Ultra Low Power Data Aggregation for Request Oriented Sensor Networks

Abstract

Abstract —Request oriented sensor networks have stricter requirements than conventional event-driven or periodic report models. Therefore, in this paper we propose a minimum energy data aggregation (MEDA), which meets the requirements for request oriented sensor networks by exploiting a low power real-time scheduler, on-demand time synchronization, variable response frame structure, and adaptive retransmission. In addition we introduce a test bed consisting of a number of MEDA prototypes, which support near real-time bidirectional sensor networks. The experimental results also demonstrate that the MEDA guarantees deterministic aggregation time, enables minimum energy operation, and provides a reliable data aggregation service. Keywords —Data Aggregation, Energy Efficient, Low Power Listening, Medium Access Control, Request Oriented, Sensor Networks 1. I NTRODUCTION Over the last decade, the rapid advances in wireless sensor networks have enabled the development of a variety of sensor network applications. However, in spite of their diversity, most sensor network applications are designed based on an event-driven or periodic reportmodel. The event-driven model performs a periodic sensing function. Furthermore, only if a sensing target is detected or sensed value is above the predetermined threshold value will each sensor transmit the sensed data to the server through the sensor network. This model is mainly used in military, security, or surveillance applications. On the other hand, in the periodic report model, each sensor node transmits the sensed data to the server at a predetermined interval. Many applications for monitoring environmental changes in a certain area are mainly utilizing the periodic report model. However, since these two representative sensor network models are based on the unidirectional data transfer model, it is hard to deal with various queries or real-time requests from a server. Recently, demands for more flexible and extensible sensor network applications that are based on bidirectional communications, such as the service-centric sensor network model [1], in which a variety of tasks (services) are executed cooperatively according to various service requests or missions from a server, are arising. In order to support such applications, a request oriented sensor network model is required, instead of an event-driven or periodic report model. The request oriented sensor network model has the specific requirements, in addition to the