5G In India

India is gearing up for 5G. This is evident from the fact that the government of India has set up a forum to facilitate its roll out. In order to meet that objective, spectrum for 5G needs to be identified and cleared in advance. The purpose of this note is to evaluate possible spectrum blocks and major issues if any, for its use for 5G services. Before I dwell on identifying spectrum blocks, it might be worthwhile to understand what 5G is all about, and what value it brings to the table.

5G Technology Overview

In simple terms, 5G has the ability to efficiently aggregates large quantum spectrum to drive extremely high data speeds. While doing so it uses innovative antenna technologies to overcome the "Shannon limit" of the communications channel (the theoretical maximum limit for transferring information at a particular noise level). It does so by using innovative antenna technologies like MIMO (multiple-input and multiple-output) and beam steering. MIMO physically separates the transmitting signal into multiple physical paths, and combines them at the receiver, thereby overcoming the "Shannon limit". Beam steering, on the other hand, uses a closely packed antenna subsystem to dynamically move the radio beam to follow the users for increased efficiency and coverage. For these technologies to work, the antennas in the subsystem need to be closely packed, to prevent the overall system from becoming too unwieldy. Technically, the individual antennas are spaced out by distances in the order of the wavelength of the transmitting radio wave. Hence, these antenna technologies work best at the higher frequency bands where the wavelengths are shorter. Also, at these frequencies, we can find large contiguous blocks of spectrum - a must for driving higher data speeds. Therefore, while evaluating 5G spectrum bands these factors need to be taken into account.

700 MHz Band

The following is the band structure of 700 MHz as it is available in India.

Total spectrum available for commercial use is 2x35 MHz since 10 MHz has been reserved for defense usage. If BSNL is given 5 MHz, then other three operators (Bharti, Voda+Idea, RJIO) can have 10 MHz each. Also, lower frequency makes the antenna spacing a little challenging - making the band less effective in supporting various antenna enhancement techniques as described earlier.

3400 MHz Band

The following is the band structure of 3400 MHz as it is available in India. See the block shaded in grey color at the bottom of the picture.

A total of 275 MHz of TDD spectrum is available in this band. The problem is that a 25 MHz block (as shown in the picture above) is unusable, thereby fragmenting it into two blocks of 100 MHz and 175 MHz. Hence, distributing it between three operators in uniform blocks of 100 MHz each will be a challenge.

24 GHz Band

The following is the band structure of 24 GHz in India (bottom) when compared with our global counterparts (top).

One can see that 24.25 GHz to 26.5 GHz (2.25 GHz) is the globally preferred band for 5G. However, Korea, Brazil, Sweden & US is doing 5G trials in the block 26.5 GHz to 29.5 GHz (3 GHz).

The spectrum blocks relevant for India is marked as 24.25 to 25.5 GHz (1.25 GHz), and 27.5 to 29.5 GHz (2 GHz). The reason is that the former is free except for Tata using it for LMDS in Maharashtra, and the latter is used by terminals on the ground for uplinking to the satellites operating in this band. Hence, it is possible to use this block of spectrum for 5G services subject to the outcome of coexistence studies (which is define the operating parameters like power etc). Please note that the block of spectrum between 25.5 to 27 GHz is unusable due to the presence of the receivers of metrological satellites operating in this band. These receivers are susceptible to interference as they are tuned for very low power signals coming from the satellites.

Conclusion

For India to be ready for 5G in time it needs to open up the two above-mentioned bands (3.4 GHz and 24 GHz) in time. 3.4 GHz is free and only needs to be auctioned. However, the 24 GHz band needs a lot of work is required to make it palatable for 5G. The most important one is to carry out coexistence studies for defining the working parameters for working 5G in this band. Preparing and assigning these bands in time will also signal the ecosystem players to start developing equipment for these bands. Hence, any delay carrying out these actions will prevent us from achieving our overall objective.

(Views expressed are of my own and do not reflect that of my employer)

PS: Find the list of other relevant articles in the embedded link.