# Coordination of Macro Base Stations for 5G Network with User Clustering
## 2 Energy Management Model of 5G Macro Base Station Network
### Optimization Step 2: Energy Management of the Standard Equipment in 5G Macro BSs Network  
The energy management model of communications equipment in the 5G macro BS network was described in the previous section. BS sleeping and user allocation strategies were adopted to minimize the energy consumption of the communication equipment. However, ACs, backup batteries, and renewable generation units can be optimized to further reduce the electricity costs of 5G networks. In this section, the operation of ACs, backup batteries, and renewable generation units are jointly optimized under the given power consumption profile of the communicationsequipment. Two-way energy trading between the 5G network and the grid was not considered in this study. The objective is to minimize the electricity costs of the entire 5G macro BS network, as shown in Equation (25). \[\text{min}F_{2}=\text{min}\underset{t\in\mathbb{T}}{\sum}c_{t}P_{grid}^{t} \Delta t \tag{25}\]  
where \(c_{t}\) denotes the electricity price, and \(P_{grid}^{t}\) represents the input power to the 5G macro BS network from the grid. The operation of the above equipment needs to meet the following constraints. 1. Power balance constraints of 5G macro BSs network: \[P_{grid}^{t}=\underset{m\in\mathbb{M}}{\sum}P_{in}^{m,t}\] (26) \[P_{grid}^{t}\geq 0\] (27) where \(P_{in}^{m,t}\) represents the input power of BS \(m\), which can be either positive or negative. 2. Power balance constraints of a single BS: \[P_{in}^{m,t}+P_{dis}^{m,t}+(1-Cur_{t}^{m})P_{RE}^{m,t*}=P_{air}^{m,t}+P_{ch}^{ m,t}+P_{com}^{m,t*}\] (28) where \(P_{ch}^{m,t}\), \(P_{dis}^{m,t}\), and \(P_{air}^{m,t}\) are the charging/discharging power of the backup battery and power of the AC in BS \(m\); \(Cur_{t}^{m}\) denotes the wind/solar curtailment rate of the renewable generation unit in BS \(m\); and \(P_{RE}^{m,t*}\) and \(P_{com}^{m,t*}\) are the given power profiles of the renewable generation unit and communication equipment in BS \(m\), respectively. 3. AC-related constraints: \[P_{air}^{m,t}=P_{air}^{m,N}U_{air}^{m,t}\] (29) \[P_{cool}^{m,t}=\delta^{air}P_{air}^{m,t}-\delta^{hot}(P_{RBU,AC}^{m,t*}U_{bs }^{m,t*}+P_{other})\] (30) \[T_{in}^{m,t}=T_{in}^{m,int},t=1\] (31) \[T_{in}^{m,t}=T_{out}^{t-1}-R_{eq}^{m}P_{cool}^{m,t}-(T_{out}^{t-1}-R_{eq}^{m,t}P_{cool}^{m,t}-T_{in}^{m,t-1})^{e^{\frac{\Delta t}{R_{eq}^{m,t}-\Delta t}}},t=2,3,\ldots,T+1\] (32) \[T_{in}^{m}\leq T_{in}^{m,t}\leq T_{in}^{\max},t=1,2,\ldots,T+1\] (33) \[U_{air}^{m,t}\in\{0,1\}\] (34) where \(P_{air}^{m,N}\) is the rated power of the fixed frequency of AC in BS \(m\); \(U_{air}^{m,t}\) denotes the on/off state of AC; \(P_{cool}^{m,t}\) represents the equivalent cooling power inside BS m; \(\delta^{air}\) is the energy efficiency ratio of AC in BS \(m\); and \(P_{other}\) represents the heating power in the cabinet of BS \(m\). \(T_{in}^{m,t}\) represents the indoor temperature; \(T_{in}^{m,int}\) denotes the initial indoor temperature in the cabinet of BS \(m\) when \(t=1\), \(T_{in}^{max}\), and \(T_{in}^{min}\) are the preset upper and lower bounds of the indoor temperature inside the cabinet, respectively; and \(R_{eq}^{m}\) and \(C_{eq}^{m}\) denote the equivalent thermal resistance and equivalent thermal capacity of the cabinet of BS \(m\), respectively. 4.