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Thread: Decrease CSFB Delay

  1. #11
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    Default Re: Decrease CSFB Delay

    Quote Originally Posted by mounir34 View Post
    no Alerting because during the test we called the Operator server that why
    if we call normal number the Delay will be much higher
    Dude,
    so cell change from LTE to 3G during CSFB is 159 ms which in my opinion is very good
    the call will be setup in less than 2 sec which is very good as well
    there are other messages of RANAP &NBAP and IU/IUB resource allocation which we can not see from DT
    based on my experiences it is really a good call setup time
    what else you can check is the TN delay on Iub and IU to reduce the delay but believe me less than 2 sec is far good to spend your time on TN delay... others are normal messaging flow which causes delay

    anyway it is good to compare call setup time of CSFB with the user who camped on 3G and establishes call on 3G I don't think you will see a big difference

    cheers
    Last edited by babak1349; 2017-08-25 at 01:58 AM

  2. #12
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    Default Re: Decrease CSFB Delay

    ok thanks freind

    Quote Originally Posted by babak1349 View Post
    Dude,
    so cell change from LTE to 3G during CSFB is 159 ms which in my opinion is very good
    the call will be setup in less than 2 sec which is very good as well
    there are other messages of NBAP IU/IUB resource allocation which we can not you see
    based on my experiences it is really a good call setup time
    what else you can check is the TN delay on Iub and IU to reduce the delay but belive me less than 2 sec is far good to spend your time on TN delay... others are normall messaging flow which causes delay

    anyway it is good to compare call setup time of CSFB with the user who camped on 3G and establishes call on 3G I don't think you will see a big difference

    cheers

  3. #13
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    Default Re: Decrease CSFB Delay

    Quote Originally Posted by mounir34 View Post
    ok thanks freind
    another point.. if your using IP RAN you may consider implementation of QOS in order to give higher priority on signaling on TN but it may help in congested TN or with high load

  4. Thanks mounir34 thanked for this post
  5. #14
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    Default Re: Decrease CSFB Delay

    Quote Originally Posted by mounir34 View Post
    check the below call signaling the delay is high
    Extended service request ==> 4G_RRCConnectionRelease 205 ms
    4G_RRCConnectionRelease ==> 3G_RRCConnectionRequest 159 ms
    RRC Connection Request ==> Call Proceding 1.636 s
    Call Proceding ==> RRC Connection Release Complete 600s
    Hello. Time from call attempt (after the call button is pressed) to Extended service request is about 500ms. Is it normal or not? How decrease it?
    Attached Images Attached Images

  6. #15
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    Default Re: Decrease CSFB Delay

    One more question. Time from 4GRRCconnectionRelease to 3G RRCconnectionRequest is about 1000ms. How to decrease it?
    We use CSFB Blind redirection.
    Attached Images Attached Images
    Last edited by Karlson; 2018-01-17 at 09:56 PM

  7. #16
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    Default Re: Decrease CSFB Delay

    is better to use Flash CSFB

    Quote Originally Posted by Karlson View Post
    One more question. Time from 4GRRCconnectionRelease to 3G RRCconnectionRequest is about 1000ms. How to decrease it?
    We use CSFB Blind redirection.

  8. #17
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    Default Re: Decrease CSFB Delay

    Quote Originally Posted by Karlson View Post
    One more question. Time from 4GRRCconnectionRelease to 3G RRCconnectionRequest is about 1000ms. How to decrease it?
    We use CSFB Blind redirection.
    Is it Huawei Equpment?

    These parameters may help:

    · DeferMcReadInd: Whether SIB3 carries the Deferred measurement control reading support IE. the RNC carries the Deferred measurement control reading support IE in the SIB3. During the LTE-to-UMTS CSFB through redirections, the UE does not immediately read SIB 11 and SIB 11bis until it has accessed the network, which accelerates the access process and reduces the CSFB delay.

    · When PERFENH_SIB3_SCHEDULE_OPT_SWITCHH is set to ON, a new scheduling algorithm applies to system information blocks (SIBs) of UMTS, which shortens the scheduling period of SIB3. When PERFENH_SIB3_MAX_PEROID_LIMIT_SWITCH is set to OFF, the maximum scheduling period of SIB3 is 40,960 ms. When PERFENH_SIB3_MAX_PEROID_LIMIT_SWITCH is set to ON, the maximum period of SIB3 is 160 ms. These two methods optimize the scheduling of SIB3, which quickens UEs' access process and reduce the CSFB delay during the LTE-to-UMTS CSFB through redirections.

    · The PERFENH_DCH_TRCH_OPT_SWITCH switch enables the RNC to optimize the contents of the RB setup message during the LTE-to-UMTS CSFB through redirections or PS handovers, which quickens message transmission and reduces the CSFB delay.

    · PERFENH_CSFB_1ST_PS_AS_CSPS_COMB_SWITCH: Whether the RNC processes the first PS BE service set up by a CSFB UE in the same way as it processes a PS BE service in the CS+PS combined service. When this switch is set to on, the RNC processes the first PS BE service set up by a CSFB UE in the same way as it processes a PS BE service in the CS+PS combined service. The bearer channel type and initial data rate for the PS BE service are set by the "BeInitBitrateTypeforCsPs" parameter in the "SET UFRC" command. DRD for service steering (specified by the "ServiceDiffDrdSwitch" parameter in the "SET UDRD" command) takes the CS service as the highest priority service for selecting a cell. When this switch is set to off, the RNC processes the first PS BE service set up by a CSFB UE in the same way as it processes a single PS service.

    · CSFB_UE_DELAY_RAU_SWITCH: When the RNC delays the transmission of a routing area update message to the CN in the following scenario: A CS service on an LTE network is transferred to a UMTS network by CS fallback (CSFB) and the CS service has not established on the UMTS network. The UE has sent a DIRECT TRANSFER or INITIAL DIRECT TRANSFER message to the CN.
    o 1: This switch is turned on. The RNC sends a routing area update message to the CN only after it receives a RADIO BEARER SETUP COMPLETE message or after "Delayed Routing Area Update Timer for CSFB UEs" expires.
    o 0: This switch is turned off. The RNC does not delay the transmission of the routing area update message.

    · CSFB_UE_CS_IMEI_QUERY_DISABLE_SWITCH: Whether the RNC initiates the IMEI-based Identity Request procedure before the CS service is established on the UMTS network in the case of CSFB.
    o 1: This switch is turned on. The RNC does not initiate the IMEI-based Identity Request procedure.
    o 0: This switch is turned off. The RNC initiates the IMEI-based Identity Request procedure.

    · CSFB_DELAY_OPT_ENH_SWITCH: Whether the enhancement of CSFB delay optimization is enabled. When this switch is set to ON, the RNC uses an existing method as well as RRC messages to identify CSFB UEs.
    o 1: Indicates that this switch is set to ON. The RNC optimizes the CSFB delay of all identified CSFB UEs by delaying routing area updates (RAUs) for these CSFB UEs and by not querying these CSFB UEs' CS IMEIs. All identified CSFB UEs include the CSFB UEs that are identified by using the existing method and RRC messages.
    o 0: Indicates that this switch is set to OFF. The RNC optimizes the CSFB delay of only CSFB UEs that are identified by using the existing method.

  9. #18
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    Default Re: Decrease CSFB Delay

    Thank you. I will try this settings.

    Quote Originally Posted by mounir34 View Post
    is better to use Flash CSFB
    It is impossible for us. We use blind redirection without neighboor cell, only utran frequency. Is Flash CSFB possible for blind redirection without neighboor cells?

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