Selecting a Wireless Sensor Development PlatformThe plethora of wireless sensor network development solutions offered today is overwhelming. It is not possible in any way to give a comprehensive coverage of the market.
Depending on your selection criteria this could be an easy choice or could be a difficult process. I spent more than a month looking at solutions from different vendors before jumping into the depths of new hardware, APIs and mountains of documentation. Since all these standards are evolving, the updates from the vendors are exacerbating the already steep learning curve.
Navigating the proprietary and official standards is difficult, depending on the marketing flavor experiences at some of the web sites. Another difficulty is that different hardware/software solutions are hard to compare, because there is no metric.
It is too hard to determine quantitatively how much better is certain technology compared to another. The best alternative is to rely on common sense and some guiding principles, such as open source versus proprietary code, open communication standard versus one company solution, etc. This article will present the problems a designer will face when implementing a wireless sensor network and the factors that are important in deciding which development platform to select.
Design Challenges for Wireless
There are some specifics as far as wireless sensor networks are concerned. These make the deployment and maintenance of such networks very different than other widespread network technologies. We need to be aware of these specific characteristics in order to do a better job when developing our engineering solutions. Here is a brief description of the major challenging facts about wireless sensor networks.
Cost. It is possible, depending on the application, to have hundreds or thousands of sensor nodes deployed in a single site. That makes the project cost sensitive. For some trivial uses like light switches and tire pressure control the expected price is also very low to making their use economically feasible.
Scalability. The number of sensor in a deployment may be in the thousands of node, even millions. With such high numbers new network management issues arise. This will have a significant impact on maintenance and diagnostics and will necessitate the widespread use across the application of new network diagnostic tools.
Fault Tolerance. Since sensors can be deployed everywhere - on bridges, industrial sites, homes, farms, etc. - they will be subjected to harsh environmental conditions and may vandalized, stolen or damaged. What you want is a network configuration that continues to operate even if one or more node in the network fails, is stolen or is damanged.
Localization. In some applications the sensors are deployed sporadically in a geographical location and thy have to organize them selves and find out where they are in relation to each other.
Routing. Traditional routing schemes are not designed to be energy and processing efficient and are of little use in sensor networks. The approach that should be pursued in this case is to keep the routing to a minimum, and activated only when absolutely necessary.
Energy Efficiency Constraints. Energy efficiency is a very serious concern, because the sensor nodes have small and limited energy source such as batteries. Very rarely device will be able to be plugged into an electrical power outlet. There are software solutions that can optimize the consumption of the device by switching to energy saving modes. These solutions take advantage of the hardware features of the smart sensor chips available today.