A Comparison Between One-way Delays in Operating HSPA and LTE Networks

miststizzaMobile - Wireless

Dec 10, 2013 (3 years and 6 months ago)

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A Comparison Between One-way Delays in
Operating HSPA and LTE Networks
Markus Laner,Philipp Svoboda,Peter Romirer-Maierhofer,
Navid Nikaein,Fabio Ricciato and Markus Rupp
Vienna University of Technology,Austria
FTW,Austria
EURECOM,France
WINMEE'12,May18,2012,Paderborn,Germany
Intro.Measurements Results Interpretation Conclusion
Outline
1 Introduction
2 Measurements
3 Results
4 Interpretation
5 Conclusion
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 2=16
Intro.Measurements Results Interpretation Conclusion
Outline
1 Introduction
2 Measurements
3 Results
4 Interpretation
5 Conclusion
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 1=16
Intro.Measurements Results Interpretation Conclusion
Motivation
I
Latency aects user experience
I
Increasing importance/attention
I
What to improve?!Measurements
Low Latency
Future Appl.
?
Video
Gaming
Voice
M2M
Alarm
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 2=16
Intro.Measurements Results Interpretation Conclusion
Contributions
I
Measurements of LTE and HSPA latency
I
Verication of LTE design goals (popular estimates)
I
Comparing in uences of
 Packet size
 Data rate
I
QoS estimates for latency
sensitive applications
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 3=16
latency estimates [Holma,2010]
20
0
30
10
RTT (ms)
HSPA
NodeB
TTI
UE
Buffering
Retransm.
Scheduling
UE
LTE
TTI
Buffering
Retransm.
Scheduling
Core
RNC
eNodeB
HSPA High Speed Packet Access
LTE Long Term Evolution
RTT Round Trip Time
QoS Quality of Service
Intro.Measurements Results Interpretation Conclusion
Outline
1 Introduction
2 Measurements
3 Results
4 Interpretation
5 Conclusion
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 3=16
Intro.Measurements Results Interpretation Conclusion
Denition of Latency
I
Latency [3GPP,TS 25.913]:
 Control-plane:Transition time from idle to connected state
 User-plane:Packet (0 Bytes) available at IP layer of UE/GW
I
Ambiguities:
 Size:IP datagrams vs.IP fragments
 Availability:Start vs.end
 Intermediate interfaces:No IP
I
Def.:Last bit of an IP datagram passing each interface
I
Q:Is this def.enough for low data rate applications?
IP datagram,4 fragments
Interface 1
Interface 2
Interface 3
time
Δ
1,2
Δ
2,3
Δ
1,3
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 4=16
Intro.Measurements Results Interpretation Conclusion
Setup
I
3G and 4G networks (3GPP Rel.8)
I
Modem:Huawei E392,triple-mode
I
FDD:10 MHz (HSPA) vs.20 MHz (LTE)
I
Radio:Line-of-sight,130 m
Server
Server
Server
Probe
Internet
RNC GGSN
NodeB
Gn
SGi
Gi
USB
Δ
Δ
Δ
Modem
S1−U
HSPA
LTE
owd
cnran
eNodeB
Probe
Probe
Probe
Probe
SAE GW
PC
Client
PC
Server
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 5=16
Intro.Measurements Results Interpretation Conclusion
Measurement Devices
I
Passive packet sning (wiretaps) - ve Probes
I
GPS synchronized
I
Protocol parsing
I
Packet identication!timestamp comparison
Server
Server
Server
Probe
Internet
RNC GGSN
NodeB
Gn
SGi
Gi
USB
Δ
Δ
Δ
Modem
S1−U
HSPA
LTE
owd
cnran
eNodeB
Probe
Probe
Probe
Probe
SAE GW
PC
Client
PC
Server
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 6=16
Intro.Measurements Results Interpretation Conclusion
Trac Generation
I
Data-trac in uences latency
I
Independent uplink and downlink
I
Random packet size and inter-arrival time
[IETF,RFC 2330][Fabini,2009][Baccelli,2007]
I
Blocked measurements!xed data-rate
Internet
HSPA
modem
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 7=16
Intro.Measurements Results Interpretation Conclusion
Outline
1 Introduction
2 Measurements
3 Results
4 Interpretation
5 Conclusion
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 7=16
Intro.Measurements Results Interpretation Conclusion
Comparison RTT
I
LTE:36 ms median RTT
I
HSPA:42 ms median RTT
I
Minor improvements of 14%
0
20
40
60
80
0
0.5
1
overall round−trip time (ms)
empirical CDF


LTE
HSPA
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 8=16
RTT Round
Trip Time
CDF Cumulative
Distribution Function
Intro.Measurements Results Interpretation Conclusion
One-way Delay in RAN
I
Downlink:LTE very fast (7 ms)
I
Uplink:HSPA fast (15 ms)
I
Main reasons for minor performance of LTE:
Low layer signaling,scheduling,DRX,and cell conguration
(e.g.SR periodicity)
0
15
30
45
60
0
0.5
1
one−way delay RAN (ms)
empirical CDF


LTE downlink
LTE uplink
HSPA downlink
HSPA uplink
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 9=16
RAN Radio Access
Network
CDF Cumulative
Distribution Function
Intro.Measurements Results Interpretation Conclusion
One-way Delay in Core
I
Uplink and Downlink equal (1.5 ms)
I
HSPA and LTE similar (1.5 ms)
I
Caution:high load in HSPA!tail
0
1
2
3
4
5
0
0.5
1
one−way delay CN (ms)
empirical CDF


LTE downlink
LTE uplink
HSPA downlink
HSPA uplink
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 10=16
Intro.Measurements Results Interpretation Conclusion
LTE Delay vs.Packet Size
I
Scatterplot:No diagonal components
)no correlation
I
Reason:High bandwidth & LTE scheduling
Downlink
0
10
20
30
40
50
0
1
2
3
4
5
overall one−way delay (ms)
datagram size (kByte)


0
1
Uplink
0
10
20
30
40
50
0
1
2
3
4
5
overall one−way delay (ms)
datagram size (kByte)


0
1
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 11=16
Intro.Measurements Results Interpretation Conclusion
LTE Delay vs.Packet Size
I
Scatterplot:Diagonal components
)positive correlation
I
Reason:HSPA scheduling & network load
Downlink
0
10
20
30
40
50
0
1
2
3
4
5
overall one−way delay (ms)
datagram size (kByte)


0
1
Uplink
0
10
20
30
40
50
0
1
2
3
4
5
overall one−way delay (ms)
datagram size (kByte)


0
1
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 12=16
Intro.Measurements Results Interpretation Conclusion
Delay vs.Data-rate
I
LTE:independent of packet-size
I
HSPA:dependent of packet-size (2 curves)
I
Delay decreasing with increasing rate
strong contrast to xed networks (queuing)
256
1k
4k
16k
64k
256k
1M
0
15
30
45
60
data rate (Byte/s)
median overall one−way delay (ms)


LTE downlink
LTE uplink
HSPA downlink
HSPA uplink
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 13=16
Intro.Measurements Results Interpretation Conclusion
Outline
1 Introduction
2 Measurements
3 Results
4 Interpretation
5 Conclusion
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 13=16
Intro.Measurements Results Interpretation Conclusion
Latency Sensitive Trac
Online Gaming
I
Data-rate:1 kByte/s { 16 kByte/s
I
Latency:Impairments at RTT > 50 ms
M2M (e.g.,event-driven,real-time)
I
Data-rate:< 1 kByte/s
I
Latency:Impairments at RTT > 20 ms
VoIP,video call
I
Data-rate:4 kByte/s { 256 kByte/s
I
Latency:Impairments at RTT > 200 ms
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 14=16
Intro.Measurements Results Interpretation Conclusion
Network Type vs.Trac
I
QoS requirements vs.network performance
I
Not accounting for IP backbone and server processing delays
I
3G/4G networks not (yet) ready to host certain apps.
I
Source of QoS parameters [LOLA,D3.6,2012]
Application
LTE (up=down)
HSPA (up=down)
Online Gaming
( 31= 13 ) ms
( 12= 17 ) ms
M2M
( 30= 10 ) ms
( 10= 16 ) ms
VoIP
( 30= 15 ) ms
( 35= 16 ) ms
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 15=16
QoS Quality of Service
M2M Machine to Machine
VoIP Voice over IP
Intro.Measurements Results Interpretation Conclusion
Outline
1 Introduction
2 Measurements
3 Results
4 Interpretation
5 Conclusion
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 15=16
Intro.Measurements Results Interpretation Conclusion
Conclusions
I
LTE shows improved latency over HSPA (14%)
I
Decreasing latency with increasing data-rate
I
HSPA uplink scheduling outperforms LTE
I
New low-latency transmission techniques [LOLA project]
I
Semi-persistent scheduling in LTE
I
Latency sensitive apps.require improvements
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 16=16
Intro.Measurements Results Interpretation Conclusion
Thank you for your attention!
Markus Laner,Philipp Svoboda,Peter Romirer-Maierhofer,
Navid Nikaein,Fabio Ricciato and Markus Rupp
Vienna University of Technology,Austria
FTW,Austria
EURECOM,France
mlaner@tuwien.ac.at
www.tc.tuwien.ac.at
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 16=16
Ref.
References
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3GPP.TS 25.913,Requirements for Evolved UTRA and Evolved UTRAN,
http://www.3gpp.org/.
I
H.Holma and A.Toskala,WCDMA for UMTS:HSPA Evolution and LTE (5th
Edition).Wiley,2010.
I
M.Laner,P.Svoboda,and M.Rupp,Dissecting 3G Uplink Delay by Measuring
in an Operational HSPA Network,in PAM'11,Atlanta,Georgia,2011.
I
J.Fabini,L.Wallentin,and P.Reichl,The importance of being really random:
methodological aspects of IP-layer 2G and 3G network delay assessment,in
ICC'09,Dresden,Germany,2009.
I
V.Paxson et al.(1998) RFC 2330,Framework for IP Performance Metrics,
http://www.ietf.org/rfc/rfc2330.txt.
I
F.Baccelli et al.,On Optimal Probing for Delay and Loss Measurement,in
IMC'07,San Diego,California,2007.
I
libpcap - library for network trac capture,http://www.tcpdump.org/.
I
Darwin Project,http://userver.ftw.at/ricciato/darwin/.
I
Endace DAG,http://www.endace.com/.
I
LinuxPPS,http://wiki.enneenne.com/index.php/LinuxPPS support.
I
EU FP7 LOLA Project,http://www.ict-lola.eu/.
M.Laner,TUV Comparison of Delays in HSPA and LTE 2012-05-18 17=16