3G brought mobile data; 4G built an all internet protocol network that made video and apps practical; and 5G was designed by the International Telecommunication Union (ITU) for three uses at once, very high speed for phones, ultra reliable links with latency near one millisecond for machines, and huge numbers of connected sensors.
• 5G uses three main techniques. Massive multiple input multiple output (MIMO) puts dozens of antennas on one base station, beamforming steers the signal towards each user instead of spraying it everywhere, and network slicing divides one physical network into several virtual ones, so a hospital and a video service get different guarantees on the same towers.
• 6G is the next standard, not yet a product. The ITU adopted its framework for 6G, called IMT-2030, in 2023, and the first standards are expected near 2030; research points to terahertz frequencies, networks that sense their surroundings as well as communicate, artificial intelligence built into the network and seamless links with satellites.

Fibre and satellites

• Optical fibre carries most of the world's data. A glass core with a higher refractive index than the cladding around it traps light by total internal reflection, so pulses of infrared light travel many kilometres with little loss, and one fibre can carry many wavelengths at once.
• Satellite internet fills the gaps. A geostationary satellite at about 35,786 kilometres sees about two fifths of the Earth but adds a round trip delay of about half a second, while low earth orbit constellations at a few hundred to about 1,200 kilometres cut the delay to tens of milliseconds, at the cost of needing thousands of satellites; the orbits themselves are explained in the satellites note.

Dimensions

• Economic. Connectivity is the base on which digital payments, e commerce and online services run, and cheap mobile data after 2016 is what made India's digital public infrastructure usable at scale.
• Social. A phone with data brings banking, education and government services to a village, so a gap in coverage or skills becomes a gap in access to the state.
• Strategic. Telecom equipment sits inside every network, so who builds it decides who could watch or switch it off; this is why trusted source rules and an indigenous network stack matter.
• Legal. Spectrum belongs to the people, so its allocation is a question of law, settled by the Supreme Court in 2012 and by the Telecommunications Act, 2023.
• Security. Shutdowns, interception, fraud with subscriber identity module (SIM) cards and attacks on network software are threats that the cybersecurity note covers in full.

In practice

Scale and the institutions

• India is the second largest telecom market. In June 2026 it had about 134.8 crore telephone subscribers, a teledensity of about 94 per cent and about 108.7 crore broadband subscribers, according to the Telecom Regulatory Authority of India (TRAI).
• Three bodies run the sector. The Department of Telecommunications (DoT) grants authorisations and assigns spectrum, TRAI, set up under the TRAI Act of 1997, recommends reserve prices and policy and regulates tariffs and quality, and the Telecom Disputes Settlement and Appellate Tribunal hears appeals.
• 5G arrived fast. Services began on 1 October 2022 after an auction that raised bids of about Rs 1.5 lakh crore, and by October 2025 operators had installed about 5.08 lakh 5G base stations covering almost every district.
• An Indian network stack. In September 2025 Bharat Sanchar Nigam Limited (BSNL) launched a 4G network built on Indian technology, with the core from the Centre for Development of Telematics (C-DOT), radio equipment from Tejas Networks and integration by Tata Consultancy Services, on nearly one lakh sites.
• 6G as a goal. The Bharat 6G Vision of March 2023 and the Bharat 6G Alliance of July 2023 aim to make India a supplier of 6G technology, with a stated target of about 10 per cent of 6G intellectual property by 2030.
• BharatNet is the programme to bring optical fibre to every gram panchayat, now funded through the Digital Bharat Nidhi.

How spectrum is allocated

• Auction is the rule. In the 2G case of 2012 the Supreme Court cancelled 122 licences given on a first come first served basis and held that a scarce natural resource must be allotted by a fair and transparent method, normally an auction.
• The Telecommunications Act, 2023 replaced the Indian Telegraph Act, 1885 and the Indian Wireless Telegraphy Act, 1933. It keeps auction as the default but lists in its First Schedule the uses for which spectrum may be assigned administratively, satellite communication among them. It replaces licences with authorisations, renames the Universal Service Obligation Fund as the Digital Bharat Nidhi, creates a right of way regime for towers and cables, and keeps the Centre's powers to intercept messages and take over networks in an emergency.
• Satellite internet. Starlink, Eutelsat OneWeb and Jio's satellite venture hold authorisations, TRAI recommended administrative assignment of satellite spectrum in May 2025, and the final decision on pricing rests with the government.

Issues and way forward

• Debt from spectrum costs. High auction prices and the 2019 Supreme Court ruling on adjusted gross revenue left operators with heavy dues, and the market shrank to three private players and BSNL; longer payment periods, moderate reserve prices and the 2021 relief package that allowed payment deferrals point the way.
• The rural gap. Towers follow paying customers, so remote areas lag; the Digital Bharat Nidhi, BharatNet and satellite links for the last mile are the answer, provided the fund is spent on connectivity and not on unrelated projects.
• Dependence on foreign equipment and chips. Most radio and core equipment and almost all chips are imported; the indigenous 4G stack, the production linked incentive scheme for telecom equipment and the India Semiconductor Mission address this, as the chips note explains.
• Powers without oversight. Critics point to interception and shutdown powers without an independent check and a definition of telecommunication broad enough to reach internet apps; clear rules, review by an independent body and published reasons for every shutdown are the reforms asked for.

Common confusions

• Bandwidth and speed. Bandwidth is the width of the frequency band a link uses, measured in hertz, while speed or data rate is how many bits it carries each second; more bandwidth allows more speed, but the signal quality matters too.
• Latency and speed. Latency is the delay before data starts to arrive, while speed is how fast it flows once it does; a geostationary link can be fast and still feel slow because its latency is high.
• Auction and administrative assignment. An auction gives exclusive use to the highest bidder, while administrative assignment gives shared or special use at a price set by the government.
• TRAI and DoT. TRAI recommends and regulates tariffs and quality, while DoT decides policy, grants authorisations and assigns spectrum.
• 5G standalone and non standalone. A non standalone 5G network uses a 4G core with 5G radios, while a standalone network has its own 5G core, which is needed for slicing and very low latency.

For the exam

• Keyword bank: spectrum as a scarce public resource, Shannon limit, cellular reuse, millimetre wave, massive MIMO, beamforming, network slicing, latency, low earth orbit constellation, total internal reflection, administrative assignment, First Schedule, Digital Bharat Nidhi, indigenous 4G stack, Bharat 6G Alliance.
• Previous year questions: Practise the previous year questions on this topic →
• Use in an answer:
  • Introduction with data: India had about 134.8 crore telephone subscribers and 108.7 crore broadband subscribers in June 2026 (TRAI), which makes connectivity the base layer of its digital economy.
  • Introduction with a source: In the 2G case of 2012 the Supreme Court held that a scarce natural resource such as spectrum must be allotted by a fair and transparent process, which is why auction became the rule.
  • Conclusion: The Telecommunications Act, 2023 answers the auction or assignment question by asking whether a use needs exclusivity, and that principle can guide spectrum for 6G and satellites too.
  • Conclusion: India's next step is to move from being the largest user of telecom to being a maker of it, through an indigenous stack, a share of 6G standards and connectivity that reaches the last village.