Sierra Wireless MC7354 remains in Registered - RRC Idle indefinitely on LTE mode

Diego López dlopezm at teltronic.es
Tue Apr 26 15:27:45 UTC 2016


Hi,

I'm still working with Sierra Wireless MC7354 modem, this time with only 
LTE connection. My tests are made by using a signal attenuator with only 
one cell.

Bringing the modem al low signal levels I discovered two different cases:

* Case 1 - High signal - low signal - high signal (slowly) OK:

Modem state machine transist correctly 
(connected->disconnecting->enabled->searching->registered->connecting->connected)

* Case 2 - High signal - low signal - high signal (slowly) FAILURE:

This test case attempts to simulate something similar to the 
entrance/exit of a tunnel.

ModemManager state machine doesn't transist, it remains connected and 
the bearer doesn't disconnect. Reset MM service doesn't recover 
connection, only reset modem works.

But querying Modem by AT!GSTATUS? command, we can see that it is on RRC 
Idle indefinitely:

!GSTATUS:
Current Time:  1518        Temperature: 40
Bootup Time:   0        Mode:        ONLINE
System mode:   LTE            PS state:    Attached
LTE band:      B13            LTE bw:      5 MHz
LTE Rx chan:   5230        LTE Tx chan: 23230
EMM state:     Registered         No Cell
RRC state:     RRC Idle
IMS reg state: No Srv

RSSI (dBm):    -87        Tx Power:    0
RSRP (dBm):    -106        TAC:         0001 (1)
RSRQ (dB):     -6        Cell ID:     00000100 (256)
SINR (dB):     19.2

MM log between RRC connected and RRC Idle states:

ModemManager[11185]: [/dev/cdc-wdm0] Received message (translated)...
 >>>>>> QMUX:
 >>>>>>   length  = 31
 >>>>>>   flags   = 0x80
 >>>>>>   service = "nas"
 >>>>>>   client  = 2
 >>>>>> QMI:
 >>>>>>   flags       = "response"
 >>>>>>   transaction = 14
 >>>>>>   tlv_length  = 19
 >>>>>>   message     = "Get Signal Strength" (0x0020)
 >>>>>> TLV:
 >>>>>>   type       = "Result" (0x02)
 >>>>>>   length     = 4
 >>>>>>   value      = 00:00:00:00
 >>>>>>   translated = SUCCESS
 >>>>>> TLV:
 >>>>>>   type       = "Signal Strength" (0x01)
 >>>>>>   length     = 2
 >>>>>>   value      = 9E:08
 >>>>>>   translated = [ strength = '-98' radio_interface = 'lte' ]
 >>>>>> TLV:
 >>>>>>   type       = "Strength List" (0x10)
 >>>>>>   length     = 4
 >>>>>>   value      = 01:00:83:02
 >>>>>>   translated = { [0] = '[ strength = '-125' radio_interface = 
'cdma-1xevdo' ] '}
ModemManager[11185]: <debug> [1461671245.821746] 
[mm-broadband-modem-qmi.c:2841] 
signal_strength_get_quality_and_access_tech(): Signal strength (lte): 
-98 dBm
ModemManager[11185]: <debug> [1461671245.821772] 
[mm-broadband-modem-qmi.c:2860] 
signal_strength_get_quality_and_access_tech(): Signal strength 
(cdma-1xevdo): -125 dBm
ModemManager[11185]: <debug> [1461671245.821794] 
[mm-broadband-modem-qmi.c:2874] 
signal_strength_get_quality_and_access_tech(): Signal strength: -98 dBm 
--> 25%
ModemManager[11185]: <debug> [1461671245.821866] [mm-iface-modem.c:1204] 
update_signal_quality(): Modem /org/freedesktop/ModemManager1/Modem/0: 
signal quality updated (25)
ModemManager[11185]: [/dev/cdc-wdm0] Received message...
 >>>>>> RAW:
 >>>>>>   length = 42
 >>>>>>   data   = 
01:29:00:80:01:09:02:05:00:24:00:1D:00:02:04:00:00:00:00:00:1A:08:00:D8:09:00:00:00:00:00:00:19:08:00:E1:18:00:00:00:00:00:00
ModemManager[11185]: [/dev/cdc-wdm0] Received message (translated)...
 >>>>>> QMUX:
 >>>>>>   length  = 41
 >>>>>>   flags   = 0x80
 >>>>>>   service = "wds"
 >>>>>>   client  = 9
 >>>>>> QMI:
 >>>>>>   flags       = "response"
 >>>>>>   transaction = 5
 >>>>>>   tlv_length  = 29
 >>>>>>   message     = "Get Packet Statistics" (0x0024)
 >>>>>> TLV:
 >>>>>>   type       = "Result" (0x02)
 >>>>>>   length     = 4
 >>>>>>   value      = 00:00:00:00
 >>>>>>   translated = SUCCESS
 >>>>>> TLV:
 >>>>>>   type       = "Rx Bytes Ok" (0x1a)
 >>>>>>   length     = 8
 >>>>>>   value      = D8:09:00:00:00:00:00:00
 >>>>>>   translated = 2520
 >>>>>> TLV:
 >>>>>>   type       = "Tx Bytes Ok" (0x19)
 >>>>>>   length     = 8
 >>>>>>   value      = E1:18:00:00:00:00:00:00
 >>>>>>   translated = 6369
ModemManager[11185]: <debug> [1461671250.815327] [mm-port-serial.c:1288] 
mm_port_serial_open(): (ttyUSB2) device open count is 2 (open)
ModemManager[11185]: <debug> [1461671250.815749] 
[mm-port-serial-at.c:459] debug_log(): (ttyUSB2): --> 'AT!GSTATUS?<CR>'
ModemManager[11185]: <debug> [1461671250.932135] 
[mm-port-serial-at.c:459] debug_log(): (ttyUSB2): <-- '<CR><LF>!GSTATUS: 
<CR><LF>Current Time: 1506\9\9Temperature: 40<CR><LF>Bootup Time: 
0\9\9Mode:        ONLINE         <CR><LF>System mode: LTE        \9PS 
state:    Attached     <CR><LF>LTE band:      B13    \9\9LTE bw:      5 
MHz   <CR><LF>LTE Rx chan:   5230\9\9LTE Tx chan: 23230<CR><LF>EMM 
state:     Registered     \9Normal Service <CR><LF>RRC state:     RRC 
Connected  <CR><LF>IMS reg state: No Srv \9\9<CR><LF><CR><LF>RSSI 
(dBm):    -98\9\9Tx Power:    0<CR><LF>RSRP (dBm):    -126\9\9TAC: 0001 
(1)<CR><LF>RSRQ (dB):     -9\9\9Cell ID: 00000100 (256)<CR><LF>SINR 
(dB): 0.2<CR><LF><CR><LF><CR><LF>OK<CR><LF>'
ModemManager[11185]: <debug> [1461671250.932764] [mm-port-serial.c:1345] 
_close_internal(): (ttyUSB2) device open count is 1 (close)
ModemManager[11185]: <debug> [1461671256.942383] [mm-port-serial.c:1288] 
mm_port_serial_open(): (ttyUSB2) device open count is 2 (open)
ModemManager[11185]: <debug> [1461671256.943353] 
[mm-port-serial-at.c:459] debug_log(): (ttyUSB2): --> 'AT!GSTATUS?<CR>'
ModemManager[11185]: <debug> [1461671257.061151] 
[mm-port-serial-at.c:459] debug_log(): (ttyUSB2): <-- '<CR><LF>!GSTATUS: 
<CR><LF>Current Time: 1512\9\9Temperature: 40<CR><LF>Bootup Time: 
0\9\9Mode:        ONLINE         <CR><LF>System mode: LTE        \9PS 
state:    Attached     <CR><LF>LTE band:      B13    \9\9LTE bw:      5 
MHz   <CR><LF>LTE Rx chan:   5230\9\9LTE Tx chan: 23230<CR><LF>EMM 
state:     Registered     \9Normal Service <CR><LF>RRC state:     RRC 
Connected  <CR><LF>IMS reg state: No Srv \9\9<CR><LF><CR><LF>RSSI 
(dBm):    -98\9\9Tx Power:    0<CR><LF>RSRP (dBm):    -122\9\9TAC: 0001 
(1)<CR><LF>RSRQ (dB):     -14\9\9Cell ID: 00000100 (256)<CR><LF>SINR 
(dB): 2.6<CR><LF><CR><LF><CR><LF>OK<CR><LF>'
ModemManager[11185]: <debug> [1461671257.061991] [mm-port-serial.c:1345] 
_close_internal(): (ttyUSB2) device open count is 1 (close)
ModemManager[11185]: [/dev/cdc-wdm0] Received message...
 >>>>>> RAW:
 >>>>>>   length = 50
 >>>>>>   data   = 
01:31:00:80:03:02:04:00:00:24:00:25:00:29:05:00:A8:01:A8:01:01:12:0C:00:A8:01:A8:01:07:34:32:34:2D:34:32:34:11:02:00:01:0B:01:06:00:01:01:01:02:01:08
ModemManager[11185]: [/dev/cdc-wdm0] Received message (translated)...
 >>>>>> QMUX:
 >>>>>>   length  = 49
 >>>>>>   flags   = 0x80
 >>>>>>   service = "nas"
 >>>>>>   client  = 2
 >>>>>> QMI:
 >>>>>>   flags       = "indication"
 >>>>>>   transaction = 0
 >>>>>>   tlv_length  = 37
 >>>>>>   message     = "Serving System" (0x0024)
 >>>>>> TLV:
 >>>>>>   type       = "MNC PCS Digit Include Status" (0x29)
 >>>>>>   length     = 5
 >>>>>>   value      = A8:01:A8:01:01
 >>>>>>   translated = [ mcc = '424' mnc = '424' includes_pcs_digit = 
'yes' ]
 >>>>>> TLV:
 >>>>>>   type       = "Current PLMN" (0x12)
 >>>>>>   length     = 12
 >>>>>>   value      = A8:01:A8:01:07:34:32:34:2D:34:32:34
 >>>>>>   translated = [ mcc = '424' mnc = '424' description = '424-424' ]
 >>>>>> TLV:
 >>>>>>   type       = "Data Service Capability" (0x11)
 >>>>>>   length     = 2
 >>>>>>   value      = 01:0B
 >>>>>>   translated = { [0] = 'lte '}
 >>>>>> TLV:
 >>>>>>   type       = "Serving System" (0x01)
 >>>>>>   length     = 6
 >>>>>>   value      = 01:01:01:02:01:08
 >>>>>>   translated = [ registration_state = 'registered' 
cs_attach_state = 'attached' ps_attach_state = 'attached' 
selected_network = '3gpp' radio_interfaces = '{ [0] = 'lte '}' ]
ModemManager[11185]: <debug> [1461671260.670856] 
[mm-broadband-modem-qmi.c:4607] common_process_serving_system_3gpp(): 
Processing 3GPP info...
ModemManager[11185]: <info>  [1461671260.671082] 
[mm-iface-modem-3gpp.c:1171] update_registration_state(): Modem 
/org/freedesktop/ModemManager1/Modem/0: 3GPP Registration state changed 
(roaming -> registering)
ModemManager[11185]: <info>  [1461671260.671336] 
[mm-iface-modem-3gpp.c:1096] 
update_registration_reload_current_registration_info_ready(): Modem 
/org/freedesktop/ModemManager1/Modem/0: 3GPP Registration state changed 
(registering -> home)
ModemManager[11185]: <debug> [1461671263.072413] [mm-port-serial.c:1288] 
mm_port_serial_open(): (ttyUSB2) device open count is 2 (open)
ModemManager[11185]: <debug> [1461671263.072658] 
[mm-port-serial-at.c:459] debug_log(): (ttyUSB2): --> 'AT!GSTATUS?<CR>'
ModemManager[11185]: <debug> [1461671263.092805] 
[mm-port-serial-at.c:459] debug_log(): (ttyUSB2): <-- '<CR><LF>!GSTATUS: 
<CR><LF>Current Time: 1518\9\9Temperature: 40<CR><LF>Bootup Time: 
0\9\9Mode:        ONLINE         <CR><LF>System mode: LTE        \9PS 
state:    Attached     <CR><LF>LTE band:      B13    \9\9LTE bw:      5 
MHz   <CR><LF>LTE Rx chan:   5230\9\9LTE Tx chan: 23230<CR><LF>EMM 
state:     Registered     \9No Cell        <CR><LF>RRC state:     RRC 
Idle       <CR><LF>IMS reg state: No Srv \9\9<CR><LF><CR><LF>RSSI 
(dBm):    -87\9\9Tx Power:    0<CR><LF>RSRP (dBm):    -106\9\9TAC: 0001 
(1)<CR><LF>RSRQ (dB):     -6\9\9Cell ID: 00000100 (256)<CR><LF>SINR 
(dB): 19.2<CR><LF><CR><LF><CR><LF>OK<CR><LF>'
ModemManager[11185]: <debug> [1461671263.093076] [mm-port-serial.c:1345] 
_close_internal(): (ttyUSB2) device open count is 1 (close)
ModemManager[11185]: [/dev/cdc-wdm0] Received message...
 >>>>>> RAW:
 >>>>>>   length = 18
 >>>>>>   data   = 01:11:00:80:03:02:04:00:00:02:00:05:00:10:02:00:B5:08
ModemManager[11185]: [/dev/cdc-wdm0] Received message (translated)...
 >>>>>> QMUX:
 >>>>>>   length  = 17
 >>>>>>   flags   = 0x80
 >>>>>>   service = "nas"
 >>>>>>   client  = 2
 >>>>>> QMI:
 >>>>>>   flags       = "indication"
 >>>>>>   transaction = 0
 >>>>>>   tlv_length  = 5
 >>>>>>   message     = "Event Report" (0x0002)
 >>>>>> TLV:
 >>>>>>   type       = "Signal Strength" (0x10)
 >>>>>>   length     = 2
 >>>>>>   value      = B5:08
 >>>>>>   translated = [ strength = '-75' radio_interface = 'lte' ]
ModemManager[11185]: <debug> [1461671266.334031] 
[mm-broadband-modem-qmi.c:7030] event_report_indication_cb(): Signal 
strength indication (lte): -75 dBm --> 62%
ModemManager[11185]: <debug> [1461671266.334135] [mm-iface-modem.c:1204] 
update_signal_quality(): Modem /org/freedesktop/ModemManager1/Modem/0: 
signal quality updated (62)

Diego López
Teltronic


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