On Prolonging Sensornode Gateway Lifetime by Adapting Its Duty Cycle

In this paper we discuss the lifetime of an battery powered device which acts as a gateway between a wireless sensor network and a standard network. The wireless communication standards used are IEEE802.15.4 and IEEE802.11g. The two parameters which are of utmost importance but also contradicting each other are communication delay and lifetime of the gateway node. Our results clearly show that duty cycling i.e. switching o the gateway node improves its lifetime. Depending on the radio modules used the lifetime can be increased from seven hours up to 3 months using only 3 AA batteries. Our results also proove that prolonging the sleep intervals beyond a certain limit (about 10 seconds for a typical WLAN PC card) does not longer improve the lifetime but only worsens the delay.