2002-12-11
Implementation of the Mid
Term Guidelines (MTG) in
the real network project
Jakov Stojanović, MOBTEL ”Serbia”, Belgrade,
Serbia and Montenegro,
Network Planning Centre,
Radio Network Optimisation Group Manager
Milan Gospic, ERICSSON d.o.o., Belgrade,
Serbia and Montenegro,
Senior Support Engineer
Damascus, Syria, 13 - 15 June 2005
Agenda
• Implementation of MTG in Serbia and Montenegro for
Mobile Operator Mobtel
• GSM/GPRS network as a first step in transition of
existing 2G network towards IMT-2000:
– GSM (Evolved) Core Network
– GPRS protocols and coding schemes
– EDGE/EGPRS implementation
– some examples of Radio-Network statistics
– definition and descriptions of major KPIs
• Pre-commercial trial WCDMA/UMTS network
Damascus, Syria, 13 - 15 June 2005
Rev PA1
1
2002-12-11
Implementation of MTG
• Transition towards IMT-2000
– A core network with links to the PSTN, ISDN, the
Internet/Intranet and external mobile and data
network
– Radio Access Network based on the radio-interface
IMT-2000 CDMA Direct Spread (WCDMA/UMTS)
– Dual-mode and multi-mode terminals allowing
subscribers to enjoy services on pre-IMT-2000 and
IMT-2000 network
Damascus, Syria, 13 - 15 June 2005
GSM (Evolved) Core Network
• For the support of packet data services, GSM
(Evolved) Core Networks have been complemented by
IP-based GPRS-backbone networks providing a
specific fast Mobile Management to the packet data
services, capable of handling fast handovers for realtime packet data services (Mid Term Guidelines)
Damascus, Syria, 13 - 15 June 2005
Rev PA1
2
2002-12-11
GSM/GPRS network diagram
Damascus, Syria, 13 - 15 June 2005
GPRS protocols
Appl.
Appl.
TCP
UDP
TCP
UDP
IP
IP
SNDCP
SNDCP
GTP
GTP
IP
IP
L2
L2
L1
L1
LLC
LLC Relay
LLC
RLC
RLC BSSGP
BSSGP
MAC
MAC
FR
FR
PHY
PHY
L1
L1
MS
BSS
SGSN
L2
L2
L1
L1
GGSN
Host
Damascus, Syria, 13 - 15 June 2005
Rev PA1
3
2002-12-11
Network upgrades
Damascus, Syria, 13 - 15 June 2005
EDGE – 8 PSK modulation
Currently:
GMSK Modulation
EDGE:
8PSK Modulation
Q
(0,1,0)
(0,0,0)
“1”
(0,1,1)
I
I
(0,0,1)
“0”
Q
(1,1,1)
(1,0,1)
(1,1,0)
(1,0,0)
“1 bit per symbol”
“3 bits per symbol”
Damascus, Syria, 13 - 15 June 2005
Rev PA1
4
2002-12-11
GPRS/EGPRS coding schemes
kbps
60
59.2
54.4
50
40
44.8
30
29.6
20.0
20
12.0
11.2
8.
0
14.8
17.6
GPRS
MCS9
MCS8
MCS7
MCS6
MCS5
MCS4
MCS3
MCS2
MCS1
CS4
8.4
CS3
CS1
0
14.4
CS2
10
22.4
EGPRS
8PSK modulation
GMSK modulation
Damascus, Syria, 13 - 15 June 2005
EDGE/EGPRS implementation
Internet
GPRS
MS
GPRS Protocol
EDGE
BTS
TRU
EDGE
MS
EDGE Protocol
SGSN GGSN
GGSN
PCU
No changes
Damascus, Syria, 13 - 15 June 2005
Rev PA1
5
2002-12-11
Radio Network Performance
(Circuit Switched)
•
•
•
•
Accessibility – relates to blocked calls
Retain ability – relates to dropped calls
Integrity – relates to speech quality
All of these can be measured and translated to into a
user perception of service quality
Damascus, Syria, 13 - 15 June 2005
Radio Network Performance
(Packet Switched)
• It is much more difficult to define counters and
formulas and relate these to the user perception of
service quality
• There are two main reasons:
– GPRS/EDGE (EGPRS) system has many layers of
protocols
– GPRS/EDGE (EGPRS) is a bearer for a number of
different applications, so user perception of
network performance can vary depending on
application used in session
Damascus, Syria, 13 - 15 June 2005
Rev PA1
6
2002-12-11
Radio Network Performance
(Packet Switched)
• The Key Performance Indicators (KPIs) focus on the
main task – transfer of IP packets and are grouped
into following areas:
– Level one performance indicators – directly
related to the ability to transport IP packets (for
example the IP throughput on cell level)
– Level two performance indicators - indirectly
related to the ability to transport IP packets. They
should be used for trouble-shooting purposes to
identify the specific factors that are causing the
level one indicators to show poor performance
Damascus, Syria, 13 - 15 June 2005
Radio Network Performance
(Packet Switched)
• The factors that can affect the user perception of the
GPRS/EDGE (EGPRS) services:
– Quality of the radio link
– Circuit Switched (CS) traffic load
– Packet Switched (PS) traffic load
– Channel allocation and reservation
– MS capability
– Users mobility and QoS profile
– Operator parameter setting
– TCP/IP and other effects
Damascus, Syria, 13 - 15 June 2005
Rev PA1
7
2002-12-11
Radio Network Performance PS
Level One - IP throughput
• IP throughput (measured on LLC layer) - similar to
"modem speed" concept for fixed internet
• The factors that can affect:
– Poor radio link quality (Level two)
– Less PDCH reserved than requested by user (Level
two – Multi slot utilisation)
– PDCH reserved by other users (Level two – GPRS
traffic load)
– QoS scheduling prioritizing different users
– Delays in setup of downlink Temporary Block Flow
(TBF)
Damascus, Syria, 13 - 15 June 2005
Radio Network Performance PS
Level One - IP throughput
• The factors that could affect the IP throughput but are
not included in the measured IP throughput:
– Discard of the contents of the IP buffer in the MS or
in the PCU (Level one – IP buffer discard)
– Cell reselection during transfer (Level one –
discards due to flush)
– Delays in setup of uplink Temporary Block Flow
(TBF)
Damascus, Syria, 13 - 15 June 2005
Rev PA1
8
2002-12-11
Radio Network Performance PS
Level One - IP throughput
• Additional factors:
– The total time to perform a data transfer
– Effects of protocol layers above the LLC layer (for
example TCP slow start)
– Outside events that cause IP packets to be
retransmitted by the TCP protocol
Damascus, Syria, 13 - 15 June 2005
Radio Network Performance PS
Level One - IP throughput
• The Mobile Station capability is another factor that can
impact the measured IP throughput. Factors are:
– GPRS or EDGE (EGPRS) capable
– Multi-slot capability (Level two – Multi slot
utilisation)
– Frequency band capability
– 3GPP Release of the mobile station
Damascus, Syria, 13 - 15 June 2005
Rev PA1
9
2002-12-11
Radio Network Performance PS
Level One - IP buffer discards
• IP throughput measures the speed with witch the IP
packets are shipped to and from user
• IP packets can’t transfer to user – the entire contents
of the IP buffer will be discarded (user experience is
dependent on the application running)
• The contents of the IP buffer may be discarded due to
inter Routing Area or Inter Cell Reselection –
“planned” IP buffer discard
Damascus, Syria, 13 - 15 June 2005
Radio Network Performance PS
Level One - IP buffer discards
• Absolute number of IP buffer discards is a relevant
performance indicator
• It is suggested to calculate the number of IP buffer
discards per data transfer session minutes
Damascus, Syria, 13 - 15 June 2005
Rev PA1
10
2002-12-11
Radio Network Performance PS
Level Two – Radio Link Quality
• The quality of each users radio link determines the
maximum IP throughput they can achieve
• The perfect radio link quality is represented by:
– Close to 12 kbit/s for CS-1/2 transfers
– Close to 20 kbit/s CS-1/2/3/4 transfers
– Close to 59 kbit/s for EDGE (EGPRS) transfers
Damascus, Syria, 13 - 15 June 2005
Radio Network Performance PS
Level Two – Mobility
• The mobility of the user will affect the IP throughput
• If they remain in one cell for the duration of the data
session than there will be no impact
• If they move rapidly between cells there will be a large
impact
• User experiences due to cell reselection is very
dependent on the application type
Damascus, Syria, 13 - 15 June 2005
Rev PA1
11
2002-12-11
GPRS/EGPRS radio network dimensioning
• The objective is that GPRS/EGPRS users will
experience an estimated throughput on application
level
• The throughput achieved is depended on the channel
capabilities, amount of GPRS and EGPRS traffic,
interference environment, Mobile Station multi slot
class and the type of traffic generated by the users
• It is based on Radio Network statistics
Damascus, Syria, 13 - 15 June 2005
Radio Network Performance PS
Level One - IP buffer discards
20.00
18.00
16.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
BSC TKC 1
BSC TKC 2
BSC ANEX
BSC AERO
BSC NOVI SAD 1
BSC NOVI SAD 2
BSC NIŠ
27-May-05
26-May-05
25-May-05
24-May-05
23-May-05
22-May-05
21-May-05
20-May-05
19-May-05
18-May-05
17-May-05
16-May-05
15-May-05
14-May-05
13-May-05
12-May-05
11-May-05
9-May-05
10-May-05
8-May-05
7-May-05
6-May-05
5-May-05
4-May-05
0.00
BSC KRAGUJEVAC
Damascus, Syria, 13 - 15 June 2005
Rev PA1
12
2002-12-11
Radio Network Performance PS
Level Two – Radio Link Quality
14.00
12.00
10.00
8.00
6.00
4.00
2.00
BSC TKC 1
BSC T KC 2
BSC ANEX
BSC AERO
BSC NOVI SAD 1
BSC NOVI SAD 2
BSC NIŠ
27-May-05
26-May-05
25-May-05
24-May-05
23-May-05
22-May-05
21-May-05
20-May-05
19-May-05
18-May-05
17-May-05
16-May-05
15-May-05
14-May-05
13-May-05
12-May-05
11-May-05
9-May-05
10-May-05
8-May-05
7-May-05
6-May-05
5-May-05
4-May-05
0.00
BSC KRAGUJEVAC
Damascus, Syria, 13 - 15 June 2005
GSM/UMTS - Common Core Network
Damascus, Syria, 13 - 15 June 2005
Rev PA1
13
2002-12-11
Core Network upgrades
• Horizontally layered network architecture
• Separation of control and connectivity layer
• Network elements are evolving to adapt to new
architecture (control and connectivity)
Damascus, Syria, 13 - 15 June 2005
Horizontally Layered Network Architecture
MGW controlled by
network servers,
adapt and connect
different access
types to a common
backbone network
Damascus, Syria, 13 - 15 June 2005
Rev PA1
14
2002-12-11
UMTS Layered Network Architecture
Damascus, Syria, 13 - 15 June 2005
Radio Access Network
• IMT-2000 CDMA Direct Spread (WCDMA/UMTS):
– A spread spectrum system based on direct
sequence
– It is spectrally efficient – high data rates
– Flexibility to manage multiple traffic types (voice
and data)
– HSDPA (High Speed Downlink Packet Access) is an
enhancement – achieves high speeds through the
addition of higher order modulation such as 16
QAM
Damascus, Syria, 13 - 15 June 2005
Rev PA1
15
2002-12-11
Mobtel - Ericsson WCDMA/UMTS Network
Diagram – Trial Configuration
AEROINŽENJERING
LEGEND:
TSM -1 Fiber Optic
E1
Fast Ethernet
Gigabit Ethernet
Mut
Mut
Mp, Gr
/2
Mp, Gr
/2
/1
/1
MSC Server 3.0
TKC
Iub
/1
Iu-C
/2
RXI
AERO
RBS 1
Iub
/2
/10
HLR
MSC/STP 2
SMSC
/2
/2
MGW 3.0
Iu-C,
Iu-U
/2
MSC/STP 1
O&M Interface
/1
O&M Interface
/1
Existing Mobtel
GSM Network
Mur /1
Mur /1
RXI TKC
RNC P2.1
Iub
/1
Iu-U
Gom, Gn
/2
/2
Iu-C, Gr
Gom, Gn
/2
/2
Iub
SGSN W 5.5
/1
1 1
0
1
1 3
1 2
1 5
1 4
1 7
1 6
1 9
1 8
2
2 0
1
3
2
2 2
2
2 4
5
2 7
2 6
2 9
2 8
1
3
0
3
3 3
2
3
4
3
3 5
3 6
7
3
3 9
3
8
4
4
0
1
4 2
1
3
2
G
5
4
7
6
9
8
1
0
1
1 3
1
2
1 5
1
4
7
1
6
1
1
1 8
9
2
2 0
1
2
2 3
2
5
2
4
2
2 6
7
2 9
2
8
1
3
3 0
3 3
2
3
3 5
3
4
3 7
3 6
3 9
3 8
4
1
4 0
T M
Summit 48i
R
Iub
/1
PM
O
RBS 15
O
C
N
S
OE
L
9
4
5
0
4
4 2
3
4
4 4
5
7
4
4 6
8
4
Summit 48i
/1
O&M Interface
Traffic Interface
Mur,Mub
ECDS 2.0
/2
1 1
0
1
RBS 16
1 3
1 2
1 5
1 4
1
1 6
7
1 9
1 8
2 1
2 0
2 3
2 2
2 5
2 4
2 7
2 6
2 9
2 8
1
3
3 0
3 3
2
3
3 5
3 4
3 7
3 6
3 8
3 9
4 0
4 1
4 2
Gn,Gom,Gi
/2
Gn,Gom,Gi
/2
Netgear switch
RBS 20
OMINF
RANOS P2.1
OSS RC1.1
GGSN R2
Existing equipment
AXI 520 - 4
O&M Network
Damascus, Syria, 13 - 15 June 2005
Thank you for your attention !
Contacts :
jakov.stojanovic@mobtel.co.yu
milan.gospic@ericsson.com
Damascus, Syria, 13 - 15 June 2005
Rev PA1
16