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A MULTIMEDIA DELIVERY SYSTEM
FOR DELAY-/DISRUPTION-TOLERANT
NETWORKS
Christian Raffelsberger
Hermann Hellwagner
Multimedia Communications Group
Institute of Information Technology
Klagenfurt University
Austria
bridgeproject.eu
This research was funded by the European Union Seventh Framework Programme (FP7/2007-2013) under grant
agreement no. 261817, the BRIDGE project, and was partly performed in the Lakeside Labs research cluster at AAU.
MOTIVATION
 First responders may be equipped with mobile
devices, capable of recording and transmitting
multimedia data
 Multimedia data may help to increase situation
awareness and to create a common operational
picture
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CHALLENGES
 Internet-connectivity may be hampered
 Local wireless networks may be disrupted
 Current multimedia delivery protocols and
systems do not work in DTNs
 assume the existence of end-to-end paths
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EXAMPLE USE CASE
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MULTIMEDIA USAGE IN EMERGENCY
RESPONSE
 Results from real world studies
 mobile video is beneficial for emergency response
 different usage patterns
•
•
•
•
live use
near live use
scheduled use
post incident use
delay-tolerant usage
 first responders prefer short video sequences
(<1 min)
- Landgren J. and Bergstrand F., “Mobile Live Video in Emergency Response: Its Use and Consequences, 2010.
- Bergstrand F. and Landgren J., “Information Sharing Using Live Video in Emergency Response Work”. 2009.
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MULTIMEDIA DELIVERY
 Alternatives
 Realtime Transport Protocol (RTP)
 HTTP Adaptive Streaming (HAS)
• e.g. MPEG-DASH, Microsoft Smooth Streaming
 Assessed applicability in DTN scenarios
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REALTIME TRANSPORT PROTOCOL
 Traditionally used for multimedia delivery
 Not well-suited for DTNs
 complex session setup/maintenance (RTSP, RTCP)
 sending bit rate aligned to media bit rate
 packetization (decoding dependencies)
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HTTP ADAPTIVE STREAMING
Server
Client
high bit rate
segment
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HTTP
HTTP client
low bit rate
representation
HTTP server
manifest
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manifest
parser
demuxer/
decoder
adapatation
logic
player
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MULTIMEDIA DELIVERY IN DTNS
 HAS advantages over RTP
 content segmented into self-contained chunks
 less complex session setup and control
 better bandwidth utilization
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HTTP ADAPTIVE STREAMING
 HAS well-suited for DTNs
 Open issue: transport via HTTP in disrupted
networks requires to break up end-to-end TCP
connection
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HTTP-DTN
 Extension of HTTP to support communication in
disrupted networks
 GET/PUT requests to transfer data
 Changes end-to-end semantics of HTTP
 hop-by-hop transfer between HTTP-DTN nodes
 files and requests are buffered
 additional Content-* headers used for store-carryforward routing requests and files (e.g., ContentSource, Content-Destination)
Wood L. and Holliday P., „Using HTTP for Delivery in Delay/Disruption-tolerant Networks“, Internet Draft draft-wood-dtnrg-httpdtn-delivery-09, Jun. 2014.
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SYSTEM ARCHITECTURE
Content-Source:
Content-Destination:
HTTP transfer
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HTTP transfer
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EVALUATION
 Explosion in a chemical facility
 first responder record videos and send them to
incident commander
 Evaluate how multimedia delivery performs
using different routing protocols
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DISASTER SCENARIO
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PROTOCOLS
 Epidemic
 forwards packets to all nodes (flooding)
 Prophet
 forwards packets to nodes offering a higher delivery
probability (based on history of encounters)
 Spray and Wait (SaW)
 distributes a limited number of copies in the network
 MANET-SaF
 packet buffering on top of MANET routing
 Combined MANET/DTN Routing (CoMANDR)
 packet buffering and selection of custodian nodes based
on MANET routing tables
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SIMULATION SETUP
 Videos recorded by 3 sources, send to 1
consumer
 two representations with different bit rates
 all segments pushed to consumer
 Important simulation parameters




transmission bandwidth 2Mbps
2 representations with 0.5 and 2.5 Mbps
video duration: 15-60s; interval 120-360s
unlimited buffers with FIFO forwarding strategy
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RESULTS
 Metrics
 video delivery ratio: ratio of videos for which all
segments have been delivered (in any represenation)
 delivery delay: time until segments have been
received
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DELIVERED VIDEOS, VARYING RANGE
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IMPROVED FORWARDING STRATEGY
 Multimedia-aware forwarding instead of FIFO to
make better use of available resources
 Forwarding priority
1. manifest files
2. segments from lower representations
3. segments with older recording time stamps
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VIDEO DELIVERY: MM-AWARE
FORWARDING
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DELIVERY DELAY
MM-aware forwarding, 60m transmission range
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DISCUSSION
 Video delivery is delay-tolerant in emergency
response scenarios
 Presented multimedia delivery system that can
operate in DTNs
 Evaluated different routing protocols
 hybrid MANET/DTN protocols performed best
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FUTURE WORK
 Implementation and real-world tests
 Investigate streaming use-case
 adaptation techniques that work well in DTNs
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THANK YOU FOR YOUR ATTENTION!
QUESTIONS?
bridgeproject.eu
DISASTER SCENARIO
 Mobility model [1]
 „separation of room“ between first responder teams
 shortest path between sub-areas, random
movements within sub-areas
 Obstacle model [2]
 attenuation applied to signal if obstacle in line-of-sight
path 𝐿𝑂𝑏𝑠 𝑑𝐵 = 𝛽 ∙ 𝑛 + 𝛾 ∙ 𝑑𝑚
 Connectivity characteristics
 well-connected network that gets partitioned regularly
[1] Aschenbruck, N.; Gerhards-Padilla, E.; Gerharz, M.; Frank, M. & Martini, P.: Modelling Mobility in Disaster Area Scenarios Proc. 10th ACM Symp. on Modeling,
Analysis, and Simulation of Wireless and Mobile Systems, ACM, 2007, 4-12 .
[2] Sommer, C.; Eckhoff, D.; German, R. & Dressler, F.: A Computationally Inexpensive Empirical Model of IEEE 802.11p Radio Shadowing in Urban Environments
Proc. 8th Int. Conf. on Wireless On-Demand Network Systems and Services), 2011, 84-90 .
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CONNECTIVITY CHARACTERISTICS
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DELIVERED VIDEOS, VARYING SEG LEN
MM-aware forwarding, 40m transmission range
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DELIVERED VIDEOS, VARYING SEG LEN
FIFO forwarding, 40m transmission range
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HTTP-DTN
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HTTP-DTN NODE ARCHITECTURE
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HTTP-DTN PUT EXAMPLE
PUT content HTTP/1.1
Content-Source: node1
Content-Destination node3
Host:node2
...
PUT content HTTP/1.1
Content-Source: node1
Content-Destination node3
Host:node3
...
Christian Raffelsberger
node 1 <--> node 2
HTTP/1.1 200 OK
...
node 2 <--> node 3
HTTP/1.1 200 OK
...
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MULTIMEDIA DELIVERY PROTOCOLS:
SESSION SETUP
1xRTT
4xRTT for session setup
DASH
RTP
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BEACON PACKET FORMAT
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