Deriving an upper bound on the average operation time of a wireless sensor network

One of the main challenges in implementing wireless sensor networks (WSN) is to minimize power consumption in order to maximize network lifetime. To accomplish this, we derive an upper bound on the average network lifetime. The upper bound was derived for a code division multiple access (CDMA) communication system. The communication procedure that consumes most of the energy is transmission. But, it is possible to reduce energy consumption by increasing the antenna gain of the base station which collects information from the sensors. However, a problem that arises is that the spot size of high gain antenna is smaller than low gain antenna and as a result the base station provides only partial coverage to the network, which is obviously an undesirable situation. Therefore we propose to shape the base-station antenna gain in such a way that maximizes network lifetime, by taking advantage of the spatial non-uniformity distribution of the sensors on the ground.