auto_art
2014-09-24, 02:16 PM
Overview : Some intelligent UEs on a live network send a Signaling Connection Release Indication (SCRI) message to the RNC after PS data transmission is complete. By sending the SCRI message, intelligent UEs request for a transition to idle mode or the CELL_PCH or URA_PCH state to reduce battery consumption. Upon receiving the SCRI, the RNC can release the signaling connection and put the UE into idle mode, or the RNC can maintain the signaling connection and put the UE to CELL_FACH or CELL_PCH/URA_PCH state.RSVDBIT1_BIT29 of the RsvdPara1 parameter in the SET URRCTRLSWITCH command controls the UE through CELL_FACH to CELL_PCH/URA_PCH or directly to CELL_PCH/URA_PCH. These procedures can reduce battery consumption, depending on the UE capability and feature activation on the RNC. By default, the RNC puts the UE into idle mode. A UE setting up PS services in idle mode consumes more signaling resources than that in the CELL_PCH or URA_PCH state. If there are a large number of UEs transited between idle mode and CELL_DCH state, signaling storms may occur. The EFD feature puts UEs into the CELL_FACH or CELL_PCH state to reduce signaling resource consumption and eliminate signaling storms.
Huawei provides a comprehensive end-to-end solution based on network characteristics to respond to network challenges. EFD is one component of the solution. This feature alone is not enough to eliminate signaling storms caused by intelligent UEs. However, when applied with professional services, EFD can be used to optimize the quality of service (QoS) for the entire network.
The UEs on a live network can be divided into three types:
* UEs that do not send SCRI messages because there is no PS data to be transmitted.
* Pre fast dormancy UEs : This type of UE does not read the T323 information element (IE) carried in the system information block type 1 (SIB1) message. After PS data transmission is complete, this type of UE sends an SCRI message to the RNC, but the SCRI message does not carry the IE Signaling Connection Release Indication Cause. Both T323 and Signaling Connection Release Indication Cause are introduced in 3GPP Release 8.
* R8 fast dormancy UEs : This type of UE reads the T323 IE carried in the SIB1 message and sends an SCRI message to the RNC after PS data transmission is complete. The SCRI message carries the IE Signaling Connection Release Indication Cause that is set to "UE Requested PS Data session end."
The T323 IE carried in the SIB1 message controls the frequency at which the R8 fast dormancy UEs send SCRI messages with the IE Signaling Connection Release Indication Cause set to "UE Requested PS Data session end". The T323 timer starts after an SCRI message is sent by the R8 fast dormancy UEs, and the second SCRI message with the IE Signaling Connection Release Indication Cause set to "UE Requested PS Data session end" can be sent only after the T323 timer expires.
The EFD feature applies only to the pre fast dormancy UEs and R8 fast dormancy UEs. Users can configure EFD to be enabled for only the pre fast dormancy UEs or R8 fast dormancy UEs.
When this feature is disabled, the RNC releases the signaling connection and puts the UE into idle mode after receiving the SCRI message regardless the UE types.
When this feature is enabled, the RNC performs different processing based on the UE type:
* For the pre fast dormancy UEs, the RNC checks for compatibility issues after receiving an SCRI message. If there are no compatibility issues, the RNC puts the UE into the CELL_FACH or PCH state. If there is a compatibility issue, the RNC puts the UE into idle mode.
* For the R8 fast dormancy UEs, the RNC puts the UE into the CELL_FACH or PCH state after receiving an SCRI message.
Technical Description :
When there is no PS data to be transmitted, the intelligent UE sends the RNC an SCRI message to request the UTRAN to release the signaling connection. This procedure saves power. In addition, the UE periodically sends heartbeat messages to the core network, for example, to check for new mails on the mail server. If the EFD feature is disabled, the RNC releases the signaling connection and puts the UE into the idle state. In this case, sending heartbeat messages leads to the procedures for RRC connection setups, authentication, encryption, and RAB setups. These procedures increase the RNC signaling processing load.
EFD addresses this problem. With EFD, the RNC transits a UE to the CELL_FACH or PCH state instead of idle mode upon receiving an SCRI message from the UE. In this case, when the UE periodically sends heartbeat messages, the signaling procedure between the UE and RNC is simplified because the RRC connection is maintained. As the number of signaling exchange messages decreases, significant CPU resources can be saved for the RNC, and the UE consumes about the same low amount of battery power as a UE in idle mode.
This feature is controlled by FAST_DORMANCY_SWITCHof the PROCESSSWITCH parameter in the SET URRCTRLSWITCH command.
attached fig shows the signaling processing procedures for pre fast dormancy UEs and R8 fast dormancy UEs before and after EFD is enabled.
Identifying Fast Dormancy UEs :
The RNC identifies the pre fast dormancy UEs and R8 fast dormancy UEs using the following mechanisms:
* R8 fast dormancy: The T323 parameter that can be set in the SET UCONNMODETIMER command is sent to the UE by the SIB1 message. The R8 fast dormancy UEs send an SCRI message with the IE Signaling Connection Release Indication Cause set to "UE Requested PS Data session end" after PS data transmission is complete. The RNC identifies the R8 fast dormancy UEs by reading the value of IE Signaling Connection Release Indication Cause.
This mechanism is standardized by 3GPP Release 8.
* Pre fast dormancy: The RNC identifies the pre fast dormancy UEs using the Type Allocation Codes (TACs).
This mechanism, which is not standardized, is used for the early proprietary implementations of fast dormancy.
The international mobile equipment identity (IMEI), which consists of 14 decimal digits and one check digit, contains TAC and SNR. TAC indicates a particular type of device that has been approved by a national GSM/WCDMA approval body. SNR is the serial number identifying the UE. The structure of the IMEI, which is shown as follows, is specified in 3GPP TS 23.003.
To identify pre fast dormancy UEs,FD_TAC_MATCH_SWITCH of the PROCESSSWITCHparameter on the RNC side needs to be turned on. The TAC parameter has been set for the pre fast dormancy UEs by theADD UIMEITAC command. The RNC checks the TAC of the IMEI in the IDENTITY REQUEST message. If the TAC is included in the EFD list, the UE can use EFD.
To identify pre fast dormancy UEs,FD_TAC_MATCH_SWITCH of the PROCESSSWITCHparameter on the RNC side needs to be turned on. The TAC parameter has been set for the pre fast dormancy UEs by theADD UIMEITAC command. The RNC checks the TAC of the IMEI in the IDENTITY REQUEST message. If the TAC is included in the EFD list, the UE can use EFD.
Huawei provides a comprehensive end-to-end solution based on network characteristics to respond to network challenges. EFD is one component of the solution. This feature alone is not enough to eliminate signaling storms caused by intelligent UEs. However, when applied with professional services, EFD can be used to optimize the quality of service (QoS) for the entire network.
The UEs on a live network can be divided into three types:
* UEs that do not send SCRI messages because there is no PS data to be transmitted.
* Pre fast dormancy UEs : This type of UE does not read the T323 information element (IE) carried in the system information block type 1 (SIB1) message. After PS data transmission is complete, this type of UE sends an SCRI message to the RNC, but the SCRI message does not carry the IE Signaling Connection Release Indication Cause. Both T323 and Signaling Connection Release Indication Cause are introduced in 3GPP Release 8.
* R8 fast dormancy UEs : This type of UE reads the T323 IE carried in the SIB1 message and sends an SCRI message to the RNC after PS data transmission is complete. The SCRI message carries the IE Signaling Connection Release Indication Cause that is set to "UE Requested PS Data session end."
The T323 IE carried in the SIB1 message controls the frequency at which the R8 fast dormancy UEs send SCRI messages with the IE Signaling Connection Release Indication Cause set to "UE Requested PS Data session end". The T323 timer starts after an SCRI message is sent by the R8 fast dormancy UEs, and the second SCRI message with the IE Signaling Connection Release Indication Cause set to "UE Requested PS Data session end" can be sent only after the T323 timer expires.
The EFD feature applies only to the pre fast dormancy UEs and R8 fast dormancy UEs. Users can configure EFD to be enabled for only the pre fast dormancy UEs or R8 fast dormancy UEs.
When this feature is disabled, the RNC releases the signaling connection and puts the UE into idle mode after receiving the SCRI message regardless the UE types.
When this feature is enabled, the RNC performs different processing based on the UE type:
* For the pre fast dormancy UEs, the RNC checks for compatibility issues after receiving an SCRI message. If there are no compatibility issues, the RNC puts the UE into the CELL_FACH or PCH state. If there is a compatibility issue, the RNC puts the UE into idle mode.
* For the R8 fast dormancy UEs, the RNC puts the UE into the CELL_FACH or PCH state after receiving an SCRI message.
Technical Description :
When there is no PS data to be transmitted, the intelligent UE sends the RNC an SCRI message to request the UTRAN to release the signaling connection. This procedure saves power. In addition, the UE periodically sends heartbeat messages to the core network, for example, to check for new mails on the mail server. If the EFD feature is disabled, the RNC releases the signaling connection and puts the UE into the idle state. In this case, sending heartbeat messages leads to the procedures for RRC connection setups, authentication, encryption, and RAB setups. These procedures increase the RNC signaling processing load.
EFD addresses this problem. With EFD, the RNC transits a UE to the CELL_FACH or PCH state instead of idle mode upon receiving an SCRI message from the UE. In this case, when the UE periodically sends heartbeat messages, the signaling procedure between the UE and RNC is simplified because the RRC connection is maintained. As the number of signaling exchange messages decreases, significant CPU resources can be saved for the RNC, and the UE consumes about the same low amount of battery power as a UE in idle mode.
This feature is controlled by FAST_DORMANCY_SWITCHof the PROCESSSWITCH parameter in the SET URRCTRLSWITCH command.
attached fig shows the signaling processing procedures for pre fast dormancy UEs and R8 fast dormancy UEs before and after EFD is enabled.
Identifying Fast Dormancy UEs :
The RNC identifies the pre fast dormancy UEs and R8 fast dormancy UEs using the following mechanisms:
* R8 fast dormancy: The T323 parameter that can be set in the SET UCONNMODETIMER command is sent to the UE by the SIB1 message. The R8 fast dormancy UEs send an SCRI message with the IE Signaling Connection Release Indication Cause set to "UE Requested PS Data session end" after PS data transmission is complete. The RNC identifies the R8 fast dormancy UEs by reading the value of IE Signaling Connection Release Indication Cause.
This mechanism is standardized by 3GPP Release 8.
* Pre fast dormancy: The RNC identifies the pre fast dormancy UEs using the Type Allocation Codes (TACs).
This mechanism, which is not standardized, is used for the early proprietary implementations of fast dormancy.
The international mobile equipment identity (IMEI), which consists of 14 decimal digits and one check digit, contains TAC and SNR. TAC indicates a particular type of device that has been approved by a national GSM/WCDMA approval body. SNR is the serial number identifying the UE. The structure of the IMEI, which is shown as follows, is specified in 3GPP TS 23.003.
To identify pre fast dormancy UEs,FD_TAC_MATCH_SWITCH of the PROCESSSWITCHparameter on the RNC side needs to be turned on. The TAC parameter has been set for the pre fast dormancy UEs by theADD UIMEITAC command. The RNC checks the TAC of the IMEI in the IDENTITY REQUEST message. If the TAC is included in the EFD list, the UE can use EFD.
To identify pre fast dormancy UEs,FD_TAC_MATCH_SWITCH of the PROCESSSWITCHparameter on the RNC side needs to be turned on. The TAC parameter has been set for the pre fast dormancy UEs by theADD UIMEITAC command. The RNC checks the TAC of the IMEI in the IDENTITY REQUEST message. If the TAC is included in the EFD list, the UE can use EFD.