AOMDV-E: energy aware event-based routing protocol for environmental monitoring

Due to rapid changes in climatic conditions worldwide, environmental monitoring has become one of the greatest concerns in the last few years. With the advancement in the wireless sensing technology, it is now possible to monitor and track fine-grained changes in different environments. Wireless sensor networks (WSN) provide very high quality and accurate analysis for monitoring of both spatial and temporal data thus providing the opportunity to monitor harsh outdoor environments. But to deploy and maintain a WSN in such harsh environments are great challenges for researchers and scientists. Several routing protocols exist for data dissemination and power management but they suffer from various disadvantages including lack of energy-aware operation, lack of ability to react to sudden environmental changes, etc. There are a lot of challenges which need to be addressed for latest WSNs applications which include timely delivery of data, particularly for real-time applications. Moreover, reactive event-based routing functions are required to deal with changing outdoor environments. For example, with limited water resources in the Middle East, soil moisture measurements must be taken into account to manage irrigation and agricultural projects. The main factors for changing the soil moisture are the seasonal rains. So an event-based routing protocol to determine the correct routing path for sending the data is needed for optimizing irrigation operations.
This study outlines the challenges in supporting such an environment and demonstrates а solution approach based on the modification of a popular reactive routing protocol known as AdHoc On-Demand Multiple Path Distance Vector (AOMDV). Moreover, additional enhancements have been proposed for AOMDV to make it an energy-aware routing protocol with the additional characteristic of being capable of acquiring energy from the solar system. The proposed modifications, AOMDV-E (event-based, energy-aware routing functions) in AOMDV are desirable to facilitate better wireless connectivity for current and future needs. In our case study, there are very limited water resources in the Middle East, hence soil moisture measurements must be taken into account to manage irrigation and аgriculturаl projects. In order to meet these challenges, a testbed that supports an energy aware, reactive, event-based routing protocol is developed using AOMDV. A prototype WSN network of 5 nodes was built. Three simulations have been done to test the proposed algorithms and their scalability: the first consisted of 5 nodes with one of them affected by rain. The second simulation considered 7 nodes in which 2 of them are affected by rain while the final simulation is based on 30 nodes with 5 of them affected by rain.
AOMDV-E event-driven enhancements not only increase the performance of the proposed protocol but also make it energy efficient as the energy consumption is considerably reduced for the nodes experiencing the rainfall and also in general because we use the sleep mode when it is not raining. Simulation results also show that when the rainfall is heavier, then also the amount of energy consumed is reduced which shows that the proposed AOMDV-E protocol is robust in terms of the amount of rainfall.
The simulation results also show that the enhanced AOMDV-E protocol is scalable. Its performance is compared with prior AOMDV protocol. The results clearly show that AOMDV-E reduces average delay while at the same time increases the throughput of the nodes being affected by rain.