nRF91 no cellular service power consumption

Question

To preface: 
 
 Board: Custom with nRF9151 module 
 nRF Connect SDK / Toolchain: 3.1.0 
 Modem Firmware 2.0.3 
 PSM enabled 
 Propriety PSM enabled (Enables fallback for when cell network doesn't support / grant regular PSM) 
 eDRX disabled 
 RAI enabled 
 Carrier: Verizon 
 
 Hello, 
 I am testing modem power consumption in the scenario where the modem does not have cellular service (CEREG: 4). Essentially, I am disconnecting the antenna from our board to simulate this scenario. A shield box would also achieve the same results. These are my current measurement results: 
 
 This is on a custom board so the currents won't match a nRF9151DK exactly, but the takeaway is that the modem stays in a periodic high-current on state while searching for a network indefinitely it seems. I have only monitored this condition for 10-15 minutes with the power profiler kit 2. Based on the above, I have a few questions: 
 1. Does Nordic employ any power saving techniques when the nRF9151 module doesn't have cellular service (Out of coverage)? If so, what are they? 
 2. If the answer to #1 is no, then I assume it is up to the developer (me) to implement my own power saving techniques in the event of no cellular service? 
 Thanks, 
 Derek

Øyvind · Accepted Answer

Hi Derek, my sincere apologies for the late reply. My answer did not get sent last week. 
 Our modem team points out that AT%FEACONF will improve the power saving in very low signal conditions where it’s easy to lose the serving cell. Also, adding Periodic cell search configuration AT%PERIODICSEARCHCONF will provide ready made configs for ultra low power. i.e.

AT%FEACONF --> Improves power efficiency in scenarios with very weak signal strength, where the serving cell can easily be lost.

AT%PERIODICSEARCHCONF --> Provides predefined configurations for ultra-low-power operation by controlling periodic cell search intervals, and designed for cases where no cells or service are available.

Data profile %XDATAPRFL (tied to above mentioned periodicsearch), i.e. more generic command that adjusts various modem operations based on the requested setting. Note: XDATAPRFL command modifies the PERIODICSEARCH settings based on the selected profile 
 
 AT+CFUN=2 - Sets the device to receive only functionality. Can be used for operations that do not require TX, such as network search for connection readiness, Evaluating connection parameters %CONEVAL , Environment evaluation %ENVEVAL , and Neighboring cell measurement and notification %NCELLMEAS

Supports network search, selection, and notifications while in Rx-only mode.

Enables +CEREG and %MDMEV SEARCH STATUS reporting.

Allows all AT commands that do not require transmission capability.

Adds support for AT%NCELLMEAS and improves AT%CONEVAL performance in this mode.

Consider CFUN=4 (Flight Mode) if the ULTRA_LOW_POWER configuration does not meet requirements IF e.g. ULTRA_LOW_POWER configuration example is not meeting the requirements: AT%PERIODICSEARCHCONF=0,0,0,1,"0,10,40,,5","1,300,600,1800,1800,3600" ' 
 This sets modem search intervals before entering power-save cycles. Note: Flight mode shutdown must be handled by the application. Additional app-side logic is required if minimizing current consumption is critical. 
 
 Let me know how that works for you! 
 Kind regards, Øyvind

nRF91 no cellular service power consumption

Top Replies