In my town, BSNL is the sole provider of wireline broadband. The ADSL 2+ connection speed I get is 2048Kbps download speed and 784 Kbps upload speed. I get 512 Kbps unlimited download, upload speed.
I had to share this 512 kbps with other members of family. I like watching youtube videos and upload a lot of it. So 512 Kbps is quite low for me. So I requested TRAI to increase the broadband speed to 1 Mbps or more. Since ADSL speed is capped to 2 Mbps here I won't be getting more than that unless BSNL upgrades their hardware.
Lets look at bandwidth requirement of India urban population
Urban Population of India = 41,92,34,061
If each house has six members in family then total number of urban houses = 41,92,34,061/6 = 6,98,72,343
If each urban house requires 1 Mbps internet speed then approx total bandwidth requirement of India urban population = 69872343 Mbps = 69872 Gbps
Using latest 100 Gbps Fiber optic Ethernet technology, the number of fiber optic ribbons required to install = 699
I don't think any company will install 699 fiber optic cables as backbone internet for INDIA. All telecom companies combined can layout 699 fiber optic cables and can provide 1 Mbps internet connection to all urban houses.
Maximum number of fiber optic cable a company will install as backbone = 100
So maximum bandwith achieved of backbone using 100 fiber optic cable = 10000 Gbps = 10 Tbps
How many indians can get constant 1 Mbps internet speed using 100 Fiber optic cable backbone network = 1,00,00,000 = 1 crore
India international submarine cable link combined maximum bandwidth = 150 Tbps
How many indians can get constant 1 Mbps internet speed using 150 Tbps bandwidth = `15,00,00,000 = 15 crore
So maximum of 15 crore homes can get constant 1 Mbps ( 1 Mbps upload & 1 Mbps download ) internet connection speed if 150 Tbps backbone internet capacity is installed.
India has 400 million 10-24 year-olds which will use most of the internet bandwidth.
To provide each of 400 million a 4 Mbps internet connection the total bandwidth required is 400,000,000 * 4 Mbps = 1,600,000,000 Mbps = 1600000 Gbps
It is not possible now to provide 4 Mbps to each youth in India.
In near future 400 Gbps fiber optic Ethernet will be available. But it won't be enough to provide 4 Mbps connection to 400 million youth of India.