Initial research shows that LoRa in the range of 433 MHz has a short range and poor urban (penetration). The best results seem to come from LoRa frequencies in the 900 - 925 MHz band.

However, this is only based on a handful of articles on the net and conference papers, including this elementary one by Thai researchers attached.

If I had a good spectrum analyzer in this frequency range it would help things along, but I don't own one, and don't want to buy one for this single project; and don't yet know where to rent or borrow one for a few days.

I have fiber (maybe 7 unused strands) from my condo on the 27th floor to the 4th floor; but that would require a lot of gear to set up a fiber transmitter and receiver; and then an outdoor LoRa gateway node on the 4th floor in an unsecure area; and that still may not penetrate from the 4th floor on the opposite side of the big building to the lower floors of the basement on the opposite side of the building.

Without a receiver and spectrum analyzer available, and being not willing to shell out thousands of dollars for one, my options are narrowing.... need to think about this more.

I will search AliExpress and maybe try to buy some cheap spectrum analyzer or build one that works "OK" for this project.

Another crazy idea is to set up a relay node using a solar panel and battery in one of the trees; and try to relay from the 27th floor into the entrance of the parking garage and back

Another idea is to get a commercial LoRa device from an NB-IoT telecom company and see if a commercial LoRaWAN service can penetrate into the lower basement. The device costs about $50 bucks and they service is about $12 a year to use their LoRaWAN service (yes, about a dollar a month).

In Thai:

Code:

https://loraiot.cattelecom.com/site/home

See also:

In English:

Code:

http://www.ais.co.th/nb-iot/en/?intcid=index-en-livemore-indexrevenue-nbiot

In Thailand now, there is a big IoT push and a lot of new services are rolling out.

But unlicensed, I think (need to confirm) I can transmit up to 500mW in the 920-925 MHz band.

Or instead of LoRa, I may also test 3GPP which is the basis for two of the three commercial services in Thailand:

Code:

https://en.wikipedia.org/wiki/Narrowband_IoT

I think will buy an Arduino shield NT-IoT device which uses 3GPP, configure it to send out UDP pings to the Internet (like this site) and use UDP pings to see if it will work in my underground parking garage.

It it works, then I can just send UDP packets from deep in basement to 3GPP (NB-IoT) WAN services and then relay those to my server back on the 27th floor of my condo; and / or use two NB-IoT devices, one in the deep parking basement and one in the 27th floor of my condo.

So, today I will go talk to AIS about their Arduino NB-IoT 3GPP shield and ask them if they think it will work in our lower parking level. If they think it will, I will buy it and test it.

Here is an AIS promotional video for NB-IoT:

Code:

https://www.youtube.com/watch?v=IMILu-KUPV4

For early testing, I may just use IoTweet.com

Code:

https://iottweet.com/

Also, I'm looking at LoRa services from CAT Thailand:

Code:

https://loraiot.cattelecom.com/