I. Introduction
The hype around 5G technology has been fuelled over the recent years with the advent of groundbreaking features such as phenomenal data throughput and ultra-low latency communication. Predictions made by several report expect the number of connected devices to soar exponentially and reach the astronomical figure of 100 billion by 2030. Moreover, it is anticipated that 5G networks will handle up to 1000 times more data as compared to 4G networks [1] . This can be attributed mainly to the densification of cells in 5G and 6G networks in order to cater for the superior service sets in terms of enhanced Mobile Broadband and Ultra Reliable Low Latency Communication [2] . However, the alarming concerns regarding the energy consumed by 5G networks constitute the other side of the coin [3] . Consequently, energy efficiency has emerged as a major consideration for 5G and beyond 5G networks [4] [5] . As a step further, it was claimed in [6] that energy efficiency should be at the heart of all innovative approaches devised holistically for the planning, deployment, operations and continuous optimization of 5G networks. Therefore, it is primordial to elaborate metrics for measuring the energy efficiency of 5G networks to ascertain that its deployment occurs in a sustainable manner from both a cost effectiveness perspective as well as for abiding to the worldwide green development policies.