challenge is that the deployment ofРadvanced wireless es at the costРof high energy consumption. The increase ofРenergy consumption in municationРsystems causes an increase of CO 2 emission indi-Рrectly, which currently is considered as a majorРthreat for the environment. Moreover, it hasРbeen reported by cellular operators that theРenergy consumption of base stations (BSs) con-Рtributes to over 70 percent of their electricity billР[5]. In fact, energy-munication wasРnot one of the initial requirements in 4G wire-Рless systems, but it came up as an issue at a laterРstage. Other challenges are, for example, aver-Рage spectral efficiency, high data rate and highРmobility, seamless coverage, diverse quality ofРservice (QoS) requirements, and fragmentedРuser experience (patibility of different
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