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  1. #1
    Registered User
    Join Date
    May 2008
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    7

    Cool IP Performance of Nokia 3G Handsets

    Hello Nokia Experts,

    I hope that this is the correct place to ask the following questions. If not, I will place in the VoIP area.

    Anyway, my questions relates to the different performance capabilities of Nokia handsets with respect to the quality of 3G packet data (IP) service.

    For 5 months I have been testing the quality of VoIP via 3G/UMTS on a Nokia N95 8GB. I have found that over this time the quality of voice calls via the VoIP client on the N95 8GB to be good to very good. In fact we have found it to be comparable to a normal circuit switched call. The used codec was G729a with a 40 msec payload cycle.

    I then decided to carry out the same test with a E51 handset.
    Using the same procedure as with the N95, it was found that the voice quality was no where as good. In fact, I found that as I walked around the office I could cause the speech to break up at more or less the same location every time. It is highly repeatable. On both handsets the signal strength display was full strength.

    To carry out some further testing, I then connected, via the usb cable, a laptop pc running a SIP softphone. I then carried out similar tests. That is, make a voice call via the laptop and walk around the office. ! The results, however, were the same. N95 was perfect and E51 breaking up in the same locations.

    So, my questions to the Nokia experts are, should the 3G packet data capabilities of these two phones be the same? Are the handsets working as designed or is it an issue?

    It is my feeling that the E51 does not handle reflections as well as the N95. Also, from the testing I have done, with the correct handset (N95 8GB) doing VoIP on 3G (In Australia on Telstra's Next G network) can be done, and to an acceptable voice quality.

    BTW, I will be testing a Nokia 6120 after I find a suitable VoIP client to load.

    Regards,

    Steve

  2. #2
    Super Contributor
    Join Date
    Mar 2003
    Location
    Finland
    Posts
    9,569

    Re: IP Performance of Nokia 3G Handsets

    In the case of the E51, you have one processor handling both telephony side and Symbian/S60.

    The N95 is a dual processor design with a dedicated telephone (baseband) processor and a separate application processor for Symbian/S60.

    That hardware design difference might be enough to impact the VoIP software behaviour (the single-CPU device will have to do much more work alone than the dual-CPU device which spreads the load across the processors).

  3. #3
    Registered User
    Join Date
    May 2008
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    7

    Re: IP Performance of Nokia 3G Handsets

    Hello petrib,

    Thanks for that. It could be..

    The only issue I have with that is, that the result was exactly the same when running the VoIP client on my laptop and the phone was acting as a USB Modem. I then did the same test on an el cheapo USB 3G dongle modem ands laptop and it was ok.

    I then did the test via WLAN and both handsets appeared to have the same performance. If it were a CPU issue, should it also be evident on WLAN?

    The next test that I did was the most interesting.

    I down loaded the "TiviPhone" and retested again.
    This time rather than have the speech "break" up with periods of silence, I got sections of speech that was repeated.

    That could indicate two things, firstly it would appear that multiple RTP packets could be present. Secondly the TiviPhone must not be checking sequence numbers in the rtp stream before playing them. Maybe the Nokia client does, and that could explain the periods of silence rather than repeated speech.

    Anyway, I would be good if someone from Nokia could give me some feed back on this issue. I would like to know if this is as you suggest, related to dual CPUs or something else.

    Thanks,

    Steve

  4. #4
    Registered User
    Join Date
    May 2008
    Posts
    7

    Re: IP Performance of Nokia 3G Handsets

    Hello,

    An update for this issue. Further testing leads me to believe that the performance of the Nokia handsets in this regards is affected by which band the handset operates in. I found that, in Australia, if I manually select the "Operator" to be "3Telstra" then the performance was the same (E51 and 6120) as the N95 8GB. When the "Operator" was set to be "Telstra" then I had the issues.

    The difference is "3Telstra" operates on the 2100 Mhz band and "Telstra" operates on the 850 MHz band. The N95 8GB does 2100 MHz only.

    As I am not a RF engineer, my question is:

    From a theoretical point of view should IP performance of the Nokia handsets be the same in either the 850 MHz or the 2100 MHz bands? Because it does not appear to be.

    Regards,

    Steve

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