Performance analysis of Enhanced
Uplink in UMTS network
Jukka Pihonen
Supervisor: Prof. Riku Jäntti
Instructor: Laura Koskela, M.Sc.
2008-05-30
Outline
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2
Background
Objectives and Methodology
Introduction to Enhanced Uplink
Introduction to Measurements
Measurement Cases and Results
Conclusions
Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Background
• Enhanced Uplink (EUL) = High Speed Uplink Packet Access
(HSUPA) = Enhanced Dedicated Channel (E-DCH)
• Currently in UMTS network, the uplink transmission rate is
restricted to 384 kbps
• Downlink transmission rate was improved over a year ago with
HSDPA, which enables up to 14.4 Mbps throughput for downlink,
today 3.6 Mbps is used in commercial network
• EUL balances uplink and downlink performances by enabling
1.45 Mbps uplink throughput
• EUL also shortens response times and uses frequency band
more effectively
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Objectives and Methodology
• Objectives
 Introduce Enhanced Uplink
 Carry out measurements using Enhanced uplink both in
commercial network and in a closed laboratory network
 Find out and analyze the performance of Enhanced Uplink
 Compare the performance to previous R99 uplink
• Methodology
 Introduction to Enhanced Uplink is based on 3GPP
specifications, IEEE papers and books.
 Measurements were made both in laboratory and in
commercial network
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Introduction to Enhanced Uplink (1/4)
• Enhanced Uplink is defined in 3GPP Release 6
• Combines HSDPA by enabling a fast uplink connection
• EUL enhances uplink throughput first to 1.4 Mbps, later to 5.76
Mbps
• Main features are
 Fast Node B scheduling for uplink
 Fast Hybrid Automatic Repeat Requests (HARQs)
 Short Transmission Time Interval (TTI)
 Multicode transmission
• Introduces 5 new physical channels and 2 new MAC layer
protocols
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Introduction to Enhanced Uplink (2/4)
• Provides following new features:
 Fast Node-B scheduling
 Scheduling is moved from SRNC to Node B, enables faster
response times to constantly changing radio environments
 Node B based scheduling keeps noise raise as high as possible
-> each user gets best possible uplink throughputs
 Fast HARQ
 Retransmission control moved from SRNC to Node B, enables
faster retransmission
 Short TTI
 New 2 ms TTI option to combine mandatory 10 ms TTI
 Enables faster retransmissions -> reduced round trip times
 2 ms TTI was not tested
 Multicode transmission
 Up to 4 parallel E-DPDCHs (2 x SF2 & 2 x SF4 = 5.76 Mbps
uplink throughput in Layer 1)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Introduction to Enhanced Uplink (3/4)
•
Introduces 5 new physical channels, 2 for uplink and 3 for downlink
 Uplink channels
 E-DPDCH (E-DCH Dedicated Physical Data Channel)
 Carries uplink user data = E-DCH traffic channel
 SF 2-256, power controlled
 Number of parallel E-DPDCHs is 1-4
 E-DPCCH (E-DCH Dedicated Physical Control Channel)
 Carries uplink control information
 SF 256, power controlled
 Carries E-DCH Transport Format Combination Identifier (E-TFCI),
Retransmission Sequence Number (RSN) and a single bit called “happy bit”
 Downlink channels
 E-AGCH (E-DCH Absolute Grant Channel)
 Carries absolute scheduling grants, SF 256
 E-RGCH (E-DCH Relative Grant Channel)
 Carries relative scheduling grants, SF 128
 E-HICH (E-DCH HARQ Indicator Channel)
 Carries ACKs/NACKs, SF 256
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Introduction to Enhanced Uplink (4/4)
• New MAC-layer protocols
 MAC-e
 Between UE and Node B
 Controls HARQs and scheduling
 MAC-es
 Between UE and SRNC
 Reorders MAC-es Protocol Data Units (PDUs) in case of soft
handover
 Disassembles dedicated channels in RNC
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Measurements
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•
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•
9
Measurements were done in commercial network
and in a closed laboratory network
Totally four measurement cases were carried out
1) General performance of EUL
2) Performance of EUL in different environments
3) Uplink performance comparison between EUL
and R99
4) Connection setup times and round trip times
Measurements in commercial network were made
as a drive tests i.e. the UE was placed in a car and
a certain route was driven through
Measurements in laboratory were made in a stabile
place, nearby Node B
 Laboratory has its own isolated network ->
minimize external interferences
Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Measurement unit
Measurement routes (1/2)
Long route
• Measurements: General performance of EUL and
EUL performance in different environments
•
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Lengths:
 Urban 3.5 km
 Suburban 18.1 km
 Motorway 6.7 km
Purple line
Urban
Green line
Suburban
Red line
Motorway
Measurement routes (2/2)
Short route
• Measurement: EUL to R99 Uplink comparison
•
•
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Urban area is rounded
with a red circle
Total length 11.1 km
Case 1 (1/7)
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First test case was about general EUL performance
Idea was to figure out how the EUL works in practice
Test was carried out in commercial network
Results in this case covers following things
 Throughputs in different layers
 Happy bit status handling
 MAC-e retransmission rates
 E-DCH channel configurations
 Tx power in different RSCP values
Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Case 1 (2/7)
Distribution of measured samples
• Best reliability between -55 dBm to -100 dBm
Percent of averaged samples
5%
4%
3%
Percent of
averaged
samples
2%
1%
RSCP (dBm)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
-109
-105
-101
-97
-93
-89
-85
-81
-77
-73
-69
-65
-61
-57
-53
-49
-45
0%
Case 1 (3/7)
Uplink throughputs in different layers
• Application layer throughput was 89 % of total carried bits in
physical layer
1400
Uplink throughput (kbps)
1200
1000
Application
Throughput UL
RLC TP UL
800
600
Mac-e TP UL
400
E-DPDCH
200
RSCP (dBm)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
-109
-105
-101
-97
-93
-89
-85
-81
-77
-73
-69
-65
-61
-57
-53
-49
-45
0
Case 1 (4/7)
Uplink application throughput and happy bit handling
• EUL performed even when RSCP was -110 dBm
• Happy bit started to be “happy” when RSCP reached -90 dBm
 To inform unhappy, following 3 conditions must be fulfilled:
 UE transmit as much scheduled data as allowed by scheduling grant
 UE has enough power to transmit at higher data rate
 Total buffer status in UE requires more transmission
100
90
1000
80
70
800
60
600
50
40
400
30
20
200
Happy bit status percentage
Application Throughput UL (kbps)
1200
10
-1
00
-1
05
-1
10
-9
5
-9
0
-8
5
-8
0
-7
5
-7
0
-6
5
-6
0
-5
5
0
-5
0
-4
5
0
RSCP (dBm)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Application
Throughput UL
(avg)
Happy bit status
percentage (%
of happy)
Case 1 (5/7)
Retransmission rates in MAC-e
• Describes the retransmission rates, adjusted by HARQ process
• Retransmission were immune to variation of RSCP value -> link
adaptation worked properly
5%
Retransmission percentage
4%
4%
3%
MAC-e 1st
retransmission rate
3%
MAC-e 2nd
retransmission rate
2%
MAC-e 3rd
retransmission rate
2%
1%
1%
-109
-105
-101
-97
-93
-89
-85
-81
-77
-73
-69
-65
-61
-57
-53
-49
-45
0%
RSCP (dBm)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Case 1 (6/7)
E-DPDCH channel configurations
• The highest throughputs (up to 1.38 in Radio Link Control Layer) can be
reached with 2 x SF 4
80 %
Percent of averaged samples
70 %
60 %
50 %
40 %
30 %
20 %
10 %
0%
2 * SF 4
(68 %)
17
SF 4
(22 %)
SF 8
(5.8 %)
SF 16
(0.1 %)
Jukka Pihonen – Master’s Thesis presentation 2008-05-30
SF 32
(4 %)
SF 256
(0.2 %)
Case 1 (7/7)
Transmit power
• Increases linearly, reached maximum value when RSCP -103 dBm
30
25
20
Tx power (dBm)
15
10
5
Tx power (avg)
0
-5
-10
-15
-109
-105
-101
-97
-93
-89
-85
-81
-77
-73
-69
-65
-61
-57
-53
-49
-45
-20
RSCP (dBm)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Case 2 (1/3)
• Second test case analyzed the performance in different
environments
• Idea was to figure out how the EUL works in different
environments (urban, suburban & motorway)
• Results in this case covers following things
 Uplink throughputs
 Transmit powers
 Retransmission rates
 Happy bit status
• Founds out that the performance was depended on the
environment type
• The best field strength was noticed in urban part, the weakest
field strength was in the suburban part
• Following figure shows the distribution of samples
• Following table summarizes the result of this case
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Case 2 (2/3)
Statistics and RSCP value distribution
Urban
Suburban
Motorway
Average speed (km/h)
21.3
37.5
80.8
Measurement duration (min)
9:45
28:57:00
5:00
Number of measured samples
585527
1737413
299745
Number of averaged samples
1133
3354
580
Percent of averaged samples
7%
6%
5%
Urban
4%
Suburban
3%
Motorway
2%
1%
RSCP (dBm)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
-109
-105
-101
-97
-93
-89
-85
-81
-77
-73
-69
-65
-61
-57
-53
-49
-45
0%
Case 2 (3/3)
•
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This table summarizes the results which were gathered from
different environments
 Retransmission rates were immune to different environments
 In all environment, the same Max UL throughput was reached
 In suburban, the happy bit was most as “happy”
Urban
Suburban
Motorway
Uplink application throughput (kbps)
919
719
618
Max UL application throughput (kbps)
1383
1382
1383
Tx Power (dBm)
1.36
7.8
7.62
MAC-e 1st Retransmission rate (%)
2.26
2.37
1.87
MAC-e 2nd Retransmission rate (%)
0.98
1.09
0.64
MAC-e 3rd Retransmission rate (%)
0.95
1.03
0.47
Happy bit status (% of happy)
1.34
7.58
1.82
Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Case 3 (1/2)
• Third test case compared R99 uplink and EUL in performance
manner
• Idea was to find out how much better performance can be
expected with EUL compared to R99 uplink
• EUL provided 2.3 times better average uplink throughput
compared to R99
• EUL used 4.5 dB more transmit power
 Circumstances were not stabile between routes, when EUL
was measured, the average RSCP value was 4 dB higher due
to better weather conditions.
 increases more the power difference between EUL and R99
uplink
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Case 3 (2/2)
Uplink application throughputs in EUL and R99 networks
• Continuous file uploading
• R99 uplink was immune to variation of RSCP value
• In all RSCP values, EUL provides better throughput
1200
UL Throughput (kbps)
1000
800
Application
Throughput UL
(avg) EUL
600
Application
Throughput UL
(avg) R99
400
200
-109
-105
-101
-97
-93
-89
-85
-81
-77
-73
-69
-65
-61
-57
-53
-49
0
RSCP (dBm)
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Case 4
•
•
•
•
The last test case was performed in laboratory environment
 Free of traffic and low interference levels.
 UE was in fixed place, used one certain Node-B located nearby the UE
Purpose was to find out the connection setup times and round trip times
Results are summarized in the following table
2 ms TTI was not tested
PDP-context activation time (s)
R99/R99
1.41
R99/HSDPA
EUL/HSDPA
1.38
1.36
Round Trip Times (ms)
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Packet size
R99/R99
R99/HSDPA
EUL/HSDPA
32 bytes
129
79
68
128 bytes
131
90
84
512 bytes
260
172
160
Jukka Pihonen – Master’s Thesis presentation 2008-05-30
Conclusions
• Max UL throughput was 1.38 Mbps in application layer
• Scheduling worked properly keeping retransmission rates constant
through the RSCP value scale
• Happy bit status stayed “unhappy” until RSCP reached -85 dBm. In
lower RSCP values, happy bit was more often “happy”
• Best throughputs measured in urban environment
• EUL provided better throughput in all RSCP values compared to
R99 uplink
• EUL required more transmit power compared to R99 uplink
• Round trip times decreased by 9 % compared to R99/HSDPA
network configuration and 40 % compared to R99/R99 network
configuration
Future aspects in EUL
• Mobility enhances
• Uplink throughput raises up to 5.76 Mbps
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Jukka Pihonen – Master’s Thesis presentation 2008-05-30