Control Slice O-RAN SM

Overview

A slice-level-PRB-quota control xApp, utilizing the O-RAN standarized service model RC SM, is developed to control slices within E2-Nodes. It offers support for three policy ratios: 1) minimum PRB, 2) maximum PRB, and 3) dedicated PRB by following the structure of RRMPolicyRatio in 3GPP TS 28.541.

It includes the following stages:

• Init: initializes xApp based on configuration to set up the E42 connection with NearRT-RIC
• xApp Logic: creates the control request data based on O-RAN specification
• Control Service: sends control request to each E2-Node
• Exit: terminates xApp

Sequence Diagram

Detail

source code: link

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Init - Step 2 to 6

• Used Functions
  • init_fr_args()
  • init_xapp_api()
  • e2_nodes_xapp_api()

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xApp Logic - Step 7

Develop your xApp logic to generate the control request data by following the structure in O-RAN.WG3.E2SM-RC-v01.03 (8.4.3.6 Slice-level PRB quota). For example, utilize the following functions to generate a control request data:

• Header: gen_rc_ctrl_hdr()

  • Input:

    Parameter	Type in C	Comment
    hdr_frm	e2sm_rc_ctrl_hdr_e	Format of header for RIC Control Request
    ue_id	ue_id_e2sm_t	UE ID used on E2 interface (6.2.2.6, O-RAN.WG3.E2SM-v02.01)
    ric_style_type	uint32_t	Control service style type (7.6.1, O-RAN.WG3.E2SM-RC-v01.03)
    ctrl_act_id	uint16_t	Control action ID ((7.6.2.1, O-RAN.WG3.E2SM-RC-v01.03)

  • Output:

    Parameter	Type in C	Comment
    rc_ctrl.hdr	e2sm_rc_ctrl_hdr_t	Header of RIC Control Request

  • Example:

  // Define a RC control reuqest data
  rc_ctrl_req_data_t rc_ctrl = {0};
    
  // Define header's format
  e2sm_rc_ctrl_hdr_e hdr_frm = FORMAT_1_E2SM_RC_CTRL_HDR
  
  // Generate UE ID, utilized by the RAN function to identify the UE to be controlled
  ue_id_e2sm_t ue_id = gen_rc_ue_id(GNB_UE_ID_E2SM);
    
  // Define control service style type
  // Note: 2 is mapped to control radio resource allocation
  uint32_t ric_style_type = 2;
    
  // Define control action ID
  // Note: 6 is mapped to control the split ratio of a DRB across its RLC entities 
  uint16_t ctrl_act_id = 6;
  
  rc_ctrl.hdr = gen_rc_ctrl_hdr(hdr_frm, ue_id, ric_style_type, ctrl_act_id);
• Message: gen_rc_ctrl_msg()

  • Input:

    Parameter	Type in C	Comment
    msg_frm	e2sm_rc_ctrl_msg_e	Format of message for RIC Control Request

  • Output:

    Parameter	Type in C	Comment
    rc_ctrl.msg	e2sm_rc_ctrl_msg_t	Message of RIC Control Request

  • Example:

  rc_ctrl.msg = gen_rc_ctrl_msg(FORMAT_1_E2SM_RC_CTRL_MSG);

  Note: The function gen_rc_ctrl_msg() calls gen_rc_ctrl_msg_frmt_1_slice_level_PRB_quota() to fill the required parameters n accordance with Section 8.4.3.6 (Slice-level PRB quota) of the O-RAN.WG3.E2SM-RC-v01.03 specification, adhering to the e2sm_rc_ctrl_msg_frmt_1_t structure.

  Section 8.4.3.6:

  RRM Policy Ratio List, LIST (len 1)
  > RRM Policy Ratio Group, STRUCTURE (len 4)
  >>  RRM Policy, STRUCTURE (len 1)
  >>> RRM Policy Member List, LIST (len 1)
  >>>> RRM Policy Member, STRUCTURE (len 2)
  >>>>> PLMN Identity, ELEMENT
  >>>>> S-NSSAI, STRUCTURE (len 2)
  >>>>>> SST, ELEMENT
  >>>>>> SD, ELEMENT
  >> Min PRB Policy Ratio, ELEMENT
  >> Max PRB Policy Ratio, ELEMENT
  >> Dedicated PRB Policy Ratio, ELEMENT

  For further details, please refer to the source code.

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Control Service - Step 8 to 12

• Used function
  • control_sm_xapp_api()

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Exit - Step 13 to 14

• Used function
  • rm_report_sm_xapp_api()
  • try_stop_xapp_api()