NR SA Network Slicing Guideline
<?xml version='1.0' encoding='UTF-8'?>
<bulkCmConfigDataFile xmlns="configData.xsd" xmlns:es="EricssonS
pecificAttributes.xsd" xmlns:xn="genericNrm.xsd">
<fileHeader fileFormatVersion="32.615 V4.5" vendorName="Ericss
on"/>
<configData dnPrefix="Undefined">
<xn:SubNetwork id="subNW">
<xn:MeContext id="gNB1">
<xn:ManagedElement id="gNB1">
<xn:VsDataContainer id="1">
<xn:attributes>
<xn:vsDataType>vsDataGNBDUFunction</xn:vsDataTyp
e>
<xn:vsDataFormatVersion>EricssonSpecificAttribut
es</xn:vsDataFormatVersion>
<es:vsDataGNBDUFunction/>
</xn:attributes>
<xn:VsDataContainer id="gNB1-1" modifier="update">
<xn:attributes>
<xn:vsDataType>vsDataNRCellDU</xn:vsDataType>
<xn:vsDataFormatVersion>EricssonSpecificAttrib
utes</xn:vsDataFormatVersion>
<es:vsDataNRCellDU>
<es:sNSSAIList>
<es:sst>1</es:sst>
<es:sd>1</es:sd>
</es:sNSSAIList>
</es:vsDataNRCellDU>
</xn:attributes>
</xn:VsDataContainer>
</xn:VsDataContainer>
</xn:ManagedElement>
</xn:MeContext>
</xn:SubNetwork>
</configData>
<configData dnPrefix="Undefined">
<!---add more MO operations with <configData> elements---->
</configData>
<fileFooter dateTime="2021-04-20T07:46:55+01:00"/>
</bulkCmConfigDataFile>
→
→
→
→
→
The following example shows the same configuration using the EDFF:
# Example file to configure the S-NSSAI attribute in the NRCellD →
U MO for gNB1
SET
FDN:"SubNetwork=SubNW,MeContext=gNB1,ManagedElement=gNB1,GNBDUFu →
nction=1,NRCellDU=gNB1-1"
sNSSAIList:[{sst=1,sd=1}]
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Principles and Guidelines
The ENM is responsible for translating the bulk configuration file to a
corresponding gNodeB configuration based on the Ericsson Common
Information Model (ECIM). This configuration is then pushed to the affected
nodes through the Network Configuration (NETCONF) interface.
2.9.3
Ericsson Orchestrator-Based Network Slice Provisioning
This section describes the Ericsson-based E2E network slice provisioning
solution. Figure 36 shows the high-level architecture, which includes the
following main products:
ENM
Ericsson Orchestrator
Contains the EMS for RAN, transport network, and core
network, and the SDN controller functions, which play the
roles of the AN-NFMF, TN-NFMF and CN-NFMF,
respectively.
Contains the Service Orchestration, Network Functions
Virtualization Orchestrator (NFVO), and EvolvedVirtualized Network Function Manager (E-VNFM)
functions. The Service Orchestration function plays the
role of the AN-NSSMF and CN-NSSMF.
Figure 36 Ericsson Orchestrator Solution for Network Slice Provisioning
Currently, E2E slice provisioning and configuration are done separately for each
network domain: RAN, transport network, and core network.
The configuration of network slices in the RAN can be realized by using the
Service Orchestration functionality in the Ericsson Orchestrator or, in case the
Ericsson Orchestrator is not deployed, by using ENM scripts (using RAN EMS)
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NR SA Network Slicing Guideline
supporting bulk configurations. ENM scripts can also be used to augment the
RAN configuration with slicing related parameters not provided through the
Service Orchestration function. Bulk configuration is a web-based application in
ENM and allows the simultaneous configuration of a set of nodes belonging to
one slice. It allows importing configuration management data to Baseband
Radio Nodes in the live network based on the created bulk configuration file.
Alternatively, the configuration can be done manually node by node, which
results in a higher configuration effort.
If the transport network is based on traditional VPN technologies (for example IP
or MPLS VPN), the configuration is done using ENM configuration scripts
(through transport network EMS) or manually. Otherwise, if SDN technologies
are used in the transport, the configuration can be conducted automatically by
the SDN controller.
A core network slice is deployed as Containerized Network Functions (CNF). With
CNFs, the configuration can be automated together with core network slice
orchestration by the Service Orchestration function in the Ericsson Orchestrator.
The Service Orchestration handles the core network slice orchestration according
to a given slice requirement definition. It instantiates the core network slice with
minimal configuration through NFVO and E-VNFM. Once the core network slice
instance is active, Service Orchestration also sends the configurations
requirements to the core network EMS in ENM, which then finishes the core
network slice configuration.
2.9.4
Observability
A network slice must fulfill the performance requirements of the traffic type that
it carries and the subscribers that use that slice. The monitoring of relevant PM
Counters and calculation of KPIs per slice is therefore important. This can be
done either on an E2E network level (if supported) or per domain: RAN,
Transport, Core Network.
Figure 37 shows the network slice observability solution for the RAN domain,
which requires following applications:
— ENM supporting the Event Based Statistics for NR (EBS-N) application
EBS-N collects PM Events from the gNodeB to generate RAN Performance
Statistics (EBS-N counters) that the node does not provide. The performance
of network slices cannot be monitored without using EBS-N.
— PM applications supporting the definition and monitoring of KPIs based on
the ENM EBS-N counters
Ericsson Network IQ Statistics (ENIQ-S) shown in Figure 37 is one example
of such an PM application that supports the KPI monitoring for network
slices. Alternative PM applications or tools that are capable of processing the
EBS-N information and defining related performance KPIs might be used
instead of ENIQ-S.
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Principles and Guidelines
Figure 37 RAN Slice KPIs Observability Solution
Performance Management Initiation and Collection (PMIC) is an application
within ENM and used to create PM event subscriptions in the gNodeB which are
automatically determined based on the selected EBS-N counters. The collection
of PM events obtained from the gNodeB and the creation of EBS-N related PM
counters in ENM is done by the EBS-N function which maps the received PM
event data to the corresponding EBS-N counters. EBS-N writes the counters into
3GPP compliant PM files.
Two types of EBS-N counters can be created: Base EBS-N counters (pmEbs<xyz>)
and Flexible EBS-N counters (pmEbs<xyz>_<filter>). Flexible EBS-N counters
can be defined through the Flexible Counter management (FCM) application in
ENM and allow the differentiation of certain Base EBS-N counters through filter
criteria. The filter criteria selected in FCM are appended with underscores to the
Base EBS-N counter name.
The relevant filter criteria to observe network slice performance KPIs include for
example:
— S-NSSAI
— PLMN ID
— QoS (5QI)
For example, filtering the Base EBS-N counter for DRB establishment attempts
(pmEbsDrbEstabAtt5qi) for 5QI 9 in a network slice with STT=1/SD=1 and
PLMN with MCC=262/MNC=80, the resulting Flexible EBS-N counter looks as
follows:
pmEbsDrbEstabAtt5qi_Qos9_mcc262mnc80_sst1sd1
Note:
The PM events contain the corresponding PlmnId, Snssai, QoS, and
other filter parameters that allow ENM EBS-N to construct the Flexible
EBS-N counters from the corresponding Base EBS-N counters.
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NR SA Network Slicing Guideline
ENIQ-S is a standalone product that can be used to process the EBS-N counters
and generate specific KPI reports in real time or to provide a historical view. The
report conveys detailed KPI information in a dashboard representation and
provides a comprehensive overview of the network performance. ENIQ-S can be
used to assure that the offered services comply to the negotiated SLAs and, also,
to observe performance trends which can help to plan necessary network
optimizations as needed.
For the level of support to define and monitor slice-specific KPIs based on the
supported Base and Flexible EBS-N counters described in this section, see the
respective ENM and ENIQ-S CPI documentation.
Table 4 lists the KPI categories to be supported for the network slice observability
in RAN. They can be used to observe the RAN contribution to the SLA fulfillment
of a network slice. The choice of the categories and KPIs to monitor depends on
the network slice type and it is required service characteristics. For example, the
throughput-related KPIs in the Integrity category are more important to monitor
for data services provided by an FWA slice that has to guarantee throughputrelated SLAs, than for similar services in an eMBB slice not providing such
guarantees to consumers. In contrast, the KPIs in the Availability, Retainability,
and Accessibility categories may need to be monitored commonly for any
network slice and service type.
Table 4
72
KPI Categories for Network Slice Observability in RAN
KPI Category
Measurement
Slice or Service
Description (High- Type Examples
Level)
Availability
Amount of time a
service is
delivered
according to an
agreed QoS
Common
Accessibility
Setup success
rate related to
DRBs or PDU
sessions
Common
Retainability
Abnormal release
rate related to
DBRs or PDU
sessions
Common
Mobility
Successful
Handover rate
related to PDU
session
Common
Resource Utilization
Use of resources,
for example, in
terms of RBSyms,
DRBs, PDU
Common
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Principles and Guidelines
KPI Category
Integrity
Measurement
Slice or Service
Description (High- Type Examples
Level)
Sessions, or RRC
Connections
Latency(1)
The gNodeB
contribution to
the E2E packet
transmission
latency
experienced by an
end user in the
downlink
direction
Latency-sensitive
services, for
example, voice in
eMBB or FWA
slice
Throughput
Downlink and
Uplink
Throughput per
DRB and UE
Data services in
an FWA slice
Reliability
Packet loss rate
Mission critical
services
(1) This KPI describes the average time for scheduling the first DL packet in a burst of packets on
the air interface to the UE (NR-Uu), determined from the time the packet was received by the
gNodeB-Distributed Unit (DU). The KPI is not measured for each packet in the burst. Currently,
it can only be measured in a slice-agnostic way, for example by using the gNodeB PM counters:
pmMacLatTimeDlDrxSyncQos, pmMacLatTimeDlNoDrxSyncQos, among others. To monitor the
E2E latency across RAN, TN, and CN, the latency between RAN and CN needs to be considered
in addition.
The KPIs for availability, accessibility, retainability, mobility, and resource
utilization need to be monitored on network slice level by filtering the respective
Base EBS-N counters per S-NSSAI in a PLMN. Optionally, the bearer (DRB)
related Base EBS-N counters can also be filtered per QoS (5QI) in a network slice
if needed.
The KPIs for integrity, however, differentiate the requirements of service types
per network slice. Each slice can support multiple types of services (for example,
Voice, Internet), which can have different performance requirements. Since
service types are associated with certain QoS characteristics, the respective PM
counters must be monitored per slice based on the S-NSSAI and 5QI.
Because network slices can span across a cluster of NR cells and gNodeBs, the
aggregation of those KPIs needs to be considered to calculate the total KPI per
network slice (S-NSSAI) or service type (5QI) in the RAN.
The Ericsson gNodeB and ENM products currently support the monitoring on
network slice level for the KPI categories listed in Table 5. The related Base EBSN counters can be filtered by using a combination of the parameters shown in the
Filter Granularity column resulting in the creation of the corresponding Flexible
EBS-N counters.
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NR SA Network Slicing Guideline
Additional details about the currently supported Based EBS-N counters are
provided per KPI category and described below Table 5 in dedicated sections
together with some KPI formula examples.
Table 5
List of Supported KPIs
Category
Description
Filter Granularity
Accessibility
DRB setup success rate
PlmnId, Snssai, QoS
PDU session setup
success rate
PlmnId, Snssai
DRB abnormal release
rate
PlmnId, Snssai, QoS
Retainability
PDU session abnormal
release rate
PlmnId, Snssai
Resource Utilization
Utilization of DL and UL
spectrum resources
(RBSym) per radio
resource partition
partitionId,
serviceId
Integrity/Throughput
Downlink DRB
throughput
PlmnId, Snssai
Downlink DRB
throughput per QoS
(5QI)
Uplink UE throughput
Mobility
UE successful handover
rate
PrefUeGrpId, UeGrpId(1)
(1) The mobility-related Base EBS-N counters cannot be directly filtered by the PlmnId and
Snssai. Instead, the UE Grouping framework must be used to group UEs per PLMN and SNSSAI. The slice-specific observability is then achieved by filtering the Base EBS-N counters for
mobility by the respective UE group ID. This only works reliably for UEs that use one slice.
For supplementary performance management and EBS-N counter information,
see also the following NR documents:
— Manage Performance
— Key Performance Indicators for NR SA
— Lists and Delta Lists - Referral Document
In the OSS Counters section, Lists and Delta Lists - Referral Document describes
all the EBS-N counters that are currently supporting the monitoring (filtering) on
network slice level, including the applicable filter criteria and corresponding
gNodeB PM event information.
For the management of Flexible EBS-N counters in ENM, see the Flexible Counter
Management section of the ENM Product Description in the ENM library.
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Principles and Guidelines
Accessibility KPIs
The Accessibility KPIs on a PDU session-level are calculated per NR cell from the
corresponding Flexible EBS-N counters as shown below:
Similar KPI calculations can be done on the DRB-level either across all 5QIs or
filtered per 5QI.
Table 6 lists the Accessibility Base EBS-N counters that currently support the
flexible filtering for network slices together with the corresponding PM Events
and filter criteria obtained from the gNodeB.
Table 6 Accessibility KPIs: Relation between EBS-N Counters, Filter
Parameters, and gNodeB PM Events
Base EBS-N Counter
Applicable Filters
gNodeB PM Event
pmEbsPduSessionEstab
Att
PlmnId
CuCpProcInitialCtxtE
stab
Snssai
pmEbsPduSessionEstab
Succ
pmEbsPduSessionModif
yAtt
CuCpProcPduSessionRe
sourceSetup
PlmnId
Snssai
CuCpProcPduSessionRe
sourceModify
pmEbsPduSessionModif
ySucc
pmEbsDrbEstabAtt5qi
PlmnId
pmEbsDrbEstabSucc5qi
Snssai
QoS
CuCpProcInitialCtxtE
stab
CuCpProcPduSessionRe
sourceModify
CuCpProcPduSessionRe
sourceSetup
Retainability KPIs
The Retainability KPIs on PDU session-level are calculated per NR cell from the
corresponding Flexible EBS-N counters as shown below:
Similar KPI calculations can be done on the DRB-level either across all 5QIs or
filtered per 5QI.
The use of the NR RRC Connection Re-establishment feature (FAJ 121 5346) has
a positive impact on this KPI by lowering the PDU session abnormal release rate
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NR SA Network Slicing Guideline
due to Radio Link Failures (RLFs) detected by UEs. If UEs can re-establish failed
RRC connections, their PDU sessions are maintained instead of being abnormally
released.
There is a related Performance Indicator (PI) that can be used to observe the
RRC connection re-establishment success rate per network slice. This PI can
additionally be monitored to check in how far the PDU session abnormal release
rate is affected by conditions causing RLFs. The PI can be calculated per slice
with following Flexible EBS-N counters:
Note:
In Intra-gNodeB scenarios a UE can only re-establish a failed RRC
connection through a new cell if latter supports all the network slices
that are used by the UE in PDU Sessions. In Inter-gNodeB scenarios it is
sufficient if the target cell supports a subset of the network slices. In
latter case, only the bearers for PDU sessions of supported slices are reestablished.
Table 7 lists the Retainability Base EBS-N counters that currently support the
flexible filtering for network slices together with the corresponding PM Events
and filter criteria obtained from the gNodeB.
Table 7 Retainability KPIs: Relation between EBS-N Counters, Filter
Parameters, and gNodeB PM Events
Base EBS-N Counter
Applicable Filters
gNodeB PM Event
pmEbsPduSessionRelNo
rmal
PlmnId
CuCpProcUeCtxtRel
Snssai
CuCpProcPduSessionRe
sourceRelease
pmEbsPduSessionRelAb
normalAmf
PlmnId
CuCpProcUeCtxtRel
Snssai
CuCpProcPduSessionRe
sourceRelease
PlmnId
CuCpProcUeCtxtRel
Snssai
CuCpProcPduSessionRe
sourceRelease
pmEbsPduSessionRelAb
normalGnb
pmEbsDrbRelNormal5qi
QoS
CuCpProcPduSessionRe
sourceModify
pmEbsDrbRelAbnormalA
mf5qi
pmEbsDrbRelAbnormalA
mfAct5qi
PlmnId
CuCpProcUeCtxtRel
Snssai
CuCpProcPduSessionRe
sourceModify
QoS
pmEbsDrbRelAbnormalG
nb5qi
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