Energy Efficiency in MIMO Underlay and Overlay Device-to-Device Communications and Cognitive Radio Systems

Abstract

Abstract-This paper addresses the problem of resource allocation for systems in which a primary and a secondary link share the available spectrum by an underlay or overlay approach. After observing that such a scenario models both cognitive radio and D2D communications, we formulate the problem as the maximization of the secondary energy efficiency subject to a minimum rate requirement for the primary user. This leads to challenging non-convex, fractional problems. In the underlay scenario, we obtain the global solution by means of a suitable reformulation. In the overlay scenario, two algorithms are proposed. The first one yields a resource allocation fulfilling the first-order optimality conditions of the resource allocation problem, by solving a sequence of easier fractional problems. The second one enjoys a weaker optimality claim, but an even lower computational complexity. Numerical results demonstrate the merits of the proposed algorithms both in terms of energyefficient performance and complexity, also showing that the two proposed algorithms for the overlay scenario perform very similarly, despite the different complexity.

A Survey of Energy-Efficient Techniques for 5G Networks and Challenges Ahead

“…A promising answer is represented by the framework of sequential fractional programming, which provides a systematic approach to extend fractional programming to interference-limited networks with affordable complexity. Sequential fractional programming has been recently shown to be effective in optimizing the energy efficiency of a number of candidate technologies for 5G, such as C-RAN, CoMP, and multi-cell systems, also with multi-carrier transmissions [23], [47], multi-cell massive MIMO systems [47], heterogeneous relay-assisted interference networks [46], full-duplex systems [45], and device-to-device systems [94], [162].…”

Energy Efficiency of Rate-Splitting Multiple Access, and Performance Benefits over SDMA and NOMA

“…However, the EE performance of RSMA has never been studied. In the literature, the two-user RSassisted EE maximization problem in MIMO Interference Channel (IC) has been investigated in [9] by allowing one of the two users to use RS. Different from [9], we initiate the investigation of RS-assisted EE maximization problem in MISO BC.…”

Overlay spectrum sharing for device‐to‐device communications in two‐way cellular networks with nodes mobility

“…where ,ı and́, are defined after Equation 19. Thereafter, on the basis of the conditions given in Appendix A.…”

“…Recently, the analysis for transmission capacity for overlay and underlay D2D modes has been performed in Yang et al by considering stochastic geometry model into account. More recently, Zappone et al have addressed the problem of energy efficiency and resource allocation in overlay and underlay D2D communication with multiple‐input multiple‐output techniques. On another front, considering the nodes mobility in relay‐based systems makes them commensurate to the practical outdoor scenarios …”

“…Research works in previous studies [13][14][15][16][17][18][19] have focused on the overlay approach of spectrum sharing, which is of our particular interest in this paper. Specifically, Li et al 13 have proposed an spectrum-sharing scheme to enhance the outage performance of the primary system based on decode-and-forward (DF) two-way relaying.…”