addressed by the ComaaS and other XaaS platforms.

Energy-as-a-Service (EaaS)
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Energy-as-a-service (EaaS) provides a promising approach to reduce energy costs and improve energy efficiency for both mobile users and telecommunication operators. From the perspective of mobile users, heavy energy consuming tasks can be offloaded to cloud servers with unlimited computing and energy resources to fill the gap between battery capacity limitations and high performance expectation. Furthermore, the emerging simultaneous wireless information and power transfer (SWIPT) technology enables mobile terminals to “recycle” the transmit power to prolong the battery lifetime while receiving data [@Chang2].

On the other hand, with the advancing technologies of distributed energy generation (DER) and distributed energy storage (DES) [@Zhou], smart BSs with energy harvesting (EH) capabilities enables operators to save excess energy in batteries and sell it back to utility companies during peak periods, or to exploit environmental friendly renewable energies to further reduce electricity prices through smart energy management systems. In addition, BSs with self-generation capabilities can compose a small-scale microgrid and operated in islanded mode during a blackout to ensure safe and reliable service provision. Thus, together with the emerging energy Internet, EaaS is able to motivate the study on fundamental relation between energy 