A wireless sensor network consists of many micro-sensor nodes distributed throughout an area of interest. Each node has a limited energy supply and generates information that needs to be communicated to a sink node. The basic operation in such a network is the systematic gathering and transmission of sensed data to a base station for further processing. During data gathering, sensors have the ability to perform in-network aggregation (fusion) of data packet routes to the base station. The lifetime of such a sensor system can be defined as the time during which the sensor information is gathered from all of the sensors and combined at the base station. Given the location of the sensors, the base station and the available energy at each sensor, the main interest is to find an efficient manner in which data can be collected from the sensors and transmitted to the base station, so as to maximize the system lifetime. We address the zone based data aggregation scheduling scheme for maximizing network lifetime. The experimental results demonstrate that the proposed protocol significantly outperforms other data aggregation protocols in terms of the energy saving and system lifetime.