We work on Wireless Sensor Networks (WSNs). Specifically, on hardware development for the nodes.
We have a HW platform for WSN called Cookies. Here you can find some topics in which we are actually working in:
1.- Wake-up radio circuits based on ultra low power FPGAS:
The number of applications for wireless sensor networks is growing continuously. One of the main scenarios is based on ultra low energy WSNs. The main target of these applications is to get the longest lifetime possible. In order to maximize this lifetime low energy consumption is mandatory. For these reason these WSNs work in applications with a very low duty cycle (~1%) and low data rates (< 1 bit per second). One of the techniques used to minimize communication power comsumption is wake up radio (WuR)
Focusing on the communication control, this means that the main radio channel is switched on only if an event that requires communications occurs, i.e., a neighbor node wants to communicate with a remote gateway node; otherwise the radio remains switched off. Usually, an ultra low power auxiliary radio channel that remains always active while the node sleeps is used to wake up a remote node. This auxiliary radio, the WuR, is used for non-intense data communications; only simple data, like the address or simple command, are enclosed. These kinds of communications are completely asynchronous and un-slotted, avoiding the synchronization problem of the TDMA based protocol and the periodic listening of contention based schemes
2.- High Performance WSNs with RAM based FPGAS:
Wireless Sensor network platforms have been constantly evolving during the last decade. Traditionally, these platforms have been based on low cost and low performance 8-bit microcontrollers since the tasks carried out by the nodes do not demand many resources. Moreover, the duty cycle of wireless sensor network applications is normally very low. However, new demands are being established recently, due to new application requirements regarding to two main aspects: first, more demanding applications are being introduced in the WSN field, and second, the requirements for traditional applications are increasing. In this context, traditional hardware platforms reaches a limitation and new approaches must be considered, keeping in mind the low power consumption and low cost constraints inherent to WSNs.
To focus this new paradigm, at CEI an innovative architecture for nodes in WSNs is proposed. This architecture is based on a high performance high capacity state of the art FPGA (Xilinx Spartan 6), to take advantage of the intrinsic parallelism of such a device. Increasing the execution speed, lead to energy savings for certain applications, even though the FPGA has instant power consumption much higher than a microcontroller. Moreover, several strategies have been implemented to be competitive in power consumption; this is, using dynamic and partial reconfiguration capabilities of the FPGA and the inclusion of power islands to isolate sectors of the node in terms of power supply.
3.- Test-beds for WSNs
The Cookie platform is being used as the main node of a test bed, which main target is to test deployments in the lab, previously to real deployments.
The work is based on a back channel (ethernet), a main channel (ZigBee) and the modular nodes (Cookies), with a PC application to manage all the system.