Asynchronous power saving protocols via quorum systems for ieee 802 11 ad hoc networks
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Asynchronous Power-Saving Protocols via Quorum Systems for IEEE 802.11 Ad Hoc Networks. Jehn-Ruey Jiang Hsuan-Chuang University. To Rest, to Go Far!. Outline. IEEE 802.11 Overview Power Saving Issues Asynchronous Quorum-based PS Protocols Optimal AQPS Protocols Analysis and Simulation

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Asynchronous Power-Saving Protocols via Quorum Systems for IEEE 802.11 Ad Hoc Networks

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Asynchronous power saving protocols via quorum systems for ieee 802 11 ad hoc networks

Asynchronous Power-Saving Protocols via Quorum Systems forIEEE 802.11 Ad Hoc Networks

Jehn-Ruey Jiang

Hsuan-Chuang University


To rest to go far

To Rest, to Go Far!


Outline

Outline

IEEE 802.11 Overview

Power Saving Issues

Asynchronous Quorum-based PS Protocols

Optimal AQPS Protocols

Analysis and Simulation

Conclusion


Outline1

Outline

IEEE 802.11 Overview

Power Saving Issues

Asynchronous Quorum-based PS Protocols

Optimal AQPS Protocols

Analysis and Simulation

Conclusion


Ieee 802 11

IEEE 802.11

  • Approved by IEEE in 1997

  • Extensions approved in 1999

  • Standard for Wireless Local Area Networks ( WLAN )


Ieee 802 11 family 1 2

IEEE 802.11 Family(1/2)

  • 802.11a:6 to 54 Mbps in the 5 GHz band

  • 802.11b (WiFi, Wireless Fidelity):5.5 and 11 Mbps in the 2.4 GHz band

  • 802.11g:54 Mbps in the 2.4 GHz band


Ieee 802 11 family 2 2

IEEE 802.11 Family(2/2)

  • 802.11c: support for 802.11 frames

  • 802.11d: new support for 802.11 frames

  • 802.11e: QoS enhancement in MAC

  • 802.11f: Inter Access Point Protocol

  • 802.11h: channel selection and power control

  • 802.11i: security enhancement in MAC

  • 802.11j: 5 GHz globalization


Ieee 802 11 market

IEEE 802.11 Market

Source: Cahners In-Stat

($ Million)


Ieee 802 11 components

IEEE 802.11 Components

  • Station (STA) - Mobile host

  • Access Point (AP) - Stations are connected to access points.

  • Basic Service Set (BSS) - Stations and the AP within the same radio coverage form a BSS.

  • Extended Service Set (ESS) - Several BSSs connected through APs form an ESS.


Infrastructure vs ad hoc modes

Infrastructure vs Ad-hoc Modes

infrastructure network

AP

AP

wired network

AP

Multi-hop ad hoc network

ad-hoc network

ad-hoc network


Ad hoc networks

Ad hoc Networks

  • Ad hoc: formed, arranged, or done (often temporarily) for a particular purpose only

  • Mobile Ad Hoc Network (MANET):A collection of wireless mobile hosts forming a temporary network without the aid of established infrastructure or centralized administration


Applications of manets

Applications of MANETs

  • Battlefields

  • Disaster rescue

  • Spontaneous meetings

  • Outdoor activities


Single hop vs multi hop

Single-Hop vs Multi-Hop

  • Single-Hop

    • Each node is within each other’s transmission range

    • Fully connected

  • Multi-Hop

    • A node reaches other nodes via a chain of intermediate nodes

    • Networks may partition and/or merge


Outline2

Outline

IEEE 802.11 Overview

Power Saving Issues

Asynchronous Quorum-based PS Protocols

Optimal AQPS Protocols

Analysis and Simulation

Conclusion


Power saving overview

Power Saving - Overview

  • Battery is a limited resource for portable devices

  • Power saving becoming a very hot topic is wireless communication

  • Solutions:

    • PHY: transmission power control

    • MAC: power mode management

    • Network Layer: power-aware routing


Transmission power control

Transmission Power Control

  • Tuning transmission energy for higher channel reuse

  • Example:

    • A is sending to B (based on IEEE 802.11)

    • Can (C, D) and (E, F) join?

Source: Prof. Tseng


Power mode management

Power Mode Management

  • doze mode vs. active mode

  • example:

    • A is sending to B

    • Does C need to stay awake?

Source: Prof. Tseng


Power aware routing

N2

N1

SRC

DEST

+

+

+

+

+

+

N3

N4

Power-Aware Routing

  • Routing in an ad hoc network with energy-saving (prolonging network lifetime) in mind

  • Example:

Source: Prof. Tseng


Ieee 802 11 ps mode 1 2

IEEE 802.11 PS Mode(1/2)

  • PowerConsumption: (ORiNOCO IEEE 802.11b PC Gold Card)

Vcc:5V, Speed:11Mbps


Ieee 802 11 ps mode 2 2

IEEE 802.11 PS Mode(2/2)

  • Environments:

    • Infrastructure

    • Ad hoc (infrastructureless)

      • Single-hop

      • Multi-hop


Ps infrastructure 1 3

PS: Infrastructure (1/3)

  • Clock synchronization is required (via TSF)

    • The AP is responsible for generating beacons each of which contains a valid time stamp

    • If the channel is in use, defer beacon transmission until it is free


Ps infrastructure 2 3

PS: Infrastructure (2/3)

  • A host always notifies AP its mode

  • A PS host periodically wakes up to listen to beacons

  • AP keeps a PS host awake by sending”traffic indication map (TIM)”in a beacon for unicast data

  • AP keeps all PS hosts awake by sending”delivery traffic indication map (DTIM)”in a beacon for broadcast data


Ps infrastructure 3 3

PS: Infrastructure (3/3)


Ps 1 hop ad hoc network 1 2

ATIM Window

ATIM Window

power saving state

active state

ATIM

data frame

Beacon

BTA=2, BTB=5

power saving state

ACK

ACK

Beacon

PS : 1-hop Ad hoc Network (1/2)

Beacon Interval

Beacon Interval

Host A

Host B

Source: Prof. Tseng


Ps 1 hop ad hoc network 2 2

Beacon Interval

Beacon Interval

Beacon

Beacon

Beacon

PS: 1-hop Ad hoc Network (2/2)

Target Beacon Transmission Time (TBTT)

Beacon Interval

Beacon Interval

Power Saving Mode

ATIM Window

Beacon

ATIM

Data Frame

Host A

ATIM

Data Frame

Host B

ACK

ACK

Host C

ACK

ACK


Ps m hop ad hoc network 1 3

PS: m-hop Ad hoc Network (1/3)

  • Problems:

    • Clock Synchronization is harddue to communication delays and mobility

    • Network Partitionunsynchronized hosts with different wakeup times may not recognize each other


Clock drift example

Clock Drift Example

Max. clock drift for IEEE 802.11 TSF (200 DSSS nodes, 11Mbps, aBP=0.1s)


Network partitioning example

A

D

C

F

Network Partition

B

E

Network-Partitioning Example

Host A

ATIM window

Host B

Host C

Host D

Host E

Host F

Source: Prof. Tseng


Ps m hop ad hoc network 3 2

PS: m-hop Ad hoc Network (3/2)

  • Solution:

    • Not to synchronize hosts’ clocks

  • But to achieve

    • Wakeup prediction

    • Neighbor discovery


Ps m hop ad hoc network 3 3

PS: m-hop Ad hoc Network (3/3)

  • Three asyn. solutions:

    • Dominating-Awake-Interval

    • Periodical-Fully-Awake-Interval

    • Quorum-Based

      Ref:“Power-Saving Protocols for IEEE 802.11-BasedMulti-Hop Ad Hoc Networks,”Yu-Chee Tseng, Chih-Shun Hsu and Ten-Yueng HsiehInfoCom’2002


Outline3

Outline

IEEE 802.11 Overview

Power Saving Issues

Asynchronous Quorum-based PS Protocols

Optimal AQPS Protocols

Analysis and Simulation

Conclusion


Quorum based ps protocol

Quorum-based PS Protocol


Quorum interval

Quorum interval


Touchdown

Touchdown

  • A PS host’s beacon can be heard twice or more for every n consecutive beacon intervals, which in turn solves

    • Wakeup prediction

    • Neighbor discovery


Observation

Observation

  • A quorum system may be translated to a power-saving protocol, whose power-consumption is proportional to the quorum size.


Questions

Questions

  • Can any quorum system be translated toan asyn. PS protocol?

NO!

  • Which can be?

Those with the Rotation Closure Property!!


Outline4

Outline

IEEE 802.11 Overview

Power Saving Issues

Asynchronous Quorum-based PS Protocols

Optimal AQPS Protocols

Analysis and Simulation

Conclusion


Contributions

Contributions

  • Propose the rotation closure property

  • Propose the lower bound of the quorum size

  • Propose a novel quorum systems to be translated to an adaptive PS protocol


What are quorum systems

What are quorum systems?

  • Quorum:

    a subset of universal set U

    • E.G. q1={1, 2} and q2= {2, 3} are quorums under U={1,2,3}

  • Quorum system:

    a collection of mutually intersecting quorums

    • E.G. {{1, 2},{2, 3},{1,3}} is a quorum system under U={1,2,3}


Rotation closure property

Rotation Closure Property

  • For example,

    • Q1={{0,1},{0,2},{1,2}} under U={0,1,2}

    • Q2={{0,1},{0,2},{0,3},{1,2,3}} under U={0,1,2,3}

Because {0,1} rotate({0,3},3) =


Examples of quorum systems

Examples of quorum systems

  • Majority quorum system

  • Tree quorum system

  • Hierarchical quorum system

  • Cohorts quorum system

  • ………


Optimal quorum size

Optimal Quorum Size

  • Optimal quorum size:k, where k(k-1)+1=n and k-1 is a prime power (K n)


Optimal quorum systems

Optimal Quorum Systems

  • Near optimal quorum systems

    • Grid quorum system

    • Torus quorum system

    • Cyclic (difference set) quorum system

  • Optimal quorum system

    • FPP quorum system


Torus quorum system

Torus quorum system


Cyclic difference set quorum system

Cyclic (difference set) quorum system

  • Def: A subset D={d1,…,dk} of Zn is called a difference set if for every e0 (mod n), thereexist elements di and djD such that di-dj=e.

  • {0,1,2,4} is a difference set under Z8

  • { {0, 1, 2, 4}, {1, 2, 3, 5}, {2, 3, 4, 6}, {3, 4, 5, 7},{4, 5, 6, 0}, {5, 6, 7, 1}, {6, 7, 0, 2}, {7, 0, 1, 3} }is a cyclic (difference set) quorum system


Fpp quorum system

FPP quorum system

  • FPP:Finite Projective Plane

  • Proposed byMaekawa in 1985

  • For solving distributed mutual exclusion

  • Constructed with a hypergraph

  • Also a Singer difference set quorum system


E torus quorum system

E-Torus quorum system


Outline5

Outline

IEEE 802.11 Overview

Power Saving Issues

Asynchronous Quorum-based PS Protocols

Optimal AQPS Protocols

Analysis and Simulation

Conclusion


Analysis 1 3

Analysis (1/3)

  • Active Ratio:the number of quorum intervals over n,where n is cardinality of the universal set

  • neighbor sensibility (NS)the worst-case delay for a PS host to detect the existence of anewly approaching PS host in its neighborhood


Analysis 2 3

Analysis (2/3)


Analysis 3 3

Analysis (3/3)


Simulation model

Simulation Model

  • Area: 1000m x 1000m

  • Speed: 2Mbps

  • Radio radius: 250m

  • Battery energy: 100J.

  • Traffic load: Poisson Dist. , 1~4 routes/s, each having ten 1k packets

  • Mobility: way-point model (pause time: 20s)

  • Routing protocol: AODV


Simulation parameters

Simulation Parameters

L: packet length


Simulation metrics

Simulation Metrics

  • Survival ratio

  • Neighbor discovery time

  • Throughput

  • Aggregate throughput


Simulation results 1 10

Simulation Results (1/10)

Survival ratio vs. mobility (beacon interval = 100 ms, 100 hosts, traffic load = 1 route/sec).


Simulation results 2 10

Simulation Results (2/10)

Neighbor discovery time vs. mobility(beacon interval =100 ms, 100 hosts, traffic load = 1 route/sec).


Simulation results 3 10

Simulation Results (3/10)

Throughput vs. mobility(beacon interval = 100 ms, 100hosts, traffic load = 1 route/sec).


Simulation results 4 10

Simulation Results (4/10)

Survival ratio vs. beacon interval length(100 hosts,traffic load = 1 route/sec, moving speed = 0~20 m/sec withmean = 10m/sec).


Simulation results 5 10

Simulation Results (5/10)

Neighbor discovery time vs. beacon interval length

(100hosts, traffic load = 1 route/sec, moving speed = 0~20 m/secwith mean = 10m/sec).


Simulation results 6 10

Simulation Results (6/10)

Throughput vs. beacon interval length

(100 hosts, traffic load = 1 route/sec, moving speed = 0~20 m/sec with mean =10m/sec).


Simulation results 7 10

Simulation Results (7/10)

Survival ratio vs. traffic load

(beacon interval = 100 ms, 100 hosts, mobility = 0~20 m/sec with mean = 10 m/sec).


Simulation results 8 10

Simulation Results (8/10)

Throughput vs. traffic load(beacon interval =100 ms, 100 hosts, mobility = 0~20 m/sec with mean = 10 m/sec).


Simulation results 9 10

Simulation Results (9/10)

Survival ratio vs. host density

(beacon interval = 100ms, traffic load 1 route/sec, mobility = 0~20 m/sec with mean= 10 m/sec).


Simulation results 10 10

Simulation Results (10/10)

Throughput vs. host density

(beacon interval = 100ms, traffic load 1 route/sec, mobility = 0~20m/sec with mean= 10 m/sec).


Outline6

Outline

IEEE 802.11 Overview

Power Saving Issues

Asynchronous Quorum-based PS Protocols

Optimal AQPS Protocols

Analysis and Simulation

Conclusion


Conclusion 1 2

Conclusion (1/2)

  • Quorum systems with the rotation closure property can be translated to an asyn. PS protocol.

  • The active ratio is bounded by 1/ n, where n is the number of a group of consecutive beacon intervals.

  • Optimal, near optimal and adaptive AQPS protocols save a lot of energy w/o degrading performance significantly


Conclusion 2 2

Conclusion (2/2)

  • Future work:

    • To incorporate AQPS protocols with those demanding accurate neighboring node’s information, e.g., geometric routing protocols

    • To incorporate quorum system concept to wireless sensor networks

    • To incorporate quorum system concept to Bluetooth technology


Asynchronous power saving protocols via quorum systems for ieee 802 11 ad hoc networks

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