EM7455 Slow Upload - 400kbps, site-specific

IoT Modules MC/EM Series
1

Here’s the situation – Brand new, fresh install of Ubuntu 20.04 from ISO in our office and the modem works fine. 30M down, 30Mish up. Consistent. Steady. Great. No issues at all.

Take it to the site, about 30-35 miles away. MAJOR urban area, city, lots of sites. 30M down, 0.4M up. Steady, consistent, never moves. I can’t get any decent upload speeds. Its the same SIM, same hardware, same EVERYTHING that was working 30M/30M just 45 minutes earlier, but when it gets to the new location the upload speeds are non-existent.

So, I check AT!GSTATUS and see that my SINR is low, 6-8. I create some band plans based on cellmapper info since I know that I have a tower with Bands 2, 5, 13, and 66 nearby. B2 is no good, SINR is typically around 5. So I change my band plan to 5 and 13. AT!RESET and reboot.

Now I’m on B5 and everything (to me) looks great:

!GSTATUS: 
Current Time:  848              Temperature: 37
Reset Counter: 3                Mode:        ONLINE         
System mode:   LTE              PS state:    Attached     
LTE band:      B5               LTE bw:      10 MHz  
LTE Rx chan:   2560             LTE Tx chan: 20560
LTE CA state:  NOT ASSIGNED
EMM state:     Registered       Normal Service 
RRC state:     RRC Connected  
IMS reg state: Full Srv         IMS mode:    Normal       

PCC RxM RSSI:  -62              RSRP (dBm):  -86
PCC RxD RSSI:  -63              RSRP (dBm):  -86
Tx Power:      -15              TAC:         6701 (26369)
RSRQ (dB):     -11.3            Cell ID:     018C2625 (25962021)
**SINR (dB):     17.6**

And then my speedtest:

Hosted by Sprint (Springfield, MA) [22.29 km]: 52.641 ms
Testing download speed................................................................................
Download: 31.60 Mbit/s
Testing upload speed......................................................................................................
Upload: 0.40 Mbit/s

What am I missing here? How does it work great in one location, but as soon as I take a 30 mile drive the thing isn’t worth a darn for upload speeds? It can’t be a software issue, because it works fine in our office. It has nothing to do with the SIM, it’s the same SIM. The antenna is even the same, except at the current location it’s mounted higher and on a better ground plane.

2

Hi @sean ,
There could be lots of variables that can hinder the speed. It may not be due to the modules. Could be the location conditions as you shared the new location is more crowded/lots of site…Have you tried the another SIM (of the other operator) on new location. How is the upload speed?
Sierra provides Diversity Antenna which is the second antenna for improved performance. You can get the reference at
https://source.sierrawireless.com/resources/airprime/application_notes_and_code_samples/airprime-diversity_and_mimo_second_antenna-application_note/#sthash.qLFCJrYO.dpbs
Again, the module provides the perfect speeds on the location but not the other it cannot be module issue. Also double check with operator if they got same your problem.
Please share if you have any concerns.
Thanks

3

Thank you @Vianney.

Is there anything we can check, any AT command output, any log file, or any method at all to pinpoint the carrier or congestion as the cause? I’d like to have something concrete to reference if we need to get the carrier involved.

We currently have a MIMO antenna on it.

Thanks.

4

Hi @sean ,
You can provide !GSTATUS information and speedtest on your office and new location to the carrier for the comparison. It provides the necessary parameters (Cell ID, SINR, RSSI…) for more investigation. Also please check whether the module is upgraded to latest FW which is posted
https://source.sierrawireless.com/resources/airprime/minicard/74xx/airprime-em_mc74xx-approved-fw-packages/#sthash.ZZqYsThU.dpbs

Please share if you have any concerns
Thanks

5

@Vianney,

I may have narrowed it down. We have 5 devices in the same area. Yesterday I took 1 that had consistent, slow download speeds (0.4Mbps) to a site that was working perfectly (20M up / 20M down). The slow device was slow at the other site, too, with the same antenna.

The only thing I see different between the 2 is the firmware. When I look at the firmware and hardware revisions of both this is what I see:

Working Device
Model EM7455
Firmware SWI9X30C_02.33.03.00
HW Revision EM7455

NON-Working (slow) Device
Model EM7455
Firmware SWI9X30C_02.33.03.00 r8209 CARMD-EV-FRMWR2 2019/08/28 20:59:30
HW Revision “1.0”

I tried to re-flash with the latest firmware for Verizon and it still shows “SWI9X30C_02.33.03.00 r8209 CARMD-EV-FRMWR2 2019/08/28 20:59:30”.

Could there be something special about these devices? Could they be some kind of sample that doesn’t have the full capabilities or bands? Is there someway I can get them to flash to just SWI9X30C_02.33.03.00?

6

Hi @sean,

Can you provide the response after sending AT!IMPREF? and AT!PRIID? command to your Working Device? According that, I can provide the suitable FW for your request

Thanks,

7

@Vianney

For the working device:

!IMPREF: 
 preferred fw version:    02.33.03.00
 preferred carrier name:  VERIZON
 preferred config name:   VERIZON_002.079_001
 preferred subpri index:  000
 current fw version:      02.33.03.00
 current carrier name:    VERIZON
 current config name:     VERIZON_002.079_001
 current subpri index:    000

OK

PRI Part Number: 9909765
Revision: 001.000
Customer: Generic-M2M

Carrier PRI: 9999999_9904780_SWI9X30C_02.33.03.00_00_VERIZON_002.079_001
Carrier PRI: 9999999_9904594_SWI9X30C_02.32.11.00_00_ATT_002.070_000
Carrier PRI: 9999999_9905153_SWI9X30C_02.24.05.06_00_BELL_001.005_000
Carrier PRI: 9999999_9904609_SWI9X30C_02.33.03.00_00_GENERIC_002.072_000
Carrier PRI: 9999999_9905151_SWI9X30C_02.24.03.00_00_ROGERS_001.001_000
Carrier PRI: 9999999_9904779_SWI9X30C_02.32.11.00_00_SPRINT_002.062_000
Carrier PRI: 9999999_9905152_SWI9X30C_02.32.11.00_00_TELUS_001.040_000
Carrier PRI: 9999999_9904930_SWI9X30C_02.24.03.00_00_VODAFONE_001.001_000

For the non-working device:

!IMPREF: 
 preferred fw version:    02.33.03.00
 preferred carrier name:  VERIZON
 preferred config name:   VERIZON_002.079_001
 preferred subpri index:  000
 current fw version:      02.33.03.00
 current carrier name:    VERIZON
 current config name:     VERIZON_002.079_001
 current subpri index:    000

OK

PRI Part Number: 9909765
Revision: 001.000
Customer: Generic-M2M

Carrier PRI: 9999999_9904780_SWI9X30C_02.33.03.00_00_VERIZON_002.079_001

OK

For the working device:

           |         manufacturer: Sierra Wireless, Incorporated
           |                model: EM7455
           |    firmware revision: SWI9X30C_02.33.03.00
           |       carrier config: default
           |         h/w revision: EM7455

For the non-working device:

       |.    manufacturer: Sierra Wireless, Incorporated
       |                model: EM7455
       |    firmware revision: SWI9X30C_02.33.03.00 r8209 CARMD-EV-FRMWR2 2019/08/28 20:59:30
       |       carrier config: default
       |         h/w revision: 1.0
8

Hi @sean,

I tried upgrading my EM7455 to the latest firmware for Verizon (link: https://source.sierrawireless.com/resources/airprime/minicard/74xx/airprime-em_mc74xx-approved-fw-packages/#sthash.VDE0no6I.dpbs ), Firmware revision and HW revison on my module is similar with your non-working device (Firmware revision: SWI9X30C_02.33.03.00 r8209 CARMD-EV-FRMWR2 2019/08/28 20:59:30 and HW revision: 1.0).

image

I have tried to do on 3 EM7455 modules, and the results are the same.

About your working and non-working device, assuming that you already did the same steps, same antenna, same SIM registering to the same network operator on the same area, then you observed that 2 results on two devices: working device with good speed as expected and non-working device with slow speed, right?

If yes, and based on the information you provided, the differences showed between your working device and your non-working device, specially on h/w revision. Maybe these are the causes of issue here.

Beside that, did you try restoring to Factory-calibrated configuration for your non-working device? If not, you can try to restore to default following steps:

a, AT!UNLOCK=“A710”
b, AT!RMARESET=0
c, Load FW you need to use

Please try to test again.

If this issue still happens, I think it’s better that you should consider contact your distributor to ask about these differences.

Thanks,

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