Using 5G cellular

Ten64 Forum
1

I’ve been testing a SIM8200EA modem in this box now.
I can get it to connect to my provider both under OpenWRT, and under Fedora.
However I am not getting great speeds…

[root@fonzie ~]# speedtest-cli
Retrieving speedtest.net configuration...
Testing from Swisscom (178.197.236.173)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by TelemaxX Telekommunikation GmbH (Karlsruhe) [236.72 km]: 45.944 ms
Testing download speed................................................................................
Download: 57.28 Mbit/s
Testing upload speed......................................................................................................
Upload: 48.92 Mbit/s

mmcli -m 0 shows me that 5g is enabled and preferred. However, the 5G bands are not shown…

[root@fonzie ~]# mmcli -m 0
  -----------------------------------
  General  |                    path: /org/freedesktop/ModemManager1/Modem/0
           |               device id: 2e07f1d9e9addb271e0d18946a5a5fc4b8325bbd
  -----------------------------------
  Hardware |            manufacturer: QUALCOMM INCORPORATED
           |                   model: 0
           |       firmware revision: MPSS.HI.2.0.c3-00180.2-SDX55_CPEALL_PACK-1  1  [Oct 02 2020 10:00:00]
           |          carrier config: Swiss-Comm
           | carrier config revision: 0A010411
           |            h/w revision: 20000
           |               supported: gsm-umts, lte, 5gnr
           |                 current: gsm-umts, lte, 5gnr
           |            equipment id: 864284040121233
  -----------------------------------
  System   |                  device: /sys/devices/platform/soc/3110000.usb/xhci-hcd.2.auto/usb4/4-1/4-1.2
           |                 drivers: option, qmi_wwan
           |                  plugin: simtech
           |            primary port: cdc-wdm0
           |                   ports: cdc-wdm0 (qmi), ttyUSB0 (qcdm), ttyUSB1 (gps),
           |                          ttyUSB2 (at), ttyUSB3 (at), ttyUSB4 (audio), wwan0 (net)
  -----------------------------------
  Status   |                    lock: sim-pin2
           |          unlock retries: sim-pin (3), sim-puk (10), sim-pin2 (3), sim-puk2 (10)
           |                   state: connected
           |             power state: on
           |             access tech: lte
           |          signal quality: 100% (cached)
  -----------------------------------
  Modes    |               supported: allowed: 3g; preferred: none
           |                          allowed: 4g; preferred: none
           |                          allowed: 3g, 4g; preferred: 4g
           |                          allowed: 3g, 4g; preferred: 3g
           |                          allowed: 5g; preferred: none
           |                          allowed: 3g, 5g; preferred: 5g
           |                          allowed: 3g, 5g; preferred: 3g
           |                          allowed: 4g, 5g; preferred: 5g
           |                          allowed: 4g, 5g; preferred: 4g
           |                          allowed: 3g, 4g, 5g; preferred: 5g
           |                          allowed: 3g, 4g, 5g; preferred: 4g
           |                          allowed: 3g, 4g, 5g; preferred: 3g
           |                 current: allowed: 4g, 5g; preferred: 5g
  -----------------------------------
  Bands    |               supported: utran-1, utran-3, utran-4, utran-6, utran-5, utran-8,
           |                          utran-2, eutran-1, eutran-2, eutran-3, eutran-4, eutran-5, eutran-7,
           |                          eutran-8, eutran-12, eutran-13, eutran-14, eutran-17, eutran-18,
           |                          eutran-19, eutran-20, eutran-25, eutran-26, eutran-28, eutran-29,
           |                          eutran-30, eutran-32, eutran-34, eutran-38, eutran-39, eutran-40,
           |                          eutran-41, eutran-42, eutran-43, eutran-48, eutran-66, eutran-71
           |                 current: utran-1, utran-3, utran-4, utran-6, utran-5, utran-8,
           |                          utran-2, eutran-1, eutran-2, eutran-3, eutran-4, eutran-5, eutran-7,
           |                          eutran-8, eutran-12, eutran-13, eutran-14, eutran-17, eutran-18,
           |                          eutran-19, eutran-20, eutran-25, eutran-26, eutran-28, eutran-29,
           |                          eutran-30, eutran-32, eutran-34, eutran-38, eutran-39, eutran-40,
           |                          eutran-41, eutran-42, eutran-43, eutran-48, eutran-66, eutran-71
  -----------------------------------
  IP       |               supported: ipv4, ipv6, ipv4v6
  -----------------------------------
  3GPP     |                    imei: 864284040121233
           |           enabled locks: fixed-dialing
           |             operator id: 22801
           |           operator name: Swisscom
           |            registration: home
  -----------------------------------
  3GPP EPS |    ue mode of operation: csps-1
           |     initial bearer path: /org/freedesktop/ModemManager1/Bearer/0
           |      initial bearer apn: GPRS.SWISSCOM.CH
           |  initial bearer ip type: ipv4
  -----------------------------------
  SIM      |        primary sim path: /org/freedesktop/ModemManager1/SIM/1
           |          sim slot paths: slot 1: /org/freedesktop/ModemManager1/SIM/0
           |                          slot 2: none (active)
  -----------------------------------
  Bearer   |                   paths: /org/freedesktop/ModemManager1/Bearer/1

Only the LTE bands are shown, not the newer 5G NR. But that could be a ModemManager issue?

Note that where I live 5G uses the n1 band.

Is there something I overlooked? Something I need to set?

2

It sounds like the modem is only using LTE. It’s difficult to tell exactly what is happening from ModemManager or qmicli alone as they don’t expose enough information for 5G yet.

At the very least you should be able to get signal info from qmicli.
This has to be done while a download is active, in non-standalone mode (NSA) the modem will only maintain a 5G connection when there is traffic.

qmicli -d /dev/cdc-wdm0 -p --nas-get-signal-info
[/dev/cdc-wdm0] Successfully got signal info
LTE:
        RSSI: '-66 dBm'
        RSRQ: '-18 dB'
        RSRP: '-98 dBm'
        SNR: '3.0 dB'

5G:
        RSRP: '-94 dBm'
        SNR: '21.0 dB'
        RSRQ: '-12 dB'

qmicli -d /dev/cdc-wdm0 --nas-get-tx-rx-info=5gnr
[/dev/cdc-wdm0] Successfully got TX/RX info
RX Chain 0:
        Radio tuned: 'yes'
        Power: '-81.9 dBm'
        ECIO: '-12.0 dB'
        RSRP: '-93.9 dBm'
        Phase: '0.00 degrees'
RX Chain 1:
        Radio tuned: 'yes'
        Power: '-88.3 dBm'
        ECIO: '-14.3 dB'
        RSRP: '-102.6 dBm'
        Phase: '0.00 degrees'
RX Chain 2:
        Radio tuned: 'yes'
        Power: '-83.7 dBm'
        ECIO: '-14.8 dB'
        RSRP: '-98.4 dBm'
        Phase: '0.00 degrees'
RX Chain 3:
        Radio tuned: 'yes'
        Power: '-103.0 dBm'
        ECIO: '-14.2 dB'
        RSRP: '-117.2 dBm'
        Phase: '0.00 degrees'
TX:
        In traffic: 'yes'
        Power: '0.0 dBm'

If you open up a minicom session to one of the AT tty’s (ttyUSB2 or ttyUSB3) you can get a bit more information:

# If AT+COPS? returns "7" as the network code instead of "13", you are on LTE only.
AT+COPS?
+COPS: 0,0,"Vodafone AU",13

#AT+CPSI is the SIMCOM command for network status
AT+CPSI?
+CPSI: LTE,Online,505-03,0xA130,294933,235,EUTRAN-BAND3,1800,5,5,-96,-959,-602,8
+CPSI: NR5G,235,636192,-11,-83,148

This could be part of the issue. There is limited support in the first generation of 5G cards (like the SIM8200) for non-standalone combinations apart from the ‘typical’ N41 (2.5GHz) or N77/N78 (3.5GHz).
They will only connect to the other 5G bands in full 5G standalone mode.
Your operator likely has dynamic spectrum sharing (DSS) on N1 so you will still get an LTE connection with similar speeds.

3

Thanks. I just wanted to exclude that I had missed something obvious. I do intend to take the box with me to a place with proper 5G reception.
Here in Switzerland Swisscom operates two kinds of 5G, the first one just uses a recycled frequency (hence the n1) band, and they did that so they could claim to cover the whole country by just rolling a software update on all their cell towers (or something like that).
The other kind they call 5G+, and it uses the n78 band.

I also noticed that minicom is not very reliable when communicating with the modem. I switched to socat, and now no longer get truncated output.