  With the current exponential growth in traffic and service demands,
device-to-device (D2D) cooperation is identified as a major mechanism to enable
5G networks to effectively and efficiently augment network resources. The
effectiveness of D2D cooperation depends on a wide range of decision making
processes that include cluster formation, resource allocation, in addition to
connection and mobility management. Irrespective of the D2D cooperation
scenario whether in sensor, ad hoc, or cellular networks, the literature
normally assumes that devices selected as relays or data sources are reliable;
this means that they will maintain the connection till the communication
session ends. Yet, this assumption is challenged in practice since devices'
batteries can be depleted (e.g., sensors in an IoT network) and devices can
move leading to connection termination (e.g., mobile users in a WiFi network or
cars in a vehicular ad hoc network). To this end, we address the problem of
reliable D2D cooperation in wireless networks by proposing a novel approach
that is proactive by utilizing reliability metrics in the decision making
process, and scalable by having low implementation complexity suitable for
dense networks. These differentiating factors are shown to enhance the overall
network reliability compared to standard techniques and to facilitate dynamic
operation which is essential for practical implementation. Performance is
evaluated using extensive simulations in addition to test bed experimental
demonstration in order to quantify gains and extract insights on a range of
existing design tradeoffs.
