Evaluation of directed diffusion and content-based routing wireless sensor network protocols

Networks of sensors and actuators due to advancements in sensor, radio and microprocessor technology as well as wide range of application fields are already widely used in our day to day lives. Such networks require novel approach to data dissemination well adapted to its application context and related challenges. Wireless Sensor Networks (WSNs) are built of sensors devices called nodes, which are small resource constrained computers that are connected to physical world through sensors and are able to respond in autonomous way to the environmental stimuli. In such context routing protocols play much more important role then in other types of networks. Routing algorithms not only have to deal with issues such as physical and hardware design constraints (e.g. small footprint), scares energy resources, limited processing, storage and communication capabilities but also satisfy the design requirements of high scalability and dynamic nature of the network. This work is focused on providing evaluation of two context aware WSN protocols, Context and Content-Based Routing (CCBR) and Directed Diffusion (DD) both proposed by the academic community. Given that, in context of WSN communication cost can be several orders of magnitude higher then processing cost, for the purpose of analysis series of tests has been design to compare performance of the protocols through simulation in two key areas: deliverability and message delivery cost. Test Scenarios has been design to examine behaviour of the protocols in static low density and high density networks and its response to changes of interest duration (DD) and interest lease time (CCBR). The parameters determine validity period and frequency of interests reposting by sinks and have direct impact on how paths are established between sensors and sinks as well as deliverability, cost and communication overhead. To execute the tests, TinyOS simulation platform – TOSSIM, was used. Collected data and test results suggest that CCBR overall outperforms DD in terms of the key metrics: deliverability and communication cost. Simulation results indicate also that CCBR is less volatile to changing network density and configuration, which is desired characteristic for WSN protocols.