29-05-2013, 01:11 PM
Improving Energy Saving and Reliability in Wireless Sensor Networks Using a Simple CRT-Based Packet-Forwarding Solution
Improving Energy Saving.pdf (Size: 2.41 MB / Downloads: 46)
Abstract
This paper deals with a novel forwarding scheme for
wireless sensor networks aimed at combining low computational
complexity and high performance in terms of energy efficiency and
reliability. The proposed approach relies on a packet-splitting algorithm
based on the Chinese Remainder Theorem (CRT) and is
characterized by a simple modular division between integers. An
analytical model for estimating the energy efficiency of the scheme
is presented, and several practical issues such as the effect of unreliable
channels, topology changes, andMACoverhead are discussed.
The results obtained show that the proposed algorithm outperforms
traditional approaches in terms of power saving, simplicity,
and fair distribution of energy consumption among all nodes in the
network.
INTRODUCTION
AWIRELESS sensor network (WSN) is composed of a
large number of low-cost devices distributed over a geographic
area. Sensor nodes have limited processing capabilities,
therefore a simplified protocol architecture should be designed
so as to make communications simple and efficient. Moreover,
usually the power supply unit is based on an energy-limited
battery, therefore solutions elaborated for these networks
should be aimed at minimizing the energy consumption. To this
purpose, several works have shown that energy consumption
is mainly due to data transmission, and accordingly energy
conservation schemes have been proposed aimed at minimizing
the energy consumption of the radio interface [1], [2], [10].
RELATED WORKS
Energy saving, reliability, and complexity are three key issues
With regards to energy saving, two main approaches can be
found in the literature: duty cycling and in-network aggregation;
see [2] and [10], respectively. The first approach consists
in putting the radio transceiver on sleep mode (also known as
power-saving mode) whenever communication is not needed.
Although this is the most effective way to reduce energy
consumption, a sleep/wakeup scheduling algorithm is required
(which implies solving critical synchronization issues), and
energy saving is obtained at the expense of an increased node
complexity and network latency. The second approach is intended
to merge routing and data aggregation techniques and
is primarily aimed at reducing the number of transmissions. In
this perspective, and in the specific target to improve robustness
of data aggregation, multipath routing algorithms together with
erasure codes can be employed. However, as will be discussed
in Section VI, the most commonly used erasure codes are not
suitable for WSNs.
ANALYTICAL RESULTS
In this section, we derive some analytical results regarding
the proposed CRT-based forwarding method. The main results
are briefly summarized as follows.
1) It is shown that by fixing the length of the packet, , a
maximum value of the number of CRT components, ,
exists above which the energy reduction factor starts to
decrease. We explain the reason for this behavior and how
to obtain this threshold, .
2) The impact of the number of admissible failures, ,
on the ERF and on the network reliability is evaluated
analytically.
3) An analytical model that can be used to estimate the mean
energy reduction factor achievable with the proposed forwarding
scheme is derived, and it is proved that, under
proper conditions, the proposed forwarding algorithm is
able to reduce the mean energy consumption by about 37%.
4) The overhead due to a possibleMAC header is analytically
derived.
Analytical Model
Here, we derive an analytical model that can be used to estimate
the mean energy reduction factor achievable with the proposed
forwarding scheme. Furthermore, we prove that when
compared to a traditional forwarding algorithm, and when a
large number of nodes and messages are considered, the proposed
algorithm is able to reduce the mean energy consumption
by about 37%.
CONCLUSION
In this paper, we have presented a novel forwarding technique
forWSNs based on the Chinese Remainder Theorem (CRT). In
particular, we have derived an analytical model able to predict
the energy efficiency of the method, and we have especially focused
on some implementation issues.
First, we have discussed the choice of the CRT algorithm parameters
in order to keep the processing complexity low, then
we have derived a tradeoff between energy consumption and
reliability.
Finally, we have investigated the overhead introduced in
terms of packet header size. Simulation results have confirmed
the results obtained analytically and have shown that applying
the CRT-based technique significantly reduces the energy consumed
for each node, and consequently increases the network
lifetime.