Imperfect D2D association in spectrum-shared cellular networks under interference and transmit power constraints

This paper presents generalized modeling and analysis of the impact of imperfect device-to-device (D2D) association for direct D2D communication in spectrum-shared downlink cellular networks. It also addresses practical interference and energy constraints that are imposed on the underlying D2D communication network. Specifically, new decentralized schemes to identify and then establish point-to- point D2D communication links between well-identified groups of active devices when downlink cellular resources can be accessed by the underlying D2D network are proposed. Through the analysis, detailed characterization of devices that can serve others are first presented, wherein each of which is required to meet a specific transmit power constraint it can dedicate to serve others. Then, the downlink resources (i.e., physical channels) that can be used by serving devices to serve others via D2D communication links are identified cooperatively in the D2D network, while meeting an interference constraint per channel as imposed by the primary cellular network. The analysis then proceeds to analyze the proposed D2D association, which aims to simultaneously improve the desired link quality while minimizing the effect of interference at each served device, considering various practical but imperfect operating scenarios. Numerical results are presented to clarify some of the main outcomes of this work.