To analyze the energy efficiency of 5G wireless backhaul networks in two backhaul solutions, default parameters are configured as follows: the radius of the small cell is 50 m, the macrocell radius is 500 m, the bandwidth of the macrocell and small cell is 100 Mb/s, the average spectrum efficiency of the macrocell is 5 b/s/Hz [12], and the path loss coefficient is 3.2 for the urban environment [14]. In macrocells, parameters of BS operating power are configured as a = 21.45 and b = 354.44 W, respectively. In small cells, parameters of BS operating power are configured as a = 7.84 and b = 71.50 W, respectively. The lifetime of MBSs and SBSs are assumed to be 10 and 5 years, respectively [15]. Other parameters are listed in Table 1.