  In this paper, energy-efficient scheduling for grouped machine-type devices
deployed in cellular networks is investigated. We introduce a scheduling-based
cooperation incentive scheme which enables machine nodes to organize themselves
locally, create machine groups, and communicate through group representatives
to the base station. This scheme benefits from a novel scheduler design which
takes into account the cooperation level of each node, reimburses the extra
energy consumptions of group representatives, and maximizes the network
lifetime. As reusing cellular uplink resources for communications inside the
groups degrades the Quality of Service (QoS) of the primary users, analytical
results are provided which present a tradeoff between maximum allowable number
of simultaneously active machine groups in a given cell and QoS of the primary
users. Furthermore, we extend our derived solutions for the existing cellular
networks, propose a cooperation-incentive LTE scheduler, and present our
simulation results in the context of LTE. The simulation results show that the
proposed solutions significantly prolong the network lifetime. Also, it is
shown that under certain circumstances, reusing uplink resource by machine
devices can degrade the outage performance of the primary users significantly,
and hence, coexistence management of machine devices and cellular users is of
paramount importance for next generations of cellular networks in order to
enable group-based machine-type communications while guaranteeing QoS for the
primary users.
