Measuring Online Game Application
in GPRS and UMTS
Author: Anssi Hämäläinen
Supervisor: Professor Raimo Kantola
Instructor: Mikko Mäkinen M.Sc. (Tech.)
Contents
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Scope definition
Research problem and objectives
Online game applications and architectures
Performance
Measurements
Results
Conclusions
Future research
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Scope definition
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The scope is limited to existing mobile networks (GPRS, EDGE
and UMTS) in a controlled laboratory environment and the
measurements are done by using one selected real-time online
game application.
GPRS (General Packet Radio Service)
EDGE (Enhanced Data Rates for Global Evolution)
UMTS (Universal Mobile Telecommunications Systems)
UMTS uses WCDMA (Wideband Code Division Multiple Access)
radio access
Functionality &
IMT-2000
capable systems
capabilities
WCDMA
2 Mbps
EDGE/IS-136
384 kbps
GPRS
115 kbps
Packet Switched
HSCSD
57.6 kbps
Circuit Switched
Circuit data
< 9.6 kbps
Speech
1997
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1999
2000
2001
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Research problem and objectives
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The Research problem is to investigate the possibilities to use
mobile networks for online gaming and especially for real-time
gaming
The goal of this thesis is to study how the online game
applications work in the 2G and the 3G mobile communication
systems
The main objective of this thesis is to measure the online game
performance over the mobile networks
The second objective of this thesis is to evaluate the online game
application latency derived from each of the mobile networks and
to compare them with each other
The target of this research is to find out the potential of the mobile
networks for real-time gaming
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Online game applications
 Real-time action games
– usually contain virtual people moving in a real–time virtual
environment
– have real-time requirements, meaning that a certain delay
and bit rate need to be guaranteed by the network in order
to provide an acceptable end-user quality
 Real-time strategy games
– although this type of game has an interactive nature,
normally higher delays can be accepted than in action
games
 Turn-based games
– have the loosest delay requirements, allowing even several
seconds between any interactions between players
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Online game architectures
 Game server in network
– In this architecture one node acts as the game server
– This architecture avoids the game state inconsistencies of
peer-to-peer architecture by limiting game control to one
server node
– The players receive all necessary state information over the
network from the server
 Peer-to-peer gaming
– The traditional approach and does not use a game server
– Player actions are broadcasted over the network to all the
other players in the game
– This approach requires a very reliable communication link,
because any lost or corrupted data can easily lead to
inconsistencies between the perceived game states of
individual players
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Performance
 There are three main factors that cause lag in onlinegames: high network latency, packet loss, and
insufficient bandwidth
 Latency
– The latency of a connection is the time it takes for a packet
to travel from the source to the destination host
 Packet loss
– Packet loss occurs when the network is congested
 Bandwidth
– Bandwidth is the amount of information that can be
transmitted over a connection in a given amount of time
– Bandwidth is the limiting factor in mobile networks (GPRS)
– Bandwidth requirements tend to increase with the number
of players participating in a game
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Round trip time (RTT)
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RTT is an essential feature for online game applications and
affects the gaming performance
RTT was measured by using a protocol analyzer
RTT is possible to be calculated from the packets’ sending time
and receiving time
A
B
TAtransmit packet 1
TBreceive packet 1
TBtransmit packet 2
TAreceive packet 2
RTTAB = TAreceive packet 2 – TAtransmit packet 1 – (TBtransmit packet 2 – TBreceive packet 1)
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Acceptable quality from the end-user point of view
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The RTTs will be estimated and compared with different
thresholds, that define the maximum delays for experiencing a
good or acceptable quality from the end-user point of view
The estimated RTTs for experiencing a good or
acceptable quality from the end-user point of view:
© Ericsson AB 2005
Action game good
RTT < 200 ms
Action game acceptable
200 ms < RTT < 600 ms
Real-time strategy good
600 ms < RTT < 900 ms
Only turn-based games
RTT > 900 ms
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Measurements
 In the measurements the main objective was to find out
the differences in the RTT in the UMTS, EDGE and
GPRS networks
 Another objective was to measure the performance
over the UMTS emulator and to find out the one-way
transfer delay for uplink and downlink directions.
 The connection time to the game server was also
measured in the emulated UMTS.
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Measurement set-up for emulated UMTS Network
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The emulator is a flexible research, development and testing
environment, that can be used to emulate fixed and / or wireless
network transport
1
2
3
LAPTOP 1
WCDMA
EMULATOR
GAME
SERVER
LAPTOP 2
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Measurement set-up for real UMTS, EDGE and GPRS
networks in a laboratory
UMTS
R
LAPTOP 1
(TE)
MT
Uu
1
Iu
NODE B
RNC
Gi
SGSN
CORPORATE
INTRANET
GGSN
R
LAPTOP 2
(TE)
UTRAN
MT
2
GAME
SERVER
CN
UE
GPRS/EDGE
R
LAPTOP 1
(TE)
MT
1
Um
Gb
BTS
BSC
Gi
SGSN
GGSN
R
LAPTOP 2
(TE)
MT
BSS
2
CORPORATE
INTRANET
GAME
SERVER
CN
MS
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Measurement tools
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Protocol Analyzer
–
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The protocol analyzer is a program or a device, which can capture
traffic over a given interface and usually can decode it to be
readable by people
In this research a protocol analyzer is used to capture traffic
timestamps from which the end-to-end delays and all the needed
results can be calculated
Automation Language
–
–
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In this research an automation language is used to help to
measure the connection time to the server
Automation language is useful for repetitive measurements
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Measurement application
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Application: A Real-Time Action Game
There is a wide range of real-time online action games on the
market and one of them was selected for the measurements
The selected application is a very popular first person shooter
(FPS) game, because it is a freeware product and designed for
network environment
This real-time action game is an online game application for
multiple players
The minimum requirements for the network game are a modem or
a better Internet connection or a LAN network
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Results in real networks
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The RTTs were measured over all the three mobile networks in a
laboratory environment
The average RTTs were 150,0 ms in UMTS, 696,7 ms in EDGE
and 896,6 ms in GPRS
The average RTT in GPRS is about six times higher than in UMTS
The average RTT in UMTS is good enough for online game
applications and real-time action games
The EDGE and GPRS networks are more suitable for applications
which do not have critical delay requirements
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Average RTT
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The average RTT in UMTS, EDGE and GPRS
1000
900
800
RTT [ms]
700
600
500
400
300
200
100
0
UMTS
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EDGE
GPRS
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Packet size
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The average packet sizes in UMTS, EDGE and GPRS
180
160
140
Packet size [byte]
120
100
UL
DL
80
60
40
20
0
UMTS
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EDGE
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GPRS
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Packet loss rate
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The packet loss rate in UMTS, EDGE and GPRS
0,9
0,8
0,7
Packet loss rate [%]
0,6
0,5
DL
UL
0,4
0,3
0,2
0,1
0
UMTS
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EDGE
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GPRS
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Conclusions
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In this thesis the online game performance over the mobile
networks was measured
The measurements were done with real networks and an emulator
According to the measurement results the RTT delay performance
is good for real-time online action games only in UMTS
In EDGE and GPRS the RTT delay performance is too low for
real-time action games
The needed throughput in the uplink direction is too high to be
transferred over GPRS
–
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For that reason, the packet loss rate rises too high in the uplink
direction and playing is impossible
The online game performance between the different network
technologies depends on the specifications (3GPP), and
especially on the radio interface specifications
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Conclusions
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There are lower data rate capabilities in GPRS and EDGE than in
UMTS
The frame length in UMTS is different from GPRS and EDGE
frame length and affects the performance
The performance values are also dependent on the network
configurations
Mobile networks are designed to provide higher data speed in the
downlink direction than in the uplink direction
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–
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According to the measurement results, when two clients are
playing, more bandwidth is needed in the uplink direction than in
the downlink direction
This feature is not a problem for UMTS or EDGE performance, but
it would affect GPRS performance results
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Future research
 A study of the online game application in wireless
packet networks with more than only two players
 Another interesting research objective could be the
high-speed downlink packet access (HSDPA)
 HSDPA technology will reduce the delay and the online
game performance should be improved
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