Superimposed radio signals in wireless sensor networks

Author/s :Krohn, Albert
First examiner :Prof. Dr.-Ing. Beigl, M.
Institute / Publisher :Institut für Betriebssystem und Rechnerverbund
Faculty :01 - Mathematics and Computer Science
Date :2007-03-09
Documents :
Size :211 S.
Language :german
Abstract :Wireless sensor networks consist of a number of embedded computers. These embedded computers are typically very weak in energy and computing power but carry a wireless communication unit to exchange packet messages with other embedded computer (called nodes). The messages can be transported from one to another node building multi-hop communication. Nodes are capable of automatically forwarding messages and establishing routes for messages through the network. Such systems of a number of weak nodes can greatly benefit of cooperative mechanisms. Superimposed radio signals are such a cooperative mechanisms. They occur whenever two or more nodes emit radio signals at the same time and in the same frequency band. This work presents a new concept for superimposed radio signals and shows various use-cases in wireless sensor network. The constraints are the weak hardware with limited computing and energy resources. New models are derived and presented that can solve principal problem in wireless sensor networks such as time synchronization, channel usage, reliability and data fusion. Basis for all contributions is the new modulation scheme for superimposed radio signals call ESK (energy shift keying). ESK is a multi-stage modulation based on energy detection in the receiver, enabling superimposed radio signals for a group of sensor nodes. Various Implementations and studies are presented that illustrate the practical use of superimposed radio signals. The applications range from ultrasound location systems over item handing in a retail store to real-time access protocols in wireless distributed systems.
Subject :004 Data processing and computer science
Type :dissertation
Format :text/document
URN:NBN :urn:nbn:de:gbv:084-12829
Permalink :http://www.digibib.tu-bs.de/?docid=00020767