5G NR RRC INACTIVE State and RAN-Based Notification Area (RNA)

  • RRC_INACTIVE is a new state that specified by 3GPP in Release 15 for 5G NR and EUTRA technology where a device remains in CM-CONNECTED (form Core Network(CN) point of view) and can move within an area configured by 5G BS (the RNA) without updating the location information.

  • The RAN Notification Area (RNA) is a single or group of cells belonging to a single or multiple 5G BS(s) and it should be confined within the Core Network (CN) registration area. If the last serving 5G BS receives downlink data from the UPF, or signalling from the AMF, it sends the paging messages to every cell in the RNA. The paging message can also be sent to neighbour 5G BS(s) belonging to the RNA, across the Xn interface.

  • If 5G Base Station and 5G device support RRC_INACTIVE state, the 5G BS then can release the UE to RRC_INACTIVE state rather than RRC_IDLE state when inactivity on uplink and downlink with the help of inactivity timer is detected. To send the device to RRC_INACTIVE state, the 5G BS sends the RRC Release message with suspendConfig.

  • The 5G device and last serving gNB node keep the device’s Inactive AS Context(e.g. radio protocol information and security parameters).The last serving 5G BS also maintains the UE-associated NG connection(NG-C&NG-U) with the serving AMF and UPF.

  • The AMF provides to the 5G BS node the Core Network Assistance Information to assist the 5G BS’s decision whether the device can be sent to RRC_INACTIVE, and to assist UE configuration and paging in RRC_INACTIVE.

  • Here I try to depict RAN-Based Notification Area and 5G NR RRC_INACTIVE sate.

The AMF provides to the 5G BS node the Core Network Assistance Information to assist the 5G BS’s decision whether the device can be sent to RRC_INACTIVE, and to assist UE configuration and paging in RRC_INACTIVE.

LinkedIn: Rahim Navaei on LinkedIn: #5g #5gnr #4g | 11 comments

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