I have somewhat of a generic question.
Does anyone with telecommunications knowledge know how long one cellular module can be connected to one tower?
Generally my phone’s cell module does not get powered down or reset (as far as I know, but who knows what the cell’s firmware is doing) unless I let the battery run down. However, during my day, the phone is constantly jumping from one tower to another as I commute and go about my day.
However, this is not the case for a persistent data gathering system like a weather station for example. If the embedded cellular module does not move, I assume that it will more or less stay connected to the same tower. Is there a recommended best practices timeout for how often the cellular module should be made to reconnect to the tower? Will the tower automatically kick the cellular modules connection after it has stayed connected for a day? A week? A month?
Thank you for any information!
PS: A note about my username, I used to work for SFE, but I don’t anymore. I should probably delete this account, but I’m not sure how, and I was feeling lazy this morning and didn’t want to make a new one.
In the most basic terms, when you are talking about something like a “weather station” communicating over GSM there are 2 aspects of the connection. The first is registration, where the tower and the GSM device establish a communications link. Typically, this link will remain open indefinitely for a device at a fixed location.
The second part of the communications occurs when the device wants to send data over the network. To do this, the device establishes a GPRS connection and sends its data. If this connection is left idle the network will terminate it after a prescribed time. This is dependent on the carrier, but is typically about 15 minutes. The carrier may also sever the connection if it the device has been connected for an extended period of time.
Most carriers have a notion of “registered/active” vs. “registered/dormant”. Due to inactivity, the dormant state/mode happens in most cellular. Going from dormant to active due to a new packet, can take seconds. Or tens of seconds on AT&T’s crummy old networks.
AT&T also tends to not sustain TCP connections for long periods of time.
The comments above are for an immobile device. For a mobile, it gets worse.