Data from Global Mobile Suppliers Association (GSA) suggests that one third of today’s 96 commercial LTE operators have deployed 4G / LTE using the 1800MHz spectrum in their networks. The benefits are many, as the coverage area is 1.5x – 2x compared with deploying the 2.6 GHz band and there is a possibility of re-using network assets – antenna cables of GSM1800 or WCDMA HSPA 2100.
The Following chart Shows the Advantages of 1800MHz LTE
Source: Starhub, LTE 1800MHz Review in Asia-Pacific.
While 4G / LTE is theoretically possible with 5MHz of spectrum, it is unlikely to deliver the same quality of service and the cost per MB is likely to be higher. Atleast 10MHz of Spectrum is Required for optimum performance and throughput as shown in the Chart below. 
Source: Starhub, LTE 1800MHz Review in Asia-Pacific
The aforesaid ecosystem developments are positive and present an opportunity for the regulator to monetize 1800 MHz spectrum; better packaging may help the government to maximise prices. Critical to this will be raising spectrum
limits per operator and not differentiating between new players and incumbent players.
Indian Operators are in no hurry to launch nationwide 4G / LTE as they have seen tepid demand for 3G data and are still trying to milk the remnant growth in 2G Voice Business. Videocon likely backed by Reliance Jio Infocomm is launching 4G LTE using the 1800MHz spectrum. Idea and Vodafone which do not have Wired Broadband services and facing turbulence with their PAN India 3G coverage should explore the option of 4G / LTE on a circle by circle basis, in my view.