Comparing GSM, UMTS & LTE Technologies

© 2013 AIRCOM International Ltd
AIRCOM LTE Webinar Series:
Comparison between GSM, UMTS & LTE
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2 © 2013 AIRCOM International Ltd
About the Presenters
Graham Whyley – Lead Technical Trainer
 AIRCOM Technical Master Trainer since 2005
 Currently responsible for all LTE training
course creation and delivery
 Over 20 years of training experience at
companies including British Telecom and
Fujitsu
Contact us at training@aircominternational.com
Paul Raby –
 Paul Raby Ph.D, B.Sc(ENG), MIET, MIEEE
 RAN Planning Expert at Aircom since 2001
 Over 17 years at LJMU Principal Lecturer
Telecommunications

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Agenda- Comparison between GSM,
UMTS & LTE
Comparison
 Base Station Identity Code, Scrambling code
& Physical Cell Identity
 Frequency re-use
 UMTS REL’99
 UMTS REL’5
 Comparison Rel’99 /Rel’5
 3GPP Release 8/9/10

Global System for Mobile Communications
(GSM)
The first cellular systems avoided interference between the cells by assigning a
particular operating frequency to each cell; cells in the same vicinity were assigned
different frequencies.
The total number of frequencies used is termed the frequency reuse factor.
A high frequency reuse factor gives good isolation between cells
Same
Frequency
F2
F1 F1
Low interference between the cells. Poor Capacity
F1 F1
High interference between the cells
8 Timeslots/freq

Global System for Mobile Communications
(GSM)
The Base Station Identity Code (BSIC), is a code used in GSM to uniquely identify a
base station Each base-station has its own BSIC,
this code is at all times transmitted
on the broadcast channel, so the
Mobile Stations can distinguish
between base stations
Base Station Identity Code (BSIC)
GSM
TRX
200khz
Separation
Frequency 1
Frequency 2
TRX
One TRX 8 Timeslots
CS traffic will take
priority
Very poor data rates
CS1- Data Rate = 181 payload bits per 20mS sample = 9.05kbps
CS2-Data Rate = 268 payload bits per 20mS sample = 13.4kbps

C/I ratio
CARRIER (f1) INTERFERER (f1)
C
I
C/I = 10 log 100/10
=+10
C/I = 0dB
C/I = 10 log
10/10 =0
C/I = 10 log
10/100 =-10
Co-channel
Interfering Cell
RATES DEPENDANT ON C/I RATIO
CS1
CS4

Coding Scheme Performance
C / I
CS-2
CS-3
CS-4
CS-1
Average Data Throughput per TS vs Average Connection C/I
Datathroughput4 levels of channel coding schemes (CS-1
to CS-4)
Scheme selected according to
interference level (C/I)
Very poor data rates

Circuit/Packet Data Separation
BTS BSC PCU
Visited
MSC/VLR
Serving
GSN
Gateway
MSC
Gateway
GSN
HLR
Circuit Switched
Packet Switched
PSTN
PDN
A
Gb
Gb interface LAYER TWO-FRAME RELAY
NO QoS
THIS IS NOT AN ALL IP NETWORK:
Lots of SS7 links
UMTS uses Ethernet or ATM (depends on
Release) both give good QoS
LTE is an ALL IP NEWORK. You can set QOS at Network layer(Layer) DSCP, or at Ethernet layer
(Layer2)
LTE DOES NOT SUPPORT CIRCUIT SWITCHED. But CS fallback

Frequency reuse
The use of CDMA/LTE requires a fundamental change in cellular network planning
and deployment strategies, largely resulting from the fact that it enables a
frequency reuse factor of 1 to be used.
GSM900/1800: 3G (WCDMA):
WCDMA GSM
Carrier spacing 5 MHz 200 kHz
Frequency reuse
factor
1 yes

Carrier Shared Between HSDPA and R99
f1
= R5 HSDPA
= R99 DCH
Can cause performance degradation to R99 users
Will cause reduced capacity to R99 users
SF = 128
SF = 256
SF = 64
SF = 32
SF = 8
SF = 16
SF = 4
SF = 2
SF = 1
Codes for the cell common channels
Code for one
HS-SCCH
Codes for 5
HS-PDSCH's
Common Channels
Powerfor
HSDPA
Power
for
REL’99
Variable SF codes for
REL’99
HS-
DSCH
Category
max. No. of
HS-DSCH
Codes
Modulation
(16QAM
supported)
Peak
Rate
1 5 YES 1.2 Mbps
2 5 YES 1.2 Mbps
3 5 YES 1.8 Mbps
4 5 YES 1.8 Mbps
5 5 YES 3.6 Mbps
6 5 YES 3.6 Mbps
7 10 YES 7 Mbps
8 10 YES 7 Mbps
9 15 YES 10 Mbps
10 15 YES 14 Mbps
11 5 NO 1 Mbps
12 5 NO 1.8 Mbps

Carrier Shared Between HSDPA and R99
SF = 128
SF = 256
SF = 64
SF = 32
SF = 8
SF = 16
SF = 4
SF = 2
SF = 1
Codes for the cell common channels
Code for one
HS-SCCH
Codes for 5
HS-PDSCH's
Variable SF codes for REL’99

ONE
PER
CELL
Max number of
codes 15.
Each code SF 16
2mS
UE 1
2mS
UE 2
2mS
UE 3
Max Speed
14.4Mb/s
2mS
UE 3
High Speed Physical Downlink Shared Channel
(HS-PDSCH, Downlink Data Channel)
UMTS REL’5 On one 5Mhz BW – Can support REL’99 & REL’5(REDUCED
BIT RATE FOR REL’5)
OR one 5Mz for REL ’99, one 5Mz for REL ’5
5 MHZ
modulation and coding scheme
16QAM
4bits/Hz
QPSK
2bits/Hz

Dedicated HSDPA Carrier
f1
f2
= R5 HSDPA
= R99 DCH
Can provide high HSDPA throughput
HS-
DSCH
Category
max. No. of
HS-DSCH
Codes
Modulation
(16QAM
supported)
Peak
Rate
1 5 YES 1.2 Mbps
2 5 YES 1.2 Mbps
3 5 YES 1.8 Mbps
4 5 YES 1.8 Mbps
5 5 YES 3.6 Mbps
6 5 YES 3.6 Mbps
7 10 YES 7 Mbps
8 10 YES 7 Mbps
9 15 YES 10 Mbps
10 15 YES 14 Mbps
11 5 NO 1 Mbps
12 5 NO 1.8 Mbps

CELL-DCH
REL’99
HSDPA
REL’5
Variable SF YES NO
Fast Power Control YES NO
Adaptive Modulation NO YES
Soft handover YES NO
TTI times 10,20,40,80 mS 2mS
Maximum channel Rate 2 Mbps 14.4 Mbps
Modulation QPSK QPSK/16-QAM
Comparison Rel’99 /Rel’5

Universal Mobile Telecommunication System
(UMTS).
Scrambling code
UMTS
Group 0
Code 0
Code
Code 7
Group 63
Code 0
Code
Code 7
S-SCH
Identify the code group
A cell must be allocated 1 of a possible 512
scrambling codes. (64x8)
Cluster group
512 scrambling codes.

Scrambling code-UMTS
Once the scrambling code for a CPICH is known, the
channel can be used for measurements of signal
quality, usually with RSCP and Ec/N0.
• The 512 codes are divided into 64 groups with 8 codes
in each group
• The scrambling code is the pilot channel
.
Group 0
Code 0
Code 7
Group 63
Code 0
Code 7
64 X 8=512
The received quality of the
CPICH is quantified by its Ec/Io
and Received Signal Code
Power (RSCP)
Maximum
power43dbm
+33 dBm = 2W
CPICH
RSCP
RSCP
Ec/Io
Ec/Io
Common Pilot Channel
CPICH Ec/Io =
CPICH RSCP
UTRA carrier RSSI

Scrambling code-UMTS
+33 dBm = 2W
CPICH
RSCP
Common Pilot Channel
Ec
Io
OWNCELL
INTERFERENCE
RSCP
Ec/Io
Cell Selection
Handover decisions
Ec/Io (Own plus Other)

CPICH Ec/Io

HSDPA-Rel’5
RSCP
Ec/Io
HSDPA
Maximum
power43dbm
+33 dBm = 2W
CPICH
Powerfor
HSDPA
Signal Strength
for HSDPA
Own cell
Interference
SINR ave = S
I + N
I = Iown + Iother
Maximum
power43dbm
REL 99 – Circuit Switched
PS Data –Typical 384kbit/s
HSDPA-REL 5
Same Frequency
F1- Shared
Power/Share Codes

HSDPA-Rel’5
Maximum
power43dbm
CPICH
RSCP
Ec/Io
HSDPA
Powerfor
HSDPA
HSDPA-REL 5
16 QAM
QPSK
Shared with Rel’99 –
Typically 5 codes
HSDPA-REL 5
Same Frequency
F1- Shared
Power/Share Codes
Frequency
F1
Frequency
F2
HSDPA-REL 5
Different coding
Rates
The benefit of 16 QAM is
that 4 bits of data are
transmitted in each radio
symbol as opposed to 2
bits with QPSK.
Under good radio conditions, an advanced
modulation scheme—16 QAM

0 20 40 60 80 100 120 140 160
-2
0
2
4
6
8
10
12
14
16
Time [number of TTIs]
QPSK1/4
QPSK2/4
QPSK3/4
16QAM2/4
16QAM3/4
InstantaneousEsNo[dB]
C/I received
by UE
Link
adaptation
mode
C/I varies
with fading
BTS adjusts link adaptation
mode with a few ms delay based
on channel quality reports from
the UE
Fast Link Adaptation in HSDPA
Mobile devices report the quality of the downlink channel via channel quality indicator (CQI) reports to the
mobile network. Using these reports, the system continuously optimises performance (at 10% BLER) by
choosing the best transmission speed for the next TTI.
channel quality reports

HSDPA-Rel’5
Maximum
power43dbm
CPICH
RSCP
Ec/Io
HSDPA
PowerforHSDPA
HSDPA-REL 5
16 QAM
QPSK
Dedicated
FrequencyHSDPA-REL 5
Max number of
codes 15.
Each code SF 16
2mS
UE
1
2mS
UE
2
2mS
UE
3
Max Speed
14.4Mb/s
2mS
UE
3
SINR ave = S
I + N
I = Iown + Iother
You could get
poor levels of
Ec/Io and
good SINR

HSPA Evolution- HSPA+
Three main directions can be observed for this evolution:
• Higher-order modulation (64 QAM, 16QAM, QPSK)
• Advanced multiple-antenna techniques
• Multi-carrier operation
Dual-carrier HSDPA was introduced, whereby two adjacent
5-MHz radio channels can be used simultaneously to a single UE
QPSK16QAM64QAM
QPSK16QAM64QAM
TX
TX
5 MHz
41.00 Mbps

Poll Question
What is the function of the RSCP?
a. It is received quality of the CPICH .
b. It changes with cell loading.
c. It measures the coverage of a service (VoIP for example).
d. It measures the signal strength of the pilot (CPICH) .

• Bit Rates after accounting for the overheads generated by Reference
Signals, Synchronisation Signals and other Physical Channels
• . Coding rate hasn’t been included
Resultant Bit Rates - Downlink
Channel Bandwidth
1.4 MHz 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz
QPSK 1.61 4.27 7.23 14.63 22.03 29.43
16QAM 3.21 8.54 14.46 29.26 44.06 58.86
64QAM 4.82 12.81 21.69 43.89 66.09 88.29
64QAM (2+2 MIMO) 9.08 24.20 41.00 83.00 125.00 167.00
64QAM (4+4 MIMO) 17.07 45.58 77.26 156.46 235.66 314.86
Figures in Mbps
Compare with the
equivalent HSPA+
bit rate

Physical Cell Identity- LTE
Physical Cell Identity
504 Physical Layer Cell Identities
• Physical layer Cell Identity (PCI) identifies a cell within a
network equivalent of UMTS scrambling code
• There are 504 Physical Layer Cell Identities compared to 512
UMTS scrambling codes
• PCI are organised in 168 groups of 3 codes compared to 64
groups of 8 for UMTS scrambling codes
• RSRP (Reference Signal Received
Power)
• RSRQ (Reference Signal Received
Quality

PCI planning
Physical layer Cell Identity = (3 × Group(0 to 167)) + Code 0-2
= (3 x 2) + 2 =8
Group(0 to 167)
Code (0-2)

RSRQ
RSRQ = n x RSRP/RSSI
RSRQ = 10 log 25 + (-102.77 –(- 82 .71)
=13.97 + (-20.06)
=-6.09
RSRP
RSRQ
LTE
RSCP
Ec/I0
3G

3GPP Release’s
 3GPP Release 8
 4x4 MIMO in the Downlink
 1x1 MIMO in the Uplink
 Home eNode B
 Inter Cell Interference Coordination
(ICIC)
 SON – Self Establishment of eNode B
 SON – Automatic Neighbour Releations
 3GPP Release 9
 MBMS
 SON – Mobility Load Balancing
 SON – Mobility Robustness
Optimisation
 SON – RACH Optimisation
 SON – Energy Saving
20MHz
15MHz
10MHz
5MHz
3MHz
1.4MHz
REL’8
CC Cell Edge
CC Cell Edge
Inter Cell Interference Coordination (ICIC)
MIMO in the Downlink

3GPP Release’s
• 3GPP Release 10
– Carrier Aggregation
– 8x8 MIMO in the Downlink
– 4x4 MIMO in the Uplink
– Relays
Each aggregated carrier is referred to as a
component carrier.
The component carrier can have a bandwidth
of 1.4, 3, 5, 10, 15 or 20 MHz
Component carriers can be aggregated.
REL 10
20 MHz
Optic Fibre cable
into core
REL 8
Relay

Questions

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Comparing GSM, UMTS & LTE Technologies

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