METHODS FOR EFFECTIVE MANAGEMENT AND MAINTENANCE OF ACTIVE USER EQUIPMENT CONTEXT IN THE 5G gNodeB
A method for stale user context detection and removal is implemented at one of Open Radio Access Network (O-RAN) Centralized Unit (gNB-CU) or Distributed Unit (gNB-DU). In a first variant which utilizes the gNB-CU, the gNB runs a configurable periodic timer for initiating the stale UE detection procedure, i.e., the gNB configures, for every UE context stored in its database, a special Event A1 with the low a1-Threshold=−120 dBm, reportInterval=512 ms, and reportAmount=2. In a second variant which utilizes the gNB-CU, stale UE detection mechanism can be based on a periodic Event A1 configured during initial User admission procedure, i.e., the gNB configures a special Event A1 with the low a1-Threshold=−120 dBm, reportInterval=1 minute, and reportAmount=infinity. In a further variant, stale UE contexts can be identified at the gNB-DU based on periodic Channel State Information (CSI) reports.
1 . A method for at least one of stale user equipment (UE) context detection and removal in Open Radio Access Network (O-RAN), the method comprising:
one of:
a) 1) using one of O-RAN gNB Centralized Unit (gNB-CU) or O-RAN gNB Distributed Unit (gNB-DU) to implement a reporting requirement for receiving from an active user equipment (UE) information indicating the presence of the active UE, and
2) deleting by the one of the gNB-CU or the gNB-DU at least one UE context for which no information indicating the presence of the active UE is received; or
b) one of:
1) i) configuring periodic reporting requirement for periodically exchanging, between the gNB-CU and the gNB-DU, UE contexts maintained at the gNB-CU and UE contexts maintained at the gNB-DU, and
ii) deleting UE contexts present only in one of the gNB-CU or the gNB-DU; or
2) i) configuring periodic reporting requirement for periodically exchanging, between gNB-CU Control Plane (gNB-CU-CP) and gNB-CU User Plane (gNB-CU-UP), UE contexts maintained at the gNB-CU-CP and UE contexts maintained at the gNB-CU-UP, and
ii) deleting UE contexts present only in one of the gNB-CU-CP or the gNB-CU-UP.
2 . The method according to claim 1 , wherein the gNB-CU implements the reporting requirement, and wherein the reporting requirement is configured as a periodic timer with a specified reporting interval for transmitting measurement reports from the UE.
3 . The method according to claim 2 , wherein:
the gNB-CU configures, for every stored UE context, a special event A1 with the following reporting requirements: A1 Threshold=−120 dBm; report interval=512 ms; and report amount=2; and
at least one stored UE context for which no measurement report is received within a specified time period is deleted.
4 . The method according to claim 3 , wherein:
the gNB-CU configures, for every stored UE context, a special event A1 with the following reporting requirements: A1 Threshold=−120 dBm; report interval=1 minute; and report amount=infinity; and
at least one stored UE context for which no measurement report is received within a specified time period is deleted.
5 . The method according to claim 2 , wherein the gNB-DU implements the reporting requirement, and wherein the reporting requirement is configured as periodic transmission of Channel State Information (CSI) reports from the UE.
6 . The method according to claim 5 , wherein:
the reporting requirement is specified by configuring a CSI reporting configuration parameter csi-ReportConfigToAddModList, and reporting configuration type block reportConfigType in the parameter csi-ReportConfigToAddModList is set to periodic.
7 . The method according to claim 6 , wherein the reporting configuration type block reportConfigType in the parameter csi-ReportConfigToAddModList is set to periodic in one of Radio Resource Control (RRC) Setup Request or RRC Reconfiguration message sent to the UE.
8 . The method according to claim 6 , wherein:
in the case consecutive n number of periodic CSI reports are not received at the gNB-DU for a UE context, n 2 , the UE context is deleted.
9 . The method according to claim 1 , wherein:
the gNB-CU initiates UE context audit procedure by sending an ACTIVE UE STATUS REQUEST message to gNB-DU to request reporting of the UE contexts maintained at the gNB-DU.
10 . The method according to claim 9 , wherein:
gNB-DU sends to the gNB-CU an Active UE Status Response message including each Active UE context present at the gNB-DU.
11 . The method according to claim 10 , wherein:
gNB-DU periodically sends an ACTIVE UE STATUS UPDATE message to gNB-CU to report the list of Active UE contexts present at GNB-DU.
12 . The method according to claim 1 , wherein:
the gNB-DU initiates UE context audit procedure by sending an ACTIVE UE STATUS REQUEST message to gNB-CU to request reporting of the UE contexts maintained at the gNB-CU.
13 . The method according to claim 12 , wherein
gNB-CU sends to the gNB-CDU an Active UE Status Response message including each Active UE context present at the gNB-CU.
14 . The method according to claim 13 , wherein
gNB-CU periodically sends an ACTIVE UE STATUS UPDATE message to gNB-DU to report the list of Active UE contexts present at GNB-CU.
15 . The method according to claim 1 , wherein:
the gNB-CU-CP initiates UE context audit procedure by sending an ACTIVE UE STATUS REQUEST message to gNB-CU-UP to request reporting of the UE contexts maintained at the gNB-CU-UP.
16 . The method according to claim 15 , wherein:
gNB-CU-UP sends to the gNB-CU-CP an Active UE Status Response message including each Active UE context present at the gNB-CU-UP.
17 . The method according to claim 16 , wherein:
gNB-CU-UP periodically sends an ACTIVE UE STATUS UPDATE message to gNB-CU-CP to report the list of Active UE contexts present at GNB-CU-UP.
18 . The method according to claim 1 , wherein:
the gNB-CU-UP initiates UE context audit procedure by sending an ACTIVE UE STATUS REQUEST message to gNB-CU-CP to request reporting of the UE contexts maintained at the gNB-CU-CP.
19 . The method according to claim 18 , wherein
gNB-CU-CP sends to the gNB-CU-UP an Active UE Status Response message including each Active UE context present at the gNB-CU-CP.
20 . The method according to claim 19 , wherein
gNB-CU-CP periodically sends an ACTIVE UE STATUS UPDATE message to gNB-CU-UP to report the list of Active UE contexts present at GNB-CU-CP.