Node Group
Synchronization
Introduction
Contents
• NGS evolution history
• NGS Introduction
• NGS Benefit
• NGS Pre-request
• NGS contents
• NGSM Configuration
• Node Group Sync Topologies
• NGS limitation
• Additional info
• NGS troubleshooting Skills
• MR3920 NGS Test
NGS evolution history
• NGS:
•
•
•
•
•
MR826: support SR(16B)
MR2657: support slave DU(17A)
MR2747: support DMMA(GSM enhancement, support AIR21 G17.Q2)
MR3920: GSM support SP (DUG AS SP, G17.Q3)
MR2484: all(Dynamic NGS)
NGS Introduction
• Node Group Synchronization can be used in for example Mixed Mode Radio or MultiOperator RAN configurations.
• Most operators are evolving their mobile networks by deploying 4G networks in conjunction
with existing 2G and 3G networks. This leads to that more and more MSMM configurations
are being built and need to be supported.
• The node that is using the external synchronization reference is called the Synchronization
Provider (SP). The other nodes of the Node Group are called Synchronization Receivers (SR).
• MSMM (MORAN) Synchronization solutions:
GPS Out Solution
GPS Receiver Solution
(new) Node Group Synchronization (Sync over CPRI)
NGS Benefit
The main benefits of node group-based synchronization are:
• More robust Mixed Mode Radio and Multi-Operator RAN synchronization
solution.
• CPRI gives the possibility to optical transmission, which in practice
removes the distance limitation between the nodes, supported length of
CPRI (< 40 kilometers)
• Redundancy by using several shared radios as possible synchronization
interconnects.
• Gives more flexibility to operators in how they build their MSMM
configurations
NGS Pre-request
•Necessary network synchronization-related licenses must be
installed and activated.
•Only the SP can provide the Node Group with Time
Synchronization, but SRs can run Time Synchronization if the
SP provides it
•The Network Synchronization Plan must be prepared.
•License for Mixed Mode Radio or Multi-Operator RAN must
be installed and activated.
NGS contents
•Node group: The set of nodes that are connected to each other by
shared radios. All nodes in the group must be synchronized to each
other, both in frequency and time.
•SP: Synchronization Provider, Each Node Group uses only one
external synchronization reference, the node using external
synchronization reference called SP
•SR: Synchronization Receivers, The other nodes of the Node Group.
•Attribute under MO NodeGroupSyncMember
NGSM Configuration
•
•
•
SP
• Synchronization Provider
• Provide Sync info in the node group
SR
• Synchronization Receiver
syncRiPortCandidate
• The RiPort which can receiver Sync info
NGS Configuration
•Node Priority: each node must be given a unique node priority.
•For SP the priority is 1, for SR can be value 2–15 (initially only odd
values).
•The number of hops from the SP to the most remote SR is limited to
two hops
•For WCDMA and LTE, the priority defined in MO
NodeGroupSyncMember.
localNodeInformation:
• for SP node is SYNC_PROVIDER for SR node is
SYNC_RECEIVER_TIME_LOCKED
•syncRiPortStatus : for SP OK_NOT_ACTIVE for all RI Ports Candidates.
For SR OK_ACTIVE for one of the RI Port candidates. OK_NOT_ACTIVE
for all other RI Ports Candidates.
NGSM Configuration-L/W G1
The Local node info:
Hop counter: the distance to SP
LocalStatus: local clock status
Node Priority
The Riport Candate status:
1 means the node is recevice Sync info from
The SP status
Prot.
2 means this port is ok and stand by.
In normal case, the Riport Status should be only
One active
and others should be OK_NOT_CTIVE
SyncRiPortStatus
•0 UNKNOWN
•1 OK_ACTIVE
•2 OK_NOT_ACTIVE
•3 CPRI_LINK_NOT_AVAILABLE
•4 FREQUENCY_ERROR
•5 PHASE_ERROR
•6 LOSS_OF_FREQUENCY_MEASUREMENTS
•7 LOSS_OF_PHASE_MEASUREMENTS
NGS Configuration
Parameters on L
NGS Configuration
Parameters on W
NGS configuration
NRJ LAB NGS with BB R503
SR2
SP
SR1
SR3
Node Group Sync Topologies
NGS limitation
• Only RUs connected via CPRI links terminating in Main DU in a Multi DU node
configuration, can be used for Inter Node synchronization in the Node Group.
Improvement:MR2657: support slave DU(17A)
• DUG can’t be used as SP
NGS configuration
Slave DU share the sync
DUG2(Slave)
RRUS32 B3
DUW(SR)
RUS02 B8
DUS(SP)
IDL2
DUG1(Master)
IDL2
RUS01 B2
DUW (SR)
DUG3(Slave)
RUS02 B8
Additional info:
NGS minimum software version
The recommendation is to have 16A baseline for system sharing Radio Units
with GSM, so for the combination example given the following SW baselines
are recommended:
LTE + WCDMA + GSM MSMM is L16A, W_RBS15B, W_RNC14B, G_BTS16A
and OSS14B.
Link ：
https://eqna.lmera.ericsson.se/questions/20175/ltewcdmagsm-node-group-s
ynchronization
Additional info:
GPS configuration
• GPS out configuration
• GPS out limitation
Additional info:
GPS out Configuration
•
For Sync provider :
•
•
Set TimingUnit=1
gpsOutEnabled true
For Sync receiver:
•
•
cr subrack=1,Slot=1,PlugInUnit=1,TimingUnit=1,GPSoutsynclink=1
acc Synchronization=1 addSyncRefResource (to add this sync ref to synclist)
Additional info:
GPS Out Solution
MSMM W+G, L+G, W+L
GPS Receiver Solution
MSMM W+G, L+G, W+L
Additional info:
GPS out limitation
• The recommended synchronization solution for MSMM configurations, the GPSOut solution,
have following limitations:
• GPSOut occupies both GPS ports on the two DUs in MSMM configuration – No GPS as external
reference.
• GPS port is an electrical interface so that it is distance limited (<15 meters).
• Only one-way communication over GPSOut, from GOG (GPSOut Generator) to GOS (GPSOut
Slave).
• The GPSOut signal is a separate path from the communication flow; it’s supposed to
synchronize and align the CPRI links that transport the I/Q data that are combined in the Radio
Units. This leads to complicated fault handling scenarios and difficulties to build robust MSMM
configurations.
• Distance is only limited by supported CPRI lengths
NGS troubleshooting
Ngsm Configurate–G1 W/L
Configuration:
>cr TransportNetwork=1,Synchronization=1,nodegroupsyncmember=1
-syncNodePriority (long): 1
syncRiPortCandidate (sequence:structRef-SyncRiPort):
dunumber=1,duriport=1;dunumber=1,duriport=2;dunumber=1,duriport=3;dunumber=1,duriport=4
>deb NodeGroupSyncMember
NGS_DUW.mos
NGS troubleshooting Skills
Ngsm configuration –G2 W/L
Configuration:
>cr ManagedElement=1,Transport=1,Synchronization=1,RadioEquipmentClock=1,NodeGroupSyncMember=1
Attribute 1 of 2, syncNodePriority
(derivedRef:RsyncNodeGroupSyncMember.RsyncNodeGroupSyncMember_NodeGroupSyncMember_syncNodePriority): 2
Attribute 2 of 2, syncRiPortCandidate (sequence:moRef-ReqRiPort.RiPort):
Enter LDN, or sequence of LDNs (separated by spaces): FieldReplaceableUnit=1,RiPort=A FieldReplaceableUnit=1,RiPort=B
FieldReplaceableUnit=1,RiPort=C FieldReplaceableUnit=1,RiPort=D FieldReplaceableUnit=1,RiPort=E
>deb NodeGroupSyncMember
NGS troubleshooting Skills
MSMM configuration
• L/W G1:
• set AuxPlugInUnit=RRUW mixedModeRadio true
• set AuxPlugInUnit=RRUW isSharedWithExternalMe true (17B)
• set NodeBFunction=1
featureStateMixedMode 1 (W)
• set Licensing=1,OptionalFeatureLicense=MixedModeRadioLte featureState 1(L)
• L/W G2:
• set FieldReplaceableUnit=RRU mixedModeRadio true
• set FieldReplaceableUnit=RRU isSharedWithExternalMe true (17B)
• set SystemFunctions=1,Lm=1,FeatureState=CXC4011018 featureState 1
NGS troubleshooting
• Check W/L sync state ：
• syncinfo clk
W/L troubleshooting
• G1 BCM message check:
• nssmpinfo rec_bcm ---------------print received BCM message
• nssmpinfo sent_bcm --------------print sent BCM message
• G2 BCM message check
• syncngsmlocal info bcm
• Qualification rules for BCMs:
• Added new class which checks if values are out of range
• NGRefC, NGRefS, hop counter, …
• e.g.
received „hop counter” exceeds 10 -> not valid BCM, discard the entire BCM
W/L troubleshooting
G2 BCM info:
G1 BCM info :
[2017-07-25 06:27:37.320848]: BCM received - clientRef = 0xdf0ec126, nodePriority = 4, syncRefCandidate = TIME_REF_1,
duNumber = 1, riPortNo = 2, sharedId = 4, lockedTo = 1, syncRefSelected = TIME_REF_1, spSyncState = RNT_LOCKED,
syncProviderTimeAcc = 0, syncProviderCbfnJumpInd = 0, hopCounter = 1, esfc = 1157225, mfn = 21, dataRTOSeconds = 0,
dataRTONanoseconds = 0, syncProviderLooseTimeSyncState = 1, syncProviderLooseTimeDiffSec = 0,
syncProviderLooseTimeDiffMicroSec = 0, selectionMode = 1, bcmValid = 1
W/L troubleshooting
spSyncState, allowed values are:
•0 - RBS_IW_SP_SYNC_STATE_UNKNOWN
•1 - RBS_IW_SP_SYNC_STATE_FREERUNNING
•2 - RBS_IW_SP_SYNC_STATE_FREQUENCY_HOLDOVER
•3 - RBS_IW_SP_SYNC_STATE_FREQUENCY_LOCKED
•4 - RBS_IW_SP_SYNC_STATE_TIME_OFFSET_HOLDOVER
•5 - RBS_IW_SP_SYNC_STATE_TIME_OFFSET_LOCKED
•6 - RBS_IW_SP_SYNC_STATE_RNT_TIME_HOLDOVER
•7 - RBS_IW_SP_SYNC_STATE_RNT_TIME_LOCKED
ngsmSelectionMode:
•
1 - NODE_PRIORITY, node is using only node priority when determining NG role (node with prio different than 1 can become SP if there is no node with lower prio in the
group)
•
2 - REFERENCE_AND_NODE_PRIORITY, node is using reference priority and node priority when determining NG role (node with best external reference will become SP)
W/L troubleshooting
INCI_PV4 values
INCI_PV2/3 values
Reference Type
Accuracy
Hysteresis (15%)
15
6
Time reference
1-50
8
14
6
Time reference
51-100
15
13
6
Time reference
101-200
30
12
6
TIME_1_REF (GNSS reference)
201-400
60
11
6
Time reference
401-600
90
10
5
Time reference
601-800
120
9
5
Time reference
801-1100
165
8
5
TIME_2_REF (PTP_TIME reference)
1101-1500
225
7
5
Time reference
1501-2000
300
6
5
Time reference
2001-4000
600
5
5
Time reference
4001-10000
1500
4
4
TIME_HOLDOVER
Uknown accuracy
1500
3
4
LOOSE TIME SYNC reference
Future use
Not defined
2
3
FREQUENCY_LOCKED
N/A
N/A
1
2
FREQUENCY_HOLDOVER
N/A
N/A
0
1 and 0
FREE_RUNNING reference - DNU
N/A
N/A
https://wcdma-confluence.rnd.ki.sw.ericsson.se/pages/viewpage.action?pageId=124289630
W/L troubleshooting
• Other useful command ：
•
•
•
•
•
•
sts-----------check the external sync source status
st ru/unit/air--------------check radio status
alt------------check alarm
bl/deb mo name/proxy id-----block/deblock MO
llog -l -----------check DU restart time and reason
lh ru llog –l---------check RU restart time and reason
• G1
• syncinfo scspi
• syncinfo clk
• G2
• synccentral info all
• syncngsmcentral info all
• syncngsmlocal info all
NGS case.log
MR3920 description
› 105 65-0937/03920
› GSM DUG shall be able to act as Synchronization
Provider. It shall be supported in all configurations
with 1, 2 or 3 DUGs in a DUG cluster in Mixed
Mode Radio configurations using Node group
Synchronization.
MR3920 Background/Problem Description
• DUG could not act as Sync Provider;
• In some configurations, DUG could not be SP will cause problems.
X
DUW
Master
DUG
Slave
DUG
DUS
GPS
State diagram
No qualified SoCC &
HO ends
Role SP
RNGRefS > NGRefS
Locked to external ref
Role SR
Locked to SP
Restart
RNGRefS > NGRefC
(RNGRefS < NGRefC) &
(RNGRefC < NGRefC)
RNGRefS < NGRefC
RNGRefS > NGRefC
Startup
Role ND & free running
RNGRefS < NGRefC
No qualified SoCC
Restart or
(No ext ref)
Standalone
Locked to external ref
Restart or
(no ext ref)
No qualified SoCC
MR3920 test Topology
MR3920 test case
Test case
status comment
TC1.1: Setup Configuration 1 test environment
Passed
TC2.1: Node power on sync provider first
Passed
SP->SR3->SR2->SR4
TC2.2: Node power on sync receiver first
Passed
SR4->SR2->SR3->SP
TC2.3: Multi restart GSM.SP node: Cold restart
Passed
5 times
TC2.4: Multi restart GSM.SP node: Warm restart
Passed
5 times
TC2.5: Multi Restart all SRs : Cold restart
Passed
5 times
TC2.6: Restart all SRs: Warm restart
Passed
Restart at the same time
MR3920 test case
test case
status comment
TC3.1: Add_Remove SoCC candidate with traffic background
Passed
use G1 LTE
TC3.2: SR loss and regain of SoCC by RU restarts
Passed
restart all RUs
TC3.3: SR loss and regain of one_all SoCC by CPRI break
Passed
TC3.4: SP loss external reference(GPS_PCM) and regain
Passed
lock SP GPS
TC4.1: Configure same priority on 2 nodes (SP+SR and SR+SR)
TC5.1: CPRI link regain after break more than 5min with UE
attach_traffic
TC5.2: Operate CPRI breaking and DU restarting at the same
time
Passed
will raise alarms
Passed
use G1 LTE
TC5.3: Plug in_out IDL cable between master DUG and slave
DUG
Passed
Passed