A Hybrid PowerSaving Protocol by DualChannel and DualTransmissionRange Clustering for IEEE 802'11Bas

1
A Hybrid Power-Saving Protocol byDual-Channel
and Dual-Transmission-Range Clustering for IEEE
802.11-Based MANETs

• Presented by
• Jehn-Ruey Jiang
• Department of Computer Science and Information
  Engineering
• National Central University

2
To Rest, to Go Far!!
3
Outline

• IEEE 802.11 MANETs
• Power Saving Problem
• Hybrid Power Saving Protocols
• Simulation Results
• Conclusion

4
Outline

• IEEE 802.11 MANETs
• Power Saving Problem
• Hybrid Power Saving Protocols
• Simulation Results
• Conclusion

5
IEEE 802.11 Overview

• Approved by IEEE in 1997
• Extensions approved in 1999 (High Rate)
• Standard for Wireless Local Area Networks (WLAN)

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WLAN Market
Source wireless.industrial-networking.com
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IEEE 802.11 Family(1/2)

• 802.11 (1997)
• 2 Mbps in the 2.4 GHz band
• 802.11b (1999) (WiFi, Wireless Fidelity)
• 5.5 and 11 Mbps in the 2.4 GHz band
• 802.11a (1999) (WiFi5)
• 6 to 54 Mbps in the 5 GHz band
• 802.11g (2001)
• 54 Mbps in the 2.4 GHz band
• 802.11n (2005) (MIMO)
• 108 Mbps in the 2.4 and the 5 GHz bands

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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

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Infrastructure vs. Ad-hoc Modes
Infrastructure Network
Wired Network
AP
AP
AP
Multi-hop Ad Hoc Network
Ad-Hoc network
Ad-Hoc network
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Ad Hoc Network (1/3)

• A collection of wireless mobile hosts forming a
  temporary network without the aid of established
  infrastructure or centralized administration
• by D. B. Johnson et al.
• Also called MANET(Mobile Ad hoc Network)
• by Internet Society IETF

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Ad Hoc Network (2/3)

• Single-Hop
• Each node is within each others transmission
  range
• Fully connected
• Multi-Hop
• A node reaches another node via a chain of
  intermediate nodes
• Networks may partition and/or merge

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Ad Hoc Network (3/3)

• Application
• Battlefields
• Disaster Rescue
• Spontaneous Meetings
• Outdoor Activities

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Outline

• IEEE 802.11 MANETs
• Power Saving Problem
• Hybrid Power Saving Protocols
• Simulation Results
• Conclusion

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Power Saving Problem

• Battery is a limited resource for portable
  devices
• Battery technology does not progress fast enough
• Power saving becomes a critical issue in MANETs,
  in which devices are all supported by batteries

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Solutions to Power Saving Problems

• PHY Layer transmission power control
• Huang (ICCCN01), Ramanathan (INFOCOM00)
• MAC Layer power mode management
• Tseng (INFOCOM02), Chiasserini (WCNC00)
• Network Layer power-aware routing
• Singh (ICMCN98), Ryu (ICC00)

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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?

No!
Yes!
B
C
D
A
E
F
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Power Mode Management

• Doze mode vs. Active mode
• Example
• A is sending to B
• Does C need to stay awake?

No!
It can turn off its radio to save energy!
B
A
But it should turn on its radio periodiclally for
possible data comm.
C
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Power-Aware Routing

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

N2
N1
SRC
DEST
Better!!
N3
N4
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Our Focus

• Among the three solutions
• PHY Layer transmission power control
• MAC Layer power mode management
• Network Layer power-aware routing

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IEEE 802.11 PS Mode

• An IEEE 802.11 Card is allowed to turn off its
  radio to be in the PS mode to save energy
• Power Consumption(ORiNOCO IEEE 802.11b PC Gold
  Card)

Vcc5V, Speed11Mbps
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MAC Layer Power-Saving Protocol

• Two types of MAC layer PS protocol for IEEE
  802.11-based MANETs
• Synchronous (IEEE 802.11 PS Protocol)
• Synchronous Beacon Intervals
• For sending beacons and ATIM (Ad hoc Traffic
  Indication Map)
• Asynchronous Tseng et. al. 2002Jiang et. al.
  2003
• Asynchronous Beacon Intervals
• For sending beacons and MTIM (Multi-Hop Traffic
  Indication Map)

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• Beacon
• For a device to notify its existence to others
• For devices to synchronize their clocks

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IEEE 802.11 PS Protocol
Target Beacon Transmission Time(TBTT)
Beacon Interval
Beacon Interval
ATIM Window
ATIM Window
Active mode
Power saving Mode
Host A
No ATIM means no data to send or to
receive with each other
ATIM
Power saving Mode
ATIM Window
ATIM Window
Active mode
Host B
ACK
Clock Synchronized by TSF (Time Synchronization
Function)
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IEEE 802.11 PS Protocol (cont.)

• Suitable for Single-hop environment
• Advantages
• More power efficiency
• Low active ratio (less duty cycle)
• Drawbacks
• Clock synchronization for multi-hop networks is
  costly and even impossible
• Network partitioning
• Not Scalable

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Clock Drift Example
MaximumTolerance
200 ?s
Max. clock drift for IEEE 802.11 TSF (200 DSSS
nodes, 11Mbps, aBP0.1s)
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Network-Partitioning Example
The red ones do not know the existence of the
blue ones, not to mention the time when they are
awake.
The blue ones do not know the existence of the
red ones, not to mention the time when they are
awake.
C
A
B
Host A
ATIM window
Host B
Host C
Host D
Host E
Host F
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Asynchronous PS Protocols (1/2)

• Try to solve the network partitioning problem to
  achieve
• Neighbor discovery
• Wakeup prediction
• Without synchronizing hosts clocks

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Asynchronous PS Protocols (2/2)

• Three existent asynchronous PS protocols
• Dominating-Awake-Interval
• Periodical-Fully-Awake-Interval
• Quorum-Based

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What is a quorum?

• minimum number of people who must be present at a
  meeting (of a committee, etc) before it can
  proceed and its decisions, etc can be considered
  valid-- Oxford Dictionary

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(No Transcript)
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What is a quorum again?

• From Math.quorumsmutually intersecting subsets
  of a universal set U
• E.G.1, 2, 2, 3 and 1,3 are quorums under
  U1,2,3

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Numbering Beacon Intervals
n consecutive beacon intervals are numbered as 0
to n-1
And they are organized as a ?n ? ?n array
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Quorum Intervals (1/4)
Intervals from one row and one column are
called Quorum Intervals
Example Quorum intervals arenumbered by 2, 6,
8, 9, 10, 11, 14
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Quorum Intervals (2/4)
Intervals from one row and one column are
called Quorum Intervals
Example Quorum intervals arenumbered by 0, 1,
2, 3, 5, 9, 13
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Quorum Intervals (3/4)
Any two sets of quorum intervals have two common
members
For example The set of quorum intervals 0, 1,
2, 3, 5, 9, 13 and the set of quorum
intervals 2, 6, 8, 9, 10, 11, 14 have two
common members 2 and 9
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Quorum Intervals (4/4)
Host D
2
15
14
13
12
11
10
9
8
7
6
5
4
3
1
0
Host C
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
2 overlapping quorum intervals
Even when the beacon interval numbers are not
aligned (they are rotated), there are always at
least two overlapping quorum intervals
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Structure of Quorum Intervals
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Networks Merge Properly
C
A
B
Host A
ATIM window
Host B
Beacon window
Host C
Monitor window
Host D
Host E
Host F
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Quorum Systems Help with the Proof

• What is a quorum system?A collection of mutually
  intersecting subsets of an universal set U, where
  each subset is called a quorum.E.G. 1, 2,2,
  3,1,3 is a quorum system under U1,2,3,
  where 1, 2, 2, 3 and 1,3 are quorums.
• Not all quorum systems are applicable to QAPS
• Only those quorum systems with the rotation
  closure property are applicable.

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Optimal Quorum System (1/2)

• Quorum Size Lower Bound for quorum systems
  satisfying the rotation closure propertyk,
  where k(k-1)1n, the cardinality of the
  universal set, and k-1 is a prime power(k? ?n )

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Optimal Quorum System (2/2)

• Optimal quorum system
• FPP quorum system
• Near optimal quorum systems
• Grid quorum system
• Torus quorum system
• Cyclic (difference set) quorum system
• E-Torus quorum system

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QAPS Quorum-based Asynchronous Power Saving
Protocols

• Advantages
• Do not need synchronized clocks
• Suitable for multi-hop MANETs
• Asynchronous neighbor discovery and wakeup
  prediction
• Drawbacks
• Higher active ratio than the synchronous PS
  protocol
• Not suitable for high host density environment

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Outline

• IEEE 802.11 MANETs
• Power Saving Problem
• Hybrid Power Saving Protocols
• Simulation Results
• Conclusion

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HPS Overview

• A Hybrid PS protocol
• Synchronous IEEE 802.11 PS protocol
• Asynchronous QAPS
• Forming clustering networks
• Utilizing the concepts of dual-channel and
  dual-transmission-range
• Taking advantages of two types of PS protocols
• To reduce the active ratio
• Suitable for multi-hop MANETs

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Cluster Forming
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Dual transmission ranges

• Cluster head uses
• Range RA for inter-cluster transmission
• Range RB for intra-cluster transmission

F
RA
E
RB
E, F cluster heads
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Dual channels

• Two non-interfering comm. channels are used
• Channel A for inter-cluster transmission
• Channel B for Intra-cluster transmission

F
E
RA
RB
Channel A
Channel B
E, F cluster heads
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Two types of beacon frames

• Intra-cluster beacon
• Send in channel B with transmission range RB
• For cluster forming
• For clock synchronization
• Inter-cluster beacon
• Send in channel A with transmission range RA
• For neighboring cluster heads discovery
• For wakeup prediction

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Practical Considerations

• Dual transmission ranges
• Practical for IEEE 802.11 Standard
• More power efficiency
• Dual channels
• Practical for IEEE 802.11 Standard
• Non-interfering channels (such as 1, 6, 11)
• Inter-cluster and Intra-cluster comm. can take
  place simultaneously

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Clustering

• Who is Boss?
• If somebody near me says that he/she is Boss,
  then I am his/her employee.
• If nobody is Boss, then I am Boss.
• Boss should keep whistling periodically to summon
  employees. He/She should relay messages for
  employees and thus spend more energy.
• An employee just keep watching if Boss is there.

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State Transition
A host enters the network initially
Do not receive intra-cluster beacon in channel B
over ( q1 beacon intervals a random backoff
time)
Listening State
Receive an intra-cluster beacon in channel B
during (q1 beacon intervals a random backoff
time)
Do not receive intra-cluster beacon in channel B
from cluster head over q1 beacon intervals
Broadcast intra-cluster beacon every non-quorum
interval
Cluster Head State
Cluster Member State
Receive an intra-cluster beacon in channel B from
the cluster head
Dismissal mechanism is invoked
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RA v.s. RB
x
y
RB
One extreme case for infinite host density RA
RB
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RA v.s. RB
x
RB
RB
y
One extreme case for infinite host density RA
2RB-
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RA v.s. RB
RB
x
y
RB
RB
z
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Structure of Beacon Intervals
quorum Interval
non-quorum Interval
B
M
B
M
B
M
Cluster Head
Active period
Active period in channel B
Active period in channel A
non-quorum Interval
quorum Interval
B
M
Cluster members
Active period in channel B
B
M
Beacon window and MTIM window in channel A
B
M
Beacon window and MTIM window in channel B
Monitor mode in channel A
PS mode
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Dismissal Mechanism (1/2)

• To keep the fraction of cluster heads ASAP when
  network topology changes
• To balance the load of cluster heads
• But how?

To detect if hosts are moving too close. To take
service time and residual engergy into
consideration.
Dismissal (back to listening state)
Low priority
Dismissal Mechanism is invoked
High priority
Cluster heads
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Dismissal Mechanism (2/2)

• Distance
• Default Dismissal Range 1/5 RB
• By RSSI estimation
• Priority (exchanged in inter-cluster beacons)
• Cluster head service time
• Short service time Low priority
• Remaining battery energy
• High remaining battery energy Low priority
• Cluster head ID
• Small cluster head ID Low priority

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Cluster Forming (1/2)
100 hosts 33 cluster heads 67 cluster members
RB
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Cluster Forming (2/2)
RB
500 hosts 45 cluster heads 455 cluster members
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Routing (1/5)

• Based on AODV
• RREQ (Route request) ONLY rebroadcast by
  cluster heads
• Intra-RREQwithin a cluster using channel B
• Inter-RREQbetween cluster heads using channel A
• RREP (Route reply)
• Intra-RREPwithin a cluster using channel B
• Inter-RREPbetween cluster heads using channel A

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Routing (2/5)

• If the source host is a member, it undergoes
  MTIM-ACK-RREQ-RREQ message exchange with the
  cluster head using channel B with transmission
  range RB.
• If the cluster head receives no RREP in the same
  beacon interval, it will rebroadcast the RREQ to
  all its neighboring cluster heads using channel A
  with transmission range RA.
• If a host originates or receives a RREP, it will
  remains in active mode in channel A. This is
  prepared for the upcoming data transmission.

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Routing (3/5)
Non-Quorum Interval
ATIM Window
Active mode
Cluster member X
RREQ
ATIM
ATIM Window
Active mode
Cluster head
ACK
RREP
RREQ
ATIM Window
Active mode
Cluster member Y
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Routing (4/5)
Cluster head B
Cluster head C
RA
RREQ
Cluster head A
MTIM
RREQ
X
ACK
RREP
Cluster member
RREQ
Y
RB
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Routing (5/5)
RB Intra-cluster broadcast
Destination
RA Inter-cluster broadcast
Source
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Outline

• IEEE 802.11 MANETs
• Power Saving Problem
• Hybrid Power Saving Protocols
• Simulation Results
• Conclusion

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Simulation Results

• Parameters
• Area size 1000mx1000m
• RA 250m
• RB 125m
• Mobility010m/sec with pause time 20 seconds
• Traffic load 14 routes/sec
• Number of hosts 1001000 hosts
• Performance metrics
• Cluster head ratio
• Survival ratio
• Throughput

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Cluster Head Ratio
68
Survival Ratio
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Throughput Comparison with QAPS
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Outline

• IEEE 802.11 MANETs
• Power Saving Problem
• Hybrid Power Saving Protocols
• Simulation Results
• Conclusion

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Conclusion (1/2)

• Taking advantages of both the sync. and async. PS
  protocol, and utilizing the concepts of
  dual-channel and dual-transmission-range
• To save more energy
• To accommodate more hosts
• Without clock synchronization
• No network partitioning

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Conclusion (2/2)

• Adopting cluster-based routing to reduce the
  number of routing request rebroadcasts
  dramatically
• Using dismissal mechanism
• to void the ever-increasing of cluster heads
• to make the protocol adaptive to topology
  changing
• Practical for IEEE 802.11-based MANETs

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References

• Yu-Chee Tseng, Chih-Shun Hsu and Ten-Yueng
  Hsieh, Power-Saving Protocols for IEEE
  802.11-Based Multi-Hop Ad Hoc Networks,
  InfoCom2002, 2002
• Jehn-Ruey Jiang, Yu-Chee Tseng, Chih-Shun Hsu
  and Ten-Hwang Lai, Quorum-based asynchronous
  power-saving protocols for IEEE 802.11 ad hoc
  networks, ACM Journal on Mobile Networks and
  Applications, Feb. 2005. (ICPP 2003 Best Paper
  Award)
• Jehn-Ruey Jiang, Chau-Yuan Yang, Ting-Yao Chiou
  and Shing-Tsaan Huang, "A Hybrid Power-Saving
  Protocol by Dual-Channel and Dual-Transmission-Ran
  ge Clustering for IEEE 802.11-Based MANETs,"
  International Journal of Pervasive Computing and
  Communications, to appear.

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• QA

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The States (1/3)

• Listening State
• Listen in channel B for intra-cluster beacons for
  a period of (q1 beacon intervals plus a random
  back-off time)

0-15 time slots with each time slot occupying 20
µs
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The States (2/3)

• Cluster Head state
• Running async PS protocolfor inter-cluster comm.
• Running sync PS protocolfor inter-cluster
  comm.

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The States (3/3)

• Cluster Member State
• Synchronizing its clock with the cluster heads
• Running sync PS protocol
• Adopting cluster heads quorum information

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Rotation Closure Property (1/3)

• Definition. Given a non-negative integer i and a
  quorum H in a quorum system Q under U 0,,
  n?1, we define rotate(H, i) ji?j?H (mod n).
• E.G. Let H0,3 be a subset of U0,,3. We
  have rotate(H, 0)0, 3, rotate(H, 1)1,0,
  rotate(H, 2)2, 1, rotate(H, 3)3, 2

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Rotation Closure Property (2/3)

• Definition. A quorum system Q under U 0,,
  n?1 is said to have the rotation closure
  property if
• ?G,H ? Q, i ? 0,, n?1 G ? rotate(H, i) ? ?.

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Rotation Closure Property (3/3)

• For example,
• Q10,1,0,2,1,2 under U0,1,2
• Q20,1,0,2,0,3,1,2,3 under U0,1,2,3

?
?
Because 0,1 ? rotate(0,3,3) 0,1 ? 3,
2 ?
Closure
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Examples of quorum systems

• Majority quorum system
• Tree quorum system
• Hierarchical quorum system
• Cohorts quorum system

?
?
?
?
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FPP quorum system

• Proposed by Maekawa in 1985
• For solving distributed mutual exclusion
• Constructed with a hypergraph
• An edge can connect more than 2 vertices
• FPPFinite Projective Plane
• A hypergraph with each pair of edges having
  exactly one common vertex
• Also a Singer difference set quorum system

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FPP quorum system Example
A FPP quorum system 0,1,2, 1,5,6,
2,3,6, 0,4,6, 1,3,4, 2,4,5,
0,3,5
5
5
3
4
3
6
2
0
0
1
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Torus quorum system
5
4
3
2
1
0
1,7,13,8,3,10, 5,11,17,12,1,14,
11
10
9
8
7
6
17
16
15
14
13
12
One half column cover in a wrap around manner
One full column
For a t?w torus, a quorum contains all elements
from some column c, plus ?w/2? elements, each of
which comes from column ci, i1.. ?w/2?
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Cyclic (difference set) quorum system

• Def A subset Dd1,,dk of Zn is called a
  difference set if for every e?0 (mod n),
  thereexist elements di and dj?D such that
  di-dje.
• 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 C(8)

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E-Torus quorum system
Trunk
E(t x w, k)
Branch
Branch
cyclic
Branch
Branch
cyclic