BVLOS DRONE FLIGHTS : OPTIONS AND THE WAY FORWARD

 

BVLOS DRONE FLIGHTS : OPTIONS AND THE WAY FORWARD

Col CR Sundar

          Article Number 1

           At present in our country almost all drone flights take place with transmitter receiver units of Chinese origin. They could be FlySky CT6B model or the slightly up market FlySky FS i6 model. Both these models work on the free frequency of 2.4 GHz. They have a maximum range of about 300 meters and therefore in all cases the drone remains within visual line of sight (VLOS).

          Some hobbyists attempt to fly drones with do-it-yourself transmitter receiver units using Arduino NANO and nRF24L01 transceivers made by Nordic Semiconductor of Norway. If used in open space with lower baud rate this transmitter receiver can have a range of up to 100 meters.

          Thus we see that almost all drone flights in India take place within Visual Line of Sight (VLOS). There are hardly any Beyond Visual Line of Sight (BVLOS) drone flights taking place in our country.

          This is certainly a matter of concern for a nation aiming to become a drone hub. The crunch factor here is the availability of radio frequencies for BVLOS drone communication.

          In this article we will see some of the common options available for communications for BVLOS flights in general.

TV Whitespace

          For efficient BVLOS flights UHF frequencies are required for ground to drone, drone to drone and drone to tower communication. For this purpose we requested the Union Government to free-up the band known as ‘TV Whitespace’ for dronery as is done in some countries. This band of frequencies lies between 470 MHz and 790 MHz.

          In the days of analogue TV this band was allotted for television broadcast. But television has long since moved from analogue to digital transmission. And hence this band of frequencies are not used by any one for any purpose and is considered to be an ‘Unoccupied Band’.

          We took up the matter with the Wireless Planning Commission (WPC) of the Ministry of Communication. However, vide WPC letter No. R-11018/06/2017-PP dt 28/10/2022 they turned down our request.

          We had then requested them that they may please grant us some little portion of the band so that we can carry out our trials and R&D to develop communication devices and systems for flying drones BVLOS in that band. This request of ours has been met with stony silence. So in effect TV Whitespace frequencies are not an option available to Indian droners.

4G LTE and 5G

          Other than the UHF frequencies of TV Whitespace there is 4G LTE and 5G known collectively as cellular or mobile communication bands. This could also be an option. This may enable BVLOS operations and deliver long range and high data throughput to meet the requirements of dronery even when at a later stage we move to the block chain system for dronery.

          There is much doubt whether this cellular option would be available to us. However this option has a limitation. Even if these frequencies were made available its usage would be restricted only to urban areas because in rural areas cellphone towers are few and far between.

          Yet we need to take a closer look at urban wi-fi communications. In Chennai for example there are three mobile operators viz., Hathway, Airtel and Jio. Out of them Hathway is terrestrial and cannot support drone communications. Airtel on the other hand does not have resources in the narrow band for allocating bandwidth to drone communications.

          Jio has that capability. But Jio is tied to Asteria. In the Asteria website it says “Asteria Aerospace Ltd is a subsidiary of JioPlatforms Ltd, which is a majority-owned subsidiary of Reliance Industries Ltd”. So drone mobile communications is now monopolised by Reliance. What then are the chances that Jio will offer their services to us and if they do at what rate? In effect we can rule out that option.

Satellite Communications for Drones

          For long range or remote applications satellite communications become essential. Satellite communication can provide global coverage and reliable data transmission.

          Drones have to be programmed for satellite communications using languages such as python, C, java and javascript. When the drone leaves the visual line of sight the ground-control station switches to a satellite link to control it. The drone could use GPS or NavIC. If the communication link is lost the drone is programmed to fly autonomously in circles or return to base until the link can be reconnected.

          However, satellite signals have to travel a long distance form the drone to the satellite and back. This could cause latency and hinder real time communications. Also satellite communication has limited bandwidth compared to ground communications.

          In any case, the biggest impediment here is that the Union Government has not announced a policy for satellite communication for drones and no guidelines issued for its implementation. There is an urgent requirement for an accepted protocol in this regard

Free frequency option

          At present almost all drone flights in India take place within visual line of sight in the 2.4 GHz band using systems of Chinese origin. The Chinese design all remote functioning equipment exported to India to function in this frequency be it drones, computer mouse, microwave oven or even automatic gate openers.

          It is to be noted that this band has 14 channels but the user hardly has a choice about which channel he can use since in most cases the channels are embedded in the firmware of the microcontroller found in the device. Since a multitude of devices work in this band there is every chance of interference of overlapping channels. But there is nothing we can do about it.

The Way Forward

          Communication is a vital aspect in droning and due consideration should be given to it.

          In conclusion two points stand out. Firstly, UHF frequencies preferably from the TV Whitespace should be made available to dronery for BVLOS communications. Secondly there is dire need for a protocol for satellite communication. It may be originated by the government or alternatively private parties may draft it and the government may accept it.

          Whichever way it is done, allotment of frequencies and drawing up protocols for BVLOS flights has become a must to take Indian dronery forward.