Sensor node hardware can be grouped into three categories, each of which entails a different
set of trade-offs in the design choices.
● Augmented general-purpose computers: Examples include low-power PCs, embedded PCs (e.g., PC104), custom-designed PCs (e.g., Sensoria WINS NG nodes), 1 and various personal digital assistants (PDAs). These nodes typically run off-the-shelf (OTS) operating systems such as Win CE, Linux, or real-time operating systems and use standard wireless communication protocols such as Bluetooth or IEEE 802.11. Because of their relatively higher processing capability, they can accommodate a wide variety of sensors, ranging from simple microphones to more sophisticated video cameras. Compared with dedicated sensor nodes, PC-like platforms are more power hungry. However, when power is not an issue, these platforms have the advantage that they can leverage the availability of fully supported networking protocols, popular programming languages, middleware, and other OTS software.
● Dedicated embedded sensor nodes: Examples include the Berkeley mote family, the UCLA Medusa family, Ember nodes, 2 and MIT μ AMP. These platforms typically use commercial OTS (COTS) chip sets with emphasis on small form factor, low power processing and communication, and simple sensor interfaces. Because of their COTS CPU, these platforms typically support at least one programming language, such as C. However, in order to keep the program footprint small to accommodate their small memory size, programmers of these platforms are given full access to hardware but barely any operating system support. A classical example is the TinyOS platform and its companion programming language, nesC.
● System-on-chip (SoC) nodes: Examples of SoC hardware include smart dust, the BWRC picoradio node, and the PASTA node. 3 Designers of these platforms try to push the hardware limits by fundamentally rethinking the hardware architecture trade-offs for a sensor node at the chip design level. The goal is to find new ways of integrating CMOS, MEMS, and RF technologies to build extremely low power and small footprint sensor nodes that still provide certain sensing, computation, and communication capabilities. Since most of these platforms are currently in the research pipeline with no predefined instruction set, there is no software platform support available.
Source of Information : Elsevier Wireless Networking Complete 2010