How to access the UE (WP or HL LTE module) from remote server


Hi all,

I have a question on system design. Appreciate any system design expert can enlighten idea for me…

I am developing an embeded system (the UE) which requires to go standby in most of the time, but it could allow a remote server to page and wake it up, so that this device can re-establish TCP link to the server (a fixed IP) after waking up.

To save every juice of the battery, during standby the host processor has to be suspended. Meanwhile the cellular module shall also go to idle mode (and with the USB connecting to the host processor put into suspend, so the module current consumption will go down to a few mA only).

My newbie (as I don’t have much knowledge on LTE network) question is, by what means (IP or what?) the remote server can address the module?

As far as I understand (might be wrong), in idle (DRX?) mode, only the PPP (or equivalent so called) between UE and eNB is maintained. The PDP from UE to MME is not connected, not to mention to TCP link to the remote server. So there is not real IP (IPV4/V6) available to the server for paging. Then how could the server able to find the correct eNB and the correct UE and let the eNB to page the UE?

In WP series, if eNB can page the UE, there is a WAKE_ON_WWAN pin that can be used to wake up the host processor. Then host processor can re-establish TCP to the server. But how about HL series?

Sorry if my question is not precise or my previous understanding might not be exactly correct.

Any insight could bring me the light? Thanks a lot!