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www.DigiTrainee.com Company Confidential
LTE Optimization Guideline
Sect ion-5
RNO Consultant : Ray Khastur
Version: V 1.0 (20151028)
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Objectives
Upon completion of this course, you will be able to
Know Drive Test Tools, Site Audit Check.
Know definition of RSRP and how to calculate RSRP transmit power for different Bandwidth.
Know def inition of SINR and impact of traffic in different traffic usage, and understand how to improve
SINR in some Drive Test Result.
Know how LTE do Cell Search and Reselection Process and Procedure.
Know how LTE Scheduling Procedure.
Know some SON Feature and the function.
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Contents
1.Overview
2.RSRP Introduction
3.SINR Introduction
4.Cell Search & Cell Reselection
5.LTE Scheduling
6.LTE SON Feature
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Overview
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Drive Test Peripheral
Page 5
Notebook
GPS
LTE Dongle
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Daily Pre Check DT ToolsConfiguration
Page 6
Samsung
Galaxy Note 4
Mf90
SamsungGalaxy J5
To make sure
Drivetest resultshowing better
performance.
Each time DTTeam will go to
field, they have to
send toolsconfiguration by
email.
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On Site Hardware
Page 7
RRU : Radio Remote Unit
BBU : Baseband Unit
MIMO Antenna
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Site Audit Report
Page 8
Compass
View
Tilt Meter
View
ElectricalTilt Meter
View
Panoramic
View
In this part show details ofsite location
In this part show details Hardware Parameter
Value.
Make sure all data taken with correct way to
prevent wrong measurement.
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RSRP Introduction
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RSRP (Reference Signal Receive Power)
RSRE Power = Psingle port-10*log(12*Nrb)+10*log(1+Pb)
Where ; PSingle Port = PRRU - 10*log(Nport)
Pb is Power Bosting
Page 10
Psingle port = 49-10*log(4)
= 43 dBm
= 20Watt
PB
B/ A
Single
Antenna Port
2 or 4
Antenna Port
0 1 5/4
1 4/5 12 3/5
3 2/5
Impact on Radio Network
Performance: A larger value of Pb
results in a larger increase in
ReferenceSignalPwr, better
channel estimation performance,
and better PDSCH demodulation
performance, but it also leads to
lower transmit power of the PDSCH
(type B) and thus increases
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RSRP Contd
Page 11
Power Boosting for RS
PB =1 by default
RS Power for 20MHz
= 43 10*log(100*12) + 10*log10(PB+1) = 15.2dBm
Bandwidth PB PRS ( dBm)
10M 1 18.2
15M 1 16.4
20M 1 15.2
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Why RSRP Level lower than other Receive Power(2G/3G)
Page 12
Items GSM UMTS LTE
(e)NodeB power per Tx (dBm)43 43 43
Bandwidth (MHz) 0.2 5 20
Number of RB N/A N/A 100
BCCH Power/ CPICH power
/RS power per RE (dBm)
43 33 15.2
CL (dB) 120 120 120
Rx Lev/RSCP/RSRP (dBm)-77 -87 -104.8
Received RS signal strength
over whole bandwidth
-81.8
RSRP is the received signal
strength over 15KHz bandwidthwhile bandwidth of RSCP is5MHz
RSRP of LTE is much smaller than RSCP of UMTS under same radio environment
Only 1/6 REs is used for RS transmission
within one RB and hence the total
received RS power is
10*log10(100*12*1/6) = 23dB higher than
RSRP
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Recommendation Value
PB PA
0 0
1 -3
2 -4.77
3 -6
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SINR Introduction
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SINR (Signal to Interference & Noise Ratio)
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If there are 100 UE in a
cell (100RB) in the samescheduled to use PRB,each user will got 1 PRB.
More less UE got PRB
more high Tx Power willbe send from the UE.Which causing ULInterference increased
also.
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1 2 3 4 5 6 7 8 9 ~ ~ 93 94 95 96 97 98 99 100
x x x x x
x x x x x
x x x x x
1 2 3 4 5 6 7 8 9 ~ ~ 93 94 95 96 97 98 99 100
x x x
x x x
x x x
X : Available PRB on overlapped area
More smaller PRB scheduled for one UE in busy hour, will make power transmit will more high which
causing Noise Figure increase for entire cell and impact to SINR. More high PRB Utilization will causing
high probability of collision PRB on the cell edge which contribute to more degradation on cell edge.
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PCI Mod 3 RS shift among neighborcells
Page 18
Frequency domain location of the RS is determined by value of PCI mod 3
If RS is shifted, then it will help for better performance under low load
RS location vs PCI mod 3:
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SINR Comparison
Afternoon 16:00 Midnight 02:00
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SINR Comparison
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CQI Comparison
Afternoon 16:00 Midnight 02:00
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CQI Comparison
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DL Throughput Comparison
Afternoon 16:00 Midnight 02:00
During Low Utilization of DL PRB on Cell Level give benefit for single UE can get
higher DL PRB which is related to the Higher DL Throughput.
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DL Throughput Comparison
During Low Utilization of DL PRB on Cell Level give benefit for single UE can get
higher DL PRB which is related to the Higher DL Throughput.
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CQI to MCS
CQI stands for Channel Quality Indicator. As the name implies, it is
an indicator carrying the information on how good/bad the
communication channel quality is. This CQI is for HSDPA. (LTEalso has CQI for its own purpose).
CQI is the information that UE sends to the network and practically
it implies the following two
i) Current Communication Channel Quality is this-and-that..
ii) I (UE) wants to get the data with this-and-that transport block
size, which in turn can be directly converted into throughput
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LTE Cell Search & Cell Reselection
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MIB & SIB Information
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RNTI
One of the other numbers which you would very frequently come accross is RNTI. RNTI stands for Radio Network
Temporary Identifier.
As the name implies, it is a kind of Identification number. Normally we use indentification number to differntiate one thingfrom all other similar things. For example, your driver's license number let you identify yourself from all other drivers.
Social Security number do the same thing as well.
Getting more specifically into LTE, this RNTI is used to indentify one specific radio channel from other radio channel and
one user from another user. As you may recall, in WCDMA is a RNTI concept which is carried as part of MAC header to
deferentiate one user to another while in communication state. and in WCDMA case it used special channelization code to
deferentiate one radio channel from the other.
Types of RNTI
P-RNTI : It stands for Paging RNTI. Used for Paging Message.
SI-RNTI : It stands for System Information RNTI. Used for transmission of SIB messages
RA-RNTI : It stands for Random Access RNTI. Used for PRACH Response.
C-RNTI : It stands for Cell RNTI. Used for the transmission to a specific UE after RACH.
T-CRNTI : It stands for Temporary C-RNTI. Mainly used during RACH
SPS-C-RNTI : It stands for Semi persistance Scheduling C-RNTI TPC-PUCCH-RNTI : It stands for Transmit Power Control-Physical Uplink Control Channel-RNTI
TPC-PUSCH-RNTI : It stands for Transmit Power Control-Physical Uplink Shared Channel-RNTI
M-RNTI : It stands for MBMS RNTI
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Signaling Radio Bearer
SRB0 is for RRC messages using the CCCH logical channel;
SRB1 is for RRC messages (which may include a piggybacked NASmessage) as well as for NAS messages prior to the establishment of
SRB2, all using DCCH logical channel;
SRB2 is for RRC messages which include logged measurement
information as well as for NAS messages, all using DCCH logical
channel. SRB2 has a lower-priority than SRB1 and is always configuredby E-UTRAN after security activation.
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SRB Mapping
MasterInformationBlock
- Signalling radio bearer: N/A
- RLC-SAP: TM
- Logical channel: BCCH
- Direction: E-UTRAN to UE
SystemInformationBlockType1
- Signalling radio bearer: N/A
- RLC-SAP: TM
- Logical channel: BCCH
- Direction: E-UTRAN to UE
RRCConnectionRequest
- Signalling radio bearer: SRB0
- RLC-SAP: TM
- Logical channel: CCCH
- Direction: UE to E-UTRAN
RRCConnectionSetup
- Signalling radio bearer: SRB0
- RLC-SAP: TM- Logical channel: CCCH
- Direction: E-UTRAN to UE
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RRCConnectionSetupComplete
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH- Direction: UE to E-UTRAN
RRCConnectionReconfiguration
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
MeasurementReport
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: UE to E-UTRAN
MobilityFromEUTRACommand
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
UECapabilityEnquiry
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
UEInformationRequest
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH- Direction: E-UTRAN to UE
DLInformationTransfer
- Signalling radio bearer: SRB2 or
SRB1 (only if SRB2 not established
yet. If SRB2 is suspended, E-
UTRAN does not send this message
until SRB2 is resumed.)
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
Paging
- Signalling radio bearer: N/A
- RLC-SAP: TM
- Logical channel: PCCH
- Direction: E-UTRAN to UE
LTE C ll S h & U li k
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LTE Cell Search & UplinkSynchronization
In LTE User Equipment (UE) must be able to do cell search, initial synchronization and random access procedure for
downlink and uplink access. To perform cell search, and initial synchronization, two synchronization signals, PrimarySynchronization Signal (PSS) and Secondary Synchronization Signal (SSS), are periodically transmitted from the base
station in the LTE system. Using these two signals and making use of the properties of Zadoff -Chu (ZC) and Pseudo-
Noise (PN) sequence, the mobile unit will determine on which of the available cell sites it should lock into and it acquires
time and frequency synchronization. After UE will do random access procedure using Physical Random Access Channel
(PRACH). An appropriate design of PRACH preamble is essential to provide frequent enough random access
opportunities and an accurate UE synchronization estimation to adapt to different cell ranges and network conditions
without using unnecessary resources. This paper presents the complete LTE access procedure and more about PRACH
implementation and detection. Then the performance of the PRACH synchronization procedure under different parameter
settings is compared in a typical scenario of LTE.
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PRACH TDD & FDD
Random Access Channel (RACH)
RACH procedure begins with a preamble (PRACH)
PRACH resources assigned by eNB within PUSCH region
PRACH preamble fits into 6 PRBs
Sufficient for timing estimation
Invariant with bandwidth for low complexity
Zadoff Chu sequence
Excellent correlation properties
Zero correlation zone for different cyclic shifts
Flat frequency spectrum
Different sequences provided first by different cyclic shifts, then by different root sequences
Multiple PRACH formats suitable for different cell sizes
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PRACH Types
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Typical 'Contention Based' RACH Procedure is as follows :
i) UE --> NW : RACH Preamble (RA-RNTI, indicat ion for L2/L3
message size)
ii) UE NW : L2/L3 message
iv) Message for early contention resolution
Typical 'Contention Free' RACH Procedure is as follows :
i) UE NW : RACH Preamble (RA-RNTI, indicat ion for L2/L3 message
size)
iii) UE
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PRACH Performance
Monitoring Principles
The physical random access channel (PRACH) transmits preambles during random access procedures. Preamble is classified into contention
preamble and non-contention preamble. Contention preambles are used in the following scenarios: initial connection establishment,
reestablishment, handover, downlink data transmission for UEs in the out-of-synchronization state, and uplink data transmission for UEs in the out-of-synchronization state. Non-contention preambles are used in two scenarios: handover and downlink data transmission for UEs in the out-of-
synchronization state. Therefore, PRACH performance can be measured using the following factors:
Conflict probability for contention-based preambles: The more frequently the contention-based access is performed, the higher
probability that the preambles are conflicted. When the conflict probability reaches a certain extent, the access delay increases,
severely affecting user experience.
Assignment success rate for dedicated preambles: The assignment success rate for dedicated preambles decreases with the incre ase
of non-contention-based accesses. When the success rate decreases to a certain extent, the handover delay increases, affecting user
experience.
Monitoring Methods
Conflict probability for contention-based preambles = L.RA.UeRaInfoRspWithCon.Num / L.RA.UeRaInfoRsp.Num x 100%
Assignment success rate for dedicated preambles = L.RA.Dedicate.PreambleAssign.Num / L.RA.Dedicate.PreambleReq.Num x100%
whereL.RA.UeRaInfoRspWithCon.Num indicates number of times the UEInformationResponse message in which contentionDetected IE value is
TRUE is received, that is, the number of times the conflicting UEInformationResponse message is received.
L.RA.UeRaInfoRsp.Num indicates the number of times the UEInformationResponse message containing RACH information is received.
L.RA.Dedicate.PreambleAssign.Num indicates the number of times the non-connection-based preambles are ass igned.
L.RA.Dedicate.PreambleReq.Num indicates the number of times the non-contention-based preamble is requested.
Suggested Measures
If the conflict probability for contention-based preambles reaches or exceeds 5% for X days (three days by default) in a week, enable the
RACH adjustment algorithm by running the command MOD CELLALGOSWITCH: LocalCellId=x, RachAlgoSwitch=RachAdjSwitch-1.
If the assignment success rate for dedicated preambles is less than 99% for X days (three days by default) in a week, enable the RACH
resource adjustment algorithm and reuse of dedicated PRACH preambles between UEs by running the command MOD CELLALGOSWITCH:
LocalCellId=x, RachAlgoSwitch=RachAdjSwitch-1, RachAlgoSwitch=MaksIdxSwitch-1;.
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PLMN Selection
When a UE is powered on or moves from a
coverage hole to a coverage area, the UE first selects the last
RPLMN and attempts to register with that PLMN. If a UE has registered successfully with a PLMN,
the UE shows the selected
PLMN on its screen, and now it can receive service from an
operator. If the last RPLMN is
unavailable or registration on this PLMN fails, another PLMN can
be automatically or manually
selected based on the priorities of PLMNs stored in the USIM.
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Uplink Data Transmission
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Uplink Data TransmissionScheduling - Persistent SchedulingThere are a couple of Data Transmission Scheduling Scheme
in LTE. The most simple in terms of algorithm would be the
persisent scheduling. In this scheduling mode, Network send'Grant' in DCI Format 0 for every subframe.
i) Network send the first data on DL PDSCH and PDCCH
which has DCI format 1 for DL Data Decoding and DCI format
0 for UL Grant. (If there is no downlink data to be transmitted,
network transmits only DPCCH with DCI format 0 without any
DPSCH data)
ii) UE decode PCFICH to figure CFI value.
iii) UE decode PDCCH and get the information on DCI format
1
iv) Based on DCI format 1, UE decode DL data.
v) UE decode the information on DCI format 0 from PDCCH
vi) UE send ACK/NAK for DL data through UCI (UCI will be
carried by PUCCH)
vii) UE check the Grant field.
viii) If Grant is allowed, UE transmit the uplink data throughPUSCH
ix) Network decode PUSCH data and send ACK/NACK via
PHICH
x) UE decode PHICH and retransmit the data if PHICH
carries NACK
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U li k D t T i i S h d li N
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Uplink Data Transmission Scheduling - NonPersistent Scheduling
In Persistent Scheduling mode, UE can send the
data to Network anytime since Network is sending UL
Grant all the time. But what if Network does not sendUL Grant all the time ? In this case, UE has ASK the
network to send UL Grant (DCI 0). If network send
UL Grant, then UE can send UL data as allowed by
the UL Grant.
Overall procedure is as follows :
i) UE send SR (Scehduling Request) on PUCCH
ii) Network send UL Grant (DCI 0) on PDCCHiii) UE decode DCI 0 and transmit PUSCH based on
the RBs specified by DCI 0
iv) Network decode the PUSCH
v) Network send ACK/NACK on PHICH
vi) If Network send NACK, go to step i)
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Connection Management
UE State
RRC_CONNECTED
ACTIVE SLEEP
DRX
RRC_IDLE MODE
Intra Freq Cell
Reselection
Inter Freq Cell
Reselection
In this PPT only discussed about
INTRA FREQUENCY and INTER FREQUENCY
With Equal Priority
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Cell Selection Criteria
During cell selection, a UE selects an E-UTRAN cell that meets the cell selection criteria. The
UE can camp on a cell only when the RSRP and reference signal received quality (RSRQ) of
the cell are greater than the values of the CellSel.Qrxlevminand CellSel.Qqualminparameters, respectively.
A UE selects an E-UTRAN cell to camp on when the cell meets both of the following conditions:
Srxlev > 0
Squal > 0
where: Srxlev = Qrxlevmeas - (Qrxlevmin + Qrxlevminoffset) - Pcompens ation
Squal = Qqualmeas - (Qqualmin + Qqualminoffset)
The variables in the previous formulas are described as follows:
l Qrxlevmeas: measured received signal level (that is, measured RSRP), expressed in dBm.
l Qrxlevmin: minimum required received signal level configured on the eNodeB, express ed
in dBm.
l Qrxlevminoffset: offset to the value of Qrxlevmin. In cell selection, this offset is considered
when the UE in a VPLMN attempts to camp on a cell in a higher -priority PLMN.
l Pcompensation : max (PMax - UE Maximum Output Power, 0), expressed in dB.
PMax: m aximum transmit power (express ed in dBm) of the UE during uplink
transmission.
UE Maximum Output Power: maximum output power (expressed in dBm ) of the UE.
l Qqualmeas: measured received signal quality (that is , measured RSRQ), expressed in dB.
l Qqualmin: minimum required received s ignal quality configured on the eNodeB, expressed
in dB.
l QQualminoffset: offset to Qqualmin. In cell s election, this offset is cons idered when the
UE in a VPLMN attempts to camp on a cell in a higher-priority PLMN.
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Cell Reselection Trigger (Intra
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Cell Reselection Trigger (IntraFrequency)
Cell Reselection Trigger
Time Domain
RSRP-60
-70
-80
-90
-100
-110
-120
-130
-140
SIntraSearch = 29 (2dB)
= 58 dB
Srxlev < SintraSearch
RSRP + 128 < 58
RSRP < -70
Cell will implement the
Intra Freq Search if:-70 >RSRP> -128
SIn
traSearch
-70
-128 (Srxlevel)
Cell Reselection Trigger (Equal
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Cell Reselection Trigger (EqualPriority) Intra & Inter
R_s=Qmeas,s + Qhyst
R_n=Qmeas,n - CellQoffset
TRESELEUT
RAN
Cell Reselection Trigger
Time Domain
RSRP-90
-92
-94
-96
-98
-100
-102
-104
-106
Qhyst = 4 dB
CellQoffset = 0 dB
TRESELEUTRAN = 1 s
Cell Reselection with Default Value
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Cell Reselection with Default Value(Equal Priority)
R_s=Qmeas,s + Qhyst
R_n=Qmeas,n - CellQoffset
TRESELE
UTRAN
Cell Reselection Trigger
Time Domain
RSRP
R_n
R_s
Note: Please see on the Full Screen Mode
Qhyst = 4 dBCellQoffset = 0 dB
TRESELEUTRAN = 1 s
Conclusion : With default value, with Serving cell RSRP quite strong,
UE can do cell reselection after elapsed from Timer
RSRP-90
-92
-94
-96
-98
-100
-102
-104
-106
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Paging
The purpose of paging is to transmit paging information to a UE in idle mode or to inform all
UEs in the EMM-REGISTERED state about a system information change. A paging procedure
can be initiated by either an MME or an eNodeB.When an MME initiates a paging procedure, the paging message contains a tracking area list
(TAL) for the concerned UE. In all the cells within the TAs on the list, the eNodeBs transmit
the paging message over the paging control channel (PCCH) to page the UE. To increase the
probability that the UE successfully receives the message, the eNodeBs send the paging message
over the radio interface a number of times specified by the PCCHCFG.PagingSentNum
parameter. The paging message contains the domain information and UE identity. The domain
information indicates the origin of paging, and the UE identity may be the S-temporary mobilesubscriber identity (S-TMSI) or international mobile subscriber identity (IMSI) of the UE.
When system information changes, the eNodeB transmits a paging message to notify all UEs in
the EMM-REGISTERED state in the cell and transmits the updated system information in the
next modification period. To ensure that all of these UEs receive the system information, the
eNodeB transmits the paging message on all possible occasions in discontinuous reception
(DRX) cycles.
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Paging One TAL = One TAC
One TAL is same with one TAC, with this design when the
UE in idle condition then move to another TAC it will be
generate TAU to report MME where is last position for thisUE. When there is downlink packet data need to be
deliver for that UE, MME can easily to find latest position.
TAU Procedure
The tracking area update (TAU) procedure is triggered if one of the follow ingconditions is met:
The UE detec ts that the current TA does not exist in the TA list on the UE-registered netw ork.
It is a periodic TAU.
The TAU procedure is triggered during a handover procedure.
On an EPS netw ork, the basic unit of location management is TA Lis t. A TA Listconsists of one or multiple TAs. A TA list prevents a UE f rom initiating the TAU
procedure frequently. In USN1.1, a TA is regarded as a TA List by default.
S-GWInternet MME
TAC 1
TAC 2
TAC 3
TAC 4
TAUTAU
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TAL 1
Paging One TAL = Multiple TAC
One TAL contains multiple TAC, with this design when UE
in idle condition move to different TAC under one TAL
there is no TAU. When MME want to deliver downlinkpacket data for that UE MME will send to latest TAC
where the UE located. If the UE is unreachable MME willtry to paging another TAC under one TAL until found. This
design will take a time compare with the previous design.
S-GWInternet MME
TAC 1
TAC 2
TAC 3
TAC 4
TAL 2
TAC 5
TAC 6
TAC 7
TAC 8
Under One TAL
no need TAU
UE move to
new TAL needTAU
Last TAC is 8but UE move to
TAC 7, MMEw ill try paginganother TACunder TAL2
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LTE Scheduling
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List Scheduling on LTE HUAWEI
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Priority of DL Scheduling
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Control Plane DL Scheduling
During scheduling in each subframe, control-plane messages are preferentially scheduled before user-plane data. Control-plane
information consists of commoncontrol information and dedicated control information.
Common Control Information
Common control information includes broadcast messages such as SIB1 and SIB2, and paging
messages. SIB is short for system information block. Scheduling common control information
uses QPSK and low coding rates for reliable transmission.
3GPP specifications define three downlink allocation modes:
l Resource allocation of type 0
l Resource allocation of type 1
l Resource allocation of type 2
Resource allocation of type 2 is used to allocate resources to common control information. In
resource allocations of type 2, the allocations are classified into distributed virtual resource block
(DVRB) allocations and localized virtual resource block (LVRB) allocations.
The following describes DVRB allocations and LVRB allocations:
l DVRB allocation applies to the non-contiguous allocation of resource blocks and increases
the coverage of common control information. However, the system resources occupied by
common control information increases, resulting in a decrease in the UE throughput.
l LVRB allocation applies to the contiguous allocation of resource blocks and decreases the
amount of system resources occupied by common control information, which increases the
UE throughput. However, the coverage of common control information decreases.
LVRB allocations are currently used.
Dedicated Control Information
Dedicated control information includes random access (RA) response and the information
carried on signaling radio bearer (SRB) 0, SRB1, and SRB2.
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HARQ Retransmission
HARQ retransmissions cannot be performed for a UE in any of the following
scenarios:
l The UE is in a measurement gap or enters a measurement gap when itsends an HARQACK.
l The UE enters sleep time in DRX and the HARQ operating status is
discontinuous
transmission (DTX).
l The UE is not synchronized with the eNodeB or a radio link failure (RLF)
occurs.
HARQ retransmissions are scheduled after control-plane messages. The
scheduling priorities of different HARQ retransmissions are determined bythe wait time. A longer wait time indicates
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SPS S h d li
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SPS Scheduling
As the importance of supporting
voice in LTE networks (VoLTE)
increases, concerns ariseregarding the number of
simultaneous voice calls that canbe handled. One of the primary
constraints is the amount ofcapacity on the Physical DownlinkControl Channel (PDCCH). As a
quick review, the PDCCH carriesall allocation information for both
the downlink and uplink sharedchannels, PDSCH and PUSCHrespectively. Each allocation is
carried as Downlink ControlInformation (DCI) and the size of
the DCI depends upon several
factors including whether it is foruplink or downlink allocation.
Page 51
Since the PDCCH is limited size
(generally, 3 OFDM symboltimes), there is a limit as to howmany DCIs can be carried in a
subframe (1 ms). This can in-turnlimit the number of UEs which can
receive an allocation for thatsubframe when using dynamicscheduling (a 1:1 PDCCH-to-
PxSCH method.
SPS S h d li C td
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SPS Scheduling Contd
In order to support more
allocations, without increasing the
size of the PDCCH, we can usesemi-persistent scheduling (SPS).
With SPS, the UE is pre-configured by the eNB with an
SPS-RNTI (allocation ID) and aperiodicity. Once pre-configured, ifthe UE were to receive an
allocation (DL / UL) using theSPS-RNTI (instead of the typical
C-RNTI), then this one allocationwould repeat according to the pre-configured periodicity.
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SPS S h d li C td
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SPS Scheduling Contd
During SPS, certain things remain
fixed for each allocation : RB
assignments, Modulation andCoding Scheme, etc. Because of
this, if the radio link conditionschange, a new allocation will have
to be sent (PDCCH). Also, anyincremental redundancy (HARQsubsequent transmissions) will be
separately scheduled usingdynamic scheduling. Also, to
avoid wasting resources when adata transfer is completed, thereare several mechanisms for
deactivating SPS (explicit,inactivity timer, etc.).
So, with SPS which is well suited
to periodic communication likevoice, we can support many moreallocations with the same PDCCH
resource. This can allow moresimultaneous VoLTE calls.
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R All ti LTE
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Resource Allocation on LTE
Reading various LTE specification, you will see many terms
which seems to be related to resource allocation but looks
very confusing. At least you have to clearly understand the
following units.i) Resource Element(RE) : The smallest unit made up of 1
symbol x 1 subcarrier.
ii) Resource Element Group (REG) : a group of 4
consecutive resource elements. (resource elements for
reference signal is not included in REG)
iii) Control Channel Element (CCE) : a group of 9
consective REG
iv) Aggregation Level - a group of 'L' CCEs. (L can be
1,2,4,8)
v) RB (Resource Block) : I think everybody would knowwhat this is. This is a unit of 84 resource elements which is
12 subcarrier by 7 symbols (This is with normal Cylic Prefix
which is used in most of the LTE deployment. If it is with
Extended Cyclic Prefix, the number of symbols within a
subframe become 6 and the number of resource elements
in a single RB become 72).
vi) RBG (Resource Block Group) : This is a unit comprised
of multiple RBs. How many RBs within one RBG differs
depending on the system bandwidth.
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PDCCH All ti LTE
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PDCCH Allocation on LTE
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LTE SON Feature
MRO
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MRO
As mobile telecommunications technologies advance, networks continue to grow and
incorporate multiple radio access technologies (RATs), resulting in complicated
network
maintenance. To simplify maintenance, an LTE system must support self-organizingnetwork
(SON) technology. MRO is used for self-optimization in an SON.
MRO collects handover performance statistics for different scenarios, identifies
abnormal
handover scenarios, and optimizes the mobility-related parameter settings. MRO
helps to reduce
the number of handover failures and service drops caused by premature and
delayed handovers,
handovers to wrong cells, or ping-pong handovers to achieve better resourceutilization and
improve user experience.
In this document, the triggering quantity and reporting quant ity used in handover
measurements
for MRO are based on reference signal received power (RSRP).
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MRO Contd
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MRO Contd
Page 58
The eNodeB identifies
premature handovers,delayed handovers,
handovers to wrong
cells, and
ping-pong handovers,
and counts the numberof each type of abnormal
handovers.
MIMO
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MIMO
MIMO is developed to provide doubled and more spectral efficiency. As an extension of singleinput
single-output (SISO), MIMO uses multiple antennas at the transmitter and/or receiver in
combination with some signal processing techniques. Generally speaking, single-input multipleoutput(SIMO), multiple-input single-output (MISO), and beamforming also belong to the
MIMO category.
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MIMO Contd
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MIMO Contd
Page 60
ICIC
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Adaptive ICIC: Improve 30% Cell Edge Throughput
Adaptive ICIC switch on / off
Support cell edge frequency
reuse (1, 1/3, 1/6).
Frequency: reuse=1Frequency: reuse=3
Cell Edge
Interference
High
Cell edge interference leadto low throughput
Unique cell edge frequency reuse 6 in telecom
industry
Adaptive ICIC:
Cell Edge
Throughput
Low Cell EdgeInterference
Low
Cell Edge
Throughput
30%improved
eCoordinator
ICIC
ICIC RSRP C i
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ICIC RSRP Comparison
CCU Power Reduction with ICIC
ICIC Contd
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ICIC Cont d
Page 63
CEU (-1.77 dB) CCU (-6 dB)
Mod1
Mod2
Mod3
From the graph we can see on
ICIC there is power control on cell
edge more have high transmitpower than cell center to
differentiate between cell edge into3 frequency. This theory proven
from the previous slide.
ICIC SINR Comparison
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ICIC SINR Comparison
Afternoon 16:00 (Default) Afternoon 16:00 (Mod3 ON) Afternoon 16:00 (ICIC)
ICIC SINR Comparison
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ICIC SINR Comparison
ICIC is a technology that collaborates with power control and media access control (MAC)
scheduling technologies to mitigate inter-cell interference. ICIC divides the entire system
band into three frequency bands and uses different frequency bands at the edge of
neighboring cells. CEUs, which cause high interference or may be sensit ive to interference,
are preferentially scheduled in the cell edge bands to mitigate inter-cell interference. The
interference mitigation enhances the network coverage and improves the CEU throughput.
There are significant
improvement of SINR
>0dB when static ICIC
implemented on the
cell where the DL
PRB Utilization above
70%, which is good to
mitigate poor SINR
issue during busy
hour
8.06 % improvement
ANR Classification
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ANR Classification
Based on neighbor relations, ANR is classified into intra-RAT ANR and
inter-RAT ANR.
Based on the methods of measuring neighboring cells, ANR is classifiedinto event-triggered ANR and fast ANR (also known as periodic ANR).
ANR Feature Benefit and influence
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ANR Feature Benefit and influence
Benefit
- ANR is a self-optimization function. It automatically maintains the integrity andeffectiveness of neighbor cell lists (NCLs) and neighbor relation tables (NRTs) to
increase handover success rates and improve network performance. In addition, ANR
does not require manual intervention, which reduces the costs of network planning and
optimization.
- Event ANR
- Find the missing neighbor cells when handover measurement is reported, handover success rate
and call drop rate can be improved.
- Fast ANR
- Choose some UE to measure neighbor cells and report periodically, the neighbor cell relations can
be convergent more faster.
ANR Feature Benefit and influence
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ANR Feature Benefit and influence
Influence
- Event ANR- CGI report process will introduces extra delays in handovers of the UEs that meet the handover
conditions.
- Fast ANR
- In fast ANR processes, UE will report PCI periodically and read CGI when the neighbor cell is
unknown.
- In intra-frequency scene, periodical PCI reporting does not impact system performance, whereas
CGI reading interrupts UE services.
- In inter-frequency and inter-RAT scene, periodical PCI reporting impacts UE throughput, and CGI
reading interrupts UE services.
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Relation between ANR and others Intra-RAT ANR
- Intra-RAT ANR needs UE to support Long DRX cycle and ANR-related
measurement. If ANR measurements need to be performed, a temporary dedicated
DRX cycle needs to be configured for the UE. During this cycle, the UE obtains the
CGIs of neighboring cells in dormancy periods.
- Intra-RAT ANR has an impact on Feature PCI Collision Detection & Self-
Optimization. When neighboring cell information changes because of intra-RAT
ANR, PCI conflict detection is triggered.
Inter-RAT ANR
- Inter-RAT ANR needs UE to support Long DRX cycle and ANR-related
measurement. If ANR measurements need to be performed, a temporary dedicated
DRX cycle needs to be configured for the UE.
Relation between NR and others
ANR Contd (LTE Identifier)
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ANR Cont d (LTE Identifier)
Page 70
ECGI : E-Utran Cell Global Identifier
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End of Section
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