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A Hybrid Power-Saving Protocol by Dual-Channel andDual-Transmission-Rangefor IEEE 802.11-Based MANETs
Presented by
Jehn-Ruey JiangDepartment of Computer Science and Information Engineering
National Central University
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Outline
IEEE 802.11 MANETs Power Saving Problem Hybrid Power Saving Protocols Simulation Results Conclusion
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Outline
IEEE 802.11 MANETs Power Saving Problem Hybrid Power Saving Protocols Simulation Results Conclusion
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IEEE 802.11 Overview
Approved by IEEE in 1997 Extensions approved in 1999 (High Rate) Standard for Wireless Local Area Networ
ks (WLAN)
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IEEE 802.11 Family(1/3)
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(2/3)
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
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Infrastructure vs. Ad-hoc Modes
Infrastructure Network
Ad-Hoc network
APAP
AP Wired Network
Ad-Hoc network
Multi-hop 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 other’s transm
ission 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 Problem
PHY Layer: transmission power control Huang (ICCCN’01), Ramanathan (INFOCOM’0
0) MAC Layer: power mode management
Tseng (INFOCOM’02), Chiasserini (WCNC’00) Network Layer: power-aware routing
Singh (ICMCN’98), Ryu (ICC’00)
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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?
A
BCD
F E
No!Yes!
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Power Mode Management
Doze mode vs. Active mode Example:
A is sending to B Does C need to stay awake?
A
B
C
No!
It can turn off its radio to save energy!
But it should turn on its radio periodiclally for possible data comm.
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Power-Aware Routing
Routing in an ad hoc network with energy-saving (prolonging network lifetime) in mind
Example:
+
–
+
–
+
–
+
–
+
–
+
–
SRCN1 N2
DEST
N4N3
Better!!
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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 energyPower Consumption:(ORiNOCO IEEE 802.11b PC Gold Card)
Vcc:5V, Speed:11Mbps
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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 IntervalsATIM (Ad hoc Traffic Indication Map)
AsynchronousAsynchronous Beacon IntervalsMTIM (Multi-Hop Traffic Indication Map)
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IEEE 802.11 PS Protocol
Beacon Interval Beacon Interval
Host A
Host B
Data Frame
ATIM Window
ATIM Window
Beacon Frame
Target Beacon Transmission Time(TBTT)
No ATIM means no data to send
or to receive with each other
ATIM Window
Clock Synchronized by TSF
ATIM Window
ATIM
ACK ACK
Active mode
Active modePower saving Mode
Power saving Mode
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IEEE 802.11 PS Protocol (cont.)
Single-hop environment Advantages
More power efficiency Low active ratio (duty cycle)
Drawbacks Clock synchronization for multi-hop networks is
costly and even impossible Network partitioning Not Scalable
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Network-Partitioning Example
Host A
Host B
A
B
C D
E
F
Host C
Host D
Host E
Host F
╳
╳
ATIM window
╳
╳
Network Partition
The blue ones do not know the existence of the red ones, not to
mention the time when they are awake.
The red ones do not know the existence of the blue ones, not to
mention the time when they are awake.
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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
References:1. “Power-Saving Protocols for IEEE 802.11-Based
Multi-Hop Ad Hoc Networks,”Yu-Chee Tseng, Chih-Shun Hsu and Ten-Yueng HsiehInfoCom’2002
2. “Quorum-based asynchronous power-saving protocols for IEEE 802.11 ad hoc networks,” Jehn-Ruey Jiang, Yu-Chee Tseng, Chih-Shun Hsu and Ten-Hwang Lai, ACM Journal on Mobile Networks and Applications, Feb. 2005.
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Numbering Beacon Intervals
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
And they are organized
as a n n array
n consecutive beacon intervals are numbered as 0 to n-1
101514131211109876543210 …
Beacon interval
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Quorum Intervals (1/4)
Intervals from one row and one column are called
Quorum Intervals
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
Example:Quorum intervals arenumbered by2, 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
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
Example:Quorum intervals arenumbered by0, 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 915141312
111098
7654
3210
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Quorum Intervals (4/4)
1514131211109876543210
2 151413121110987654310
2 overlapping quorum intervals
Host DHost C
2 151413121110987654310Host D
1514131211109876543210Host C
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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Networks Merge Properly
Host A
Host B
A
B
C D
E
F
Host C
Host D
Host E
Host F
ATIM window
Beacon window
Monitor window
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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 wa
keup predictionDrawbacks
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 (1/5)
A Hybrid PS protocol Synchronous – IEEE 802.11 PS protocol Asynchronous – QAPS
Taking advantages of two types of PS protocols To reduce the active ratio Suitable for multi-hop MANETs
Utilizing the concepts of dual-channel and dual-transmission-range
Forming clustering networks
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HPS Overview (2/5)
Dual transmission rangesCluster head uses Range RA for inter-cluster transmission Range RB for intra-cluster transmission
E
FRA
RB
E, F: cluster heads
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HPS Overview (3/5)
Dual channelsTwo non-interfering comm. channels are used Channel A for inter-cluster transmission Channel B for Intra-cluster transmission
G H
RA
RB
E, F: cluster heads
Channel A
Channel B
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HPS Overview (4/5)
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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HPS Overview (5/5)
Two types of beacon frames Intra-cluster beacon
Send in channel B with transmission range RB
For cluster formingFor clock synchronization
Inter-cluster beaconSend in channel A with transmission range RA
For neighboring cluster heads discoveryFor wakeup prediction
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Structure of Beacon Intervals
B M B M B’ M’
Active period
Active period in channel A
quorum Interval non-quorum Interval
B
B’ M’
Cluster Head
Cluster members
M
B’ M’
: Beacon window and MTIM window in channel A
: Beacon window and MTIM window in channel B
: Monitor mode in channel A
: PS mode
Active period in channel B
quorum Interval non-quorum Interval
Active period in channel B
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State Transition
Listening State
Cluster Member State Cluster Head State
Receive no intra-cluster beacon in channel B over ( q+1 beacon intervals + a random backoff time)
A host enters the network initially
Receive an intra-cluster beacon in channel B from the cluster head
Receive no intra-cluster beacon in channel B from cluster head over ( q+1 beacon intervals + a random backoff time)
Broadcast intra-cluster beacon every non-quorum interval
Receive an intra-cluster beacon in channel B during q+1 beacon intervals
Exeunt mechanism is invoked
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The States (1/3)
Listening State Listen in channel B for intra-cluster beacons for
a period of (q+1 beacon intervals plus a random back-off time)
0-15 time slots with each time slot occu
pying 20 μs
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The States (2/3)
Cluster Head state Running async PS protocol
for inter-cluster comm. Running sync PS protocol
for inter-cluster comm.
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The States (3/3)
Cluster Member State Synchronizing its clock with the cluster
head’s Running sync PS protocol Adopting cluster head’s quorum information
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Cluster Forming (1/2)
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
Simulation area (X-axis)
Sim
ulat
ion
area
(Y-a
xis)
Cluster Head Cluster Member
100 hosts
33 cluster heads
67 cluster members
RB
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Cluster Forming (2/2)
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
Simulation area (X-axis)
Sim
ulat
ion
area
(Y
-axi
s)Cluster Head Cluster Member
500 hosts
45 cluster heads
455 cluster members
RB
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Exeunt Mechanism (1/2)
To keep the fraction of cluster heads ASAP when network topology changes
To balance the load of cluster heads But how?
: Cluster heads
High priority
Exeunt (back to listening state)
Low priority
Exeunt Mechanism is invoked
To detect if hosts are moving too close.
To take service time and residual engergy into consideration.
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Distance Default Exeunt 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 IDSmall cluster head ID Low priority
Exeunt Mechanism (2/2)
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Routing (1/5)
Based on AODV RREQ (Route request) ONLY rebroadcast by
cluster heads Intra-RREQ : within a cluster using channel B Inter-RREQ : between cluster heads using channe
l A RREP (Route reply)
Intra-RREP : within a cluster using channel B Inter-RREP : between cluster heads using channel
A
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1. 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.
2. 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.
3. 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.
Routing (2/5)
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Routing (3/5)
Non-Quorum Interval
RREQ
ATIM Window
ATIM Window
ATIM
ACK
Active mode
Active mode
Cluster member
X
Cluster head
ATIM Window
Active mode
Cluster member
Y
RREP
RREQ
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MTIMRREQ
Routing (4/5)
RB
Cluster member
Cluster head A
Cluster head C
Cluster head B
RA
ACK
RREQ
RREQ
X
Y
RREP
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Routing (5/5)
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
Simulation area (X-axis)
Sim
ulat
ion
area
(Y
-axi
s)
Cluster Head Cluster Member
Source
Destination
RB = Intra-cluster broadcast
RA = Inter-cluster broadcast
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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 Mobility : 0~10m/sec with pause time 20 secon
ds Traffic load : 1~4 routes/sec Number of hosts : 100~1000 hosts
Performance metrics Cluster head ratio Survival ratio Throughput
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Cluster Head Ratio
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000
Number of hosts
Rat
io o
f cl
ust
er h
ead
s (%
) Speed=0
Speed=5
Speed=10
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Survival Ratio (1/3)
0
20
40
60
80
100
120
100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850
Simulation time (sec)
Surv
ival
rati
o (%
)
100hosts, speed=10
200hosts, speed=10
300hosts, speed=10
400hosts, speed=10
500hosts, speed=10
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Survival Ratio (2/3)
0
20
40
60
80
100
120
100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850
Simulation time (sec)
Surv
ival
rati
o (%
)
500hosts, speed=0
500hosts, speed=5
500hosts, speed=10
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Survival Ratio (3/3)
0
20
40
60
80
100
120
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440
Simulation time (sec)
Surv
ival
rati
o (%
)
HPS, 100 hosts, speed=10
HPS, 200 hosts, speed=10
E-Torus(4x8), 100 hosts, speed=10
E-Torus(4x8), 200 hosts, speed=10
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Throughput × Lifetime
0
5000
10000
15000
20000
25000
30000
35000
40000
100 200 300 400 500
Number of hosts
Thr
ough
put x
Lif
etim
e (K
B)
0
5
10
15
20
25
30
35
40
45
Thr
ough
put (
KB
/sec
)
speed=0, Th x Life speed=5, Th x Lifespeed=10, Th x Life speed=0, Thspeed=5, Th speed=10, Th
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Throughput Comparison with QAPS
0100020003000400050006000700080009000
10000110001200013000140001500016000
0 5 10
Moving speed (m/sec)
Thr
ough
put x
Lif
etim
e (K
B)
0
5
10
15
20
25
30
35
Thr
ough
put (
KB
/sec
)
AA, Th x Life HPS, Th x LifeE-Torus(4x8), Th x Life AA, ThHPS, Th E-Torus(4x8), Th
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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 exeunt mechanism to void the ever-increasing of cluster he
ads to make the protocol adaptive to topolo
gy changingPractical for IEEE 802.11-based MANE
Ts