Hello community good morning, I have been using a lorawan module from Seed studio, but this can be applied to any LoRaWAN device, and it is the sending of large packets, I am using US915 with SF7 to send around 242 bytes and I have a waiting time to receive messages from the server of 2 to 6 seconds in total for Rx1 and Rx2 but this time is due to the time it takes to receive a message from the server and for my purpose I want to make the communication much faster and more efficient so that it takes at least 2 seconds or less, is there any strategy or methodology to send extremely large packets, quickly and efficiently using loRaWAN, or any configuration or times required for RX1 and RX2 handling them manually?, or a strategy to send packets dynamically changing channels?
I am attentive to any information, thank you very much.
If you consider the timing diagram for LoRaWAN, it’s not natural for a node to be able to send more frames, more often than once every 3 seconds (the TX window, RX1 and then RX2).
LoRaWAN operates in the unlicensed band. You would normally not need to pay for a license to use it, but there are usually restrictions to ensure fair usage for everyone. In the case of US915, you should be complying with FCC’s 400ms dwell time… Actually, are you even allowed to send 242 bytes, at SF7?
EDIT: yes, one can send 242 bytes under SF7 (DR3).
If the goal is to send more data anyway, you could use higher datarates to be able to send more and remain within your regulations.
Like DR4 (SF8BW500). Every 8-channel gateway has technically 10 channels, of which the last 2 are normally unused. They are the fixed-SF and FSK channels. The fixed-SF channel can only operate with fixed parameters, but it’s also the only channel that can operate with either 125, 250 or 500kHz bandwidth.
LoRaWAN doesn’t define FSK mode for US915. If it’s either not legal or just not worth it (US915 has the widest channels, and thus the highest bandwidths in the world), perhaps staying with LoRa modulation is probably for the best.
If you meant downlinks instead, there is nothing that says you cannot send more data in Class C mode (since the node doesn’t have to respond), so as long as you keep within your regulations. In fact, this is a behaviour of the official FUOTA mechanism.
The US915 downlink datarates are stronger, as they have 500kHz channels.
Let’s say the question is about how it can be done, regardless of whether it makes sense and its legality: the answer would be to not use LoRaWAN. You can use LoRa modulation to transmit/receive frames, but what OP wants just cannot work according to the definition of LoRaWAN.
LoRaWAN defines the messaging and semantics, on top of LoRa modulation.
@sp193
Hello, thank you very much for the answer,it is appreciated
In fact, according to the documentation for US915 DR3 and in SF7 and 125BW, a maximum of 242 bytes can be sent, but by testing the bytes added by the protocol, I can send a maximum of 238 bytes of a data packet, but in this case I am testing by sending said packet every 6 seconds about 5 times, for example every hour. In this case, would I be breaking the usage regulations for everyone? Sending on a single channel? or should I implement a strategy to send these packets by changing channels in each transmission (multiband)? This can be done, I certainly have some doubts about this.
On the other hand, for the duty cycle of the packets I have them conditioned to RX1 and RX2 plus a waiting time from there the 4 - 6 of sending time between packets, would I be setting 1% of the duty cycle or do you know of a way to efficiently calculate these specifications?
Hello, thank you very much for the answer,it is appreciated
yes in fact that is why I have quite a few doubts because I think that in this way I would be abusing any server and the policy of use for all, if the package is that big in reality at least there are minimum 4 packages of this size or well around 238 bytes that in the same way would be limited also by the server where they are sent so it can be reduced, my idea is to send these packages at least once a day but if I know that I am not including regulations and specifications by sending these 5 packages with a time of 4 to 6 seconds between them through a single channel, can these be sent without violating specifications and regulations by sending each package through a different channel, something similar to multiband?
It’s constantly evolving, to fit the regulations of the regions it was designed for.
Regarding the maximum payload length for US915, it appears that I was mistaken. Since there’s a 400ms dwell time limitation, I thought it cuts down all the maximum limits. But there’s a point where it doesn’t.
Regarding the rules for fair usage, you should refer to your local laws. It’s not appropriate for me to read your laws and interpret them on your behalf because I might not understand something.