measurements performed on the third point of measurement
showed significant values of packets loss (Figure 15). In this
kind of environment, the LR-WPAN IEEE 802.15.4 network has
suffered more with the presence of obstacles than in the external
environment, due to problems with multi-ways and reflections.
5.4 Coexistence Test Between IEEE 802.15.4
LR-WPAN, IEEE 802.11b/g and IEEE
802.15.1.
This test refers to the coexistence between networks that use the
default choice here in our study (LR-WPAN IEEE 802.15.4) and
IEEE 802.11b/g standard. The 15, 20, 25 and 26 channels can be
used by the IEEE 802.15.4 standard, since they do not interfere
of IEEE 802.11b/g standard transmissions, and vice versa. All
results were generated from the 25 channel, at 2.425 MHz,
frequency that does not interfere in the transmission of IEEE
802.11b/g standard, and the maximum power transmission in all
transceivers [3].
Used in this test, the same methodology used in [3] where the
IEEE 802.11b/g network access point was maintained at 1 meter
radius of our network at the external environment, obstacles free,
representing the field’s real implementation. The master
transceiver sent, every 1 ms, an order for reading to one of slave
transceivers, a total of 5000 packets transmitted (IEEE 802.15.4)
at the same time, it was done a file downloading (IEEE
802.11b/g), using an Internet connection link at 512 Kpbs. At the
end of the tests, the results were measured and a new battery of
tests was performed, achieving a total of 10 batteries of similar
tests.
As noted in [3], when the IEEE 802.11b/g network was enabled,
it caused little interference with the data traffic from WSN (-30
dBr), causing small packets loss, resulting in a slight increase in
the number the transmission, generating modest increase in
latency of the network IEEE 802.15.4. In our tests, this loss was
less than 1% of total packets transmitted, on average, which
shows the ideal choice of channel 25 for WSN transmission.
When the Wi-Fi was disabled, there was an immediate increase
in stability and a decrease in latency, due to lack of interference
caused by IEEE 802.11b/g network traffic. During the tests,
there was no drop in either of the two networks, and the
packages that were not sent back the WSN were retransmitted
successfully.
For the tests regarding to coexistence with the IEEE 802.15.1
(Bluetooth), it was used the same methodology used previously,
but instead to be performed a download, it was a transmission of
data between two devices (laptop and mobile). Because the IEEE
802.15.1 standard using the technique of spread spectrum, the
IEEE 802.15.4 network at any time has suffered significant
interference.
6. CONCLUSION
From studies and tests performed, it was possible to observe the
viability of the proposed project with regard to information
exchange and management of them. The link of communication
between the wireless boards proved to be reliable in the item lost
packets. As there was no equipment to carry out the
measurement of BER or PER, it was necessary to develop a
system to quantify the data loss of this link, as opposed to use in
different environments, in order to qualify it. The system has
proved robust and reliable in any two environments where it was
tested.
Some of the advantages of the proposed system are the
portability and the fact that the components of the photovoltaic
system are locally commercialized, with dimensions suitable for
implementation in the field, which recharge the batteries that
fuel sensors and transceivers located in wireless slaves modules.
Regarding MC13192 modules, it was performed tests of energy
efficiency and distance tests. Based on these tests there is the
low consumption of these, but will be conducted the same tests
with the modules connected to sensors and actuators. These tests
serve to batteries and/or solar panels dimensioning, which feed
the RF module-sensor system. Then boxes are manufactured for
each system, which should be classified into areas with
explosions risk. Then be tested in field to verify the feasibility of
the project, taking into account these and other changes that
arise.
ACKNOWLEDGMENTS
The completion of this project is only viable due to the financial
incentive of PETROBRAS, as well as Edson Henrique
Bolonhini, Engineer.
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