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Published in IET Science, Measurement and Technology
Received on 3rd August 2010
doi: 10.1049/iet-smt.2010.0094
ISSN 1751-8822
Model for power consumption of wireless
access networks
M. Deruyck E. Tanghe W. Joseph W. Vereecken M. Pickavet L. Martens B. Dhoedt
Department of Information Technology, Ghent University/IBBT, Gaston Crommenlaan 8 box 201, Ghent B-9050, Belgium
E-mail: margot.deruyck@intec.ugent.be
Abstract: The power consumption of wireless access networks will become an important issue in the coming years. In this study,
the power consumption of base stations for mobile WiMAX (Worldwide Interoperability for Microwave Access), fixed WiMAX,
UMTS (Universal Mobile Telecommunications System), HSPA (High-Speed Packet Access) and LTE (Long-Term Evolution) is
modelled and related to the coverage. A new metric, the power consumption per covered area PCarea , is introduced, to compare the
energy efficiency of the considered technologies for a basic reference configuration and a future extended configuration, which
makes use of novel Multiple Input Multiple Output (MIMO) technology. The introduction of MIMO has a positive influence on
the energy efficiency: for example, for a 4 × 4 MIMO system, PCarea decreases with 63% for mobile WiMAX and with 50% for
HSPA and LTE, compared to a Single Input Single Ouptut (SISO) system. However, a higher MIMO array size (i.e. a higher
number of transmitting and receiving antennas) does not always result in a higher energy efficiency gain.
1
Introduction
Recent studies have shown that the power consumption of ICT
is 4% of the annual energy production [1]. More importantly,
this number is expected to grow drastically in the coming years
[1]. Furthermore, the radio access networks are large
contributors to the CO2 emissions [1 – 3]. This indicates that
the power consumption of wireless access networks, and
more in particular the power consumption of the base
stations, is going to become an important issue in the coming
years. Nowadays, the base stations are responsible for
roughly two-thirds of the total CO2 emissions of the wireless
access networks. Etoh et al. [3] state that the daily energy
consumption per customer is 0.83 Wh for a terminal and
120 Wh for the mobile network, which is a consumption
ratio of terminal against network of about 1:150. The energy
consumption of the terminals is thus negligible in
comparison with the energy consumption of the networks.
Therefore it is clear that one should focus on the reduction of
energy consumption of base stations in wireless access
networks as the terminals are already optimised in terms of
energy consumption because they are powered by batteries.
The objective of this paper is to model the power consumption
of base stations of various wireless technologies and compare
their energy efficiency against the coverage range. In order to
determine the energy efficiency of the considered technologies,
a new metric, namely the power consumption per covered
area, is defined. The energy efficiency for mobile WiMAX
(Worldwide Interoperability for Microwave Access), fixed
WiMAX, UMTS (Universal Mobile Telecommunications
System), HSPA (High-Speed Packet Access) and LTE (LongTerm Evolution) is compared for bit rates of 3 and 60 Mbps.
Finally, the influence of Multiple Input Multiple Output
(MIMO) is investigated.
IET Sci. Meas. Technol., 2011, Vol. 5, Iss. 4, pp. 155–161
doi: 10.1049/iet-smt.2010.0094
In literature, some related work can be found. In [4 – 6], a
power consumption model for a base station is proposed.
However, in the cited work, it is very difficult to investigate
the influence of the individual components of the base
station on the total power consumption, as well as the
influence of possible dependencies between the components
of the base station. Furthermore, in the cited work only one
technology is used to determine the power consumption.
Our work will show that for the considered case and based
on the assumptions made for the parameters, distinct
differences in energy efficiency can be noticed between the
considered technologies.
The outline of the paper is as follows. In Section 2, a short
overview of the considered technologies is given. In Section
3, the power consumption of a base station is modelled and
related to the coverage. Section 4 gives some results
obtained with the model from Section 3. In Section 5, the
final conclusions are given.
2
Technologies
For the wireless access networks, we investigate the power
consumption of outdoor base stations for five different
wireless technologies: mobile WiMAX [7], fixed WiMAX
[8], UMTS [9], HSPA [10] and LTE [11]. We first give a
short description of the different technologies.
WiMAX is a wireless technology for broadband
communication based on the IEEE 802.16 standard. For
fixed WiMAX, we analyse the IEEE 802.16-2004 interface,
operating in the 2 – 11 GHz band and developed for fixed
wireless applications. For mobile WiMAX, we analyse the
IEEE 802.16e interface, operating in the 2 – 6 GHz band
and developed for mobile wireless applications. Fixed
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WiMAX uses OFMDA (Orthogonal Frequency Division
Multiple Access) whereas mobile WiMAX uses the novel
SOFDMA (Scalable Orthogonal Frequency Division
Multiple Access) technique which is derived from OFDMA
and supports a wide range of bandwidths to flexibly address
the need for various spectrum allocation and application
requirements.
UMTS is developed by ETSI (European Telecommunications
Standardisation Institute) and operates in the 2.1 GHz band.
UMTS has been specified as an integrated solution for mobile
voice and data. It offers mobile operators significant capacity
and broadband capabilities to support more voice and data
consumers, especially in urban centres. UMTS uses
W-CDMA (Wideband Code Division Multiple Access) as
multiple access technique.
HSPA is the successor of the widely deployed UMTS and
works in the 2.1 GHz band. It promises higher data rates,
increased cell and user throughput and reduced delay
compared to UMTS.
LTE is the newest wireless broadband technology. In
December 2009, the world’s first publicly available LTEservice was started in Scandinavia [12]. LTE is marketed as
the fourth generation (4G) of radio technologies. It uses
SOFDMA as multiple access technique and thus supports
variable bandwidths from 1.4 to 20 MHz, just like mobile
WiMAX supports scalability. LTE uses the 2.6 GHz band.
In the future, LTE will probably also use the 800 MHz
band (digital dividend frequencies).
3 Theoretical power consumption and
coverage model for wireless access
3.1
mobile stations) and the rectifier. The power consumption
of these components should be multiplied with the number
of supported sectors nsector when determining the power
consumption of the base station. In contrary to [16, 17], it
is assumed that the signal generator is part of the
transceiver. This adaptation is based on the information
retrieved from operators. Furthermore, a base station
contains equipment that is common for all the sectors such
as the air conditioning and the microwave link (responsible
for communication with the backhaul network in case no
fibre link is available). The distinction between the
components per sector and the components common for all
sectors is based on the information retrieved from operators.
In Fig. 1, the equipment of the base station and the
different notations for the power consumption Pel of the
different components are indicated.
The power consumption of each component is here
assumed to be constant, except for the power amplifier and
the air conditioning. The power consumption of the latter
depends on the internal and ambient temperature of the
base station cabinet [18]. We assumed an internal and
ambient temperature of 258C. To model the power
consumption of the power amplifier, the efficiency h of the
power amplifier is defined, which is the ratio of the RF
output power Pout/amp (in Watt) to the electrical input power
Pel/amp of the power amplifier (in Watt) [19]. In Fig. 1,
Pout/amp corresponds to the input power PTx of one sector
antenna resulting in the following equation for the
efficiency h:
h=
Power consumption of a base station
A base station is here defined as the equipment needed to
communicate with the mobile stations and with the
backhaul network. In a base station, we typically find
several power consuming components. Fig. 1 gives an
overview of these components [13 – 15]. The area covered
by a base station is called a cell. Each cell is further divided
in a number of sectors. Each sector is covered by a sector
antenna, which is a directional antenna with a sector-shaped
radiation pattern. Some equipment is used for each sector
such as the digital signal processing (responsible for system
processing and coding), the power amplifier, the transceiver
(responsible for receiving and sending of signals to the
Fig. 1 Block diagram of the base station equipment
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PTx
Pel/amp
(1)
Based on PTx , we can calculate the power consumption
Pel/amp of the power amplifier (in Watt) as follows
Pel/amp =
PTx
h
(2)
Once the power consumption of the different components of
the base station is known, the power consumption Pel of the
base station (in Watt) can be determined
Pel = nsector · (nTx · (Pel/amp + Pel/trans ) + Pel/proc + Pel/rect )
+ Pel/micro + Pel/airco
(3)
with nsector being the number of sectors in the cell, and Pel/amp ,
Pel/trans , Pel/proc , Pel/rect , Pel/micro and Pel/airco are the power
consumptions of the power amplifier, the transceiver, the
digital signal processing, the rectifier, the microwave link (if
present) and the air conditioning, respectively. In case
MIMO is used, the base station needs the same number of
power amplifiers and the same number of transceivers as
the number of transmitting antennas [20]. In order to take
the power consumption of this extra equipment into
account, the power consumption of the power amplifier and
the transceiver is multiplied by the number nTx of
transmitting antennas for one sector. MIMO influences also
the digital signal processing but this is, compared to the
transceiver, negligible. Furthermore, (3) is only valid when
one frequency is used per sector.
Table 1 summarises the power consumption of the different
components of a base station for the considered technologies.
These values are retrieved from data sheets of various
IET Sci. Meas. Technol., 2011, Vol. 5, Iss. 4, pp. 155 –161
doi: 10.1049/iet-smt.2010.0094
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Table 1 Power consumption of the base station components for
the considered technologies (mobile WiMAX, fixed WiMAX,
UMTS, HSPA and LTE)
Equipment
digital signal processing
power amplifier (SISO)
power amplifier (MIMO)
transceiver
rectifier
air conditioning
microwave link
Value
Pel/proc
h
Pel/amp (max.)
h
Pel/amp (max.)
Pel/trans
Pel/rect
Pel/airco
Pel/micro
100 W
12.8%
156 W
11.54%
10.4 W
100 W
100 W
225 W
80 W
manufacturers of network equipment and from standards [13,
21– 28]. For the power amplifier, the maximum power
consumption is indicated. The power consumption of the
digital signal processing and the transceiver are based on
confidential data retrieved from an operator. The results
presented in this paper depend on the values listed in Table 1.
The most important source of power consumption is the air
conditioning. In contrast to [16], the same air conditioning is
used for all technologies. This adaptation is made based on
the information retrieved from operators. Furthermore, a
power amplifier with a more realistic efficiency was chosen
for the reference configuration [13]. This power amplifier
can be used for all the considered technologies because it
supports the frequency of each considered technology and
the RF output power of the power amplifier covers the
needed input power of the antennas for each considered
technology. Also the power amplifier for the extended
configuration can be used for all the considered technologies.
As a validation of our model, we compare the power
consumption with available data and measurements. For a
three-sector base station with one antenna per sector, Pel
equal to 1672.6 W is found with (3) for UMTS, HSPA and
LTE. In [13, 15], Pel of 1700 and 1500 W, respectively, are
found for the traditional 3G base station, which is similar to
the Pel obtained with our model. In [4], Pel for a one-sector
base station with one antenna is 783 W. With our model,
similarly, Pel ¼ 761 W is obtained. Furthermore, a good
similarity between our Pel and confidential data from an
operator about the power consumption of 3G base stations
is obtained.
3.2 Calculation of the coverage range R of the
base station
The power consumption Pel of the base station is now related
to the wireless range R covered by this base station. To this
end, a link budget has to be constructed. A link budget
takes all of the gains and the losses of the transmitter
through the medium to the receiver into account. Firstly, we
calculate the maximum allowable path loss PLmax (in dB)
to which a transmitted signal can be subjected while still
being detectable at the receiver. The path loss is the ratio of
the radiated power to the received power of the signal; it
includes all of the possible elements of loss associated with
interactions between the propagating wave and any objects
between the transmit and receive antennas [29]. To
determine PLmax , the parameters of Table 2 are taken into
account. Table 2 lists all the gains and losses that occur.
These parameters are retrieved from the specifications
and/or are typical values proposed by the operators
IET Sci. Meas. Technol., 2011, Vol. 5, Iss. 4, pp. 155–161
doi: 10.1049/iet-smt.2010.0094
themselves in order to make a fair comparison between the
considered technologies.
Some of these parameters need a short explanation, for
example, the fading margin. The fading margin accounts for
temporal fading (e.g. varying weather conditions) and is
determined based on the projected yearly availability of
the system. The noise figure is a measure of degradation of
the SNR (Signal-to-Noise Ratio) caused by components in
the radio frequency signal chain. The receiver SNR
determines the required SNR at the receiver for a certain
BER (Bit Error Rate) and the bit rate.
Since UMTS and HSPA use W-CDMA as multiple access
technique, an extra gain needs to be taken into account.
This gain is called the processing gain PG (in dB) and is
defined as [30]
CR
PG = −10 log(SP) = −10 log
SR
(4)
with SP being the spreading factor, which is the ratio of the
chip rate CR (in Mcps) to the symbol rate SR (in bps). The
processing gain is thus the ratio of the spreaded (RF)
bandwidth to the unspreaded (baseband) bandwidth. Also
the input power of the antenna for UMTS and HSPA needs
to be scaled according to the control overhead, the target
load and the maximum number of users [31]
TCH
PTx
=
(1 − CL) · PTx
TLNusers
(5)
TCH
with PTx
being the power reserved by the base station for the
traffic channels. CL is the control overhead, TL the target load
and Nusers the maximum number of users. PTx is used to
determine the power consumption of the base station and
TCH
PTx
is used to determine the range of the UMTS and
HSPA base station (Table 2). For mobile WiMAX, fixed
TCH
WiMAX and LTE, PTx in Table 2 is equal to PTx
because
an OFDMA-based multiple access technology is used. Also,
the user interference margin UIM (in dB) needs to be taken
into account when using UMTS and HSPA [31]
UIM = −10 · log10 (1 − TL)
(6)
with TL the target load.
For mobile WiMAX, HSPA and LTE an extra gain, the
MIMO gain GMIMO needs to be taken into account for
the extended configuration (MIMO) (Section 4.3). Here, the
theoretical MIMO gain GMIMO is considered [32]
GMIMO = 10 log10 (nTx nRx )
(7)
GMIMO in (7) might be an overestimation for some realistic
cases [33], but (7) is used for all technologies to have a fair
comparison.
Once the maximum allowable path loss PLmax is known,
the maximum range R (in metres) covered by the base
station of a certain technology can be determined
R = g−1 ((PLmax − SM)| f , hBS , hMS )
(8)
with PLmax being the maximum allowable path loss (in dB),
SM the shadowing margin (in dB), f the frequency (in Hz),
hBS the height of the base station (in metres) and hMS the
height of the mobile station (in metres). The shadowing
margin depends on the standard deviation of the path loss
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Table 2
Link budget table for technologies considered
Parameter
frequency
input power of base
station ptx
effective input power of
TCH
base station PTx
antenna gain of base
station
antenna gain of mobile
station
number of MIMO TX
antennas
number of MIMO RX
antennas
cyclic combining gain
of base station
soft handover gain
feeder loss of base
station
feeder loss of mobile
station
fade margin
yearly availability
cell interference
margin
user interference
margin
bandwidth
constellation
receiver SNR
number of used
subcarriers
number of total
subcarriers
noise figure of mobile
station
implementation loss
of mobile station
processing gain
control overhead
target load
max. number of users
duplexing
building penetration
loss [34]
Mobile WiMAX
Fixed WiMAX
UMTS
HSPA
LTE
Unit
2.5
35
3.5
35
2.1
43
2.1
43
2.6
43
GHz
dBm
35
35
31.5
24.7
43
dBm
16
17
17.4
17.4
18
dBi
2
8
0
0
0
dBi
1, 2, 3, 4
1
1
1, 2, 3, 4
1, 2, 3, 4
–
1, 2, 3, 4
1
1
1, 2, 3, 4
1, 2, 3, 4
–
3
3
3
3
3
dB
0
0.5
0
0.5
1.5
2
1.5
0
0
2
dB
dB
0
0
0
0
0
dB
10
99.995
2
10
99.995
0
10
99.995
0
10
99.995
2
10
99.995
2
dB
%
dB
0
0
6
9
0
dB
1.25
2/3 64-QAM
19
85
3.5
3/4 QPSK
11.2
201
5
PS 384 data service
7
1
5
3/4 QPSK
3.4
1
1.4
[2/3 16-QAM, 2/3 64-QAM]
[19, 29.4] ([34])
76
MHz
–
dB
–
128
256
1
1
128
–
7
4.6
8
9
8
dB
2
0
0
0
0
dB
–
–
–
–
TDD (Time
Division
Duplexing)
8.1
–
–
–
–
10.0
0.25
0.75
4
12
0.25
0.875
75
–
–
–
–
dB
–
–
–
–
8.1
8.1
8.1
8.1
dB
model, the coverage percentage and the outdoor standard
deviation. Here, a coverage percentage of 90% is
considered. The function g(.) depends on the used path loss
model, for example, the HATA model and the Erceg model
[35, 36]. In this paper, the Erceg C model is used as this is
best suitable for suburban areas. The quantity before the ‘|’
in (8) is a variable and varies over a continuous interval,
whereas the quantities after the ‘|’ are parameters that take
only one discrete known value.
3.3 Parameter to quantify the power consumption
and efficiency
If multiple technologies are compared, it is very difficult
to determine which one is the most energy efficient: one
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technology could have higher power consumption but also
a higher range, another one could have a smaller range but
also a lower power consumption etc. Therefore the power
consumption PCarea per covered area (in W/m2) is defined
to quantify the power consumption and efficiency for
different technologies
Pel
(9)
pR2
with Pel being the power consumption of the entire base
station (in Watt) and R the covered range (in m). This
parameter allows us to compare the energy efficiency of
different wireless technologies and to determine which one
is the most energy efficient. The lower the PCarea , the more
energy efficient the considered technology is. The
PCarea =
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60 Mbps are considered. Only mobile WiMAX and LTE
support 60 Mbps. The different parameters can be found in
Tables 1 – 3. For 60 Mbps, a 20 MHz channel is used.
Mobile WiMAX uses 1440 out of 2048 subcarriers and
LTE 1201. Furthermore, the 2/3 64-QAM modulation
(19 dB receiver SNR for mobile WiMAX and 29.4 dB for
LTE [37]) is used.
Table 4 lists the results for R, Pel and PCarea . Based on the
assumptions made for the parameters and 3 Mbps, UMTS
is the most energy-efficient technology (lowest PCarea)
followed by (in rising order for PCarea) fixed WiMAX,
LTE, mobile WiMAX and HSPA.
The power efficiency PCarea of UMTS and fixed WiMAX
is considerably lower (,1 mW/m2) than those for mobile
WiMAX, HSPA and LTE (2.4 – 3.5 mW/m2). UMTS
performs better than fixed WiMAX because of its higher
ranges (lower receiver SNR and the processing gain in
Table 2). The higher power consumption Pel of UMTS is
owing to the higher input power PTx of the antenna. Fixed
WiMAX is more efficient than mobile WiMAX, HSPA and
LTE because of its higher range (lower receiver SNR and
higher antenna gain of the mobile station in Table 2) and its
lower power consumption (lower PTx of the fixed WiMAX
base station). Finally, LTE is more energy efficient than
mobile WiMAX and HSPA because of its higher effective
TCH
input power PTx
of the antenna resulting in a higher range.
For 60 Mbps, mobile WiMAX performs better than LTE
because of its higher range and lower power consumption.
This higher range is caused by its lower receiver SNR. The
power consumption is lower because of its higher PTx .
Important to remark is that for different modulation
schemes and coding rates, the power consumption Pel does
not change [16]. However, a different range is obtained,
which has a direct influence on PCarea .
normalisation to the area allows us to make a fair comparison
between the different technologies in terms of energy
efficiency. It is assumed that the cells are circular.
4
4.1
Applications
Configuration
In this investigation, the base stations are placed outdoor in a
suburban environment. Only macro cells with a base station
antenna height of 30 m are considered. For the mobile stations,
an indoor residential configuration with a WNIC (Wireless
Network Interface Card) for a laptop for all technologies is
considered except for fixed WiMAX, where we consider a
residential gateway. Table 3 summarises the configuration
parameters for all technologies described in Section 2.
We also define two technical configurations for the outdoor
base stations: a basic reference configuration and an extended
configuration. All the considered technologies support the
basic reference configuration. The extended configuration is
only supported by mobile WiMAX, HSPA and LTE. In the
basic reference configuration, one transmitting (Tx) and one
receiving (Rx) antenna is considered, that is, a SISO (Single
Input Single Ouput) system. In the extended configuration,
both the base station and the receiver have multiple
antennas. Six different MIMO systems are considered:
2 × 1 (2 Tx and 2 Rx), 2 × 2, 2 × 3, 3 × 3, 4 × 3 and
4 × 4 MIMO systems.
The frequencies used for the link budget calculations of the
different technologies are the following: 2.5 GHz for mobile
WiMAX, 3.5 GHz for fixed WiMAX, 2.1 GHz for UMTS
and HSPA and 2.6 GHz for LTE.
4.2
Comparison of the technologies considered
In this section, the considered wireless technologies are
compared for the reference configuration. In order to make
a fair comparison, predefined bit rates of 3 Mbps and
Table 3
Value
area type
number of sectors nsector
height of a base station
height of a mobile station
coverage requirement
path loss model
shadowing margin
Influence of MIMO
In this section, the influence of MIMO on the energy
efficiency is investigated. The considered technologies are
compared for a 2 × 1, 2 × 2, 3 × 2, 3 × 3, 4 × 3 and
4 × 4 MIMO system (Section 4.1). Fig. 2 gives an
overview of PCarea as a function of the chosen MIMO
system for mobile WiMAX, HSPA and LTE. The energy
efficiency gain is also indicated in the figure. The energy
efficiency gain, EG, indicates how much (as a percentage)
PCarea has decreased compared to the SISO system
Configuration table under consideration
Parameter
Table 4
4.3
suburban
3
30 m
1.5 m
90%
Erceg C
13.2 dB
EG =
PCarea/SISO − PCarea/MIMO
· 100
PCarea/SISO
(10)
Comparison of the technologies considered for a physical bit rate of 3 Mbps and 60 Mbps
Mobile WiMAX
Fixed WiMAX
UMTS
HSPA
LTE
3 Mbps
bit rate [Mbps]
R [m]
Pel [W]
PCarea [mW/m]2
3.6
342.5
1279.1
3.5
3.1
674.4
1279.1
0.9
3
846.1
1672.6
0.7
3.8
372.5
1672.6
3.8
3.2
470.6
1672.6
2.4
60 Mbps
bit rate [Mbps]
R [m]
Pel [W]
PCarea [mW/m2]
61.1
172.2
1279.1
13.7
–
–
–
–
–
–
–
–
–
–
–
–
67.6
138.3
1672.6
27.8
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Fig. 2 Influence of 2 × 1, 2 × 2, 3 × 2, 3 × 3, 4 × 3 and 4 × 4 MIMO on PCarea
Based on the assumptions made for the parameters and the
considered cases, Fig. 2 shows that the energy efficiency
increases when MIMO is introduced. The highest energy
efficiency is obtained with a 4 × 4 MIMO system (up to
63%). The EG is the highest for mobile WiMAX.
Compared to the SISO system, the area covered by each
technology increases with 438%, because of an increase of
132% of the range, whereas the power consumption
increases with only 95% for mobile WiMAX and 173% for
HSPA and LTE. The increase in power consumption is
lower for mobile WiMAX because of its lower input power
PTx of the antenna (Table 2). This is also the reason why
the highest EG are obtained with mobile WiMAX (34–63%)
for all considered MIMO systems.
Comparing the different MIMO systems reveals that a
higher MIMO array size (i.e. more transmitting and/or more
receiving antennas) does not always results in a higher
energy efficiency. For mobile WiMAX, EG for a 2 × 2 and
3 × 2 MIMO system are approximately equal (51%). This
can be explained as follows: The power consumption Pel of
the base station for 2 × 2 MIMO is lower (1689.5 W
against 2495.8 W for 3 × 2 MIMO) because only two
transmitting antennas are used [see (3)]. However, the range
is higher for the 3 × 2 MIMO system (794.4 m against
576.3 m for 2 × 2 MIMO) because of its higher MIMO
gain [see (7)], resulting in similar values for PCarea and EG.
Analogously for LTE, the 2 × 2 and 3 × 3 MIMO system
have higher EG than the 3 × 2 and the 4 × 3 MIMO system,
respectively. For HSPA even lower EG values for the 3 × 3
and 4 × 3 MIMO system than for the 3 × 2 MIMO system
and the 3 × 3 MIMO system are obtained, respectively.
5
compared for the considered bit rates for a basic reference
configuration and an extended future configuration. Lower
PCarea values mean that the technology is more energy
efficient.
Based on the assumptions made for the parameters, the
reference configuration and 3 Mbps, UMTS is the most
energy-efficient technology followed by (in rising order of
PCarea) fixed WiMAX, LTE, mobile WiMAX and HSPA.
For 60 Mbps (only supported by mobile WiMAX and
LTE), mobile WiMAX performs better.
The introduction of MIMO has a positive influence on the
energy efficiency. The biggest influence is obtained with a
4 × 4 MIMO system: PCarea increases up to 63% for
mobile WiMAX and up to 50% for HSPA and LTE.
Furthermore, a higher MIMO size does not always result in
higher energy efficiency.
Future research will consist of including microcells to
cover smaller areas in the model of Section 3. Also the
influence of load dependency on the range (cell breathing)
and thus the power efficiency will be investigated. When
there is little or no activity in the area of the base station,
the base station could be switched off (sleep mode).
Nowadays, this is not supported by the base station but this
should be part of future research. The sleep modes have to
be combined with an advanced management algorithm and
will have a positive influence on the power consumption
and energy efficiency.
6
Acknowledgment
W. Joseph is a Post-Doctoral Fellow of the FWO-V (Research
Foundation Flanders).
Conclusions and future research
In this paper, the power consumption for five different
wireless technologies, namely mobile WiMAX, fixed
WiMAX, UMTS, HSPA and LTE is investigated based on
the parameter assumptions for the five technologies. This
power consumption is then related to the coverage of the
base station. The base stations (macro cells) are placed
outdoor and for the mobile stations. An indoor residential
scenario with a WNIC is considered, except for fixed
WiMAX where a residential gateway is considered. The
energy efficiency per covered area PCarea was defined and
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