  WSNs are envisioned to consist of many small devices that can sense the
environment and communicate the data as required. The most critical requirement
for widespread sensor networks is power efficiency since battery replacement is
not viable. Many protocols are proposed to minimize the power consumption by
using complex algorithms. However, it is difficult to perform these complex
methods since an individual sensor node in sensor networks does not have high
computational capacity. On the other hand, many sensor nodes should transfer
the data packet to the sink node that collects the required data. Therefore,
the operations of the sensor nodes over the route are terminated. It is
difficult to deliver the data packet to the sink node even if some sensor nodes
are active. In this paper, an introduction of WSNs is presented with a deep
insight into the power-aware routing protocol for sensor networks. The
protocols considered are LEACH,VGA and PEGASIS. In addition, a comparison of
these protocols is also presented.
