Good night,
In fact, when you talk about LoRa transmission you need to analyze both directions: uplink and downlink.
Uplink you will see in the LoRa Server (at least RSSI, SNR and SF) . What is your LoRa Network Server? AWS IoT Core for LoRaWAN or TTNā¦
Download you will see at your device the same parameters: RSSI, SNR and SF.
What is you LoRAWAN Gateway? How far it is from your device?
How they are ?
Regards,
Claudio
Hi @crmrosa
My LoRa server is AWS IoT Core. I donāt believe I know how to find the server-side RSSI and SNR on that platform. At my device, the RAK Sidewalk Starter Kit using PCB antennas, 3 meters from an Echo Show 5, my performance looks like this when I test from home:
The second test is done while parked approximately 80-100 meters from my house. I can confirm that both the Amazon Test Kit and the Nordic Dev Kit both successfully communicate with the server at this distance, but the RAK Module does not. At this distance Iāve also tried using an external antenna, but unfortunately that didnāt help.
Any help/guidance you could provide would be greatly appreciated! 
Jose
Hi Jose,
If your device is very close to your LoRaWAN Gate, you will need to reduce the power of your device.
LetĀ“s analyze the scenario step-by-step:
LetĀ“s think about the architecture:
Take a look in the figure below to have a idea about what behavior that you should expect related with the distance:
What are the values that you see in your device?
SNR x RSSI
LetĀ“s take a look how what kind of relationship that you can expect between SNR x RSSI. In many cases too much power can cause a lot of problems. The power (RSSI) should be what the device need to do the job based on applications requirements. In the end of the day, a good SNR is one of the key of your success.
In the figure, each dot is a transmission with success. The SF means that 7 is the faster transmission and 12 is the slower. When you have the ADR (adaptive data rate), the device will adjust the SF for higher or lower data rate following the success or the failure in a transmission. For example, if your device try to do a transmission with SF7(faster) but a lot of packages was lost, the ADR will reduce the data rate, in other words, increase the spreading for the next transmission, for example do SF8. If the ADR is enable, the adjustment cycle will continue for all transmissions. The behavior can be good for mobile device, because the transmission scenario will change all the time, but for stationary device (no changes in the distance between the endnode and the gateway), if you see a continuous changes, you will need to analyze if you have problems in the connectors, cables and antennas. The ADR job you can see in the figure above .
Jose,
In the LoRa Network Server, you will need to configure in the AWS IoT Core for LoRaWAN, the gateway and the endnode:
Did you already did these configurations?
ClƔudio
@jose_ota At this point we were not able to pinpoint anything in the RAK that was causing it have the connection issues. What we did find is that by testing out some new antennas we were able to get a similar RSSI to that of the Nordic Dev kit. This is the antenna we are going with: Antenna. We bought a handful and most of them seemed to help improve the RSSI with this one seeming to be around the best. I would say order one of these and see how it works for you.
I also went as far as to order the RAK19007+RAK4631 starter kit to make sure it wasnāt just our board and I can confirm on the RAK starter kit the results are identical to the custom board we have made.
If you happen to find anything else that improves your range results let me know. Thanks.
@crmrosa thank you so much, this is great info!
Itās good to know that I need to reduce power if Iām close to the gateway. Itās worth noting that when Iām close to the gateway (3 meters) I donāt encounter any issues. I only encounter issues when Iām farther away (100 meters).
I only get RSSI and SNR values while successfully testing close to the gateway (3 meters). The values I get are RSSI -123 and SNR -18. When Iām testing from farther away (100 meters) I donāt get any values because it never connects, so the console doesnāt show any info. Unfortunately the SF is never shown in any of the console information as far as I can tell.
As for your questions around configuring AWS IoT Core for LoRaWAN, I havenāt configured this in the way your screenshots show. I believe I misspoke earlier when I said my LoRa server is AWS IoT core, what I really meant to say is that itās AWS Sidewalk. I have configured the devices in the following way.
Jose
@lukevawkes thank you for the antenna recommendation! Iām glad you were able to find a suitable antenna. We went through four different options and didnāt see improved performance so I had lost hope. Iāll order the one you suggested and see how we do!
I have some updates regarding my experiments with ground planes that might be worth sharing. I did a small experiment using the RAK Sidewalk Starter kit hooked up to the RAK PCB antenna 3 meters from my Amazon Echo. Using this āstockā configuration I was getting an SNR of about -18. I then used two very short jumper cables to hook up the WisBlockās two ground pins to the ground pins of a separate PCB that has a large ground plane. Immediately after doing this, the SNR improved to -9. I then swapped in the external antenna using the IPEX-SMA adapter and the SNR improved to -1! This felt like strong evidence that suggested that the RAK module did in fact need a larger ground plane.
With that in mind, Iāve begun designing our custom board (around the RAK4630) using a large ground pour in one of the layers (approximately 100mm x 50mm). We briefly considered going away from the RAK module and started looking at separate modules for the NRF and the Semtech. I found a device called the BMD-340 the incorporates the NRF. Page 26 of its data sheet suggests a ground plane of this size, which led me to believe that the RAK may also need a ground plane of this size.
The size is much too big for our final custom solution, but Iām moving forward with making the custom board for the purposes of experimentation. Did you find that the ground plane in your custom solution made a difference, or was it a non-factor?
Hi @jose_ota ,
First of all, the numbers that you are showing, the meaning is that you have a poor reception:
I have two LoRaWAN gateways 5 meters far from my Field Tester at home:
your device RSSI= -123dBm => my device at GW1 RSSI=-31 dBm , at GW2= -24 dBm => the ADR is disabled
your device SNR= -18 dB , my device at GW1=13.2 dB , at GW2= 12.5 dB
LetĀ“s pay attention that RAK4630 is the Core of the RAK Field Tester: RAK10701-P Field Tester for LoRaWAN Pro | RAKwireless Documentation Center , then numbers should be similar, but they are so far from each other.
As we can see in the IoT concepts in a endnode we have 5 components, and for each one, requirements that they should be verified if they are in compliance with the requirements:
Let me give some numbers about my Field Tester (RAK4630):
First, a Field Tester screenshot
A TTN screenshot about the reception:
I did lots of antenna testing for LoRAWAN. The ideal scenario when testing across hardware is to use the same antenna. Ideally use a 6" whip antenna, similar to what the gateways use, the bottom half of that antenna acts as a ground plane which helps remove the ground plane differences of the module + PCB. Range testing should be done at the edge of the network, should be done on the same ADR, same TX Power and same channel. All those recommendations help remove lots of external factors when comparing across hardware. Random note: There will always be asymmetry between edge node and gateway when you are at the edge of the network so dont worry too much that you get -15 SNR but the gateway is at -5 SNR.
Another random comment, When I am too close to the gateway in LoRAWAN, I found that sometimes the center frequency shifts because its so powerful and too close that the gateway thinks its on another channel and you get weird artifacts like -120 RSSI and -12 SNR even though you are like 5 feet away.
Take a look what Semtech is saying in this articule: Predicting LoRaWAN Capacity | DEVELOPER PORTAL
They are the creator, then they are reference:
Based on the table above, the SNR should be greater than -20 dB and the target should be -7.5 dB.
This kind of articule can help to understand what is the standard or baseline
@crmrosa I just want to thank you again for your very thorough answers. The information is incredibly helpful and Iām learning a lot!
I agree that thereās definitely something wrong and I have poor reception. I should definitely be seeing a much better SNR being so close to the gateway.
Iām wondering if something is wrong with the Amazon Echo Show device that Iām using and itās not actually acting as an Amazon Sidewalk Gateway. Iām going to disconnect it and do some additional testing to try to better understand what might be happening.
Thank you for the breakdown of components for the endnode. I am using the RAK Starter Kit for Amazon Sidewalk, so I think the various components should be in compliance with the requirements.
Iām going to keep investigating based on the information youāve provided to try to better understand whatās going and will share what I find.
Jose
@brolly759 thank you for the info on antenna behavior! Iām very new to RF and didnāt realize that the bottom half of whip antennas act as a ground plane, but thatās very good to know! Iāve tried using the following antennas. The first link is the Semtech dev shield, but I borrowed its antenna:
https://www.digikey.com/en/products/detail/semtech-corporation/SX1262MB2CAS/9625070
https://www.digikey.com/en/products/detail/te-connectivity-linx/ANT-916-CW-HWR-SMA/1139580
https://www.digikey.com/en/products/detail/raltron-electronics/RST-W1B6-10808-22M-FY-001/10273002
I connect those whip antennas to the RAK Starter Kit for Amazon Sidewalk module using the following adapter:
Unfortunately since Iām working with the Amazon Sidewalk network, Iām not entirely sure how to go about identifying the edge of the network and TX power/channel of the gateway. Iām going to look into the Sidewalk API documentation to see if thereās a way to retrieve this information.
You also make a good point about being too close to a gateway. I have a feeling I may be encountering something of the sort because Iām seeing very weird behavior being 8 feet away from my Echo Show which is supposed to be the Amazon Sidewalk Gateway. Iām going to leverage the info you and @crmrosa have been so kind in providing to try to see if I can find the root cause of my issues!
Jose
I talked with RAK support, I made an Amazon Sidewalk certified device using the RAK4630 which will be debuted at CES. I asked RAK support to do a range test with my device to see if they get better or worse range. I have BLE disabled after successful join to Amazon and it uses only LoRA only after BLE is disabled. Hopefully next week I will get some answers to the range test comparison.
I thought there was no way on the AWS side to know the RSSI/SNR because they were trying to hide that info so people couldnt use it for geolocating and create a security risk. I might be wrong.
Also, every Elexa device is capped at 500MB so if you use that much in a month you will need to connect to another amazon sidewalk gateway. Dont think that is the issue, but food for thought!
@brolly759 thatās awesome! Congrats on the certification and future debut at CES. Hope all goes well with the range test.
Iāll experiment with disabling BLE after successfully joining Sidewalk and see how the standalone LoRa does.
I suspect youāre right about knowing the AWS side to RSSI/SNR, and thanks for the heads up on the monthly limit!
Jose
@crmrosa @brolly759 Wanted to share a funny (and embarrassing) finding. The Echo Show Iāve been using was signed into my wifeās account, which originated in Mexico. As a result, the Sidewalk option didnāt even appear. It seemed weird that I never saw the option to disable it after checking multiple times, but I just assumed it was on and they simple removed the option to disable it. The reality was that it wasnāt acting as a Sidewalk gateway.
Iāve now restored it factory defaults and signed into my account. Lo and behold my average SNR values for my Nordic Dev Kit have gone from an average of -6 to an average of +4!
Iāll keep experimenting and share any other findings.
Hello @lukevawkes @jose_ota
We found a config is wrong on RAK4631 pin setting,
The antenna_enable pin setting is wrong and should be changed by following code.
The code is in app/rak4631_rak1901_demo/boards/rak4631_nrf52840.overlay
/{
semtech_sx1262_gpios{
compatible = "gpio-keys";
semtech_sx1262_cs: cs {
gpios = <&gpio1 10 GPIO_ACTIVE_LOW>;
label = "semtech_sx1262 CS";
};
semtech_sx1262_reset_gpios: reset {
gpios = <&gpio1 6 GPIO_ACTIVE_LOW>;
label = "semtech_sx1262 Reset";
};
semtech_sx1262_busy_gpios: busy {
gpios = <&gpio1 14 GPIO_ACTIVE_HIGH>;
label = "semtech_sx1262 Busy";
};
semtech_sx1262_antenna_enable_gpios: antena_enable {
gpios = <&gpio1 5 GPIO_ACTIVE_HIGH>;
label = "semtech_sx1262 Antena Enable";
};
semtech_sx1262_dio1_gpios: dio1 {
gpios = <&gpio1 15 GPIO_ACTIVE_HIGH>;
label = "semtech_sx1262 DIO1";
};
};
};
But We have measured the transmission power with modified and without modified, the power is still the same. I wonder it might help for field test.
@Evan once again YOU ARE THE MAN!!!
I incorporated this change with my test setup here at home and immediately the RSSI/SNR went from -122/-18 to -99/-8!!!
This absolutely feels like it was the root cause of the issue. Iāll do more field testing tomorrow to confirm!
Thank you again,
Jose
@Evan I did some additional field testing this morning and the RAK is now performing better than the Nordic Dev Kit! This was absolutely the solution!
Thank you again,
Jose
Congratulations! The network is everything