Transcript a set of sensor nodes in the same locality

Wave Addressing for
Dense Sensor Networks
Serdar Vural and Eylem Ekici
Department of Electrical and Computer Engineering
Ohio State University, Columbus
Proceedings of Second International Workshop on Sensor and Actor
Network Protocols and Applications (SANPA 2004)
jenchi
Outline
► Introduction
► The
WADS Mechanism
(Wave Addressing for Dense Sensor networks)
 Wave Source Selection
 Wave Propagation and Region Generation
 Address Ambiguity Elimination
► Performance
► Conclusion
Evaluation
Introduction
► Various
techniques have been proposed to
determine the location of sensor nodes
 Using GPS
►Increase
the cost of nodes
►Fast depletion of limited energy sources
 Signal strength measurement
►Increased
complexity of sensor nodes
Introduction
► However,
many application can tolerate higher
level of uncertainty in location information
 Intrusion detection
 Interception applications
► It
is not necessary to implement costly, energyinefficient, and infrastructure-reliant localization
schemes that provide high fidelity localization
Introduction
► Objective
of this paper
 To introduce Wave Addressing for Dense Sensor
Networks (WADS) method
►To
form a coordinate system called Wave Mapping
Coordinate (WMC)
 Without requiring specialized hardware in
sensor nodes or infrastructure support in the
network
The WADS mechanism
► System
Description and Assumptions
 To assume that the sensing application requires
densely and randomly deployed sensor nodes in
the sensing field
 Sensor nodes
►Identical
communication capabilities
►No mobility
►No synchronization
The WADS mechanism
► WADS
operation
 To create the WMC system using the hop
distance of sensors from two randomly selected
sensor nodes (wave sources)
 Every node in the network receives two wave
IDs
 Note that region IDs do not belong to a single
sensor nodes but to a set of sensor nodes in the
same locality
The WADS mechanism
8 hops
10 hops
The WADS mechanism
► WMC
system is accomplished in three steps
 Wave Source Selection
 Wave Propagation and Region Generation
 Address Ambiguity Elimination
Address Ambiguity Elimination
C
(8,10)
Wave Source Selection
► To
select the sensor nodes that will serve as the
two reference points in the network
► Two
possible wave source deployment scenarios
 Pre-deployment selection
► Two
wave sources must be placed sufficiently separated from
each other
 Post-deployment selection
► Since
the sensor network is large, it is easier to use simpler
distributed algorithms that incurs lower overhead
Wave Source Selection
— Post-deployment selection
► Every
sensor generates two numbers
 A random number (ID)
► determines
if it is a potential candidate for the first or second
wave source
 A random number Nwait between 0 and Nmax
► Nmax
determines the maximum delay tolerance of the system for
WMC system generation
► Sensor waits for T = Tturn X Nwait ,
where Tturn is the unit time period, which is in the order of the
delay of a packet that would travel the maximum diameter of
the network
Wave Source Selection
— Post-deployment selection
► Once
there two numbers are generated, the
sensor starts waiting until
 It receives an ID from another wave source with the
same source ID (1 or 2)
 Or its timer T expires
► If
a sensor receives a wave packet with a
matching source ID as its own selected ID before
its timer expires, it cancels its timer
 Otherwise, the sensor generates the first wave packet
Wave Source Selection
— Post-deployment selection
(2)
(3)
2
(3)
(3)
1
(3)
1
2
(1)
2
2
(2)
2
1
(3)
(2)
(3)
2
(1)
(3)
(2)
1
(3)
(1)
2
(3)
1
(3)
1
2
(1)
1
(3)
1
(2)
2
(3)
1
2
2
(3)
1
2
(1)
1
Wave Source Selection
— Post-deployment selection
(2)
(3)
2
(3)
(3)
1
(3)
1
2
(1)
2
2
(2)
2
1
(3)
(2)
(3)
2
(1)
(3)
(2)
1
(3)
(1)
2
(3)
1
(3)
1
2
(1)
1
(3)
1
(2)
2
(3)
1
2
2
(3)
1
2
(1)
1
Wave Source Selection
— Post-deployment selection
(2)
(3)
2
(3)
(3)
1
(3)
1
2
(1)
2
2
(2)
2
1
(3)
(2)
(3)
2
(1)
(3)
(2)
1
(3)
(1)
2
(3)
1
(3)
1
2
(1)
1
(3)
1
(2)
2
(3)
1
2
2
(3)
1
2
(1)
1
Wave Source Selection
— Post-deployment selection
► In
case two waves with the same source ID
is present in the network
(two sensors selecting the same Nwait value),
 ties may be broken by random number in the
wave packets inserted by wave sources
(Random Source Identifier)
Wave Propagation and Region
Generation
► Once
the wave sources are determined, the
sources initiate wave mapping procedure by
broadcasting wave packets
 Source ID (SID) ：take a value of 1 or 2
 Distance to Source (DS) ：incremented by one every
time the message is broadcast
 Random Source Identifier (RSI) ：a random number
generated by the wave source which is used to break
ties
► EX：The
wave source WS1 initiates the wave
packet in the format (SID=1, DS=0, RSI)
Wave Propagation and Region
Generation
► Every
sensor nodes Si is associated with an ID
pair (ID1i , IDi2 ) that indicated the region they
belong to
► Every sensor also keeps track of the random
source identifier RSI1 and RSI2 of both wave
sources
Wave Propagation and Region
Generation
(2)
(3)
2
(3)
(3)
1
(3)
1
2
(1)
2
2
(2)
2
1
(3)
(2)
(3)
2
(1)
(3)
(2)
1
(3)
(1)
2
(3)
1
(3)
1
2
(1)
1
(3)
1
(2)
2
(3)
1
2
2
(3)
1
2
(1)
1
Wave Propagation and Region
Generation
(1)
1
x
(1)
1
Wave Propagation and Region
Generation
► Once
a sensor Si obtains an ID pair, it identifies
itself as belong to a region with the same ID pair
 Rnm
► n=ID1
and m=ID2
► Note
that not all nodes in the same region are
within each other’s direct communication range
 To assume that all nodes of a region form a connected
subgraph
Address Ambiguity Elimination
C
(8,10)
Address Ambiguity Elimination
► The
first step
 To designate a sensor DSnm as the representative of a
region Rnm
► To
select the sensor node that has the highest number of
neighbors of the same ID pairon
 Once selected, each DSnm generates a random
designated sensor identifier (RDSInm) to uniquely
identify its region
 To use RDSIs to associate neighboring regions with
correlated codes
Address Ambiguity Elimination
► The
second step
 To identify the regions that lie on the line that
connects two wave sources => border regions
Address Ambiguity Elimination
Address Ambiguity Elimination
► The
third step
 To disseminate identifying codes to both sides of the
borders
 Partition identifiers (PIDs) are generated by messages
sent by both wave sources
 Each region will have a four bit PID
Address Ambiguity Elimination
PID=1010
PID=1000
Performance evaluation
►A
set of experiments on random sensor
network topologies
 There are 4X2X2=16 different scenarios
►For
each scenario, 100 independent random
networks have been generated
Square Field
750 Nodes/Km2
1000 Nodes/Km2
1500 Nodes/Km2
2000 Nodes/Km2
Corridor Field
750 Nodes/Km2
1500 Nodes/Km2
1000 Nodes/Km2
2000 Nodes/Km2
►
Example wave mapping coordinate systems for close wave
sources
Conclusions
► The
WADS create a virtual coordinate
system in dense sensor networks
► Do not require GPS device or signal
processing capabilities in the sensor nodes
► No infrastructure support such as special
location beacons are necessary
► The WADS utilizes two randomly selected
nodes to form the WMC system