Bai, WeiFor delay tolerant networks (DTNs), since there is no guarantee of end-to-end path from a source to a destination, routing protocols should make use of opportunistic contacts to deliver files. Although protocols employing network coding have been shown to achieve promising results in DTNs, they still suffer from redundant transmissions. An efficient stopping condition utilizing nullspace has been proposed recently. But more comprehensive studies are needed. In this thesis, a systematic research on effectiveness and efficiency of nullspace stopping condition is explored. We propose a novel algorithm to calculate nullspace. Using comprehensive simulations, we show that the benefits of nullspace stopping condition to network coding depend on scenarios. Moreover, performances may vary even in the same scenario with respect to the number and size of disseminated files. Finally explanations about these phenomena are given out.enThesisElectrical engineeringDelay Tolerant NetworkNetwork CodingNullspace Stopping Condition