Hi,
I hope this is the right place to post this for discussion.
Actually, my organization is having a major event this December, it is called MahaSadaShivoham.
We have guest coming from 47 countries for this event, and many of them require translation.

In past we have purchased translation kits such as
https://www.alibaba.com/product-detail/Multi-language-Translation-Equipment-for-Church_2014689395.html
https://www.alibaba.com/product-detail/Simultaneous-Interpretation-System-Equipment-For-Multi_60671207330.html?spm=a2700.7724838.2017115.37.3a85bc45i1Bvdc
The frequency range in which the existing kits operate interfere with the Wifi 2.4GHz ( Refer :  https://www.howtogeek.com/222249/whats-the-difference-between-2.4-ghz-and-5-ghz-wi-fi-and-which-should-you-use/ ). This interference with wifi destroys reliability of our local communication because 100s of translation kits running in such a closed area nearby each other is not a joke.

So we have 3 options,
We go for the same old solution : we had horrible experience, very unlikely we may go for the same thing.
Either we go higher frequency :  5GHz
Or we go lower frequency : FM for example
We did a trial run on FM 88MHz to 108MHz. So for this we thought we could go with just a simple cheap FM Transmitter and an FM radio. Cheap solution and it works, and we get many channels for different languages. The only problem in this solution is the legality issue, if some guidance can be provided how we can use FM without breaking the law, it would be the most preferred. We tested this device and a normal FM radio and it worked to our satisfaction and even better : https://www.amazon.in/Aukey-Wireless-Transmitter-Adapter-Charger/dp/B01AXTQR1I?tag=googinkenshoo-21&ascsubtag=1ef793cf-8137-489c-a1bf-dce9cefac93e 

If we go for higher frequency, like 5Ghz what could be the solution? What would be the power consumption. How many hours it can run etc. How costly it will be? Do you think there will be any standard solution provider to this ?


Additional Reading and References
433MHZ 868MHZ 900MHZ is frequency band allowed in india? Indian government frees low-frequency bands for automotive ADAS features
Read more at http://telematicswire.net/indian-government-frees-low-frequency-bands-for-automotive-adas-features/#G3m3OPHwfRGXkfZz.99 
868 MHz frequency is not license free in India - LoRa in India
http://www.raviyp.com/embedded/207-868-mhz-frequency-is-not-license-free-in-india-lora-in-india
http://www.wpc.gov.in/WriteReadData/userfiles/file/National_Frequency_Allocation_Plan-2011.pdf