IEEE Consumer Electronics Magazine - September 2018 - 37

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My event detect message (MEDM): Retains the IDs and
positional information of the event-tracking SLs.
My update SL message (MUSLM): Has the IDs of the
event-detecting SLs lying within the DOF of already-actuated camera sensors.

Every sensor S v, i estimates its mean distance from all of
the remaining scalars pertaining to the corresponding virtual
compartment v according to the following expression:
k

D Sv, l =

S v, i, S v, j,

(3)

j=0 j!i

PROPOSED CMT-MDSD ALGORITHM
The symbols used in the algorithm are illustrated in Table 1.

THE CMT-MDSD
A DESCRIPTION OF THE STEPS
OF THE CMT-MDSD ALGORITHM
STEP 1: INITIALIZATION AND SEGREGATION OF REGION
Initially, all scalar sensors S i (S 1, S 2, S 3, f, S n) and camera
sensors C j (C 1, C 2, C 3, f, C m) are randomly sprinkled throughout the geographic region. Subsequently, the scalars and cameras broadcast My Scalar Information Message (MSIM) and
My Camera Information Message (MCIM), respectively, to
know each other's ID and position information. Afterward,
they estimate the Euclidian distance Dist (S i, C j) between
one another.
Then the sensors update the MYDIST table based on the
estimated distance. If the Dist (S i, C j) < DOF of the camera,
then the scalar lies within its DOF. Otherwise, it is checked
whether the scalar is a sensing neighbor of the concerned
camera or not. Two sensors are said to be each other's sensing
neighbors if Dist (S i, C j) # 2 # Sr, where Sr is the sensing
range of a scalar sensor. If a particular camera has a scalarsensing neighbor, only then does it undergo a decision-making
process; otherwise, there is no need to actuate that camera.
The whole monitored region is segregated into a number of
virtual compartments so that
C L = 2 # DOF = M L ,
10

(1)

where C L denotes the side length of the virtual compartment
and M L represents the side length of the monitored region. In
this case, C L is considered to be twice the value of the DOF,
i.e., 2 # DOF, which is the diameter along which an omnidirectional camera ensnares an image of any object. Furthermore, the default value of the DOF is considered to be 25 m.
Thus, 2 # DOF = 50 m, which is one-tenth the length of the
monitored region. Therefore, we have chosen a monitored
region of size 500 # 500 m 2 .

STEP 2: SL DETERMINATION
The scalar sensors in each compartment are assigned compartmental IDs, which are maintained in the CSIDT table for
every virtual compartment. Then, the SLs are selected in each
virtual compartment in the following manner:
v e " 1, 2, 3, 4, 5, f, tnvc , and i # n,

where i, j e " 1, 2, 3, f, CSC ,, i ! j, and i, j # n; D Sv, l represents the mean distance of any scalar i in virtual compartment
v from the other scalar sensors there; i, j are the IDs of the
scalars belonging to virtual compartment v; and CSC represents the total number of scalars residing in a compartment.
Likewise, all of the scalar sensors S V , i calculate the D Sv, l
value with the remaining scalar sensors pertaining to the concerned virtual compartment. The scalar that has the least
mean distance value D Sv, l in a particular compartment is
selected as the SL of that compartment. In the same manner,
SLs are selected in each virtual compartment.

STEP 3: EVENT OCCURRENCE, DETECTION, AND
CAMERA COLLABORATION
When multiple events E b (b = 1, 2, 3, f, n e), where n e is the
number of prevailing events, take place in the monitored
zone, the selected SLs that come under the purview of the
prevailing events detect them. Consequently, they report to
their respective cameras regarding the events by broadcasting
MEDM. Then, each of the cameras adds the IDs of the SLs
that come within its purview to its corresponding MSLT
table. Now WL is updated so it contains the IDs of only those
camera sensors that detect the event. At the beginning, the
camera sensor that comes first in WL is activated and broadcasts MUSLM. As soon as a camera sensor is activated, its
ID is added to CAL and deleted from WL.
Suppose that C f is the first camera sensor activated and C n
is the camera sensor that comes after C f . If the IDs of all of
the SLs contained in the DOF of C n match completely with
those of C f , then there is no need to activate C n. Otherwise, C n
goes to an on state. Similarly, the rest of the camera sensors
are sequentially activated by matching their respective SL IDs

Table 1. The symbols used.
Parameters

Values

S i (S 1, S 2, S 3, f, S n)

Scalar sensors

C j (C 1, C 2, C 3, f, C m)

Camera sensors

D Sv, l

In virtual compartment v, the mean
distance of any scalar i from the
remaining scalar sensors belonging to
that compartment

CC WL

The number of cameras present in WL
and MUSLM represents a MUSLM that
retains the IDs of the scalars that reside
within the DOF of a particular camera

Any immediate camera coming after C j
in WL

(2)

where tnvc is the total number of virtual compartments, and n
is the total number of scalar sensors deployed.

september 2018

IEEE Consumer Electronics Magazine

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