1. Using Incompletely Cooperative Game Theory
in Wireless Sensor Networks
Liqiang Zhao, Hailin Zhang, and Jie Zhang
WCNC 2008
Presented by: Abolfazl Asudeh

2. Outline
 Background and Problem statement
 Incompletely cooperative game
 GMAC and Simulation Results
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3.  Wireless Sensor Networks (WSNs) have a wide
range of potential applications including environment
monitoring, smart spaces, medical systems and
robotic exploration.
 Energy Consumption is usually the more important
metric
 other metrics: Delay, Throughput, …
 A lot of interest in performance analysis and
improvement, specially in Medium Access Control
(MAC) protocols.
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4. Main Categories of MAC protocols of WSNs
 Scheduled Protocols: use a predefined schedule for
data transmission - TSMP
Data Ack
Sender
Tg
Data Ack
Tg
Tg
Receiver
Time Slot
 Protocols with Common Active Period: Nodes wake
up and sleep together to reduce the energy cost of
idle listening. - SMAC
 idle listening: when the nodes are awake, but there is no
packet in the channel to be transmitte
 Usually use CSMA/CA (RTS/CTS) for data transmission
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5. Main Categories of MAC protocols of WSNs
 Preamble Sampling Protocols: Every node wakes up
periodically and check if there is a packet in the
channel; the sender sends a long preamble before
sending the data. – Preamble Sampling Aloha
Preamble Data
Sender
Check Interval Data
Receiver
 Hybrid Protocols: the combinations of the protocols
of different categories
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6.  Game Theory is used broadly in distributed WSNs to
solve problems like:
 Security
 Routing
 Power Control
 The goal of this paper: to achieve energy
consumption, delay, and throughput together
 Main focus is on Common Active MAC protocols
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7.  Sensor networks are energy constraint  explicit
cooperation among nodes is impractical.
 It can be modeled as an incompletely cooperative
game, a stochastic game, which starts when a new
packet arrives at the node’s transmission buffer and
ends when the packet is transmitted successfully or
discarded.
 Each game process includes many timeslots and
each timeslot corresponds to one game state.
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8.  In each timeslot, each player (i.e., node) estimates
the current game state based on what happened in
the past timeslots.
 Then adjusts its own equilibrium strategy by tuning
its local contention parameters
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9. Framework
 Contains three major components
 a detector: detect and record current conditions
 an estimator: estimates current state, such as number of
nodes
 an adjustor: makes the decision for the strategy and
adjusts the contention parameters
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10. The Game model of N+1 nodes
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12. GMAC: the simplified MAC solution
 The Estimation of n is inaccurate in unsaturated
environments.
 GMAC is the simplified version.
 In G-MAC, after transmitting a packet, no matter it is
transmitted successfully or not, the player does not
start the next game process with the nominal
CWmin.
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13. Simulation Results
 channel rate: 1Mbps
 n = 30
 packet arrival: Poisson
 active period: 250msec
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14. References
 A. Bachir, M. Dohler, Th. Watteyne, and K.K. Leung,
“MAC Essentials for Wireless Sensor Networks”,
IEEE COMMUNICATIONS SURVEYS &
TUTORIALS, VOL. 12, NO. 2, SECOND QUARTER
2010.
 Liqiang Zhao; Hailin Zhang; Jie Zhang; , "Using
Incompletely Cooperative Game Theory in Wireless
Sensor Networks," Wireless Communications and
Networking Conference, 2008. WCNC 2008. IEEE ,
vol., no., pp.1483-1488, March 31 2008-April 3 2008
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15. Thank you
 Question?
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