Spatial Constrained Self-Join query algorithm in sensor network

The join query in sensor network is an important type of query that can find relation between different data sources. We name a join query as spatial constrained self join query in which a sensor node is only related with sensor nodes around itself. Existing SENS-join can solve this problem. But in SENS-join's pre-computing phase it wastes too much energy since it sends all attribute join tuples to base station. We put forward hierarchical grid routing method in which the sensor nodes nearby can influx together in a high level grid cluster header. Based on hierarchical grid routing method, we put forward an efficient self join algorithm by processing semi-join operator in grid cluster headers to avoid sending all join tuples in security region to the base station and to further reduce energy consumption of sensor nodes. Experimental results have shown that SCJA outperforms SENS-join in terms of both energy consumption and scalability.