# The Design of an Energy Harvesting Wireless Sensor Node for Tracking Pink Iguanas
## 6 Related Work
### Animal Monitoring Devices and Projects  
Several research projects tackled the design of wireless sensor network nodes for specific animal monitoring. Sometimes prototypes have also been developed and tested in the field. Among them, perhaps the most famous is project \"Zebranet\" [21], that in the early 2004 developed a collar for monitoring a herd of zebras. The wireless node uses a MSP430 microcontroller with an external 900 MHz wireless transponder Maxstream 9 XStream that exhibits a coverage range of about 5 miles. The device is powered with a AA lithium battery, rechargeable with a solar panel. The resulting node is about 9 cm \(\times\) 6 cm \(\times\) 3 cm without antennas and solar panel. An extension of the Zebranet project is the wildCENSE project [22] that designs a wireless node as a cows collar. The wildCENSE node is based on an ATMega128 microcontroller and has an integrated Zigbee (IEEE 802.15.4) modem in 2.4 GHz ISM band that presents a power consumption higher than the 900 MHz transponder, but allows a higher data rate with a smaller antenna. Authors reported that the resulting device has a reduced board size of 6 cm \(\times\) 5 cm, but the external battery is not accounted in this calculation. An interesting project was based on a multi-hop WSN designed for cattle [23]. The system is composed of a collar with an integrated a GPS receiver, an ATMega 128 controller and a Nordic NRF905 radio operating in the 915 MHz band. The system is powered by batteries recharged by solar cells. Similarly to the device presented in this work, that system uses UHF frequency band and data compression was implemented to reduce the energy consumption of the wireless communication. This software solution was necessary because the Wake-on Radio functionality was not available in the modem. In [24] the LynxNet system, a new collar for lynxes is presented. It is based on a CC430 controller and a CC2420 433 MHz radio modem. The prototype has been tested in an environment rich of vegetation and the radio showed a very short coverage range (about 250 m) with a packet loss ranging between 10% and 80%. A notably most recent contribution comes from the Mataki project [25] in which researchers developed an open hardware/open-source device based on a MSP430 microcontroller and a CC1101 modem operating in the 868 MHz band. The resulting device is very small (43 \(\times\) 21 \(\times\) 7 mm, without the battery) but it does not integrate the harvesting component. Another recent prototype of monitoring device for flying foxes is presented in [26]. This device is based on a CC430 wireless controller powered by a lithium battery charged by a solar panel. The communication range in this application is up to 200 m since the available transmission power is limited. However, the battery allows a longer GPS operation time and consequently an efficient estimation of the position. Many other works exist in literature, focusing on on specifics aspects of wireless node design. In [27], authors studied a device based on the IEEE 802.15.4 in the 900 MHz band for animal monitoring. The device does not integrate any GPS. It only includes sensors to monitor animal status, sending an alarm, via a wireless message, in case of alteration of some parameter. Authors produced a prototype using a Libelium Waspmote equipped with a Xbee modem. The main contribution of the paper is the decision algorithm to send the alarm. A similar work is presented in [28] where authors propose a system to rapidly detect animal's illness using a IEEE 802.15.4 network in the 2.4 GHz bandwidth. They also studied the performance of the Zigbee technology in the case of a directional antenna that could communicate with a large number of devices. A different study is reported in [29]. They define a monitoring scenario for tigers and design a system based on a multihop IEEE 802.15.4 operating in the 2.4 GHz band. They simulate up to 2000 nodes in a 7 km \(\times\) 25 km area and a UAV device that collects the information using the wireless channel.