Wireless Sensor Networks
Wireless sensor networks (WSNs) have been around for quite some time now and have found widespread use in the natural environment. They can be deployed for a number of different purposes, ranging from military surveillance to environmental monitoring. Many implementations include a number of inexpensive, low-power wireless sensors that can be remotely activated and controlled. Their operation is based on a simple algorithm: when a sensor detects a condition (either physically or electronically) that needs to be monitored, it immediately transmits a measurement to a central device, which processes the information and potentially takes further action.
WSNs are extremely versatile and can be implemented in a variety of ways. One particular implementation that we will explore in detail involves harvesting solar energy to power wireless sensors. We will cover the following topics:
When designing a wireless sensor network, a number of considerations must be taken into account, beyond just putting the hardware in place. As the name would suggest, this type of network is usually designed to work without the intervention of human operators, who would otherwise be needed to continuously run the network and collect data. This requirement puts additional constraints on the system’s design, as there are a number of things that the designer must ensure happens seamlessly without any errors. One of the most important areas where human intervention is minimal is in the power management of the sensors, as improper management can lead to damage or malfunction of the device. To keep things simple, let’s consider a scenario where a batch of 10 wireless sensors are being deployed in an area where there is no grid power available. Depending on the design of the sensors, this could mean they are constantly drawing power from a rechargeable battery, which will eventually run out, or they could be completely independent of any type of power supply, in which case they will need to be manually switched on and off by the user or programmable controller (such as a microcontroller or Arduino). Regardless of what type of sensor you choose, one thing is for sure – the power consumption of these devices is always going to be higher than a traditional sensor node, which is equipped with its own energy source (such as solar or wind power).
Where Do I Put the Hardware?
Another important element to consider when designing a wireless sensor network is where do I put the various hardware components? This will depend on a number of different factors, ranging from space availability to the placement of other devices or furniture in the vicinity. In most cases, it’s better to put all the electronics in one place, which in this case would be the base station. This could be a physical location (such as a building or shipping container) or a remote cloud server, depending on your requirements. In general, we would suggest putting the cloud server in a physically tamper-proof location, away from any outside access. Ideally, this would be in a secure and well-lit place; there should be no chance of any external device being plugged into this unit while it is in operation. Placing all the electronics in one place also makes it much easier to maintain and service. Keep in mind that putting all the electronics in one place does not always mean they need to be in the same physical location, but it can easily be accomplished through the use of networked computers and storage devices, such as a storage space in the cloud or a remote hard drive.
As for the placement of the various sensors themselves, we would suggest putting them in locations that provide the best overview of the area or situation that is being monitored. This could be done through a variety of means, ranging from radio-frequency (RF) propagation to light detection and ranging (LiDAR). The placement of the sensors will depend on a variety of factors, ranging from space availability to the type of environment that they are being deployed in. As an example, if you are working in a large industrial area and there are many possible RF propagation paths, then arraying a number of sensors at different locations along these paths could provide a 360-degree view of the area. A light-emitting diode (LED) illuminated circle on the ceiling could also alert people to the fact that someone is in the vicinity, even if they are not in physical proximity. In a typical warehouse setting, placing the sensors on the ceiling could provide the best overview of the entire space.
How Do I Connect the Sensors?
One of the most important aspects of any wireless sensor network is how do I connect the various sensors to the base station or gateway? A variety of different protocols could be used for this purpose, ranging from wired networking to wireless ones (such as Wi-Fi or Bluetooth). The type of connection will depend on a number of factors, ranging from the physical location of the devices to their operating requirements. In most cases, it is better to use a wireless connection for this purpose, as it allows for much easier and quicker connection and reconfiguration of the network, as well as increased range and reliability. If you are using wired connections, then either use a dedicated line for the sole purpose of connecting the devices or make sure that there are no other devices (such as phones or laptops) connected to the same network segment, as this could lead to conflicts and errors. In particular, we would suggest using a dedicated line with a known IP address for the sole purpose of connecting the sensors, as dynamic IP addresses can be difficult to track down and often lead to errors and malfunctions. In addition to being more secure, using a known IP address also makes it much easier to set up and maintain the network. In most cases, it’s best to use a firewall to enforce a secure and restricted connection between the base station and the sensors. In addition, all the communication between the devices must be monitored and logged, to ensure that no suspicious activity takes place. This could be accomplished through the use of a VPN or similar technologies. When designing this type of network, a number of things must be kept in mind:
- the range of the various sensors must be taken into account (which will often depend on the placement of other devices or buildings in the vicinity)
- the type of environment that the network is being deployed in (ambient environment vs. controlled environment)
- the number of connections that can be handled simultaneously (depending on the type of hardware)
- the security of the various connections (WLAN vs. VPN vs. etc.)
- the reliability of the various connections (cabled vs. wireless)
- electromagnetic interference (EMI) (which is more often the case in industrial settings)
- how do I power the various devices (battery vs. solar vs. etc.)
One of the most important aspects of any wireless sensor network is how do I design an effective power supply system for the various devices? Depending on the range of the various sensors and the placement of other devices or structures in the area being monitored, this could involve the use of wired or wireless power sources. There are a number of different options that can be used to power the various devices, ranging from rechargeable batteries to solar power. Rechargeable batteries are the simplest and most common solution and have the advantage of being relatively inexpensive and easily available. Depending on the design of the sensors and the area that they are being deployed in, this could involve the use of several different types of batteries (such as LR44 or CR2032 for low voltage and high voltage applications, respectively).
One of the most important aspects of any wireless sensor network that has been discussed so far is how to connect the various sensors to the base station or gateway. This aspect involves several considerations, ranging from the type of connection to be used to the physical placement of the devices and other structures in the area being monitored. In many cases, using wireless connections for this purpose is the simplest and most effective way to go about it. In particular, we would suggest using either wireless networking or Bluetooth for connecting the devices, as these are often the most popular and easiest to use protocols out there. In addition to making connections easier and more convenient, using wireless technologies for this purpose also provides the advantage of increased range and reliability. If you decide to use this option, then make sure that your firewall is configured to allow for the required connections between the devices. Otherwise, this could lead to errors and potential security breaches.