  Increasing network lifetime by reducing energy consumption across the network
is one of the major concerns while designing routing protocols for Mobile
Ad-Hoc Networks. In this paper, we investigate the main reasons that lead to
energy depletion and we introduce appropriate routing metrics in the routing
decision scheme to mitigate their effect and increase the network lifetime. For
our routing scheme, we take into consideration multiple layer parameters, such
as MAC queue utilization, node degree and residual energy. We integrate our
multi-metric routing scheme into OLSR, a standard MANET proactive routing
protocol. We evaluate via simulations in NS3 the protocol modifications under a
range of different static and mobile scenarios. The main observations are that
in static and low mobility scenarios our modified routing protocol leads to a
significant increase (5\%-20\%) in network lifetime compared to standard OLSR
and slightly better performance in terms of Packet Delivery Ratio (PDR).
