In 2015, the WRC (World Radio Conference) took up for discussion the sub 700 MHz band (470-698 MHz) for possible deployment of IMT (International Mobile Telecommunication) services. Simultaneously, the Committee of Secretaries in India met and decided to support this band (470 – 698 MHz) for IMT services. The idea was to capitalize on the opportunity (ongoing radio conference) to register our (India’s) support for this resolution. However, by the time we were ready with all approvals, the process at WRC had matured and therefore, India’s name could not get included in the footnotes (footnotes No. 5.295, 5.296A, and 5.308A) along with the group of other like-minded countries. As we speak, these countries (at the regional and global level) are discussing various frequency bands (uplink and downlink combinations) to be used in this block (470 – 698 MHz). The purpose of this note is to lay out the most efficient band plan for India in this band to reduce the cost of equipment and handsets and without sacrificing the need for spectrum for the government agencies.
The NFAP (National Frequency Allocation Plan) allows the frequency block 470 – 703 MHz to be used for both Mobile and Broadcasting services (co-primary services). Fortunately, (unlike many other countries) India’s only broadcaster (Doordarshan) has very little usage in this block of spectrum, as most of Doordarshan’s analog transmitters are deployed in the frequency block of 174 – 216 MHz. Committee of Secretaries, earlier in 2021 decided to utilize the spectrum band 526-703 MHz more effectively by using it for IMT. There were other government agencies also in some portion of this frequency range and have been asked to repurpose this band for IMT. The snapshot of the assignment in this band is shown in figures 1 and 2 below.
Figure 1: Earlier Situation
Figure 2: Current Situation
470 to 526 MHz – Doordarshan + Government Agencies.
526 to 582 MHz – Doordarshan coexisting with IMT
582 to 612 MHz – IMT and Rural backhaul connectivity
To appreciate the density of usage of this spectrum band, I will like to point to a recent study done by IIT Mumbai. The study points out that more than 80% of the TV UHF band IV (470-585 MHz) is totally free and lying unused (see Table III of page 5 of the PDF in the link above). Hence sub 700 MHz band is mostly unused and therefore, can be easily harmonized (reconfigured) to support a more optimal band structure.
Digitization of Broadcasting
It is worthwhile to note that Doordarshan’s current analog assignment (174 – 216 MHz) is due for conversion to digital very soon. The new digital standards (DVB-T2) can pack up to 6 HD channels in one single block of 8 MHz. Also, using advanced interference management techniques, it is possible to configure the adjacent transmitters to the same frequency (Single frequency Network), thereby significantly increasing spectrum efficiency of broadcasting services. This will obviate the need for them (Doordarshan) to seek an additional spectrum beyond Band IV (470-582 MHz).
Asia Pacific Work on Sub-700 MHz Band
Asia Pacific Telecommunity is deliberating on some options as Asia Pacific specific band plans for the 600 MHz band. the following band plan for IMT. Discussions on specifications for these plans are already in progress in 3GPP and are expected to get finalized soon.
Harmonization Proposal For India
Keeping in mind the actual usage of this sub-700 MHz band (470-703 MHz) and the frequency structure being discussed at the AWG, the following harmonized proposal can be considered by India. Since there is an opportunity to maximize the 600 MHz band spectrum from various options mentioned above by selecting Option B1 for India, the following is the best proposal for the 600 MHz band in India. It may be noted that in the 700 MHz band DoT has assigned 15 MHz out of 45 MHz to government agencies and therefore, maximizing the sub 1 GHz spectrum should be one of the key criteria. Also if this option is not selected then we lose 5 MHz of this band forever. Another option (B2) may work well for some countries where spectrum is assigned as a single license area, unlike India where we have 22 LSAs. Deploying the B2 option in 22 LSAs in India will almost be a nightmare for both the licensor and the licensee hence should not be supported. Harmonized band for 600 MHz in the Asia Pacific should be that of the B1 option.
Figure: Preferred Option for India (B1)
612 to 703 MHz – Commercial Usage (612-652 MHz Downlink paired with 663-703 MHz Uplink)
Note that 663 to 703 MHz is used as an Uplink to prevent interference into the adjacent 700 MHz band (698 – 806 MHz).
Hence, it is clear that a sufficient spectrum can be carved out in the sub 700 MHz band for the deployment of IMT services in India, by optimally rearranging the assignments of Government and Doordarshan. Once that is accomplished, 2×40 MHz will be available for deployment of 5G in the future. Globally, a lot of work around harmonization is happening on the above-discussed band structure in the spectrum block (612 – 703 MHz). In the interim, the Government agencies (including Doordarshan) can get accommodated within a larger block 470 – 604 MHz (63% of the total spectrum). Later, if required, this arrangement can be revisited, in case an additional spectrum is needed. This will prepare India well in advance for rolling out 5G services in a lower spectrum band (< 1 GHz), thereby creating a win-win situation for all stakeholders.