5G Call Flows

5G Call Flows (Session 2): 5G Mobility Overview is the 2nd session for 5G Call Flows where I am going to discuss 5G call flows for Intra-gNB and Inter-gNB handovers (PSCell Change) based on 3GPP 37.340 & 36.423.

5G Call Flows (Session 2): 5G Intra-gNB & Inter-gNB Mobility Overview

5G Call Flows (Session 2): The 5G Mobility Overview explains the 5G call flows for Intra-gNB and Inter-gNB handovers (PSCell Change) based on 3GPP 37.340 & 36.423.

The A3 measurement configuration is shared by the gNB to the eNB during NR leg addition and then the eNB sends it to the UE via RRC Reconfiguration. Once, the UE meets the A3 condition which means that another 5G cell within the same gNB is now a better candidate cell and has better coverage than the source cell then the UE sends A3 Measurement Report to the eNB. The eNB forwards that measurement report to the gNB over X2.

The gNB takes the handover/PSCell Change decision and sends a SgNB Modification/Change Required message to the eNB indicating a PSCell Change request to the target cell. The eNB reconfigures the UE to move it to the target NR cell and sends confirmation to the source gNB over X2 interface. The UE moves to target cell after completing RACH on the target cell.

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Ali Khalid

Senior Solution Architect at Ericsson SCU, Australia | 5G NR | VoLTE | LTE-A | Massive MIMO | NB-IoT
Ali Khalid is a Senior LTE/VoLTE RNPO, NB-IoT and 5G Solution Architect who has successfully led and delivered a number of projects in different regions across the globe including Pakistan, Bahrain, UAE, Qatar, Oman, KSA, Nigeria, Turkey, Poland and Japan. He is currently working in Strategic Competence Unit (SCU), a highly experienced global team at Ericsson, Australia. In case of any questions or feedback, please feel free to drop a comment below or connect with him on LinkedIn.

6 thoughts on “5G Call Flows (Session 2): 5G Intra-gNB & Inter-gNB Mobility Overview”

  1. what could be the reason if there is no intra or inter PSCell Change attempts, this has been noticed both the counter value and trace as well. there is no A3 even also triggered. and site is located on international border where there are some sites on own country with inter site distance >5km, but there are high elevation difference towards each sites.

  2. Could you please help with 5G PS drop optimization guidelines, 90% drops are on MeNB and 10% on SgNB.
    5G band is N78, 3.5 G TDD.

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