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  1. #1
    Nokia Developer Expert
    Join Date
    Dec 2006
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    Mountain View, CA
    Posts
    197

    WLAN U-APSD settings for VoIP and Video applications

    Overview:

    S60 3rd Edition devices with WLAN capability provide support for U-APSD (Unscheduled Automatic Power Save Delivery) scheme, part of WLAN QoS standard 802.11e/WMM. U-APSD is a power save scheme optimized for real-time applications transferring full-duplex data over WLAN (such as VoIP). By classifying outgoing IP traffic as 'Voice' data, these types of applications can increase battery life by approximately 25% and minimize transmit delays.

    Detailed description:

    With normal (non-voice) traffic, each transmitted packet causes the WLAN driver to switch from power save (PS) to active mode. PS mode is re-enabled 100ms after there are no more packets to send. While this is suitable for typical network usage, VoIP traffic would cause the WLAN to constantly stay in active mode.

    Furthermore, a WLAN device in (legacy) PS mode must wait for a 'beacon' signal from the access point and then poll for any incoming packets. Access point sends these signals at 100ms intervals.

    When traffic is classified as Voice data, the WLAN device can stay in (U-APSD) power save mode during transmit. Also, delivery of incoming packets is triggered by sent packets, thus minimizing the delay caused by separate polling.


    Solution:

    In order to set the Access Category to Voice (AC_VO), DSCP QoS bits of outgoing IP packet headers (TOS field in IPv4, TC in IPv6) must be modified.

    This can be done at socket level (RSocket) as follows:

    iSocket.SetOpt( KSoIpTOS, KProtocolInetIp, 0xE0 );

    After this, the WLAN driver will recognize sent packets as belonging to the Voice Access Category. U-APSD power save scheme will be enabled, provided that it is supported also by the WLAN access point.


    https://pro.forum.nokia.com/viewSolu...928&action=rss

  2. #2
    Registered User
    Join Date
    Apr 2007
    Posts
    4

    Unhappy Re: WLAN U-APSD settings for VoIP and Video applications

    Hi,

    maybe I'm off-topic, but your help could be helpful for us.

    I'm trying to get working an E65 with 3Com wireless infrastructure and an Asterisk's based pbx.

    It works, means that I'm able to place and receive calls, but, the big problem is the battery. Starting from full-charged battery it lasts in about 6-7 hours without any active calls, just stand-by. Without VoIP (and then WLAN active) it last in three days, so, big difference.

    When WLAN is active, the Active Connections application show me that TX power is always 50mW, also when AP is placed on my desk.

    Am I doing something wrong? Is there some hidden settings? The problem came from wireless infrastructure or from the phone?

    Another thing is that when I enable the WMM in the AP the phone is able to place and receive calls, but, after 15 seconds the connection is dropped; then, to get it back the only way is to disconnect from WLAN and reconnect again.

    Thanx in advance.

  3. #3
    Nokia Developer Expert
    Join Date
    Dec 2006
    Location
    Mountain View, CA
    Posts
    197

    Re: WLAN U-APSD settings for VoIP and Video applications

    It works, means that I'm able to place and receive calls, but, the big problem is the battery. Starting from full-charged battery it lasts in about 6-7 hours without any active calls, just stand-by. Without VoIP (and then WLAN active) it last in three days, so, big difference.
    It seems from this text that phone does not go to sleep-mode-at all. Which VoIP client are you using?

    When WLAN is active, the Active Connections application show me that TX power is always 50mW, also when AP is placed on my desk.
    This was very little impact.

    Am I doing something wrong? Is there some hidden settings? The problem came from wireless infrastructure or from the phone?
    Please make sure that you have power save on. Have you manually switched off the power save? Tools/Settings/Connection/WLAN/Options/Advanced Settings/Power saving. I would recomment to keep it on (Default value)


    Similar power save IOT issue has been noticed on WLAN access points using Broadcom chip. These access points mark on the beacon that AP has data to be sent to the terminal, even AP has nothing to send. This causes that phone tries to retrive data all the time and does not go to the sleep mode at all. This is fixed in latest firmware releases. I would suggest to upgrade the SW of your AP to the latest version.

    I would expect that the problem is in the area of battery save and it is some kind of IOT problem between the phone and WLAN AP. Battery life is close 6-7h when in active mode 100% of the time. Traces and phone (model & sw release), VoIP client and version number, WLAN AP model & sw release information would help to investigate this.

  4. #4
    Super Contributor
    Join Date
    Jun 2005
    Location
    Berlin
    Posts
    721

    Re: WLAN U-APSD settings for VoIP and Video applications

    would the battery life be increased, if the transmitpower of Wlan is set from 100mW to 4mW?

    If yes, how much?


    another question is:

    Why does the Nokia SIP Client not use the U-APSD? The ToS Flag in IP package is set to 0xB8, instead of 0xE0.



    Thanks

    Pai
    Symbian && Android && iPhoneOS

  5. #5
    Registered User
    Join Date
    Jun 2009
    Posts
    6

    Re: WLAN U-APSD settings for VoIP and Video applications

    I tried several providers, http://www.voipsipsdk.com worked teh best for me.

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