(slides) video ads dissemination through wifi-cellular hybrid networks
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Video Ads Dissemination throughWiFi-Cellular Hybrid Network (revised)
Hiroshi Hanano1, Yoshihiro Murata2, Naoki Shibata3,Keiichi Yasumoto1 and Minoru Ito1
1Nara Institute of Science and Technology2Hiroshima City University
3Shiga University
Organization
1. Background
2. Related Work
3. Problem Formulation
4. Proposed Algorithm
5. Evaluation through Simulations
6. Conclusion
2Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Demand for Context-Aware Video Ad Dissemination
• Video delivery to mobile terminals has already become common – Video advertisement dissemination now attracting public attention
• Many studies for obtaining user contexts (situation, etc)with sensors, user data (profiles, schedules, etc), and so on
• Context-aware video ad dissemination – Much higher advertisement effect than without context-
awareness
3
Movie trailers
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Challenges
• Contexts are different among users, change over time– Each video ad should be delivered to users at different
time
4
→ larger data amount transferred via cellular network→ need to consider influence to other cellular services→ number of ads may be restricted
We need a dissemination method whichdoes not overload cellular network
We need a dissemination method whichdoes not overload cellular network
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Goals
• Distribute communication load for video ad dissemination from cellular network to WiFi network as much as possible
5
CellularNetwork
load
WiFi(Ad-hoc)
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Organization
1. Background
2. Related Work
3. Problem Formulation
4. Proposed Algorithm
5. Evaluation through Simulations
6. Conclusion
6Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Complementing Cellular Network with MANET
– Some mobile terminals in congested cell area use light loaded cell via MANET
7
Hongyi, W., Chunming, Q., Swades, D. and Ozan, T.:”Integrated Cellular and Ad Hoc Relaying Systems:iCAR,”Proc. of ICC 2001
Hongyi, W., Chunming, Q., Swades, D. and Ozan, T.:”Integrated Cellular and Ad Hoc Relaying Systems:iCAR,”Proc. of ICC 2001
It does not reduce overall data amount transferred for video ads disseminationIt does not reduce overall data amount transferred for video ads dissemination
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Introducing BitTorrent into MANET
• Purpose: efficient file exchange among mobile terminals– Realized BitTorrent mechanism on MANET– Evaluation done in terms of mobility and chunk sizes– Show robustness against network partition
8
S. Rajagopalan. and C.-C. Shen:”A Crosslayer Decentralized BitTorrent for Mobile Ad hoc Networks,”Proc. of MOBIQUITOUS 2006
S. Rajagopalan. and C.-C. Shen:”A Crosslayer Decentralized BitTorrent for Mobile Ad hoc Networks,”Proc. of MOBIQUITOUS 2006
It only uses MANET, and thus achievespoor performance on data acquisition ratio/time
It only uses MANET, and thus achievespoor performance on data acquisition ratio/time
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Organization
1. Background
2. Related Work
3. Problem Formulation
4. Proposed Algorithm
5. Evaluation through Simulations
6. Conclusion
9Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Assumptions
• Many users with mobile phones in urban area– Phones can use both cellular and Wi-Fi (ad-hoc mode) networks
• Terminal automatically sets, according to user’s context:– Video ad contents (by file names)– Reception Deadline for each content
10
ex) Context: Bob has a plan to go to a movie after workContents: Trailers of movies currently runningDeadline: Time when work finishes
ex) Context: Bob has a plan to go to a movie after workContents: Trailers of movies currently runningDeadline: Time when work finishes
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Target Problem (see PerCom09 paper for more formal description)
• Input– Video ads with deadlines requested by each mobile node
• Output– Actions of mobile nodes at each moment
• Download, Broadcast, or Receive (part of) data
• Constraints– Cellular tower capacity (N connections can be admitted)– Cellular network bandwidth per connection– Wi-Fi radio range of each mobile node– Wi-Fi bandwidth shared by all nodes in each radio range– Reception deadline of each content
• Objective function– Minimize data amount transferred through cellular
network11Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Organization
1. Background
2. Related Work
3. Problem Formulation
4. Proposed Algorithm
5. Evaluation through Simulations
6. Conclusion
12Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Approach
• File division (like BitTorrent)– Divide each ad content into chunks with fixed data size– Every node can contribute ad dissemination in fair
manner
• Utilization of WiFi (ad-hoc mode)– Reduce load in cellular network by letting nodes exchange chunks through Wi-Fi network
• Fully distributed algorithm– Each terminal decides its action based only on
information of neighbor nodes – Scalable to number of nodes, number of contents, etc
13Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Possible Actions Taken by Mobile Terminal
• Download a chunk through cellular network
• Broadcast a chunk through WiFi (ad-hoc mode) network
• Wait to receive a chunk through WiFi network
14Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Algorithm for Action Decision
• Each node takes an action for global benefit– For each chunk, only one terminal should download it– In each radio range, we should avoid two or more
terminals broadcasting the same chunk
• Flow of proposed algorithm
15
Info Gathering Part
Gather neighboring info
Action Decision Part
Select a chunk
Take an action
Categorize chunks/compute impact of chunks
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Information Gathering Part
• Information required to decide action– Demand Info. : which contents each node requires– Chunk Info. : which chunks each node retains
• Create Neighbor Table by exchanging hello messages– Each node periodically (ex. 30s) broadcast hello message
including demand information and chunk information
16
a1 a2 a3 …A, B
DemandInfo.
Chunk Info.
:retain :no
Hello Message
a1 a2 a3 …A, Cb1 b2 b3 …B, Da1 a2 a3 …A, D
n1
n2
n3
↑Terminal ID
Neighbor TableVideo Ads Dissemination through WiFi-Cellular Hybrid Networks
Action Decision Part
1. Select a chunk for action– Categorize chunks• Chunks ALREADY obtained broadcast via WiFi• Chunks NOT obtained download from cellular
– Impact computation• Prioritize chunks by putting impact values
– Roulette selection• Select a chunk by roulette
2. Take an action for the selected chunk– For broadcast, we let each node take action at
probability to avoid collision
17Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Action Decision Phase – Categorizing Chunks–• C1: Chunks to be downloaded from cellular– Node wants a chunk, but no neighbor nodes retain it
• C2: Chunks to be broadcast through WiFi– Node retains a chunk, and some of neighbor nodes
want it
• C3: Other chunks– Node does not take any action to those chunks
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Node underconsideration
Node underconsideration
Neighbor nodes
Neighbor nodes
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Action Decision Phase – Impact Computation(1)–• C1: Chunk not retained by any neighbor nodes
• Num. of neighbor nodes that want chunk s:
19
Impact for chunk s:
3
1
3
1 3
1
Avoid redundant download
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Action Decision Phase – Impact Computation(2)–• C2: Chunk which some nodes retain, and some of
neighbor nodes want the chunk
• Num of neighbor nodes broadcasting chunk s:
20
Impact for s:
2
1
2
1
Avoid redundant broadcast
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Action Decision Phase – Roulette Selection–
• Roulette Selection– Prepare two roulettes for cellular and WiFi– Decide portion of each chunk in proportion to impact– Select a chunk by roulette selection– Probability of selecting a chunk with impact wi
21
High impact chunkLow impact chunk
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Problem in Basic Algorithm
• Initially, all nodes intensively use cellular network while
neighboring information is not known• As time elapses, cellular is not used (neighbor nodes have
chunks)
22
Time
100
Time
Not adaptive to remaining time for deadlineNot adaptive to remaining time for deadline
Short increase cellular usage to meet the deadlineLong reduce cellular usage so that nodes exchange chunks via WiFi
DownloadRate (%)
CellularUsage
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Adaptation Mechanism (Extended from PerCom09 WiP)
• Consider target download yield at elapsed time to deadline– Current download yield is higher than this, do not use
cellular– Current download yield is lower than this, use cellular
23
100
Elapsed Time deadline
: target DL yield
Not use cellular
Use cellular
Download Yield (%)
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Organization
1. Background
2. Related Work
3. Problem Formulation
4. Proposed Algorithm
5. Evaluation through Simulations
6. Conclusion
24Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Evaluation Experiments
Preliminary Experiment– Measure performance, changing hello message period h and
collision avoidance rate – Purpose: obtain good values for h and
Experiment1– Measure cellular network usage and download time for various
deadlines– Purpose: show adaptability for various deadline lengths
Experiment2– Measure cellular network usage and download time, changing
number of contents – Purpose: show adaptability for various number of ad contents
Metric: cellular network usage ratio (cellular usage)
25
Extensionfrom PerComversion
Cellular usage (%) =amount actually downloaded via cellular
amount when all nodes download all chunks via cellularVideo Ads Dissemination through WiFi-Cellular Hybrid Networks
Common Simulation Parameters
• We developed our own simulator for simulations in 1ms granularity
26
Common simulation parametersSize of each video ad 1.5MB (divided to 1000 chunks)Size of each chunk 1.5KB (sent in a packet)Num of ads that each node requests 2 (selected by Zipf distribution)
Mobility Random Way Point (4km/hour)Field size 500m×500m
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Network Model
27
Cellular network Rate/connection: 1.2MbpsMaximum connections: 64
WiFi(ad-hoc mode)
Bandwidth/range: 1.7MbpsRadio range: 200mFading model: Nakagami fadingMAC: CSMA/CA
M. Killat, F. Schmidt-Eisenlohr, H. Hartenstein, C. Rössel, P. Vortish, S. Assenmacher and F. Busch:”Enabling Efficient and Accurate Large-Scale Simulations of VANETs for Vehicular Traffic Management,”Proc. of VANET2007
Packet ReceptionRate (%)
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Experiment1: Adaptability to Deadline Lengths
• Evaluate adaptability to various deadline lengths
• Suppose cold start case – All nodes simultaneously start acquiring video ads
after each node decides two ad contents and their deadlines
– Hot start case is explained later
31
Parameters used in Experiment1Number of ad contents 10Number of nodes 500Deadlines 15, 30, 60, 90 minutes
from starting time (fixed)h, 5s, 0.0015
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Result of Experiment1 (DL Yield over Time)
• Without deadline adaptation mechanism– DL yield increases slowly after 90% . Many nodes miss deadlines
• With deadline adaptation mechanism– Download yield increases as expected. All nodes meet their deadlines
32
Time
DLYield(%)
Without mechanism
With mechanism(deadline=90min)
60min
30min15min
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Result of Experiment1 (Cellular Usage over Time)
• Without deadline adaptation mechanism– Uses cellular network intensively only in initial phase
• With deadline adaptation mechanism– Constantly uses cellular network, but increases usage in
finishing phase• In end phase, it takes long time to receive blank chunks via WiFi
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40.5%
16.9%
4.3%1.1%
Time
Without mechanism
15min
30min
60min 90min
Number of chunksdownloaded via cellular
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Experimental Result with “Hot Start” Configuration
• Mobile nodes join and leave the system• New nodes starts obtaining video ads just after joining• Measured for 267 nodes appearing after 200 minutes elapses
– Cellular usage was reduced further than “cold start” case– Minimum cellular usage was reduced to about 0.3%
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Deadlines
CellularUsage (%) Cold start
Hot start
ConfigurationInitially 500nodesPoisson arrivals of 15s120min lifetime10 ad contentsDeadlines: 15, 30, 60 (random)
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Experiment2: Scalability for Number of Contents
• In actual situation, many video ads may exist– Investigate if our method adaptively works for
different number of ad contents
35
Parameters for Experiment2Number of Ad Contents 10, 20, 30, 40Mobile Terminals 500Time to Deadline 60 minutes
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Result of Experiment2
• When increasing number of ad contents– Smaller number of terminals want the same ad– Our method adaptively regulated cellular usage
• All terminals completed downloading all required contents
– Even for 40 contents, cellular usage reduced to about 34.9%36
34.9%
Number of ad contents
Time
Cellular usage (%)
# of chunksvia cellular
40 contents
30
20
10
Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Conclusion• Cooperative download method for mobile phones for context-
aware video ad dissemination– Does not suppress cellular network by using Wi-Fi network
• Evaluation results supposing typical urban scenarios– Cellular network usage was reduced by up to 98.9%– In hot start scenario, the usage was reduced further– Adaptive to various lengths of deadlines and number of
video ad contents
Future Work– Experiment with realistic situation (real traces, real maps,
etc)– Incentive for mobile terminals– multi-hop paths in ad hoc network
37Video Ads Dissemination through WiFi-Cellular Hybrid Networks
Thanks
38Video Ads Dissemination through WiFi-Cellular Hybrid Networks
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