April 11, 2023]Rushin $hah1
Control Aspects in WSN UNIT : 5
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Control aspects in WSN
1. Admission Control
2. Connection control
3. Power Control
4. Baud rate Control
5. Congestion Control
6. QoS Control
Adm Conn ???he is Power full
Baud Rate of Conges
beside the QoS
April 11, 2023]Rushin $hah3
Congestion Control in ATM Networks
ATM is a key Technology for integrating broad-band
multimedia services in heterogeneous networks.
ABR guarantees zero Loss.
UBR source neither specifies nor receives a Bandwidth,
Delay or Loss guarantees.
ATM Service
Category
Guaranteed Service
Best effort Services
Unspecified Bit Rate
(UBR)
Absolute Bit Rate (ABR)
April 11, 2023]Rushin $hah4
Ambiguity of Traffic Control & Congestion Congestion: It is define as condition of an ATM network where
the network does not meet a stated performance objective.
Traffic control: It contain combination of Connection Admission
Control (CAC) to avoid congestion.
The most simplest form of congestion control scheme is the
binary feed back with FIFO queuing.
- Here when the buffer occupancy exceeds a predefined
threshold value, the switch begins to issue a binary notifications
to the sources and it continues to do so until the buffer
occupancy falls below the threshold.
Second scheme is Rate Feedback Control
April 11, 2023]Rushin $hah5
Congestion Control in Neural Network
Number of methods are available to reduce congestion in
communication network.
One of them is NN( Neural Network) Based approach.
NN based scheme possess function approximation and
learning capabilities which can be used directly in many
applications.
The NN based methods can be broadly categorized based on
the learning scheme they employ both offline and online.
The offline learning schemes are used to train the NN,
once trained NN, weights are not updated during run time.
April 11, 2023]Rushin $hah6
Congestion Control in Neural Network
The online learning NN Scheme:
Requires More real computation,
Relaxes the offline training phase,
Avoids the weight initialization problems and
Performs learning and adaptation simultaneously.
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When Congestion Occurs ?
Σ Input rate > available link capacity
Congestion occurs when the input rate is more than
available link Capacity
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When Congestion Occurs ?
Most congestion control scheme consist of adjusting the
input rates to match the available link capacity.
Depending upon the duration of congestion, different
scheme can be applied.
If congestion time is less then the connection time then
end to end feedback control scheme can be applicable.
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Network Model
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Network Model
x(k +1) = f (x(k)) +T*u(k) + d(k)
x(k) – buffer length
T – Sampling time
f(.) – non linear traffic accumulation
d(k) – disturbance at time instant k
Ini – traffic arrival rate at destination buffer
Hd – buffer size
Q – bottle neck queue level
Sr – Service Capacity
April 11, 2023]Rushin $hah11
Predictive Congestion Control for WSN
Predictive congestion control scheme for wireless sensor
network takes into account energy efficiency and
fairness.
This scheme will be implemented through feed back
obtained from one hop.
Existing congestion control scheme, for example Transport
Control Protocol when applied to wireless network, result
in:
Large number of Packet drops,
Unfair scenario and
Low throughput
with significant amount of wasted Energy due to
Retransmission.
Packet na tapkkaBadsurat scene wada
Ochha throw thya
April 11, 202312
Predictive Congestion Control for WSN
]Rushin $hah
The network congestion occurs when either:
- The incoming traffic exceeds the capacity of the outgoing
link or
- Link bandwidth drops because of channel fading caused
by path loss.
April 11, 202313
Predictive Congestion Control for WSN
]Rushin $hah
To predict onset of congestion, the proposed scheme uses
both queue utilization and transmission power under
the current channel state at each node.
When node is become congested, the traffic will
accumulate the nodes because there will be an excess
amount of incoming traffic over the outgoing one. Hence
queue utilization has been selected as an indicator of the
onset of congestion.
On the other hand in wireless networks during fading, the
available bandwidth is reduced and ongoing rate will be
lowered. The channel fading is estimated by the feedback
information provided by DPC protocol for the next packet transmission.
April 11, 202314
Predictive Congestion Control for WSN
]Rushin $hah
Working:
The DPC algorithm predicts the channel state for the
subsequent time interval and calculates the required
power, if this power exceeds the maximum threshold
then the channel is considered to be unsuitable for
transmission and proposed congestion control scheme
can initiate back-off process by reducing incoming
traffic.
There are many algorithms which can be applied for
congestion control like predictive congestion control and
Rate adaption.
Predictive congestion control minimized queue overflow
by regulating the incoming flow.
April 11, 202315
Predictive Congestion Control for WSN
]Rushin $hah
The incoming traffic can be calculated by three
factors:
Predicted Outgoing flow
Wireless Link State
Queue utilization
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Predictive Congestion Control for WSN
]Rushin $hah
Predicted Outgoing flow: The outgoing flow is
periodically measured and an adaptive scheme is used to
accurately predict the outgoing flow in the next period,
moreover the next hop node can reduce the outgoing flow
assessment by applying a control over its incoming flow.
Wireless Link State: The predicted outgoing flow rate is
further reduced when the DPC protocol predicts a severe
channel fading which will disrupt communication on the
link.
Queue utilization: The algorithm restricts the incoming
flow based on the current queue utilization and predicted
outgoing flow, thus reducing buffer overflows.
April 11, 2023]Rushin $hah17
Energy Harvesting in WSN
Energy harvesting also known as:
Power Harvesting or Energy Scavenging.
It is the process by which energy is derived from external
sources (e.g., solar power, thermal energy, wind energy and
kinetic energy), captured and stored for small wireless
autonomous devices, like those used in wearable
electronics and wireless sensor networks.
Energy harvesters provide a very small amount of power
for low-energy electronics.
April 11, 2023]Rushin $hah18
Energy Harvesting in WSN The energy source for energy harvesters is present as ambient
background and is free.
For example, temperature gradients exist from the operation of
a combustion engine and in urban areas, there is a large
amount of electromagnetic energy in the environment because
of radio and television broadcasting.
Energy harvesting devices converting ambient energy into
electrical energy have attracted much interest in both the
military and commercial sectors.
Some systems convert motion, such as that of ocean waves, into
electricity to be used by oceanographic monitoring sensors for
autonomous operation.
April 11, 2023]Rushin $hah19
Energy Harvesting in WSN Future applications may include high power output devices
(or arrays of such devices) deployed at remote locations to
serve as reliable power stations for large systems.
Another application is in wearable electronics, where energy
harvesting devices can power or recharge cell phones,
mobile computers, radio communication Equipment, etc.
All of these devices:
must be sufficiently robust to endure long-term exposure to hostile
environments and
have a broad range of dynamic sensitivity to exploit the entire
spectrum of wave motions.
April 11, 2023]Rushin $hah20
Accumulation of Energy
Energy can also be harvested to power small autonomous
sensors such as those developed using MEMS
technology .
These systems are often very small and require little power,
but their applications are limited by the reliance on battery
power
Scavenging energy from ambient vibrations, wind, heat or
light could enable smart sensors to be functional
indefinitely.
April 11, 2023]Rushin $hah21
Storage of Power
In general, energy can be stored in a capacitor, super
capacitor, or battery.
Capacitors are used when the application needs to provide
huge energy spikes.
Batteries leak less energy and are therefore used when the
device needs to provide a steady flow of energy.
April 11, 2023]Rushin $hah22
Use of the Power
Current interest in low power energy harvesting is for
independent sensor networks.
In these applications an energy harvesting scheme puts
power stored into a capacitor then boosted/regulated to a
second storage capacitor or battery for the use in the
microprocessor.
The power harvesting is usually used in a sensor
application as the data stored or is transmitted possibly
through a wireless method.
April 11, 2023]Rushin $hah23
Devices There are many small-scale energy sources that generally cannot
be scaled up to industrial size:
Piezoelectric crystals or fibers generate a small voltage
whenever they are mechanically deformed. Vibration from
engines can stimulate piezoelectric materials, as can the heel
of a shoe
Some wristwatches are already powered by kinetic energy
(called automatic watches), in this case movement of the arm.
The arm movement causes the magnet in the electromagnetic
generator to move. The motion provides a rate of change of
flux, which results in some induced emf on the coils. The
concept is simply related to Faraday's Law.
April 11, 2023]Rushin $hah24
Devices Photovoltaic is a method of generating electrical power by
converting solar radiation (both indoors and outdoors) into direct
current electricity using semiconductors that exhibit the photovoltaic
effect. Photovoltaic power generation employs solar panels
composed of a number of cells containing a photovoltaic material.
Thermoelectric generators (TEGs) consist of the junction of two
dissimilar materials and the presence of a thermal gradient. Large
voltage outputs are possible by connecting many junctions
electrically in series and thermally in parallel. Typical performance is
100-200 μV/K per junction. These can be utilized to capture mW of
energy from industrial equipment, structures, and even the human
body. They are typically coupled with heat sinks to improve
temperature gradient
April 11, 2023]Rushin $hah25
Devices
Micro wind turbine are used to harvest wind energy
readily available in the environment in the form of kinetic
energy to power the low power electronic devices such as
wireless sensor nodes. When air flows across the blades of
the turbine, a net pressure difference is developed between
the wind speeds above and below the blades. This will
result in a lift force generated which in turn rotate the
blades. This is known as the aerodynamic effect.
Special antennae can collect energy from stray radio
waves or theoretically even light (EM radiation).
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Ambient-Radiation Sources
A possible source of energy comes from radio transmitters.
Historically, either a large collection area or close
proximity to the radiating wireless energy source is needed
to get useful power levels from this source.
The nantenna is one proposed development which would
overcome this limitation by making use of the abundant
natural radiation One idea is to deliberately broadcast RF energy to power
remote devices:
April 11, 2023]Rushin $hah27
Ambient-Radiation Sources One idea is to deliberately broadcast RF energy to power
remote devices: Biomechanical harvesting Photovoltaic harvesting Piezoelectric energy harvesting Tree metabolic energy harvesting Blood sugar energy harvesting
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Ambient-Radiation Sources Biomechanical harvesting
Biomechanical energy harvesters are also being created. One current model is the biomechanical energy harvester
of Max Donelan which straps around the knee. Devices as this allow the generation of 2.5 watts of power
per knee. This is enough to power some 5 cell phones
April 11, 2023]Rushin $hah29
Ambient-Radiation Sources Photovoltaic harvesting Photovoltaic (PV) energy harvesting wireless technology
offers significant advantages over wired or solely battery-powered sensor solutions: virtually inexhaustible sources of power with little or no adverse environmental effects. Indoor PV harvesting solutions have to date been powered by specially tuned amorphous silicon (aSi)a technology most used in Solar Calculators. In recent years new PV technologies have come to the forefront in Energy Harvesting such as Dye Sensitized Solar Cells (DSSC). The dyes absorbs light much like chlorophyll does in plants. Electrons released on impact escape to the layer of TiO2 and from there diffuse, through the electrolyte, as the dye can be tuned to the visible spectrum much higher power can be produced. At 200 lux a DSSC can provide over 15 µW per cm².
April 11, 2023]Rushin $hah30
Ambient-Radiation Sources Piezoelectric energy harvesting he piezoelectric effect converts mechanical strain into
electric current or voltage. This strain can come from many different sources. Human motion, low-frequency seismic vibrations, and acoustic noise are everyday examples. Except in rare instances the piezoelectric effect operates in AC requiring time-varying inputs at mechanical resonance to be efficient.
April 11, 2023]Rushin $hah31
Ambient-Radiation Sources Blood sugar energy harvesting [edit] Another way of energy harvesting is through the oxidation
of blood sugars. These energy harvesters are called Biofuel cells. They could be used to power implanted electronic devices (e.g., pacemakers, implanted biosensors for diabetics, implanted active RFID devices, etc.). At present, the Minteer Group of Saint Louis University has created enzymes that could be used to generate power from blood sugars. However, the enzymes would still need to be replaced after a few years.[47] In 2012 a pacemaker was powered by implantable biofuel cells at Clarkson University under the leadership of Dr. Evgeny Katz.[48]
April 11, 2023]Rushin $hah32
Ambient-Radiation Sources Tree-based energy harvesting [edit] Tree metabolic energy harvesting is a type of bio-energy
harvesting. Voltree has developed a method for harvesting energy from trees. These energy harvesters are being used to power remote sensors and mesh networks as the basis for a long term deployment system to monitor forest fires and weather in the forest. Their website says that the useful life of such a device should be limited only by the lifetime of the tree to which it is attached. They recently deployed a small test network in a US National Park forest.[49]
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