The algorithm for distribution of large-size data in the Wireless Ad-Hoc Sensor Network Marcin Golański, Radosław Schoeneich and Michał Siwko Institute of Telecommunications, Warsaw University of Technology ul. Nowowiejska 15/19, 00-665 Warszawa, Poland Abstract: The article describes algorithm for distribution of large-size data in the Wireless Ad-hoc Sensor Network (WASN). The algorithm provides replication and large-size data allocation using the concept of decomposition into small pieces and random distribution in the WASN. The basic assumption is the large size of stored data, which means that the data size is much larger than the capacity of a single node. Thus, the data should be divided into small parts, with the result that can be deployed on multiple nodes. The authors also established a dynamic network partitioning, which implies data replication and partition-tolerant data storage. Proposed solution uses tree- based structure of the connections between nodes. This allows to exchange information and distribute parts of data. The article presents an algorithm, and performance measurements made using low level network metrics, such as total number of transmitted packets, and high level data availability ratio. Keywords: large data distribution, Wireless Ad-hoc Sensor Networks 1. Introduction Nowadays Wireless Ad-hoc Sensor Networks are dynamically explored. The WASN is a collaboration of tiny nodes. Nodes are connected via wireless links in the spontaneous manner. The WASN characterizes not only a changeable structure of the network, but also by attributes of the sensor node like: bandwidth, memory storage capacity and computational performance. Severe limitations of any single node is a reason for nodes grouping for the collaboration. Although the fast technological progress causes performance increasing and size minimization of each node, the