IEEE Consumer Electronics Magazine - March 2018 - 44

forward the collected data toward the base station. The elliptical path of the collector can be adjusted to maintain load
balancing when more sensors are added to the sensing area.

STATE OF THE ART
WSNs with tiny (low-power) sensors for sensing and data
forwarding (data routing) in the IoT for energy efficiency is
addressed in this article. There are several data-routing protocols proposed for IoT and wireless networks in the existing
literature. The traditional methods of data routing toward a
base station include flooding and gossiping [12]. Flooding
means repeated broadcasting, which is a simple and fast
technique for data communication. In the gossiping routing
technique, a sensor node randomly selects one of its neighbors to receive its data. After receiving the data, the neighbor
node selects another neighbor, and the process repeats.
There are three types of data routing based on finding
a route to the destination: 1) proactive, 2) reactive, and
3) hybrid. In a proactive routing protocol, all data dissemination routes to the destination are computed before it is
required, while, in reactive routing protocol, data dissemination routes are computed when it is required. A hybrid routing protocol is the combination of both proactive and reactive
protocols. The mobility model of sensors is classified into
three major categories: controlled, predictable, and random.
In random mobility, the data collector arbitrarily moves without depending on network conditions, i.e., network information is not required for mobility. In predictable mobility, the
data collector's movement is based on a certain strategy. It
does not require frequent updates of the collector's position
information. In controlled mobility, the mobility of the data
collector is managed based on a certain criterion, such as an
event position, residual energy, and so on. The sink controls
the mobility to reduce energy consumption and increases the
lifetime of the network. Security plays a vital role in the IoT,
as sensors are deployed in a hostile environment [13], [14].
Based on the mobility of the sink, the data dissemination
protocol can be further classified into two types: 1) a data dissemination protocol with a mobile sink and 2) a data dissemi-

Sensor Node

Collector Node

Data Collector

FIGURE 3. The data dissemination in railroad protocol.
44 IEEE Consumer Electronics Magazine

MARCH 2018

nation protocol with a static sink. In a specific protocol
example, Railroad constructs a virtual rail structure in the middle of the sensor field [15]. The source node locally stores
sensed data and then forwards the corresponding metadata to
the closest rail node inside the rail, as shown in Figure 3. The
sink sends a query message into the rail to collect the required
data. Railroad increases overhead and consumes more energy
as the query message travels through the rail until it obtains the
metadata of the required data. In another protocol example,
ring routing constructs a closed loop, taking sensor nodes with
single-node width around the center of the sensor field, as
shown in Figure 4 [16]. When the energy level of the ring node
decreases, it selects another neighbor node as a ring node and
constructs a new ring, i.e., the ring structure changes. The
mobile data collector selects a neighboring node as an anchor
node. After selection of the anchor node, position information
for the anchor node is forwarded to the ring. When the source
wants to send data to the sink, it sends a request message to the
ring for the anchor node position information. Then the ring
forwards a response message.

A PROPOSED DATA-ROUTING TECHNIQUE
Sensor nodes of the proposed technique play two parts: 1) the
collector node and 2) the normal node. The data-forwarding
node is the neighboring sensor node selected by the mobile
data collectors while rotating in the predefined elliptical path.
Except for the forwarding node, all of the sensors in the sensing area act as standard source sensor nodes. After the sensor
node deployment, a path is discovered for the mobile data
collectors, based on the concept of covering a maximum area
of the WSN. In the proposed technique, the data collector
repeatedly rotates in a predefined elliptical path to collect a
portion of data from the source nodes through collector nodes
and delivers it to the base station.

ASSUMPTIONS
Realistic assumptions have been made to design the routing
technique. One of the assumptions was to position the base
station at the center of the sensing area. A large number of

Ring Node

Sensor Node

Data Collector

FIGURE 4. The data dissemination in ring-routing protocol.

Table of Contents for the Digital Edition of IEEE Consumer Electronics Magazine - March 2018