09 WCDMA RNO Access Procedure Analysis WCDMA Access Procedure ReviewReview Access is associated with the call setup success rate of the network Mastering the access procedure can increase this KPI wit[.]
WCDMA Access Procedure Review Access is associated with the call setup success rate of the network Mastering the access procedure can increase this KPI with the access parameters optimization Objectives Upon completion of this course,you will be able to: Know the detailed access procedure in UMTS Know how to access procedure optimize the Course Contents Random access procedure RRC setup procedure RAB setup procedure Random access procedure Physical channel about access Random access procedure Parameters optimization PRACH access slot radio frame: 10 ms radio frame: 10 ms 5120 chips Access slot #0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 Random Access Transmission Random Access Transmission Random Access Transmission Random Access Transmission UE can start the random-access transmission at the beginning of a access slot There are 15 access slots per two frames what access slots are available is given by higher layers Structure of the random-access transmission P r ea m b le P r ea m b le P r ea m b le ch ip s P r ea m b le m s (on e r a d io fr a m e) P r ea m b le ch ip s M essa g e p a r t P r ea m b le M essa g e p a r t m s (tw o r a d io fr a m es) Each random-access transmission consists of one or several preambles of length 4096 chips and a message of length 10 ms or 20 ms Each preamble is of length 4096 chips and consists of 256 repetitions of a signature of length 16 chips Structure of the random-access transmission One access slot Acq Ind AICH access slots RX at UE τp-a Preamble PRACH access slots TX at UE Preamble τp-p Message part τp-m The preamble-to-preamble distance τp-p shall be larger than or equal to τp-p,min the minimum preamble-to-preamble distance Structure of the random-access transmission when AICH_Transmission_Timing is set to τp-p,min = 15360 chips (3 access slots) τp-a = 7680 chips τp-m = 15360 chips (3 access slots) when AICH_Transmission_Timing is set to 1, then τp-p,min = 20480 chips (4 access slots) τp-a = 12800 chips τp-m = 20480 chips (4 access slots) The parameter AICH_Transmission_Timing signalled by higher layers is Random access procedure Physical channel about access Random access procedure Parameters optimization NInSyncInd This parameter defines the successive synchronization indication times required for the NodeB to trigger the radio link recovery process The radio link set remains in the initial state until it receives NInsyncInd successive synchronization indications from L1, then NodeB triggers the radio link recovery process, which indicates that the radio link set has been synchronized Once the radio link recovery process is triggered, the radio link set is considered to be in the synchronized state Influence on the network performance: The bigger this parameter is, the stricter the synchronization process will be, and the more difficult the sync will be; the smaller it is, the easier the synchronization will be However, if the link quality is bad, a simple synchronization requirement will lead to the waste of the UE power and the increase of uplink interference; in the radio link maintenance process, this parameter is used together with the successive outof-sync indication counter NOutSyncInd NOutSyncInd defines the successive out-of-sync indication times that are required to receive to start the timer TRlFailure When the radio link set is in synchronized state, the NodeB will start the timer TRlFailure after it receives NOutsyncInd successive out-of-sync indications The NodeB should stop and reset the timer TRlFailure after receiving NInsyncInd successive sync indications If the timer TRlFailure times out, the NodeB will trigger the radio link failure process, and indicate the radio link set that is out-of-sync Influence on the network performance: If this parameter is set too small, the link out-of-sync decision will be likely to occur; if it is set too big, out-of-sync will not be likely to occur, but, if the link quality is bad, it will result in waste of the UE power and increased uplink interference In the radio link maintenance process, this parameter is adopted synchronization indication counter together with the successive TRLFailure This value defines the timer TRlFailure duration When the radio link set is in synchronized state, NodeB should start the timer TRlFailure after it receives NOutsyncInd successive out-of-sync indications; and NodeB should stop and reset the timer TRlFailure after receiving NInsyncInd successive sync indications If the timer TRlFailure times out, NodeB will trigger the radio link failure process, and indicate the radio link set that is out-of-sync Influence on the network performance: If the timer is set too short, there will few chances for link synchronization; if it is set too long, the radio link failure process will probably be delayed, and the downlink interference will be increased N312 and T312 When the UE starts to set up the dedicated channel, it starts the T312 timer, and after the UE detects N312 synchronization indications from L1, it will stop the T312 timer Once the timer times out, it means that the physical channel setup has failed Influence on the network performance: The bigger N312 is, the more difficult the dedicated channel synchronization will be; the longer T312 is, the bigger the synchronization synchronization time will be probability will be, but the longer the N313, N315, T313 After the UE detects N313 successive out-of-sync indications from L1, it will start the T313 timer And after the UE detects N315 successive sync indications from L1, it will stop the T313 timer Once the timer times out, the radio link fails Influence on the network performance: The bigger N313 is, the more difficult it will be to start T313, which will reduce the out-of-sync probability; the smaller N315 is, the longer T313 will be, and the bigger the link recovery probability will be These three parameters should be used together Course Contents Random access procedure RRC setup procedure RAB setup procedure RAB Setup Procedure Appendix: MOC signaling process UE RRC S e rving RNC N ode B S e rving R N S C C C H : R R C C o n ne c t io n R e q u e s t N BAP R a d io L ink RRC S e tup R e q ue s t NBAP S ta rt R X N BAP R a d io L ink S e tup R e s p o ns e E s ta blis h R e q ue s t Q A A L E s ta blis h C o nf irm Q A A L D C H -F P D C H -F P D o w n link S y nc h ro nis a t io n U p link S y nc h ro n is a t io n NBAP Q A A L Q A A L D C H -F P D C H -F P S ta rt T X C C C H : R R C C o n ne c t io n S e tup RRC D C C H : R R C C o nne c t io n RRC RLC RRC D C C H : R R C C o nne c t io n DCCH : S e tup C o m p le te S e tup C o m p le te a c k In ita l D ir e c t T ns fe r RRC RRC RLC RRC CN Appendix: MOC signaling process UE RRC Node B Serving RNS DCCH : Inital Direct Transfer Serving RNC CN RRC Initial UE Message RANAP RANAP RRC RRC RRC RRC RRC DCCH : Downlink Direct Transfer RRC DCCH : Uplink Direct Transfer RRC DCCH : Downlink Direct Transfer (CM Service Request) Direct Transfer (CM Service Accept) RANAP Direct Transfer (Setup) Direct Transfer RANAP (Call Proceeding) RRC DCCH : Uplink Direct Transfer RRC RANAP RANAP RANAP RANAP Appendix: MOC signaling process UE RRC RRC Node B Serving RNS DCCH : Downlink Direct Transfer Serving RNC CN RRC DCCH : Uplink Direct Transfer RRC RAB Assignment Request RANAP Q.AAL2 Q.AAL2 Radio Link Reconfiguration Prepare NBAP NBAP Radio Link Reconfiguration Ready NBAP NBAP RANAP ( Establishment ) Establish Request Establish Confirm Q.AAL2 Q.AAL2 Appendix: MOC signaling process UE Node B Serving RNS Q.AAL2 Q.AAL2 NBAP NBAP NBAP RRC Serving RNC Establish Request Establish Confirm Downlink Synchronisation Uplink Synchronisation Radio Link Reconfiguration Commit DCCH : Radio Bearer Setup CN Q.AAL2 Q.AAL2 NBAP NBAP NBAP RRC Apply new transport format set RRC RLC DCCH : Radio Bearer Setup Complete DCCH : Radio Bearer Setup Complete ack RRC RLC RANAP RAB Assignment Response (Establishment ) RANAP Appendix: MOC signaling process UE Node B Serving RNS Serving RNC RANAP RRC DCCH : Downlink Direct Transfer RRC DCCH : Downlink Direct Transfer DCCH : Uplink Direct Transfer DCCH : Uplink Direct Transfer RRC DCCH : Uplink Direct Transfer RANAP Direct Transfer (Connect Acknowledge) RANAP RRC RANAP DCCH : Downlink Direct Transfer Direct Transfer (Connect) RRC RANAP RRC RANAP RRC RANAP RRC Direct Transfer (Alerting) RRC RANAP RRC CN Direct Transfer (Disconnect) RANAP Direct Transfer (Release) RANAP Direct Transfer (Rlease Complete) RANAP RRC RRC RANAP Appendix: MOC signaling process UE Node B Serving RNS Serving RNC RANAP Q.AAL2 Q.AAL2 CN Iu Release Command Release Request Release Complete RANAP Q.AAL2 Q.AAL2 DCCH : RRC Connection Release DCCH : RRC Connection ReleaseComplete NBAP NBAP Q.AAL2 Q.AAL2 Radio Link Deletion NBAP Radio LinkDeletionComplete Release Request Release Complete NBAP Q.AAL2 Q.AAL2 RANAP Iu Release Complete RANAP Summary Random access procedure: physical channels, detailed random access procedure, access parameters optimization RRC setup procedure and parameters optimization RAB setup procedure and the whole UE outgoing call procedure