Geneva, 12-13 May 2008
ITU-T Kaleidoscope ConferenceInnovations in NGN
Gang QinThe University of Tokyo
TWO BUFFER MODEL-BASED QoSESTIMATION METHOD FOR 3G WIRELESS IP NETWORKS IN
BULLET TRAINS
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 2
Outline
Summary
The proposed measurement
The QoS estimation method
The experiment and result
Conclusions and Future Works
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 3
Summary
We are aiming at improving transport layer protocols over 3G wireless IP networks in high-speed mobile environment.
It is necessary to make a model of high-speed mobile communication environment on the simulator.
To do this, measurement of the communication quality and the raw packet transmission characteristics of the 3G is necessary
We will introduce a two buffer model-based QoSestimation method used to measure the raw packet transmission characteristics of CDMA2000 1xEV-DO in bullet trains.
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 4
Definition of communication quality and measurement(ITU-T Recommendations)
・IP packet transfer delay (IPTD) ・IP packet delay variation (IPDV) ・IP packet loss ratio (IPLR) ・IP packet error ratio (IPER)
• The measurement points (MP) are fixed and the path is invariable• Clock synchronization of two measurement points is necessary
• One-way measurement• The probe packet will be
• UDP–echo based• Time-stamped at injection
and extraction devices
Probe Packet
MP A MP B
Results
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 5
Issues of communication qualities in bullet trains1. The mobile station (MS) keep moving the entire time and
the communication channel characteristics differ according to the geographical location of the MS.• we need to define the invariant communication qualities of this
environment and find a method for the measure of communication performance.
2. In order to get the raw packet transmission characteristics of 3G wireless IP networks, we need to avoid the influence of possible packet buffers and transport layer protocols like W-TCP. • We can only observe the communication performance over IP layer.• We avoid measuring the network performance with tools using TCP.
3. The one-way measurement need to synchronize the clock of the two measurement points.• There are many tunnels along the route, so it is very difficult to realize
the clock synchronization by using GPS.
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 6
Proposed measurement
Define Route Characteristics in Bullet Trains as a set of the following measurements
RPB = {< Delayi, Jitteri, Packet_Lossi, Availabilityi>|i ∈ Locations}
Locations are sampled in a specified time-interval between the start station and the terminal station.Each measurement varies geographically.We want to get statistical values from RPB
For #1 issue
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 7
Proposed measurement
A proposed measurement from the view of users
Traditional two-way measurement (RTT)
ICMP-echo packets in a specified time-intervalThe size of probe packet is 84 bytes.The measurement interval is set to 1 secondMeasure from the starting station to the terminal station
Two buffer model-based QoS estimation method is used to measure the raw packet transmission characteristics
For #2 issue
For #3 issue
For #2 issue
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 8
How to measure:Network configurations of our experiment
Probe Packet
IP Network of au
PDSN1xEV-DO1xEV-DO The Internet
U. of Tokyo Network
IP Address given by au
Probing CEEcho CE
ACK Packet
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 9
What to Measure:The data of our experiment
We measure following data at each location segment i
RTT (Delayi, Jitteri)Packet Loss Ratio (Packet_Lossi )Probing CE Status (PCE_Statusi )
Experiment Target LineTokaido Shinkansen (Tokyo-Shin Osaka)「Nozomi」
No throughput measurement at this time
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 10
RTT data
RTT (ms) Tokyo-Shin Osaka
Shin Osaka-Tokyo Static
Min 140 132 131
Max 26199 24503 948
Average (mean) 661 575 189
Median 400 404 108
Standard deviation 1402 1088 42.6
Packet Loss Ratio 8.5% 7.9% 0%
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 11
Cumulative distribution of RTT
00.1
0.20.30.4
0.50.60.70.8
0.91
100 1000 10000 100000RTT(ms)
Tokyo-Shin Osaka Shin Osaka-Tokyo staticProbability
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 12
Cumulative distribution of packet loss length for Tokyo-Shin Osaka
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60Packet Loss Length (sec)
Probability
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 13
Tokyo-Shin Osaka RTT and Packet Loss
0
5000
10000
15000
20000
25000
30000
0 2000 4000 6000 8000 10000
Elapsed time(s)
RT
T(m
s)in-tunnel RTT packet loss
packet loss
Tokyo (0)
Shinagawa (365~443)
Shiyokohama (1084~1168)
Nagoya (6135~6250)
Kyoto (8416~8525)
Shiosaka (9322)
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 14
Model of wireless communication environment
Echo CE
Probing CE
Wired Network
CDMA2000 1xEV-DO
Buffer1
Buffer4
Buffer5
Buffer22
Buffer21
Buffer3
Buffer2Echo CE
Probing CE
Wired Network
CDMA2000 1xEV-DO
Buffer1
Buffer4
Buffer5
Buffer22
Buffer21
Buffer3 Buffer1
Buffer2
Echo CE
Probing CE
Wired Network
CDMA2000 1xEV-DO
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 15
How to eliminate the buffer function from the network
The original TCP specification had TCP update a smoothed RTT estimator (called R) using the low-pass filter:
R ←− αR + (1 − α)M, α=0.9.
RFC793 recommended the retransmission timeout value (RTO) be set to as follow:
RTO = Rβ, β=2.
From the point of transport layer protocols, a large delay is logically considered to be a link down
We consider that the packet whose RTT is larger than the 2 times of median of RTT is influenced by the buffer1 for the link-down period.
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 16
Model of CDMA2000 1xEV-DO communication environment
Buffer1
Echo CE
Probing CE
Wired Network
CDMA2000 1xEV-DO
ARQ BufferBuffer2
Buffer1
Echo CE
Probing CE
Wired Network
CDMA2000 1xEV-DO
ARQ Buffer
Echo CE
Probing CE
Wired Network
CDMA2000 1xEV-DO
Buffer
ARQ Buffer
ARQ Buffer
Buffer
ARQ Buffer
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 17
Tokyo-Shin Osaka RTT and Packet Loss(No link-down backup function)
in-tunnel RTT packet loss
0
200
400
600
800
1000
0 2000 4000 6000 8000 10000
Elapsed time(s)
RTT
(ms)
packet loss
Tokyo
(365~443)
Shiyokohama (1084~1168)
Nagoya (6135~6250)
Kyoto (8416~8525)
Shiosaka (9322) (0)
Shinagawa
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 18
Cumulative distribution of packet loss length for Tokyo-Shin Osaka
(No link-down backup function)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70
Probability
Packet Loss Length (sec)
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 19
Conclusions and future works
ConclusionsThe route characteristics are introduced in QoS metrics for communication qualities in bullet trains.Traditional two-way ICMP-echo measurement in a specified interval can be used to measure them.A two buffer model-based QoS estimation method is proposed to eliminate the influence by a large buffer in NIC of PC.The raw packet transmission characteristics of CDMA2000 1xEV-DO using the estimation method are gotten.
Future worksThe throughput will be statistically estimated by packet-pair probing. (Preliminary results were got from packets in delay spikes.) Using these parameters, make a model of high speed mobile communication environment on the simulator.
Geneva, 12-13 May 2008
Thank you for your attention!
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 21
3GPP2 Mobile IP
HLR
PDSNa
BSCa PCFa
BS
BSC
BS
PCF
RADIUSa
BSC PCFBS
BSCBS
PCF
PDSNb
RADIUSc
HAc
CNMS Access Provider
Network
Home Access Provider Network
Home IP Network (Private)
IPNetwork
HAb
RADIUSb
MS: Mobile StationRAN: Radio Access NetworkBS: Base StationBTS: Base Transceiver StationBSC: Base Station ControllerPCF: Packet Control FunctionPDSN: Packet Data Serving NodeRADIUS: Remote Authentication Dial-In User ServiceFA: Foreign AgentHA: Home Agent
MSC:Mobile Switching CenterHLR:Home Location Register
cdma2000 RAN
BTS MSCA1SS7 Network
Modified from 3GPP2, “cdma2000 Wireless IP Network Standard: Introduction,” X.S0011-001-D, http://www.3gpp2. org/Public_html/specs/X.S0011-001-D_v1.0_060301.pdf, Feb.2006.
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 22
(a) CDMA2000 1xEV-DO Protocol Reference Model for MIP4 Control and IKE
cdma2000Air Interface
PPP
IP
cdma2000Air Interface
PL
A-9
PL
A-9
PL
A-11
MS BTS,BSC PCF
PL
A-11
PL
L2
PDSN/FA
PPP
IP/IPsec
UDP
MIP4
UDP
MIP4 IKE
PL
L2
HA
IP/IPsec
UDP
MIP4IKE
Modified from 3GPP2, “cdma2000 Wireless IP Network Standard: Introduction,” X.S0011-001-D, http://www.3gpp2. org/Public_html/specs/X.S0011-001-D_v1.0_060301.pdf, Feb.2006.
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 23
(b) CDMA2000 1xEV-DO Protocol Reference Model for MIP4 User Data
PDSN/FA HA
PL
A-10
PPP
PL
L2
MS BTS,BSC PCF
cdma2000Air Interface
PPP
cdma2000Air Interface
PL
A-8
PL
A-8
PL
A-10
IP IP/IPsec
IP
PL
L2
IP IP/IPsec
CN
PL
L2
IP
PL
L2
Modified from 3GPP2, “cdma2000 Wireless IP Network Standard: Introduction,” X.S0011-001-D, http://www.3gpp2. org/Public_html/specs/X.S0011-001-D_v1.0_060301.pdf, Feb.2006.
Geneva, 12-13 May 2008 First ITU-T Kaleidoscope Conference – Innovations in NGN 24
A-8/A-9 and A-10/A-11
(c) BSC-PCF Interface (d) PCF-PDSN Interface
PL
L2
IP
GRE
PPP
PL
L2
IP
GRE
PPP
PL
L2
IP
UDP
Signalings
PL
L2
IP
UDP
Signalings
(c1) A-8 (c2) A-9 (d1) A-10 (d2) A-11