Cooperation in Wireless Grids - kom.aau.dkkom.aau.dk/group/07gr1116/Cooperation in Wireless Grids... · Cooperation in Wireless Grids ... NetLogo • NetLogo is a programmable modeling

Cooperation in Wireless GridsAn Energy Efficient MAC Protocol

for Cooperative Network with Game Theory Model

Master ThesisPuri Novelti AnggraeniSatya Ardhy Wardana

Supervisor : Frank Fitzek

Cooperation in Wireless Grids - 07gr1116

• Introduction• Theoretical Review• Problem Definition• Proposed Scheme• Numerical Results and Analysis• Conclusion and Further Works


Introduction

• Battery lifetime is a crucial factor of a wireless devices to support its mobility and quality

• Higher battery lifetime can support higher mobility and higher data rate in a long term


Introduction

http://www.batterypoweronline.com/articles/PresentationsPDFs/Strategy%20Analytics.pdf


IntroductionCooperation is proven to reduce power consumption[1]

[1] F. Albiero, “Power saving in cooperative networks: A game-theoric approach,” Master’s thesis,Universita Agli Studi di Padova (Italy) and Aalborg University (Denmark), 2005.

Game Theory is suitable to model cooperation in wireless grids

Recent work has not consider MAC layer where energy saving technology takes part

Goal : Design an energy efficient MAC protocol


Introduction


Introduction

ASSUMPTIONS– All mobile devices have two Network Interface Cards

(NICs)– IEEE 802.11 or Wireless Local Area Network (WLAN)

is used– No hidden / exposed devices problem occurred due

to close proximity– No significant interference is experienced by other

clusters due to channel assignment– Power components in the mobile devices are ideal

thus no overhead in changing state




Motivation to Cooperate

• Cooperation is a strategy of a group of entities that work together to achieve a common or individual goal

• Every entity gains advantage by giving or sharing its resources

Pc,rx + Ps,tx + (n-1) · Ps,rx < n · Pc,rx


Game Theory

• Game theory is a mathematical model for the analysis of interactive decision making processes where the decision of a player influences others and overall system

• A game consists of three basic components: a set of players, a set of actions, and a set of preferences


CSMA / CA

• CSMA/CA is the MAC layer protocol employed in IEEE 802.11 or WLAN


Power Management in IEEE 802.11

• Power Mode in a IEEE 802.11 devices is consisted of Awake and Doze states

• The states are consisted of :– Transmit– Receive– Sense– Idle


NetLogo

• NetLogo is a programmable modeling environment for modeling complex systems which are developing over time

• Modelers can give instructions to hundreds or thousands of independent agents concurrently

• This tool can be well suited for the distributed (e.g ad hoc) and centralized (e.g cellular) network and game theory

http://ccl.northwestern.edu/netlogo/docs/




Ideal System

• Ideal System Setup– Full TDMA system– Not consider MAC layer

• Theoretic Analysis

F. Albiero, “Power saving in cooperative networks: A game-theoric approach,” Master’s thesis, Universita Agli Studi di Padova (Italy) and Aalborg University (Denmark), 2005.


Ideal System

• Cooperative StrategyQuestion : Optimize Individual Gain or System Gain?

– Wise

– SelfishMD 1

MD 3

MD 2


Cooperation in Existing System

• IEEE 802.11 System Setup– TDMA for access point access– CSMA / CA for MAC protocol inside a cluster


Performance Evaluation

• Comparison of Ideal and Existing System Performance




Proposed Scheme for an Energy Efficient MAC Layer in Cooperation

• MotivationCSMA/CA implementation in the cooperation raises the energy consumption

• GoalPropose a scheme for an energy efficient MAC protocol The benefit of cooperation in terms of energy saving gain is optimized (close to the ideal case)

• The scheme should be easy to implement reuse the existing protocol with new scheme


Cluster Formation(Before the proposed scheme is performed)

• Every mobile device creates a link to its possible surrounding mobile devices within certain coverage area and calculates the links between them

• Every mobile device decides with whom it cooperates (wise or selfish strategy)

• note : This process is not included in the energy consumption calculation


The Proposed Scheme

• Setup Phase – Selection of Head Cluster (Step 1-3)The MAC layer protocol : CSMA/CAProtocol adoption is easier and simple

• Pilot Tone (Step 4)Time slot assignment for every mobile devices to access the channelAvoid collision

• Steady State Phase (Step 5)TDMA ; broadcast within cluster


Cluster Period : Tcluster

• Interface 1 : cellular link• Interface 2 : short range link

Ct : Setup PhasePi : Pilot Tone


Cluster Period : Tcluster

• The sequence of setup phase, pilot tone, and data exchange phase is repeated every Tcluster

• Npacket : Number of packets (CSMA/CA packet size is 8584 bits)

• Rc : Data rate for the cellular linkShort range data rate > Cellular data ratePossibility of idle period in Tcluster




Default Values of Parameters

• Minimum short range data rate : 24 Mbits/s• Cellular data rate : 6 Mbits/s• Number of mobile devices : 20• Strategy : Pure Wise / Pure Selfish• Tcluster : 35.766 ms• Number of packet : 25• Mobility : 1 m/s (-10o to 10o of turn)• Result (Energy Consumption) : Averaged over time and

mobile device: Normalized with non-coop


Performance Evaluation


Impact of Varying Number of Mobile Devices

• Number of mobile devices : 20, 30, 40, 50• Strategy : pure wise

• More mobile devices increase the energy saving gain

• The gain is not increasing linearly as the number of mobile devices increases, due to overhead in setup phase or contention phase


Impact of Varying Max. Range in a Cluster

(i.e Varying Minimum Short Range Data Rate)

• Max-range 4 : minimum short range data rate 24 MBits/sMax-range 6 : minimum short range data rate 12 MBits/sMax-range 7 : minimum short range data rate 9 MBits/s

• Larger max range : more probability that a cluster is using lower data rate, thus energy saving gain may reduce

• Note : the short range data range is lowest data rate from all link of every pair of mobile devices


Impact of Varying Cooperative Strategy

In pure strategy (wise or selfish) : • Wise strategy perform better energy saving gain

In mix strategy : • Selfish perform perform better energy saving gain• Selfish mobile devices ”exploit” wise mobile devices


Impact of Varying Cooperative Strategy


Impact of Varying Mobility DistributionMobility

ModelSimu-lation Case

Number ofLow Mobility

(0.1 m/s)

Number of Medium Mobility(1 m/s)

Number of High Mobility(3 m/s)

Case 1 15 mobile devices

2 mobile devices

3 mobile devices


2 mobile devices

15 mobile devices


6 mobile devices

7 mobile devices


Impact of Varying Mobility Distribution



• Different mobility distribution does not effect system performance significantly, as the system reaches its stability Due to close environment (good average over space and players)

• The system undergone a high fluctuation in the beginning of simulation;In a heterogeneous mobility environment, the system performs differently in a short period of time



Each mobile device spends almost similar power regardless its mobility and its mobility case

High number of iteration in a close environmentgood average over space and players


Impact of Varying Cluster Period (Tcluster)

• Based on [1], it is assumed that approximately every 2-3 meters distance difference results in changing the short range data rate

• If the speed of mobile devices is 1 m/s, then in worst case, the data rate between two mobile device might change after approx. 1.5 seconds (3 meters)

• Tcluster can be changed with the maximum value depends on the mobility model

[1] P. Romano, “The range vs. rate dilemma of wlans” http://www.commsdesign.com/January 2004.

http://www.commsdesign.com/


Impact of Varying Cluster Period (Tcluster)

• Tcluster period is longer energy consumption will decrease

• In the case : mobile devices are moving fastit might happen that during the Tcluster period, the data rate is changing

the energy consumption might changeMaintain the current cluster or form a new cluster ?Additional overhead to inform the changes of data rate


GPRS/WLAN Environment

• GPRS for Base Station Link– 5 and 7 dedicated Timeslots

(42.25 Kbits/s and 63.35 Kbits/s ) – Tcluster is chosen to be 2.03 seconds– Receiving power equals to 2.3 Watt and Idle

power equals to 0.04 Watt– For 50 wise users


GPRS/WLAN Performance




Conclusions

• The comparison of cooperation in ideal system and IEEE 802.11 WLAN system shows that cooperation using omnipresent technology does not perform as well as it is expected

• The proposed scheme gives significant improvement from IEEE 802.11

• The proposed scheme is also feasible to be implemented in existing technology


Conclusions

• It is also found that the proposed system works better under higher number of users, higher cluster period, and in pure wise strategy

• Smaller cluster size, indicates higher short range data rate, also contributes to better system performance and may lead to proposed system performing closely to ideal system


Future Works

• The procedure for members joining and leaving a cluster during cluster period

• Hardware imperfection can also cause higher energy consumption

• Changing power state may not be as ideal as it is in this work

DEMO

http://kom.aau.dk/group/07gr1116/

http://kom.aau.dk/group/07gr1116/

Thank You


Errata

• Page x : in the second row, the word "their" should be changed to "his"

• Page 8 : the corecet equation should be like the following :

Pc,rx + Ps,tx + (n-1) · Ps,rx < n · Pc,rx

• Page 35 : the title of Section 4.1 should be "The Proposed Scheme"

Documents

Cooperation in Wireless Grids - kom.aau.dkkom.aau.dk/group/07gr1116/Cooperation in Wireless Grids... · Cooperation in Wireless Grids ... NetLogo • NetLogo is a programmable modeling