  Internet of Things (IoT) have motivated a paradigm shift in the development
of various applications such as mobile health. Wireless body area network
(WBAN) comprises many low-power devices in, on, or around the human body, which
offers a desirable solution to monitor physiological signals for mobile-health
applications. In the implant WBAN, an implant medical device transmits its
measured biological parameters to a target hub with the help of at least one
on-body device(s) to satisfy its strict requirements on size, quality of
service (QoS, e.g., reliability), and power consumption. In this article, we
first review the recent advances of conventional cooperative WBAN. Afterwards,
to address the drawbacks of the conventional cooperative WBAN, a QoS-aware
buffer-aided relaying framework is proposed for the implant WBAN. In the
proposed framework, hierarchical modulations are considered to fulfill the
different QoS requirements of different sensor data from an implant medical
device. We further conceive some new transmission strategies for the
buffer-aided signal-relay and multi-relay implant WBANs. Simulation results
show that the proposed cooperative WBAN provides better performance than the
conventional cooperative counterparts. Finally, some open research challenges
regarding the buffer-aided multi-relay implant WBAN are pointed out to inspire
more research activities.
