HE910 Email attachment transmission time – comparison GSM UTRAN

17 thoughts on “HE910 Email attachment transmission time – comparison GSM UTRAN

  1. Hi,
     I just made some tests sending some emails with attachment (file size about 500 KByte) using the HE910. Surprisingly the file transmission time (about 5 minutes) is the same or sometimes even less when using GSM technology instead of UTRAN technology.
    Actually I thought and hoped that the transmission is ‘faster’ when using UTRAN technology.


    Is there a way to make the transmission in a UMTS Network faster, or is the described issue resulting from local network availabilities and signal quality?

    The transmission was tested in city area. The HE910 is using hardware flow control.


    Thank you,


    best regards

      1. After activation the PDP context I first enable SSL socket:




         Then SSL is configured by:








        Then I transmit the certificate and start the connection to the SMTP server




        Then I am using plain authentication for server login and the email text and attachment will be transmitted in online mode.


        Signal levels:


        GSM: -59 dBm

        UMTS: -84 dBm

        1. Maybe is something related with the handling of SSL, can you try a test over a normal unencrypted socket?

          1. Hi Cosmin,


            unfortunately we can’t test with an unencrypted socket. SMTP access requires an encrypted socket.


          2. Hi Eric,


            are you verifying the network condition during email transmition with #MONI, #SERVINFO commands?

            You can also check with #PSNT? which network type is used and if HSUPA is supported or not. This is working well on 12.00.xx5 firmware.

            Are you using the USB port?

          3. Hi Andrea,


            I just checked the network type with #PSNT?

             The HE910 is responding:


            #PSNT: 2,3,1,0,1,0


            So I conclude that HSUPA is available but not used. Is there a command for enabling HSUPA?


            USB interface is not used, the HE910 is interfaced with UART.

          4. The HSUPA channel is assigned by the network during a data connection, therefore you should check this during email sending but of course you cannot do it on UART port unless you use CMUX.

            5 minutes is the time needed to send the email from #SSLD or the time needed to transfer 500KB after the SSL hanshaking?



  2. 5 minutes is the duration from sending the first byte of the attachment file until the last byte of the file.


    During this time the effective transmission time is only about 2 minutes due to waiting time while the flow control pin is on high level.


    I tested with a M2Mair provided SIM and also with a Vodafone SIM. With the Vodafone SIM it takes 4:17 minutes for file tranmission in both cases (GSM / UMTS).

    1. Hello Eric,

      We will make some tests sending e-mails with AT#SSLD.
      I will let you know, when I have more info.


  3. Hello Eric,


    Configuring a bigger packet size with AT#SSLCFG should solve your problem.
    The dafault value is 300 bytes. If you are transfering biger amounts of data (like in your case 500k), this small packets creates a lot of overhead.

    I suggest you to try with a packet size of 1300 bytes (bigger packets will get fragmented).

    For instance:

    1. Hi Taj,


       thank you for your help and your suggestion. I will test it and will let you know about the test result.


      Kind regards

      1. Hi,


        I just tested file transmission with a packet size of 1300 bytes. Transmission time for 500kB is now about 90 seconds (for UMTS and GSM). I guess I can achieve even higher datarates when using higher UART baudrates (currently 115200 baud), but I will test this later. At the moment I am happy that file transmission is ‘quite faster’ than before.


        Kind regards

  4. Email attachments and SMTP over SSL/TLS with LE910 and LE920

    The AT command user guides of LE910 and LE920 and the §3.5 of the IP Easy User Guide seem to indicate that these modules do not support two things

    1) STMP over SSL/TLS

    2) Emails with attachments

    Could some one confirm that please?

    Or am I mistaken?

      1. Thank you for the reply Cosmin. Is it planned to introduce these features in these modules? Or should we look at other alternatives? Our SMTP server only works over SSL/TLS, so I am in a bit of a conundrum.

        1. The support for SMTP over SSL is planned for both LE910 and HE910, but is too early to talk about dates. 
          For the HE910, this feature should be included in the next official SW release, scheduled for 2H / 2015.
          I will let you know when an estimated release date will be available for the LE910.