Tradeoff Analysis and Joint Optimization of Link-Layer Energy Efficiency and Effective Capacity Toward Green Communications

Abstract

A joint optimization problem of link-layer energy efficiency (EE) and effective capacity (EC) in a Nakagami-m fading channel under a delay-outage probability constraint and an average transmit power constraint is considered and investigated in this paper. First, a normalized multi-objective optimization problem (MOP) is formulated and transformed into a singleobjective optimization problem (SOP), by applying the weighted sum method. The formulated SOP is then proved to be continuously differentiable and strictly quasiconvex in the optimum average input power, which turns out to be a cup shape curve. Furthermore, the weighted quasiconvex tradeoff problem is solved by first using Charnes-Cooper transformation and then applying Karush-Kuhn-Tucker (KKT) conditions. The proposed optimal power allocation, which includes the optimal strategy for the link-layer EE-maximization problem and the EC-maximization problem as extreme cases, is proved to be sufficient for the Pareto optimal set of the original EE-EC MOP. Moreover, we prove that the optimum average power level monotonically decreases with the importance weight, but strictly increases with the normalization factor, the circuit power and the power amplifier efficiency. Simulation results confirm the analytical derivations and further show the effects of fading severeness and transmission power limit on the tradeoff performance.

Opportunistic Spectrum Sharing for D2D-Based URLLC

“…The discrete-time block-fading channel model is considered in this paper, which means that the channel gains remain fixed within one coherence interval and vary independently at the following interval. 1 The complex channel coefficient between the DT and DR is denoted by h d [i] where i indicates the i-th interval, and h c [i] represents the channel coefficient between the DT and the cellular BS. Specifically, it is assumed that h d [i] and h c [i] are independent and identically distributed (i.i.d.)…”

“…Due to the explosive growth of data traffic in wireless services, the evolution of the fifth-generation (5G) networks is necessary to secure higher data rates while guaranteeing a highly reliable transmission [1]. In addition, wireless communication mechanisms are employed in emerging missioncritical applications and services (such as remote surgery, unmanned aerial vehicle (UAV) deliveries, smarter transportations, and augmented/virtual reality (AR/VR)), which necessitates ultra low-latency (time delay required for information exchange via wireless networks) transmissions [2].…”

Opportunistic Spectrum Access in Support of Ultra-Reliable and Low Latency Communications

“…Apparently, the provision of URLLC has greatly emphasized the stringent requirements of reliability and end-to-end latency. Hence, it is vital and challenging for us to design suitable protocols and adaptive techniques, in support of the explosive growth of URLLC services in 5G networks, such as vehicular communications, tactile Internet and virtual reality [3]- [5].…”

Low Latency Driven Effective Capacity Analysis for Non-Orthogonal and Orthogonal Spectrum Access

“…The provision of ultra-reliable low-latency communications (URLLC) has also emphasized the importance of reliability and low-latency transmissions in the 5th generation (5G) cellular networks and beyond [2]. In this paper, we adopt the concept of effective capacity (EC) to describe the maximum constant arrival rate that can be served, while guaranteeing a statistical delay requirement [3]. From the introduction about EC given in Section III, it will become evident that EC is not only a suitable, but also a flexible, metric which can represent various delay requirements.…”