Wireless days presentation_v9

Wireless Days 2012, Dublin Nov 2012
FIRST PERSON SHOOTERS ON THE ROAD:
LEVERAGING ON APS AND VANETS FOR A
QUALITY GAMING EXPERIENCE
Jose Saldana
Communication Technologies Group (GTC)
University of Zaragoza
Gustavo Marfia, Marco Roccetti
Department of Computer Science
University of Bologna

Index
1. Introduction
2. Scenarios of Interest
3. Achievements and Results
4. Conclusions

Introduction
 Mobile devices: Increasingly
important in computer gaming
 Allow playing on the move
 Players like to defeat other real
players (better than the machine)

Introduction
 Wireless connections everywhere
 Mobile devices include wireless
network interfaces
 Why not using these wireless
connections for playing online
interactive games?

Introduction
 Online game categories (videos)
 FPS: First Person Shooters
 MMORPG
 RTS: Real Time Strategy
 Sports: Racing, soccer

Introduction
 Mobile devices are also becoming popular in
vehicular scenarios
 Cars equipped with 802.11 devices
 Vehicle-to-infrastructure (V2I)
 Vehicle-to-vehicle (V2V)
 Here: support real-time streams in cars

Introduction
 Scenario considered: a person playing inside a
car (clearly not while driving)
 Interactive online game
 Against other players
 So we need to grant QoS

Scenarios of Interest
 802.11 APs are being used
in some cities as a means
for connecting to the
Internet
 3G/4G: High delay and
cost for the user
 Many open APs, and
apps for finding them

 Example: 462 APs in Zaragoza, Spain

Introduction
 Two problems:
 How to satisfy the real-time requirements
of a game
 How wireless infrastructures can provide
connectivity to vehicles

Introduction
 Contributions:
 1.- Feasibility of 802.11 for the provision of
online games in moving cars
We will use a FPS game as an example of
an application with a really critical delay

Introduction
 Contributions:
 2.- Use of V2V connections for enlarging
the AP coverage area

 A single street with an AP partially covering it
 2 km long
 The AP connects with the Internet, where
the game server, and other players are.

 FPS game traffic. Real traces of Quake IV
 Two UDP flows:
 Uplink: 64 pps. Avg. 79 bytes (40.5 kbps)
 Downlink: 14 pps. Avg. 161 bytes (18 kbps)
Uplink histograms
40 50 60 70 80 90 100 110
bytes
0 10 20 30 40 50 60 70
ms

 Translated into an ns2 scenario:
Wired network
Ad-hoc wireless
network
FPS downlink
application
FPS uplink
application
... ...
Speed according to
movement traces
AP
FN

Mean Opinion Score calculation:
 G-Model MOS formula:
x = 0.104 • ping_average + jitter_average
MOS = - 0.00000587 x3 + 0.00139 x2 - 0.114 x + 4.37
 Packet loss is not considered, unless above 35%
 Acceptable quality when MOS>3

Achievements and Results
1) Can we obtain a good MOS in this scenario?
2) Can we extend coverage keeping good MOS?
V2V
3) What if we make it even more realistic?
Real movement traces
4) Negative effect of TCP background traffic

 A single car, 50 km/h
 Only communicating with the AP

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
AP Coverage area 750-1250

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
Good quality
while under AP
coverage

 300 cars, 50 km/h. 1 second between cars
 car #150 runs the game. Ad hoc connections

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
AP Coverage area 750-1250 m
Handoff
V2V extended coverage area with acceptable MOS: 292-1736m

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
Handoff
Good quality
zone extended.
500 to 1,444 m.
288%

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
Handoff
Connection
from the
beginning (bad
quality, though)

0
10
20
30
40
50
60
70
80
90
0 200 400 600 800 1000 1200 1400 1600 1800 2000
ms
street meters
Jitter (Round Trip Time stdev) (ms)
Jitter peaks
cause bad
quality here

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
Handoff
A sort of
“handoff” when
getting out of
coverage

0
50
100
150
200
250
300
350
0 200 400 600 800 1000 1200 1400 1600 1800 2000
ms
street meters
Round Trip Time (ms)
Delay peak
when going out
of coverage
area

0
50
100
150
200
250
300
350
0 200 400 600 800 1000 1200 1400 1600 1800 2000
ms
street meters
Round Trip Time (ms)
Ad-hoc routing
protocol has to
find a new
route. Packets
have to wait

0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Loss%
street meters
Packet loss percentage
Ad-hoc routing
protocol has to
find a new
route. Some
lost packets

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
Handoff
Bad quality in
the end of the
street

0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Loss%
street meters
Packet loss percentage
lost packets in
the end of the
street

 111 different movement traces obtained in
Via Benedetto Croce, Pisa, Italy
 Divided into 5 groups, according to speed
0
25
50
75
100
125
150
175
200
225
250
275
300
325
350
375
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Streetmeters
seconds
Real movement trace #6
0
25
50
75
100
125
150
175
200
225
250
275
300
325
350
375
0 10 20 30 40 50 60 70
Streetmeters
seconds
Real movement trace #79

0
50
100
150
200
250
300
350
400
8.4 km/h 10.9 km/h 14.5 km/h 21.2 km/h 29.18 km/h
seconds
Average speed of the cars
Contact time: Average time with MOS > 3
V2V communications off
V2V communications on

0
50
100
150
200
250
300
350
400
seconds
Contact time gets
reduced with speed

0
50
100
150
200
250
300
350
400
seconds
Significant increase
with V2V

 Car #150 runs the game
 Car #151 is downloading a file using FTP

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)

1
1.5
2
2.5
3
3.5
4
4.5
5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
MOS
street meters
MOS (G-Model)
Quality is lost

0
50
100
150
200
250
0 200 400 600 800 1000 1200 1400 1600 1800 2000
ms
street meters
Jitter (Round Trip Time stdev) (ms)
Very high jitter

0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
0 200 400 600 800 1000 1200 1400 1600 1800 2000
kbps
street meters
FTP throughput
FTP is always
trying to get
more bandwidth

0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
0 200 400 600 800 1000 1200 1400 1600 1800 2000
kbps
street meters
FTP throughput
Mechanisms to
limit TCP
bandwidth
would be
necessary

Conclusions
 We have studied the feasibility of using 802.11
networks for providing connectivity to FPSs
 It has been shown that they are able to provide
a good quality
 V2V has been used to extend the coverage area
 Background traffic can seriously damage game
quality
 Future work:
 A number of cars running the game
 An agent offering different game experiences according to network status

Thank you very much!

Wireless days presentation_v9

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