energy consumption is expressed by
E
centra
system = E
macro
EM + E
macro
OP + N · (E
small
EM + E
small
OP )
= E
macro
EM init + E
macro
EMma int + P
macro
OP · T
macro
lifetime
+ N · (E
small
EM init + E
small
EMma int + P
small
OP · T
small
lifetime)
. (1)
Considering the wireless backhaul throughput in the central solution, the energy efficiency of
the central solution is defined as ηcentra = T Hcentra
sum
E
centra
system .
In the distribution solution, the system energy consumption is expressed by
E
dist
system = K · (E
small
EM + E
small
OP )
= K · (E
small
EM init + E
small
EMma int + P
small
OP · T
small
lifetime)
. (2)
Considering the wireless backhaul throughput in the distribution solution, the energy efficiency
of the distribution solution is defined as ηdist = T Hdist
sum
Edist
system.
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 meter (m), the
macrocell radius is 500 m, the bandwidth of the macrocell and the small cell is 100 Mbps, the
average spectrum efficiency of the macrocell is 5 bit/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 MBS and SBS are
assumed as 10 and 5 years, respectively [15]. Other parameters are listed in Table I