Sensor Networks can help gather real world data to form real-time models and make better business strategies. Temperature, light, humidity and motion are just a few examples of parameters that can be retrieved from sensors. The more diverse data that is collected, the more analysis and models can be developed to track and expand your business. With the advancement in technology, sensors have miniaturized in both size and power consumption. This allows them to be more commonly used in a non-invasive form and with little to no maintenance. By deploying multiple sensors and connecting them together, highly capable sensor networks can be formed. The challenge remains in how to transport this data from power striven devices, to a hub with "unlimited" power. There are multiple wireless protocols available that cut physical cords and make it possible to deploy sensors in multiple locations with just a battery.
Since the primary purpose of sensors is to retrieve information, choosing the right wireless technology for your device or application is an important part of the process. The amount of data versus the amount of power needs to be weighted in to make the most adequate decision. We will cover the benefits, drawbacks, and range for the following technologies:
- ZigBee
- Bluetooth
- WiFi
- Cellular
- Satellite
ZigBee
ZigBee is one of the several mesh network technologies available. Each device acts as a node that can rely information to another node. As long as these nodes are in close proximity, data can be transmitted to a neighboring node. Since there is no centralized point in charge, nodes don't have to utilize great amounts of power to transmit a message to a far away end point. This distributed system is resilient due its ability to establish several paths. The network can easily be expanded or modified with little disruption. One of the challenges of this approach is that managing the network can become complicated due to the unstructured nature of the system. For example funneling multiple does through a single node can cause bottle necks in periods of high traffic. Licensing can also be complicated to deal with.
Bluetooth
Bluetooth has been a popular choice among consumer electronics. In terms of sensor devices, the traditional technology can be prohibitively expensive due to its high power demands. Alternatively, Bluetooth Low Energy (BLE) has been developed to meet low power consumption with high data rates (at a somewhat limited interval). Multiple Operating Systems (OS) have support for BLE as the technology is primarily intended to interact with users. BLE is limited to a few simultaneously active devices at most with the access point. Its short range capability constrains the device connection within the same room. BLE will also soon incorporate the capability to operate in mesh networks which will go in direct competition with ZigBee. BLE has primarily exploded with wearables, devices that reside within close proximity of the user and periodically scan biometric signals.
WiFi
WiFi is the default gateway across multiple devices. Portable game consoles, laptops, cameras and any major consumer electronic have WiFi accessibility. Access points can easily be deployed and allow multiple devices to easily integrate to the network. However having a flexible and open network can pose a security threat if an outside agent gains access to the network. WiFi is better suited for applications that require a faster connection and a better range to the base station. With some degradation, the signal can also travel through certain walls. Though it offers a wider range, and the signal can be extended with repeaters, the devices are mostly fixed and bounded within a certain area. Devices are usually wired directly to a power source or carry a larger battery to satisfy usage for several hours at most.
Cellular
Using cellular opens communication beyond enclosed environments and provides extensive coverage for mobile devices. Service is available for the majority of the areas where there are inhabitants. Networks are independently managed by companies which is one less factor to worry about. The downside comes with cost as their is a recurring cost for the service being provided. For a few devices, the service can be well worth it. When thousands of devices are deployed, the service costs can quickly add up. Also, devices need to go through certification in order to deem then worthy of utilizing network resources which is a costly process. There are also certified modules in the market that can offset the cost when producing a limited quantity of devices. Power is also a concern, however, as the industries moves into IoT (Internet of Things), cellular is optimizing its standards to adapt low power devices. Another benefit is security, since there is a very low possibility in snooping the signal between any two devices connected by cellular. Cellular is beneficial for applications that are remotely located or require relocation.
Satellite
Satellite Communication may be the most expensive to use in both terms of power and design. While deploying an IoT solution in this form is complex, this will be a feasible option in the future due to its larger range and coverage. As the world becomes more globalized, businesses will find communication solutions that go beyond borders as necessary. Take GPS as an example that has made everyday location tracking a simple and everyday activity. The technology has made its way from large military structures devices to small handheld devices such as smartphones. With the reduction in cost of space launches and space exploration taking new grounds, a new market will be opening not too far from now. Cube Satellites (CubeSat) are becoming more affordable and feasible for organizations wishing to secure a dedicated spot in the skies. The evolution of sensor devices in earth will provide a fertile ground for rapid evolution of technologies. Satellite communication is more feasible when sensors in isolated areas are being deployed. It is also worth mentioning that there is some delayed introduced since signals travel a great distance.
In summary, each of these wireless technologies posses advantages and disadvantages. Depending on the scale of deployment, sometimes combining one or two technologies may complement limitations found in the other. When you have decided by what means to gather data, the next step will be to store it, process it and provide access to the results via web.