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Lab 9: Amarisoft NR intra Frequency Handover

This experiment showcases an example of running handover procedure on top of a 5G Standalone (SA) network using Amarisoft (AMR) gNBs, AMR CN, FlexRIC as the Near-RT RIC and Quectel model as an COTS UE. Additionally, an instruction to apply handover API via both terminal command line and xApp from public xApp SDK repository.

Prerequisites​

It is required to have the following components:

  1. 2 SDR-50 or 1 SDR-100
  2. Amarisoft license
  3. A Quectel model

Introduction​

open-ran-ho-intra.yaml
apiVersion: athena.trirematics.io/v1
kind: Network
metadata:
    name: handover
    namespace: trirematics
spec:
    slices:
        -   plmn: "00101"
            dnn: internet
            network-mode: IPv4
            service-type: eMBB
            differentiator: 0x000000
            ipv4-range: 12.2.1.0/24
            ipv6-range: 2001:db8:1::/64
    access:
        -   name: gnb1
            stack: 5g-sa
            model: amarisoft/ran-e2
            identity:
                an-id: 30
                tracking-area: 1
            radio:
                device: amr-sdr50
                antenna:
                    tx-gain: "90.0"
                    rx-gain: "60.0"
            cells:
                -   band: n78
                    arfcn: 637344
                    bandwidth: 20MHz
                    subcarrier-spacing: 30kHz
                    tdd-config:
                        period: 5ms
                        dl-slots: 7
                        dl-symbols: 6
                        ul-slots: 2
                        ul-symbols: 4
                    groups:
                        -   kind: hog
                            name: handover-group
                -   band: n41
                    arfcn: 518190
                    bandwidth: 20MHz
                    subcarrier-spacing: 30kHz
                    tdd-config:
                        period: 5ms
                        dl-slots: 7
                        dl-symbols: 6
                        ul-slots: 2
                        ul-symbols: 4
                    groups:
                        -   kind: hog
                            name: handover-group
            core-networks:
                - amr-cn.handover
            controller: flexric.handover
            scheduling:
                nodeSelector:
                    kubernetes.io/hostname: moto
            annotations:
                extras.t9s.io/ssb-bitmap: "10000000"
    core:
        -   name: amr-cn
            stack: 5g-sa
            model: amarisoft/basic-cn
            profiles:
                - debug
            identity:
                region: 128
                cn-group: 4
                cn-id: 5
    edge:
        -   name: flexric
            stack: 4g-5g
            model: mosaic5g/flexric
    dns:
        ipv4:
            default: 8.8.8.8
            secondary: 8.8.4.4
---
apiVersion: athena.trirematics.io/v1
kind: Terminal
metadata:
    name: quectel-001
    namespace: trirematics
spec:
    vendor: amr
    stack: 5g-sa
    model: terminal/quectel
    target-cores:
        - amr-cn.handover
    identity:
        imsi: "001010000000012"
        pin: "1234"
        opc: "0xC42449363BBAD02B66D16BC975D77CC1"
        key: "0xfec86ba6eb707ed08905757b1bb44b8f"
        sqn: "0xff9bb4000001"
    slice:
        dnn: internet
        network-mode: IPv4
        service-type: eMBB
        differentiator: 0x000000
    radio:
        bands:
            - n78
            - n41
    readiness-check:
        method: ping
        target: google-ip

Deployment​

  1. To run up the network
brc install network open-ran-ho-intra.yaml
  1. To check the network
brc observe
  1. Wait until all the Elements other than the UE are in the STATUS set to 1/1 Y state.

Handover via command line​

Example of handover API on gNB terminal

handover
Syntax: handover RAN_UE_ID pci [arfcn]
Start a handover to physical cell 'pci', using the optional DL E-ARFCN or SSB NR-ARFCN 'arfcn'.

Handover API requires 3 parameters RAN_UE_ID, pci and optional arfcn.

  1. To use the API, user goes to interactive terminal of amarisoft RAN
brc cic amr-ran.gnb1.handover --follow ran
  1. To get RAN_UE_ID, type ue on the terminal
(enb) ue
RAN_UE_ID      CN_UE_ID  Cell   RNTI
  1. To get pci and arfcn, type cell on the terminal
(enb) cell
cell
[gnb0012346] PLMN=00101 gNB_ID=0x12346
Cell    RAT BAND      TAC dl_arfcn  pci prach_seq dl_gain ul_dis plmn
  1. Apply the handover command with the following command above.
tip

For more information on these command line, please visit Amarisoft website on section 11.

Handover via xApp​

As provided, xApp SDK supports handover xApp in path /src/usr/python3/ho.py.

# Example of ho.py
import sys
import xapp_usr_sdk as xapp

xapp.init(sys.argv)
nodes = xapp.e2_nodes(xapp.HAND_OVER_USE_CASE_e)
assert(len(nodes) > 0 and len(nodes) < 3 and "Needed at least 1 or 2 E2 nodes to handover")

sum_ue = 0
for idx in range(len(nodes)):
sum_ue += len(nodes[idx].ue_ho)
assert(sum_ue > 0 and "At least one UE needed")

idx = 0 if len(nodes[0].ue_ho) > 0 else 1
n  = nodes[idx].node
ue = nodes[idx].ue_ho[0].ue
ho_pci = nodes[idx].ue_ho[0].nghbr_cell[0].target_pci
ho_ssb = nodes[idx].ue_ho[0].nghbr_cell[0].target_ssb_nr_arfcn

xapp.hand_over(n, ue, ho_pci, ho_ssb)

Similar to Amarisoft's handover command line, our handover xApp automatically extracts the UE ID, PCI, and ARFCN of the UE. This information is used by the ho.py script, which enables users to move the UE back and forth between two cells, by running the command multiple times.

Simple step by step to interact xApp with the cluster

  1. Build the project following README.md file

  2. Bind flexric IP with xApp

cd  xapp_sdk/conf/

python3 update_conf.py

# It should show this
# Select the RIC to configure:
#  1) flexric.flexric.handover (10.244.2.46)
# Choice [1-1]: 1
# No entries found for Database.
# Skipping database IP update.
# Config 'xapp.yaml' updated: ip_ric=10.244.2.46, ip_xapp=10.244.0.158
  1. Run the xApp
cd build/src/usr/python3

python3 mntr.py ../../../conf/xapp.yaml
Last updated on by nguyenk