Measuring Online Game Application in GPRS and UMTS

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Measuring Online Game Application in GPRS and UMTS

Author: Anssi Hämäläinen

Supervisor: Professor Raimo Kantola

Instructor: Mikko Mäkinen M.Sc. (Tech.)

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© Ericsson AB 2005 2005-06-022

Contents

Scope definition Research problem and objectives Online game applications and architectures Performance Measurements Results Conclusions Future research


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Scope definition 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 &capabilities

Speech

WCDMA2 Mbps

EDGE/IS-136384 kbps

GPRS115 kbps

HSCSD57.6 kbps

Circuit data< 9.6 kbps

Packet Switched

Circuit Switched

IMT-2000capable systems

1997 1998 1999 2000 2001 2002


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Research problem and objectives

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 online-games: 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)

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

TAreceive packet 2

TBtransmit packet 2

TBreceive packet 1

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

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

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

The estimated RTTs for experiencing a good or acceptable quality from the end-user point of view:


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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

The emulator is a flexible research, development and testing environment, that can be used to emulate fixed and / or wireless network transport

LAPTOP 1

WCDMA EMULATOR

GAME SERVER

LAPTOP 2

1

2 3


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Measurement set-up for real UMTS, EDGE and GPRS networks in a laboratory

LAPTOP 2(TE)

LAPTOP 1(TE)

SGSN GGSNGAME

SERVERBSCBTS

MT

MT

LAPTOP 2(TE)

LAPTOP 1(TE)

NODE B

MT

MT

CORPORATEINTRANET

SGSN GGSN GAME SERVER

RNCCORPORATEINTRANET

Gi

GiUu Iu

UTRAN CN

CNBSS

GbUm

UMTS

GPRS/EDGE

R

R

R

R

1

2

2

R

1

UE

MS


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Measurement tools

Protocol Analyzer – 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 – 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

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

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

The average RTT in UMTS, EDGE and GPRS

0

100

200

300

400

500

600

700

800

900

1000

UMTS EDGE GPRS

RT

T [

ms]


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Packet size

The average packet sizes in UMTS, EDGE and GPRS

0

20

40

60

80

100

120

140

160

180

UMTS EDGE GPRS

Pac

ket

size

[b

yte]

UL

DL


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Packet loss rate

The packet loss rate in UMTS, EDGE and GPRS

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

UMTS EDGE GPRS

Pac

ket

loss

rat

e [%

]

DL

UL


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Conclusions

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 – 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

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

– 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

Measuring Online Game Application in GPRS and UMTS

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