SIM908 application passing data via HTTP or FTP in a forest

[Amalinda]

I need to transmit GPS data from a unit in a forest. GSM signal strength is not NILL but not its best. It could be down to one bar out of 6 bars.

Is SMS or HTTP/FTP the way to go?

Does SMS need less signal strength?
or do HTTP/FTP and SMS require same amount of signals?

please note i meant GSM signals.
thank you.
Amalinda
SL.

 

[enren]

SMS are sent directly on the GSM network. IP based protocols needs GPRS on top of that.
If no GPRS is available or is unreliable, you can use SMS in PDU mode.
If there is some stable GPRS signal (even weak), You can consider light UDP frames.

 

[Amalinda]

i understand that GSM uses a certain frequency bandwidth. Do the GPRS signals also lie in the same GSM signal band? are data sent to the mobile phone sent via Frequency Division multiplexing?

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Could you tell me the difference between calling a URL and UDP frames? is it different to TCP/IP? I would appreciate your answers a lot. thank you.

 

[enren]

Ok, I'm not a GSM guru but this what I got from my experience.
GSM is the network through which you can establish SMS or voice call communications.
GPRS is only a layer added above GSM to be able to establish ip based data communications. That is why it is called 2.5G.
So, the two are equivalent frequency wise.
Like I said, not an expert, but FDM sounds about right.

Calling a URL is done with HTTP protocol on top of TCP so the choice rely between TCP and UDP.
The main differences between those two is the data communication reliability and cost.
TCP have auto-acknowledment integrated in the protocol so you are sure to receive your data or know if an error occured.
The downside, the data exchange is far superior than UDP so, the cost of your M2M SIM subscription can be greater.
UDP header is much ligter than the TCP header.
But, if a frame is never received by the other hand, you do not know it.

Two solutions:
App1: GPS data are sent regularly so communication reliability is not critical. You can afford to lose some points.
In practice, an embedded system engineer like I, will prefer UDP over TCP for this kind of application.
App2: GPS data are sent on request only.
In this case, TCP approuved.
But HTTP is over kill.

 

[Amalinda]

hey thank you for the answers. it makes a lot more sense to me now about what I had put my hands into.

I like to summarize things I extracted from your reply, please correct me if I am wrong.

I understood that to call a URL I must use TCP/IP protocol and it is not possible to call at HTTP URL using UDP

Data cost is OK where I live (0.001$ per 1M) so i don't mind spending that. moreover I am not sending data continuously rather only once an hour. So reliability is a task I need to fulfill. I guess I will look into TCP/IP more. however I will try the UDP as well.

But since my server is at hostgator, how do I send data to my server using TCP/IP without calling a URL? If I'm caling a URL I can POST or GET the data to a .php file. But I dont have root access to their servers and I am only given mySQL access , phpMyAdmin wih unlimited web hosting space( hatchling Plan). So how do you think I can send my GPS coordinates I get from the SIM908 to my web server?

Should I make a .txt file using my microcontroler and FTP it using the SIM908 via AT commands to the server?