#10708 NORM Not Tri: 3G modem problems with power management

Zarro Boogs per Child bugtracker at laptop.org
Tue Feb 22 18:05:26 EST 2011

#10708: 3G modem problems with power management
           Reporter:  tonyforster   |       Owner:               
               Type:  defect        |      Status:  new          
           Priority:  normal        |   Milestone:  Not Triaged  
          Component:  not assigned  |     Version:  not specified
         Resolution:                |    Keywords:               
        Next_action:  never set     |    Verified:  0            
Deployment_affected:                |   Blockedby:               
           Blocking:                |  

Comment(by Quozl):

 This doesn't take into account other use of a modem, such as for short
 message relay, or the yet to be connected situation.  The latter concerns
 me.  An explanation follows:

 After power is up, the modem must scan the configured channel space,
 receive the beacon, transmit in a free slot in order to be recognised,
 negotiate transmit power, and then register with and attach to the network
 provisioning servers.

 (AT+CGATT? can be used to verify whether attachment is complete, but I
 can't see that used by Network Manager sources).

 A connection attempt before this process is complete tends to fail.  The
 user retries.

 Repeat power cycles of the modem may cause more power to be used, since
 the initialisation sequence is expensive, in terms of computation and RF

 It is also slightly unfriendly to the mobile telephone network as a whole.
 (Temporary coverage loss is handled more gracefully than power loss, since
 context can be kept by the modem in volatile memory).

 Network Manager detects the availability of the modem.  Perhaps that is
 where an inhibit should be placed.

Ticket URL: <http://dev.laptop.org/ticket/10708#comment:6>
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