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Performance Evaluation of Mobile Devices
in LTE (Long Term Evolution) during handover
ENSC 833 NETWORK PROTOCOLS AND PERFORMANCE
APRIL 11, 2016 TEAM #2
James Guerra
Shams Narsinh
1
Outline
• Introduction
• Background and Overview of LTE
• Modeler Model and Test beds
• Simulation Results:• Handover Delay• EPS Bearer Throughput, EPS Bearer Delay
• Results and Conclusion
• Future Work
• References2
Introduction
LTE
• Low-cost, extremely fast, efficient, and intelligent communication network
• Communication so far was about people talking to people, now Internet of Things!
• Switchover to LTE from 3G is as simple as remote software upgrade
GOAL
The goal of the project is to evaluate the performance of mobile devices (UE’s) during handover given different traffic types (QoS); type of handover based on interface and mobility of the UE at the downlink of LTE-Uu inteface. The observed parameters are handover delay, EPS bearer throughput, EPS bearer delay and other throughput related parameters for VoLTE, Video Conferencing, and HTTP Web TV.
3
Background
• L. Zhang, T. Okamawari, T. Fujii, "Performance evaluation of TCP and UDP during LTE handover"
o performance evaluation for intra-frequency handover for TCP and UDP while varying A3-mechanism related handover parameters was done
• D. Han, S. Shin, H. Cho, J. m. Chung, D. Ok and I. Hwang, "Measurement and stochastic modeling of handover delay and interruption time of smartphone real-time applications on LTE networks"
o stochastic modelling using real devices (smartphones) where handover interruption time was further broken down in every step
• S. Trabelsi, A. Belghith and F. Zarai, "Performance evaluation of a decoupled-level Qos-aware downlink scheduling algorithm for LTE networks"
o QoS-aware and Channel aware downlink scheduling algorithms were evaluated but performance was not evaluated in terms of handover
• H. S. Park and Y. S. Choi, "Taking Advantage of Multiple Handover Preparations to Improve Handover Performance in LTE Networks"
o a “handover preparation” algorithm was proposed where multiple handover messages are sent to the UE for faster handover sequence
4
LTE Architecture
UE : User Equipment MME : Mobility Management Entity
HSS : Home Subscriber Server PCRF : Policy and Charging Rules Function
S – GW : Serving Gateway P-GW : Packet Gateway 5
LTE Overview
User plane protocol
• Modeler 18.5 encapsulates the IP datagram for the LTE network
• Modeler 18.5 has a UE, eNodeB and EPC (MME, S-GW, P-GW) node models
• Modeler 18.5 supports X2 and S1 handover and handover failures
• Modeler 18.5 supports GBR and Non-GBR bearers
• Given the huge scope of the topic and complexity of the model we focused on downlink aspect of the radio interface (LTE-Uu)
L1MAC
RLC
PDCP
IP
APP
L1
MAC
RLC
L1
L2
UDP
Relay
L1
L2
UDP UDP
L2
L1
Relay
PDCP GTP GTP GTP
L1
L2
UE eNodeB P-GWS-GW
UDP
GTP
IP
EPS bearer
IP UDP GTP IP TCP/UDP Payload
ARQ
[1]
LTE - Uu S1 S5/S8
6
LTE Handover
• Handover can be broken down into 3 sections : Handover Preparation, Handover execution, Handover completion
• We used A3 event as our handover triggering with A3-offset 2dB, triggering at -90dB mechanism focusing on intra-frequency handover
• Modeler 18.5 has a 50% weighted trigger for RSRP and RSRQ
• Graphs below shows RSRP A3 offset triggering, message coding scheme change during handover, X2 interface bits forwarded
[7] D. Han, S. Shin, H. Cho, J. m. Chung, D. Ok and I. Hwang, "Measurement and stochastic modeling of handover delay and interruption time of smartphone real-time applications on LTE networks," in IEEE Communications Magazine, vol. 53, no. 3, pp. 173-181, March 2015.
7
Simulation Parameters
Traffic Bearer Description
Voice 2 (Gold) PCM Quality Speech 16KB/s (G.711) [4],[5]
Video Conferencing 3 (Silver) Live streaming packet, CBR traffic: packet arrival 20ms (50 packets/s) target bit rate 312 kb/s; DSCP = AF41 [5]
HTTP 6 (Bronze) HTTP web TV; Best effort ToS(0); RLC acknowledge mode
Physical Layer Parameters
Value
Channel BW 20MHz
UL antenna UL SC-FDMA
DL antenna DL OFDMA
Pathloss Free space
Scheduling Link adaptation and channel dependent scheduling
Simulation Parameters
Values
Speed of UE 30, 60, 120
Size of Cell 3-cell, 7-cell, 19-cell
Background traffic
Video, Voice, HTTP
Interfaces S1, X28
Simulation #1
• Two scenarios are considered for evaluating the performance of handover:
1) 10 handovers of each application with different speeds
2) 30 minutes of simulation for VoLTEwith different speeds on all three topologies
9
Handover Delay Data
Scenario -1 Scenario - 2 10
0.0
19
4
0.0
17
3 0.0
23
1
0.0
22
9
0.0
16
8
0.0
19
4
0.0
26
9
0.0
19 0.0
22
7
0.0
19
2
0.0
18
1
0.0
17
0.0
23
2
0.0
19
1
0.0
22
9
0.0
17
0.0
16
5
0.0
16
1 2 0 6 0 3 0 1 2 0 6 0 3 0 1 2 0 6 0 3 0 1 2 0 6 0 3 0 1 2 0 6 0 3 0 1 2 0 6 0 3 0
S 1 X 2 S 1 X 2 S 1 X 2
V O I C E V I D E O H T T P W E B T V
HA
ND
OV
ER D
ELA
Y (S
EC)
SPEED (KM/H)
HANDOVER DELAY WITH 10 HANDOVERS FOR EACH FEATURE
0
0.2
0.4
0.6
0.8
1
1.2
1.4
120 60 30 3 120 60 30 3 120 60 30 3 120 60 30 3 120 60 30 3 120 60 30 3
3cell 7cell 19cell 3cell 7cell 19cell
S1 X2
Han
do
ver
De
lay
(se
c)
Speed (km/h)
Handover Delay with 30 minutes Time Frame
Simulation #2
Statistics to useEPS Bearer Throughput (bits/s), EPS bearer delay (sec), Other metrics e.g. Traffic received (bytes/s) by the UE
EPS Bearer Throughput %
When output < input, then there are retransmissions
% retransmission = ( output – input ) / output
When input > output , then there is a loss
% loss = (output / input) – 1
Sample Size10 runs per point by varying start time for the application profile
Time coverage80% of handover occurs in 304-304.25 sec for speed 30km/hr
11
EPS Bearer Throughput DataDAR – Delay and Retransmitted
12
-100.00%-80.00%-60.00%-40.00%-20.00%
0.00%20.00%40.00%60.00%80.00%
100.00%
302.5 303 303.5 304 304.5 305 305.5DA
R b
its
and
Lo
sses
%
Time (sec)
Video with No Background Traffic
Video EPS bearer througput S1 interface
Video EPS bearer througput X2 interface
-100.00%-80.00%-60.00%-40.00%-20.00%
0.00%20.00%40.00%60.00%80.00%
100.00%
302.5 303 303.5 304 304.5 305 305.5
DA
R b
its
and
Lo
sses
Time (sec)
Video with Background Voice Traffic
Video EPS bearer througput S1 interface
Video EPS bearer througput X2 interface
-100.00%-80.00%-60.00%-40.00%-20.00%
0.00%20.00%40.00%60.00%80.00%
100.00%
302.5 303 303.5 304 304.5 305 305.5
DA
R b
its
and
Lo
sses
%
Time (sec)
Video with Background Video Traffic
Video EPS bearer througput S1 interface
Video EPS bearer througput X2 interface
-100.00%-80.00%-60.00%-40.00%-20.00%
0.00%20.00%40.00%60.00%80.00%
100.00%
302.5 303 303.5 304 304.5 305 305.5
DA
R b
its
and
Lo
sses
%
Time (sec)
Video with Background HTTP Traffic
Video EPS bearer througput S1 interface
Video EPS bearer througput X2 interface
EPS Bearer Delay
13
00.005
0.010.015
0.020.025
0.030.035
0.040.045
0.05
302.5 303 303.5 304 304.5 305 305.5
EPS
Bea
rer
Del
ay (
sec)
Time (sec)
Video with No Background Traffic
Video EPS bearer delay S1 interface Video EPS bearer delay X2 interface
00.005
0.010.015
0.020.025
0.030.035
0.040.045
0.05
302.5 303 303.5 304 304.5 305 305.5
EPS
Bea
rer
Del
ay (
sec)
Time (sec)
Video with Background Video Traffic
Video EPS berer delay S1 interface Video EPS bearer delay X2 interface
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
302.5 303 303.5 304 304.5 305 305.5
EPS
Bea
rer
Dle
ay (
sec)
Time (sec)
Video with Background Voice Traffic
Video EPS berer delay S1 interface Video EPS bearer delay X2 interface
00.005
0.010.015
0.020.025
0.030.035
0.040.045
0.05
302.5 303 303.5 304 304.5 305 305.5
EPS
Bea
rer
Del
ay (
sec)
Time (sec)
Video with Background HTTP Traffic
Video EPS berer delay S1 interface Video EPS bearer delay X2 interface
Other Metrics
14
0
5000
10000
15000
302.5 303 303.5 304 304.5 305 305.5
TRA
FFIC
REC
EIV
ED (
BYT
ES/S
)
TIME (SEC)
Voice with Background HTTP
Voice traffic received S1 interface
Voice traffic receivedt X2 interface
0
20000
40000
60000
80000
100000
120000
140000
302.5 303 303.5 304 304.5 305 305.5
Traf
fic
Rec
eive
d (
byt
es/s
ec)
Time (sec)
Video with Background Voice Traffic
Video traffic received S1 interface Video traffic received X2 interface
Results and Conclusions
• Overall performance with X2 interface is better than with S1 interface in terms of throughput and handover delay
• Increasing the number of eNBs with one evolved packet core increases the interference with neighbour eNBs resulting in higher handover delay
• EPS bearer delay is more dependent on the scheduling and background traffic load during the handover than the type of interface the handover happens
• Background traffic affect the same type of traffic that is involved during handover the most
• HTTP traffic is bursty that the results must be approached with caution or with better stochastic analysis method
15
Future Work
• There is no definite point for knowing where the packet loss and retransmission occurred during the handover so we are only estimating based on the “Handover delay” location. Identifying the delay and retransmitted bits/packets would result in better analysis.
• Expand the analysis to use an increasing background traffic on a higher cell count scenario, e.g. 19-cell
• The statistics could be presented in some other form and stochastically analyzed plus more samples can be taken
16
References[1] S. Sesia and I. Toufik, LTE - The UMTS Long Term Evolution, 2nd ed. West Sussex, United Kingdom: Wiley, 2011
[2] L. Zhang, T. Okamawari, T. Fujii, "Performance evaluation of TCP and UDP during LTE handover," in Proc. 2012 IEEE Wireless Communications And Networking Conference, Shanghai, China, April 2012, pp. 1993-1997.
[3] A. Vizzarri, "Analysis of VoLTE end-to-end Quality of Service using OPNET," in Proc. 2014 UKSim-AMSS 8th European Modelling Symposium, Pisa, Italy, Oct. 2014, pp. 452-457.
[4] H. S. Park and Y. S. Choi, "Taking Advantage of Multiple Handover Preparations to Improve Handover Performance in LTE Networks," 2014 8th International Conference on Future Generation Communication and Networking, Haikou, 2014, pp. 9-12.
[5] S. Trabelsi, A. Belghith and F. Zarai, "Performance evaluation of a decoupled-level Qos-aware downlink scheduling algorithm for LTE networks," in Proc. 2015 IEEE International Conference on Data Science and Data Intensive Systems, Sydney, Australia, Dec. 2015, pp. 696-704
[6] F. Amirkhan, O. Arafat and M.A. Gregory, “Reduced packet loss vertical handover between LTE and mobile WiMAX,” in Proc. 2014 2014 International Conference on Electrical, Electronics and System Engineering, Kuala Lumpur, Malaysia, Dec. 2014, pp. 24-59
[7] D. Han, S. Shin, H. Cho, J. m. Chung, D. Ok and I. Hwang, "Measurement and stochastic modeling of handover delay and interruption time of smartphone real-time applications on LTE networks," in IEEE Communications Magazine, vol. 53, no. 3, pp. 173-181, March 2015.
[8] Modeler Documentation Set, 18.5, Riverbed Technology, San Francisco, CA, 2015, Chapter 12.
17