LTE-EPC KPIs and Signalling (SF)

1. LEKS_SF_1
Multimedia over IP
Based on SIP
Response codes
1xx – Provisional response
2xx – Success
3xx – Redirection
4xx – Request failure
5xx – Server failure
6xx – Global failure
PSTN
SIP
Proxy
RTP Real-time Transport Protocol
SDP Session Description Protocol
SIP Session Initiation Protocol
TCP Transmission Control Protocol
UA User Agent
UAC UA Client
UAS UA Server
UDP User Datagram Protocol
UE User Equipment
URI Uniform Resource Identifier
VoIP Voice over IP
Media Stream
Alice Bob
REGISTER
sip: bob@bpis.se
contact:<sip:201.32.7.1>
200 OK
INVITE
sip: bob@bpis.se
bob ?
INVITE
sip: bob@ 201.32.7.1
bob@
201.32.7.1 !
200 OK
200 OK
ACK
BYE
bpis.se
Location
Service
SIP
Registrar
SIP URI:
sip:alice@apis.se
SIP
proxy
bob@ 201.32.7.1
SIP
proxy
INVITE
sip: bob@bpis.se
apis.se
SIP URI:
sip:bob@bpis.se
200 OK
200 OK
180 Ringing
180 Ringing
180 Ringing
SIP Traffic Case
100 Trying
100 Trying
DNS
lookup
Ringback
Ringtone
Bob answers
Bob hangs up
PSTN Breakout
IP
L2 / L1
TCP UDP
AS Application Server
DNS Domain Name System
FQDN Fully Qualified Domain Name
ISUP ISDN User Part
Lx Layer x
MG Media Gateway
MGC Media Gateway Controller
PCM Pulse Code Modulation
PSTN Public Switched Telephone Network
RFC Request for Comments
RTCP Real-time Control Protocol
SIP [RFC 3261]
- Allows UAs to:
register current IP address of the UA in the network
set up, modify and release logical links
- Can carry payload from other protocols (SDP, ISUP...)
- Open to extensions (new methods, responses, headers,
header values)
SDP [RFC 2327, 3264]
- Describes real-time multimedia sessions
- Carried by e.g. SIP
RTP [RFC 3550, 3267]
- End-to-end transport of real-time data
- Sequence numbers
- Timestamps
SIP User Agent
Can act as:
- Client (UAC), or
- Server (UAS)
SIP
SIP
SIP
Any
DNS
SIP URI  IP addr.
Stores IP address
[or FQDN]
per subscriberauthentication
authorization
service access
implements policies
routes requests
Receives
registrations
200.1.1.1 201.32.7.1
Audio over RTP
5000
5001 RTCP
6544
6545
Video over RTP
7654
7655
RTCP
10002
10003
[RFC 3263]
sip:bob@bpis.se
Session
The media stream(s),
Dialogue
a peer-to-peer SIP relationship between two UAs
RTCP [RFC 3550]
- Reports quality on RTP session
port port
H.248 [RFC 3015]
Used by MGCF to control
resources in MGW
DNS
SIP
Proxy
Server
SIP
Proxy
Server
Location
Service
SIP
Registrar
S
I
P
RTP RTCP
Real-time app.
SIP URI:
sip:alice@apis.se
SIP ISUP
RTP PCM
H.248SIP
MGC
MG
Control plane (Signalling)
User plane (Transmission)
Any
Eg. VoIP

2. LEKS_SF_2
IP-CAN PDN 1: IMS
PCC Policy and Charging Control
PCEF Policy and Charging Enforcement Function
PCRF Policy and Charging Rules Function
PGW Packet Data Network Gateway
PDN Packet Data Network
QoS Quality of Service
RTSP Real Time Streaming Protocol
SDF Service Data Flow
SGSN Serving GPRS Support Node
SGW Serving Gateway
SIP Session Initiation Protocol
SPR Subscriiption Profile Repository
TDF Traffic Detection Function
UDR User Data Repository
VoIP Voice over IP
AF
AF
Node that uses PCC, e.g.:
• Media Server or CSCF
For Operator Controlled Services
GW PCEFAudio + Video over IP
One IP-CAN Session
Two IP-CAN Bearers
Three SDFs: Signaling, Audio, Video)
ADC Application detection and Control
AF Application Function
APN Access Point Name
CSCF Call Session Control Function
DPI Deep Packet Inspection
eNB Evolved Node B
EPS Evolved Packet System
E-UTRAN Evolved UTRAN
GGSN Gateway GPRS Support Node
GW Gateway
IP-CAN IP Connectivity Access Network
LTE Long Term Evolution
MMtel Multimedia Telephony
OCS Online Charging System
OFCS Offline Charging System
SIP
Default EPS Bearer
eNB PGWSGW
EPS
IP-CAN
Bearers
”Session Based Service”
PCEF
PDN 2: Internet
Video Streaming
Email
File Transfer
Example:
• One IP-CAN Bearer
• 3 Service Data Flows
SDFs identified e.g. with DPI
SDF
Dedicated EPS Bearer
IP-CAN
Session
PCRF SPR/
UDR
TDF
IP-TV
MMtel
APN X
APN Y
Gx Rx
OFCS OCS
IP-CAN Problems
Ro
GyGz
MME
HSS
1
11
1
12
1
13
1
14
1
15
HNW
VNW
1
1
6
1
1
8
1
1
9
KPI: Session setup success rate
RRC establishment S1 link establishment ERAB establishment
System events and counters
1
1
7

3. LEKS_SF_3
E-UTRAN Key Performance Indicators, KPI
PDN
Packet Data Network
IMS / Internet
PCRF
HPLMNVPLMN
Provides QoS
and charging rules
• QoS aware packet routing
• UP anchor:E-UTRAN  2G / 3G
eNB SGW PGW
• QoS aware packet routing
• User IP-address allocation
• Policy Enforcement Point
MME HSS
• Radio Base Station
• Radio Resource Mgmt
• Mobility
• Security (e.g. Authentication)
• Bearer Mgmt
• Subscriber
database
Accessibility :
The probability for an end-user to
be provided with an E-RAB at
request. (%)
A1=InitialEPSBEstabSR=
A2=AddedEPSBEstabSR=
RRC.ConnEstabAtt.Cause
RRC.ConnEstabSucc.Cause
S1SIG.ConnEstabAtt
S1SIG.ConnEstabSucc
ERAB.EstabInitAttNbr.QCI
ERAB.EstabInitSuccNbr.QCI
ERAB.EstabAddAttNbr.QCI
ERAB.EstabAddSuccNbr.QCI
Retainability:
How often an end-user
abnormally looses an E-RAB
during the time the E-RAB is used.
(Release/time)
R1QCI=x=
R2=
ERAB.RelActNbr.QCI
ERAB.SessionTimeUE
ERAB.SessionTimeQCI.QCI
Integrity:
The degree to which a service is
provided without excessive
impairments such as throughput,
latency and packet loss.
IP Throughput for a single QCI:
(kbps)
Downlink
Uplink
DRB.IPThpDl.QCI
DRB.IPThpUl.QCI
E-UTRAN IP Latency.(ms)
Downlink
DRB.IPLatDl.QCI
Availability:
E-UTRAN Cell Availability (%)
CellAvailability=
RRU.CellUnavailableTime.cause
Mobility:
E-UTRAN Mobility. (%)
MobilitySuccessRateQCI=x=
HO.ExeAtt
HO.ExeSucc
HO.PrepAtt.QCI
HO.PrepSucc.QCI
EPS Bearer = Radio Bearers + S1 Tunnel + S5/8 Tunnel
P-GWS-GW Peer
Entity
UE eNB
EPS Bearer
Radio Bearer S1 Bearer
End-to-end Service
External Bearer
Radio S5/S8
Internet
S1
E-UTRAN EPC
Gi
E-RAB S5/S8 Bearer
SRB
DRB
TS 32.450
SR Success Rate
QCI Quality Cllass Indicator
IP Internet Protocol
QoS Quality of Service
PDN Packet Data Network
IMS Internet Multimedia Subsystem
RRU Radio Remote Unit
UP User Plane

4. LEKS_SF_4
E-UTRAN Key Performance Indicators, KPI
Accessibility:
 
 
 
 
100
QCI.InitAttNbrERAB.Estab
QCIr.InitSuccNbERAB.Estab
EstabAttS1SIG.Conn
EstabSuccS1SIG.Conn
CausetabAtt.RRC.ConnEs
CausetabSucc.RRC.ConnEs
1
QCI
cause






 QCI
cause
BEstabSRInitialEPSA
 
 
100
QCIAddAttNbr.ERAB.Estab
QCI.AddSuccNbrERAB.Estab
2
QCI


QCI
stabSRAddedEPSBEA
Retanability:
. .
1
. .
QCI x
QCI x
QCI x
ERAB RelActNbr QCI
R
ERAB SessionTimeQCI QCI




 . .
2
.
QCI
ERAB RelActNbr QCI
R
ERAB SessionTimeUE


Integrity:
xQCIxQCI IPThpDlDRBThpDownlink   .
xQCIxQCI IPThpUlDRBThpUplink   .
IP Throughput for a single QCI:
xQCIxQCI IPLatDlDRBLatDownlink   .
E-UTRAN IP Latency (ms)
Availability:
100
_
]ime.[causeavailableTRRU.CellUn-t_periodmeasuremen
cause


periodtmeasuremen
bilityCellAvaila
Mobility:
 %100
.QCIHO.PrepAtt
c.QCIHO.PrepSuc
HO.ExeAtt
HO.ExeSucc
RateSuccessMobility
xQCI
xQCI
xQCI 



TS 32.450

5. LEKS_SF_5
EPC Key Performance Indicators, KPI
PDN
Packet Data Network
IMS / Internet
PCRF
HPLMNVPLMN
Provides QoS
and charging rules
• QoS aware packet routing
• UP anchor:E-UTRAN  2G / 3G
eNB SGW PGW
• QoS aware packet routing
• User IP-address allocation
• Policy Enforcement Point
MME HSS
• Radio Base Station
• Radio Resource Mgmt
• Mobility
• Security (e.g. Authentication)
• Bearer Mgmt
• Subscriber
database
Accessibility :
EPS Attach Success Rate (%)
The ratio of the number of
successfully performed EPS
attach procedures to the number
of attempted.
EASR=
MM.EpsAttachAtt.Type
MM.EpsAttachSucc.Type
Dedicated EPS Bearer Creation
Success Rate (%)
The ratio of the number of
successfully performed dedicated
EPS bearer creation procedures
by PGW to the number of
attempted.
DEBCSR=
SM.CreationPGWInitBearerAtt
SM.CreatationPGWInitBearerSucc
Dedicated Bearer Set-up Time by
MME (Mean) (Second)
Describes the valid time per
dedicated bearer set-up procedure
by MME and is used to evaluate
service accessibility.
DBSTM=
SM.EstabActDedicatedEpsBearer
TimeMean
Service Request Success Rate
(%)
Describes the ratio of the number
of successfully performed service
request procedures by UE to the
number of attempted service
request.
SRSR=
SM.EpsServiceReqAtt
SM.EpsServiceReqSucc
Mobility:
Inter-RAT Outgoing Handover
Success Rate (EPS->GSM) (%)
Inter-RAT Outgoing Handover
Success Rate (EPS->UMTS) (%)
Inter-RAT Outgoing Handover
Success Rate (EPS->CDMA2000)
(%)
Inter-RAT Incoming Handover
Success Rate (GSM->EPS) (%)
Inter-RAT Incoming Handover
Success Rate (UMTS ->EPS) (%)
Inter-RAT Incoming Handover
Success Rate (CDMA2000->EPS)
(%)
Tracking Area Update Success
Rate (%)
Utilization KPI:
Mean Active Dedicated EPS
Bearer Utilization
EPS Bearer = Radio Bearers + S1 Tunnel + S5/8 Tunnel
P-GWS-GW Peer
Entity
UE eNB
EPS Bearer
Radio Bearer S1 Bearer
End-to-end Service
External Bearer
Radio S5/S8
Internet
S1
E-UTRAN EPC
Gi
E-RAB S5/S8 Bearer
SRB
DRB
TS 132455

6. LEKS_SF_6
EPC Key Performance Indicators, KPI
TS 132455

7. LEKS_SF_7
TAC Tracking Area Code
PLMN Public Land Mobile Network
TAI Tracking Area Identity
ECM EPS Connection Managemen
ID Identityt
S1 Setup
Used to take a new eNB into
service. eNB already
configured so the purpose is
to inform the MME about the
main parameters.
S1 Setup & Initial Attach
MME 1
Weight 100
1
1
S1AP Initiating Message S1 Setup
(eNB ID, TAC (1..256)
12.122.122.5
eNB ID = Global eNB
ID + TAC (PLMN, TAI)
+ IP#.
Can serve 1..6 PLMN
S1AP Successful Outcome S1
Setup (MME, GUMMEI, relative
MME Capacity)
Relative MME Capacity (load balancing) 0 .. 255
Weight factor = probability to be choosen.
2
3 S1AP Unsuccessful Outcome S1
Setup (cause) =
• Semantic error
• CPU Overload
• HW Failure
• Unknown PLMN
• Unspecified
Example: Out of 3 UE attaches, eNB will
forward 2 attaches to MME-1 and 1 attach to
MME-2. If in case MME-1 is down, then all
calls will be routed to MME-2.
MME 2
Weight 50
MME Pool MME 1 wants to move
Ue’s:
RRC: Cause ”Load
Balancing TAU”.
ECM connected Ue’s.
UE:
RRC: TAU
eNB:
Choose MME 2
DNS
UE: Attach (not initial)
GUMMEI
eNB:
eNB: IP# GUMMEI
If no answer select new
MME …

8. LEKS_SF_8
TEID Tunneling Endpoint ID
F-TEID MME IP + TEID
Initial Attach
HSSeNB MME
Initial Attach
The subscriber need to
register to the network.
NAS EMM Attach Request
(IMSI/GUTI/S-TMSI, PDP ESM Request)
Update Location (”Service Granted”, PDN
IP#, QoS)
Origin @ Realm
Destination
@ Realm
Uu S1 MME
S11
S5/S6
S6a (DIAMETER)
SGW
DNS
Result Code:
Successful or Failure.
AMBR for Subscriber and
APN (PGW).
UL: 10 Mbps
DL: 100 Mbps
Charging Info.
QoS defined by QCI eg. 9
= Best Effort.
Default
Bearer
PGW
Create Session Req.
(F-TEID, EBI=x, ) Req./Resp.
CP IP#
UP IP#
CP IP#
UP IP#Create Session
Resp..(S1-U, SGW F-
TEID = xx + yy )
Allocate UE IP#
if dynamic.
1 1
MME get full control of UP
routing and can change route
due to mobility or load in
core.
Initial Ctx Setup Req.(E-RAB id, TEID,
Attach Accept, Activate Default B. Req)
Attach Accept, Default B. Req.
EMM
T3412=20dH
for TAU.
GUTI, QCI=9,
UE IP#,
DRB
(SRB = 1)
Attach Complete
Modify Bearer Req.
2
2 Inform SGW about UP eNB
IP# and TEID for S1-U
RRC CONNECTION REQUEST
Idle
Mode
Connected
Mode
RRC CONNECTION SETUP Config. of UE
Protocols…
RRC CONNECTION SETUP
COMPLETE
SRB 1
SRB 0
pmRrcConnEstabAtt +
pmRrcConnEstabSucc +
RRC Con. Setup
logical S1 connection
S1 Signalling Connection Establishment
RRC CONNECTION
SETUP COMPLETE
NAS ’Attach Request’
INITIAL UE MESSAGE
RRC S1AP
DOWNLINK NAS
TRANSPORT
NAS UE identity Request’
DL INFORMATION TRANSFER
pmS1SigConnEstabAtt +
pmS1SigConnEstabSucc +
MME
E-RAB Establishment (Initial)
RRC CON.
RECONFIG. COMPLETE
INITIAL CONTEXT SETUP REQUEST
Includes a list of E-RABs to be setup
RRC S1AP
RRC CONNECTION
RECONFIGURATION
pmErabEstabAttInit +
Stepped for each E-RAB
received in the list of E-
RABs to be setup
INITIAL CONTEXT SETUP RESPONSE
Authentication and security mode procedures
pmErabEstabSuccInit +
Stepped for each initial
E-RAB that has been
successfully established
MME
3
3
4
4
Initial E-RAB Establishment Success Rate [%]:
pmErabEstabAttInit
pmErabEstabSuccInitpmS1SigConnEstabSucc
pmRrcConnEstabAtt
pmRrcConnEstabSucc
= X X
pmS1SigConnEstabAtt
X 100
Added E-RAB Establishment Success Rate [%]:
pmErabEstabAttAdded
pmErabEstabSuccAdded
= X 100

9. LEKS_SF_9
After successful Attach:
UE ctx Release & Service Request
MME
HSS
SGW
PGW
MME
HSS
SGW
PGW
UE ctx Release due to inactivity
IP #
GTP-U
RRC
MAC:C-RNTI
(S-RNTI)
GTP-U
GTP-C
IMSI
MME IP#
GTP-C
CP #
UP #
CP #
UP #
TEID=1
TEID=xx
TEID=0
TEID =yy
UP #
IP#
IP #
UE timer in eNB expires and buffer
empty… t=10 .. 60 .. 120 s
UE ctx Release Req.
(cause=user inactivity)
Modify Bearer Req.(Scope
Indication=1, EBI=x)
Scope => delete EBI +
transport TEID (S1-U)Mod.B.Resp.( cause=req.
accept, EBI=x)
UE ctx Rel. Command
(cause=normal release)
1
1
Normal for the MME even
if radio conection with UE
lost…
UE ctx Release Complete2
2 RRC, C-RNTI, S1-U
But Default Bearer and other ctx
remains…
CP IP#
UP IP#
CP IP#
UP IP#
pmErabRelMme +
pmErabRelMmeAct +
Normal release: pmErabRelNormalEnb +
Abnormal release: pmErabRelAbnormalEnb +
pmErabRelAbnormalEnbAct +
MME Initiated ERAB Release
ERAB Rel. Resp.
ERAB Release COM.
(ERAB’s)
MME
UL DL
DRB and S1-U Releasad
eNB Initiated
ERAB Rel. Indication.
DRB and S1-U Releasad
pmErabRelMmeAct +
pmUeCtxtRelMmeAct +
pmErabRelMme +
pmUeCtxtRelMme +
Normal release: pmErabRelNormalEnb +
pmUeCtxtRelNormalEnb +
MME Initiated UE Ctx Release
UE Ctx Rel. Com.
MME
eNB Initiated
DRB and S1-U Releasad
UE Ctx Rel. Complete
pmErabRelAbnormalEnbAct +
pmUeCtxtRelAbnormalEnbAct +
Abnormal release: pmErabRelAbnormalEnb +
pmUeCtxtRelAbnormalEnb +
UE Ctx Rel. Req. (cause)
UE Ctx Rel. Com.
UE Ctx Rel. Complete
E-RAB Release Rate [drops/s]:
=
pmSessionTimeUe
pmErabRelRelAbnormalEnbAct + pmErabRelMmeAct
UE Session Time
Data
Transfer
Time
In session
Out of
session In session
100
msec
100
msec
pmSessionTimeUe +

10. LEKS_SF_10
UE ctx Release & Service Request
UE Service Request
After S1AP ctx release the UE remain attached…
and by sending a ”Service Request” on NAS the
con. Is resumed…
HSSeNB MME
Initial UE Message (S-TMSI, TAI, Service Req.(KASME)
Uu S1 MME S6a (DIAMETER)
Default
Bearer
PGW
Initial Ctx Setup Req.(E-RAB id, TEID)
Attach Accept, Default B. Req.
SRB = 1
Attach Complete
Opt. Auth. Info
SGW
Initial Ctx Setup Resp.(E-RAB id, TEID)
Modify Bearer Req.(TEID, F-TEID, EBI=x,
S1-U eNB F-TEID)
Update Bearer Req(IMSI,EBI=x, QCI,
Charging ID, AMBR)
Update Bearer Response
IP # GUTI
GUTI
Modify Bearer Resp.(cause=Req.Accept,
PGW F-TEID, EBI)
Create Bearer Req.(create new TFT)
ERAB Mod.Req (ERAB ID, QoS, new TFT)
(DRB = x)
ERAB Mod. Resp.(ERAB ID, QoS)
2
2 ERAB modification on S1
1
1 SGW confirms S1-U can
be used for payload…
3
3 Start UE activity timer…
KASME Access Security Management
PCRF
IP-CAN Session
Modification

11. LEKS_SF_11
Dedicated Bearer Setup
If required by the QoS parameters a dedicated bearer will
be setup…
Dedicated Bearer Setup
SPReNB MME
S1AP Init.Msg(ERAB Setup, ERAB ID=y) NAS Activate
Dedicated EPS Beraer Context Req.(RAB=Y)
Uu S1 MME
Default
Bearer RAB ID = x
Active
PGW
Create Bearer Req.(EBI=Y,
new TFT(PCC Rules))
SGW
NAS Activate Ded.B. Ctx Req.(RAB=Y)
S1AP Succ. Outcome ERAB Setup (ERAB ID=Y)
APN-AMBR
UE-AMBR
TFT
ARP
L-EBI
IP # GUTI
GUTI
PCRF
SIP(SDP) Codec
MPEG-4
SPR Subscriber Profile Respository
SDP Session Description Protocol
SIP Session Initiating Protocol
APN Access Point Name
TFT Tranport Format Template
L-EBI Linked EPSBearerId
Subscriber browsing on internet (default bearer). Finds streaming video. PCRF detects SDP=new codec and authorizes a dedicated bearer…
PCC Rule
QoS
Default
NGBR
QCI 5 - 9
Dedicated
NGBR GBR
QCI 5 - 9 QCI 1 - 4
APN-AMBR
UE-AMBR
APN
IP#
ARP
GBR
MBR
TFT
ARP
L-EBI
NAS Activate Ded.B. CTx. Resp.(RAB=Y)
NAS Activate Dedicated B. Ctx Resp(RAB ID = Y)
Create Bearer Resp..(EBI=Y, new TFT )
Multimedia Session (Browsing Best Effort), Streaming Video (GBR)
Dedicated Beraer (RAB ID=Y) and Default Bearer (RAB ID = X) active
Example VoLTE: Two ”default” and one dedicated.
Default 1: SIP signalling QCI = 5 (priority 1) IP# A with max 100 ms delay UE-PGW with max packet loss < 10 -6
Dedicated : VoIP QCI = 1 (priority 2) linked to Default 1 (L-EBI) GBR.
”Default 2”: smart phone traffic (video, chat, email, browser etc) QCI = ) (lowest priority) IP# B with max 300 ms delay UE-PGW with packet loss 10-6

12. LEKS_SF_12
Inter eNB HO over X2
When Ue changes its geographic position a
HO is required – ideally over X2.
• X2 HO prep X2AP to create tunnel
• S1AP path switch to update MME for
new S1-U
• MME needs to inform SGW.
Inter-eNB Handover over X2 & S1 HO
MMEUu S1 MME
PGW
X2AP SN Status Transfer, eRAB, PDCP SN
SGW
X2AP Succ. Outcome ”HO prep” UL/DL TEID…
GUTI
X2AP Handover Prep. Target Cell ID,
GUMMEI, eRAB, QoS
Source Target
S1AP ”DL NAS Trasnport” TAU Accept, new GUTI
S1AP ”Path Switch Req.”
CellID, TAC, RABID
GTP-C Update UP Resp.
UL GTP-U
GTP-C Update UP Req.
EBI, S1-U eNB TEID
S1AP Succ. Outcome
”Path Swtich Req”
X2AP X2AP ”UE ctx Release”
S1AP ”UL NAS Transport”, Cell ID, TAU, old GUTI
RSRP
time
sintrasearch
Qmeas(n)
R(n)
R(s)
Qmeas(s)
qHyst(s)
qoffset(s)
tReselectionEutra
Qrxlevmeas [dBm] =
measured RSRP
Qrxlevmin [dBm] = minimum
required rx signal strength (SIB
3) (-140 to -44)
pMaxServingCell [dBm]= max
UL tx power (SIB 1 serving or
SIB 3 inter freq neighbor) (-33
to 33 or 1000) (36.101)
P [dBm] = UE max power
capability (23 dBm) (36.101)
RRC Meas. Report (Event A3) pmHoPrepAttLteIntraF +
Handover Prep.
HO Req.
HO Ack.
Source Target
pmHoPrepSuccLteIntraF +
RRC Con. Reconfig. pmHoExeAttLteIntraF +
Handover Exec.
RACH Procedure
Source Target
pmHoExeSuccLteIntraF +
RRC Con. Reconfig. Complete
Path Switch
Req./ Resp.
UE ctx Rel.
T300 = Time UE waits for RRC Req.Resp (ms)
T301= Time UE waits for RRC Re-estab.Req (ms)
T310= Started after receiving N310 (”out of synch”)
T311 = Started after initiating con.re-establish proc. (if expired and no suitable cell go to RRC IDLE) (sec.)

13. LEKS_SF_13
Inter-eNB Handover over X2 & S1 HO
S1 HO
Whitout X2 we need S1HO.
• eNB trigger HO based on
measurements from UE
• HO preparations
• HO resource allocation
and modification of S1-U
KPI
Handover Prep. = eNB
”outgoing leg”
Relocation Proc. = ”MME
”incoming leg” (resource
allocation)
MMEUu S1 MME
PGW
S1AP Succ. Outcome HO Prep. (RRC Con. Reconfig. Info, Target PCI)
SGW
S1AP Handover Resource Alloc., ERAB ID, TEID
GUTI
S1AP Handover Prep. Target Cell ID, TAC
Source Target
S1AP ”UE ctx Release” cause = succ. HO”
S1AP Succ. Outcome
(RRC Con. Reconfig Info)
S1AP ”MME status transfer” UL/DL PDCP SN (source forward info to target)
GTP-C Modify B. Req. (MME switch the S1-U
DL TEID, UL not changed)
GTP-C Mod. B. Resp.(S1 SGW F-TEID,
GTP-U TEID)
S1AP ”HO Notification” CGI, TAI
S1AP ”Source eNB sends HO command to UE” and ”Status Transfer Message to MME (PDCP SN)
UE arrives…
S1AP ”UE ctx Release”
RRC Meas. Report (Event A3) pmHoPrepAttLteIntraF +
Handover Prep.
HO Req.
HO Command
Source
pmHoPrepSuccLteIntraF +
MME
RRC Con. Reconfig. pmHoExeAttLteIntraF +
Handover Exec.
RACH Procedure
Source
pmHoExeSuccLteIntraF +
RRC Con. Reconfig. Complete
UE ctx Rel.
MME
Target
SGW

14. LEKS_SF_14
Dedicated Bearer Release & Detach
Dedicated Bearer Release
Here, triggered by the NW e.g
UE inactivity timer exp in
SGW…
Or UE by means of the Bearer
Resource Modification or PDN
Disconnect procedure.
The DEACTIVATE EPS
BEARER CONTEXT
REQUEST message contains
an ESM cause :
#8: operator determined
barring
#36: regular deactivation
#38: network failure
#39: reactivation requested or
#112: APN restriction value
incompatible with active EPS
bearer context
MME SGW
S1AP (ERAB Release ERAB ID) NAS Deact. D. B.
ctx Rel. (RAB ID, ESM cause)
Delete Bearer Req (EBI)
”No cause value”
NAS Deact. D.B. ctx Rel
Start the timer T3495 and wait for UE
resp. If no resp. resend 5 times, then
deactivate EPS locally…
S1AP Succ. Outcome
NAS Deact. D.B. ctx
Resp.
S1AP (ULNASTransport, NAS Deact. Dedicated
EPS B. Resp (RAB ID) Delete Bearer
Resp.(cause = Req.
Accept, EBI)
PGW
Default
Bearer RAB ID =
x Active
HSS
eNB MMEUu S1 MME S11 S5/S6SGW PGW
Delete B. Req.
(TEID, EBI)
Detach
Normally triggered by
the UE power off…
Delete B.
Req./Resp.
Delete B. Resp..
(cause= Req. Accept)
S1AP DL NAS Transport (Detach
Request)
S1AP UL NAS Transport (Detach
Accept)
UE ctx Release Req./Resp.
DIAMETER Notification
Req./Answer
X CP IP#
UP IP#
CP IP#
UP IP#X X
IP #X
+ ppt ”Failure Cases…”

15. LEKS_SF_15
RRC Connection Problems
CCCH SRB 0 RLC-SAP TM
DCCH SRB 1 RLC-SAP AM
BCCH : BCH : PBCH
MIB (DL bandwidth/# RB)
RS RSRP
RSRQ
PSS (0, 1, 2)
5 ms loop that gives slot synch
To detect the 10 ms frame start
SSS (0 .. 167)
PDCCH
CRC : for me?
PDSCH : DL-SCH : BCCH
SIBs (tell UE how to behave)
PRACH : RACH
preamble
PCFICH
Indicates the size of the DCI
(1, 2, 3, or 4 OFDM symbols)
PDCCH
DCI UL Assignment: (UE ID,
PRBs, MCS, HARQ id, TPC)
PUSCH : UL:SCH : CCCH
RRC Connection Request (cause …)
CRC
24
TrBlk
RNTI
data
Input data vector for
a CRC, masked with
RNTI
If ERR ~= 0 then either an error has occurred or
the input CRC has been masked.
MAC-IDs
UL : RA_RNTI
DL : P-RNTI, SI-RNTI
UL/DL : C-RNTI
PCFICH
PDCCH
PDSCH : DL : SCH : CCCH
RRC Connection Response
(UE ID, DCCH, …)
RACH: MAC Rand. Acc. Preamble
(RA-RNTI, preamble index)
Error Not sent/Not received
UL-SCH/CCH: RRC Con. Req (temp
C-RNTI, NAS UE ID=IMSI or TMSI
1
2Error RRC Con. Reject
( cause=?, wait time)
RRC Security Mode Command
3Error RRC Security Mode
Failure (cause ?)
RRC Con. Reconfig.
4Error RRC Con. Re-est. Req.
(cause =”reconfig. failure”
RRC Con. Re-establ. (new
SRB 1, new security ctx).
RRC Con. Re-establ. Compl.
OK!
Error RRC Con. Re-
establ. Reject (cause ?)
5
or ...
Failure!
1
2
3
4
5
Error on Uu: interference on DL-SCH, coverage? High TA? Solution:
partial freq. Reuse!
eNB CPU overload?
Typically cell congested, no radio resources. ? =
• ”reconfig. Failure”
• ”HO failure”
• ”other reason” - wait time second before new request (1 .. 16)
Typically due to problem in handset during ciph/integr. Procedure….
Sent instead of ”RRC Con. Reconfig. Complete”. eNB must take
decision what to do…
RLC AM used for RRC sign. but ACK never received (not sent or
interference?). If repeated eNB drops the con. And release UE…
If S1AP cause = ”failure in Uu procedure” or ”release due to EUTRAN”
possible caused by AM errordue to interference or problem in UE
power control…
freq
(power)

16. LEKS_SF_16
SCH Shared Channell
QoS Quality of Service
TTI Transmission Time Interval
VoIP Voice over IP
RRC Radio Resource Control
PRB Physical Resource Block
MCS Modulation and Coding Scheme
RI Rank Indicator
PMI Precoding Matrix Indicator
MIMO Multiple Input Multiple Output
PAPR Peak to Average Power
MAC-Scheduler
Purpose:
• Efficient SCH(Data) Resources
Assignments
Consideration
• Traffic Volume, QoS (Buffer
Status, Priority…)
• Channel Condition
Scheduling Interval
• Dynamic Scheduling by MAC :
One TTI (1ms : One Sub-
frame)
• Semi-Persistent for VoIP :
Multiple TTIs by RRC
Resource Assignment :
• PRBs & MCS
MIMO
• RI and PMI
Freq.
Time.
DL OFDMA:
High Throughput
High PAPR
UL SC-FDMA:
Fair Throughput
Low PAPR saves battery…
RE MappingCell Specific
Scrambling
Layer
Mapping
(symbols
mapped on
1,2,3,4
layers)
Modulation
(QPSK,
xQAM)
Precoding
(mapping to
1, 2or
4antenna
ports)
RE Mapping
OFDM
(IFFT)
OFDM
(IFFT)
Code word, qo
Pseudo
Random bit
sequence
Depends on selected tx mode:
•Single antenna tx
• tx diversity
• spatial multiplexing (MIMO)
• beamforming
X
i
.
.
.
.
Y
i
.
.
.
.
Code
word, q1
(if MIMO)
1 modulation
Symbol -> RE
antenna
ports
.
.
.
CRC 24
Code Block
Segmentati
on
FEC
Turbo
Coding
R = 1/3To detect
bit errors
If input >
6144 bits
Bit error
correction
Sub block
Interleaving
Rate
Matching
Code Block
Concatenati
on
To achieve
high throuput
and error
correct
coding by
HARQ
Add
segmentet
blocks...
1 TB
PDU
S
P1
P2
”Code Word”
MAC PHY
Output
Assignment
(DL)
Grant (UL)
Scheduler
Data related inputs
•HARQ retransmissions
•Data buffer (DL)
User related inputs
•UE capabilities
•UE measurement gaps
•Sync status
QoS
translation
•UE prioritization
•Resource
Allocation
•PDCCH resources
•Buffer estimation
(UL)
•RB and symbols
•DL Power
Power Control
CQI (DL)
PMI(DL)
RI(DL)
MCS (DL)
QCI table
•Priorities
•LCGs
SINR(UL)
RRC Connection
Request (UL)
• UL interference based on i.e eNB sharing of load over X2 with max
20ms
• 3G quality can be measured DL/UL with ded. Ch’s. LTE user are
distributed in time x freq. Test mobiles can never measure UL quality.
• Satisfy latency and packet error loss characteristics of each QCI class
• Satisfy Guaranteed Bit Rate (GBR), Minimum Bit Rate (MBR)
• Enforce downlink maximum bit rate for sum of downlink bearers
• new users are admitted only when QoS requirements of existing and newly added
users/bearers can be met.
• perform frequency selective and frequency diverse scheduling (localized and
distributed virtual resource blocks) depending upon channel conditions,
QoS requirements etc.
• Adapt TB size, MIMO and rank depending on CQI, PMI and RI from UEs plus data buffers
• Higher priority to HARQ re-tx versus new tx…
RSRQ = NRB x
RSRP
RSSI

17. LEKS_SF_17
Radio Quality
Downlink
UL Scheduling Req.
• Power Headroom
• Buffer Status Reporting (long and Short)
The three most important tasks in LTE prelaunch radio parameter planning are:
1 Physical Cell Identity (PCI) allocation
2 Physical Random Access Channel (PRACH) parameter planning, and
3 Uplink reference signal (RS) sequence planning
During/after launch are:
4: UL Power control
5: Handover thresholds
6: Paging (MME/eNB paging capacity)
7: Control Channel planning
Also SI-time-to-release and DRX-cycle should be configured…
MIMO
MIMO
PCI
PCI
PCI
PRACH
Attach Request
Connected Mode UE
UL RS
Handover thresholds
UL PC
MME
P
a
g
i
n
g
UL Path Loss
DL Path Loss
Uplink Budget, 64
kbps, 2 RB’s, 3-
sector macro-cell
Downlink Budget,
1 Mbps, Antenna
Diversity, 10 MHz,
46 dBm
”When needed”
~ 100 Hz
UMTS CPICH
GSM RSSI
dB/dBm
t
RSRQ
RSRP
RSRQ bad while RSRP
stable = increasing DL
interference
Both RSRQ and RSRP bad
= path loss…
t1
t1 + t
Timing Advance, TA
To synch tx/rx of UL radio
(UE/eNB) in time domain
eNB sends TA value in RACH responce.
TA = 0 .. 1287 = UE sent RACH at max 200 km
distance = cell range of 100 km.
TA = 0,52 μs = 156 m
MAC timing advance command values between 0
and 63.
Using the 64 index values, a distance of 64 x
156m
= 10 km so ± 5km at 3600km/h.
PRACH Planning
839 preamble sequences available
Paging (MME/eNB paging capacity)
The process of TA dimensioning contains two main tasks:
• TA dimensioning for the MME
• TA dimensioning for the RBS
Number of ZC sequences required per cell, for a
given random access radius. A cell requires five
ZC sequences per cell for up to 7.3km radius,
which is typically sufficient for urban and
suburban macro cells. This results in sequence
reuse factor of at least 839/5 ≈ 167 cells, hence
allows for easy planning process.
Paging Failures
• defective handsets;
• insufficient coverage;
• wrong settings for broadcast cell (re)selection parameters like S0
criteria.

18. LEKS_SF_18
Performance
• ”Call Drops” due to Uu
MME
Opt: RRC Con. Release
(cause=”unspecified”)
UE ctx Rel. Request
(”failure due to EUTRAN”)
UE ctx Rel. Command
(cause=”normal release”)
UE ctx Rel. Complete
May not be seen as dropped from for the user… since UE
moves in/out from IDLE. Takes 1 – 2 seconds to setup
RRC…
Makes sence to distinguis between subscriber level (QoE)
and service level (NW).
• Should we aggregate per QCI?
• Aggregate per handset?
”Uu failure or radio connection lwith UE lost”
Coverage? Interference? Handset?
Permanent
interference due to
ext. Source?
MAC Scheduler
Algorithm?
Buildings, tunnels? Parameter errors
e.g. missing
neighbours?
Protocol? Measurements?
QoE
2000 2010 2020
User-paid
revenues
Traffic growth
Non user-paid
revenues
Voice-centric
pay-per minute
X 100%