EM7455 Can't get more than 0.26Mbps up

IoT Modules MC/EM Series
1

I’ve been struggling with an embedded EM7455 device for several months now and after trying a whole host of options, I’m throwing myself at the mercy of other experts for help. The EM7455 is installed in an embedded edge device (Core i7) that runs Ubuntu 18.04 server. Nothing magical here.

I’ve had terrible upload speeds from this device from the start. No matter what we do the upload speed is ALWAYS 0.26Mbps via speedtest-cli. We initially tried an external antenna, basic omnidirectional antenna mounted to a large metal cabinet with a great ground plane. Results were the same, 0.26Mbps upload.

We tried changing the firmware to generic from the stock Verizon firmware. Same, 0.26Mbps. We ensured that we were using the latest firmware from Sierra Wireless, SWI9X30C_02.33.03.00, no change - 0.26Mbps. We’ve tried different versions of ModemManager, no change. We even thought it might be the device itself so we ordered 2 new EM7455s, also no change.

Most recently we installed a Wilson Wideband 8.5dBi directional antenna and no matter where we aimed it, 0.26Mbps. Download speeds with the Wilson improved a lot - 30Mbps.

Thinking that perhaps we were just in a bad area, though, we tethered the device to a phone on the same network. We were able to get 5/5Mbps via Wifi, tethered. So that told us that it wasn’t some strange network/propagation issue, and that it was actually possible to get decent speeds.

So why is this EM7455 stuck at 0.26Mbps?! Help!

Thanks… Sam

2

@sam1220

So could you send the below to the unit and post the log file with all of the responses.

ati
at!priid?
at!gstatus?
at!lteinfo?
at+cgdcont?
at+cgpaddr=1
at+cops?
at+cops=?

Also with regards the host system how are you making the connection? What I mean by this are you using modemmanager (really need to uninstall this), performing a PPP dial up, QMI API’s, AT!SCACT, etc?

Regards

Matt

3

Thanks @mlw.

I tried to run some of these in minicom and the responses I get from the modem seem to be truncated:

!GSTATUS:
Current Time: 1012636 Temperature: 55
Reset Counter: 1 Mode: ONLINE
System mode: LTE

!LTEINFO:
Serving: EARFCN MCC MNC TAC CID Bd D U SNR PCI RSRQ RSRP RSSI RXLV
2050 311 480 25614 0187B52A 4 5 5 6 448 -10.0 -115.5 -86.1 –

IntraFreq: PCI RSRQ RSRP RSSI RXLV
448 -10.0 -115.5 -86.1 –

InterFreq: EARFCN ThresholdLow Threshol

Any idea what I am doing wrong that they are getting cut off?

And to answer one question, yes, I’m using modemmanager.

Sam

4

@sam1220

I am guessing the cut off is occurring because of the terminal you are using.

The big question I need to understand is how are you starting the IP data session?

Regards

Matt

5

Thanks again, Matt @mlw.

I’m sorry, this is one area that I’m not really as well versed on as I should be. I’m not new to Linux, but the EM7455 is a new device to me. We’re connecting using Modemmanager just using the simple-connect command from the CLI.

Once we connected and it created a connection file we edited it to allow it to autostart on boot.

Is there a better way?

6

FInally got this figured out, too. Here are the results. The signal levels show that they are worse than poor, but the unit will connect and we can get DL speeds of 30Mbps. But again, even with a high gain yagi we get nothing more than 0.26Mbps upload, yet a laptop tethered to an iphone on the same network gets at least 5Mbps synchronous.

Manufacturer: Sierra Wireless, Incorporated
Model: EM7455
Revision: SWI9X30C_02.33.03.00 r8209 CARMD-EV-FRMWR2 2019/08/28 20:59:30
MEID: A00000AC911DFD
ESN: 12802151217, 8020D331
IMEI: 
IMEI SV: 20
FSN: LF015547080310
+GCAP: +CGSM


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_02.32.11.00_00_GENERIC_002.064_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

OK

!GSTATUS: 
Current Time:  1306897          Temperature: 73
Reset Counter: 1                Mode:        ONLINE         
System mode:   LTE              PS state:    Attached     
LTE band:      B2               LTE bw:      10 MHz  
LTE Rx chan:   1000             LTE Tx chan: 19000
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:  -85              RSRP (dBm):  -112
PCC RxD RSSI:  -97              RSRP (dBm):  -140
Tx Power:      --               TAC:         640E (25614)
RSRQ (dB):     -13.4            Cell ID:     0187B52C (25670956)
SINR (dB):      6.6


OK

!LTEINFO: 
Serving:   EARFCN MCC MNC   TAC      CID Bd D U SNR PCI  RSRQ   RSRP   RSSI RXLV
             1000 311 480 25614 0187B52C  2 3 3  10 448 -12.6 -111.1  -77.0 --

IntraFreq:                                          PCI  RSRQ   RSRP   RSSI RXLV
                                                    448 -12.6 -111.1  -77.0 --

InterFreq: EARFCN ThresholdLow ThresholdHi Priority PCI  RSRQ   RSRP   RSSI RXLV

WCDMA:     UARFCN ThreshL ThreshH Prio PSC   RSCP  ECN0 RXLV

OK

+CGDCONT: 1,"IPV4V6","ims","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
+CGDCONT: 2,"IPV4V6","vzwadmin","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
+CGDCONT: 3,"IPV4V6","ne01.VZWSTATIC","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
+CGDCONT: 4,"IPV4V6","vzwapp","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
+CGDCONT: 5,"IPV4V6","vzw800","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0
+CGDCONT: 6,"IPV4V6","vzwclass6","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0,0,0

OK

+CGPADDR: 1,38.0.16.2.17.48.37.80.0.0.0.0.92.235.82.150

OK

+cops: 0,0,"Verizon ",7

OK

+cops: (2,"Verizon ","Verizon ","311480",7),(1,"Extended Network","Extended","310410",2),(3,"311 490","311 490","311490",7),(3,"T-Mobile","T-Mobile","310260",7),(3,"T-Mobile","T-Mobile","310260",2),(1,"Extended Network","Extended","310410",7),(1,"313 100","313 100","313100",7),,(0,1,2,3,4),(0,1,2)
7

@sam1220

So try the attached file, it was written for an old unit but the same mechanisms and principles apply.

1aec569af75a1ab07c66bf85086071fc482f614b.docx (347.1 KB)

Regards

Matt

8

I believe @mlw’s question was about the kind of network connection being setup. In the case of ModemManager, you could have the connection done either in QMI, MBIM or AT+PPP, MM can handle all those, and it all depends on how the modem is exposed in your kernel. If you have a QMI interface it will do QMI, if you have a MBIM interface it will do MBIM, and if you don’t have any of those (e…g you’re not building those drivers in your system) then MM will fallback to AT+PPP.

If you run mmcli -m 0 you’ll see the list of ports and kernel drivers in use, and that will give you a hint of the type of connection being setup.

9

A very simple way to move from DirectIP to QMI is also to use ModemManager. ModemManager users using old modules like the MC7710 in DirectIP mode can use newer modules in QMI mode without needing to do anything in their setup, MM handles both protocols nicely. :wink: