1. Energy Ecient Wireless Communications Jingon Joung ACT:
Advanced Commun. Tech. Dept. I2 R: Institute for Infocomm Research
A STAR: Agency for Science, Technology, And Research, Singapore
Tutorial 2: The 14th International Conference on Electronics,
Information and Communication (ICEIC2015), Singapore 29 January
2015 Jingon Joung Tutorial 2: Energy Ecient Wireless Communications
1 / 112
2. Index 1 Introduction and Background (35 min, 24 pages) Green
Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 2 / 112
3. Index 1 Introduction and Background (35 min, 24 pages) Green
Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 3 / 112
4. Index 1 Introduction and Background (35 min, 24 pages) Green
Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 4 / 112
5. Green Wireless Communications Green to reduce energy
consumption to reduce CO2 emission Jingon Joung Tutorial 2: Energy
Ecient Wireless Communications 5 / 112
6. Green Wireless Communications Green Information &
Communications Tech. (ICT) [1] the 5th largest industry in power
consumption energy consumption: 3% (2007) CO2 emission: 2% (2007)
will increase X35, 4% (2020) e.g., cellular networks: energy: 77.5
TWh (2/60/3.5/10 TWh for 3b/4MM/20,000/etc. subscribers/radio
stations/radio controllers/others) CO2: 35 Mt (1/20/2/5 Mt for )
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 5 /
112
7. Green Wireless Communications Wireless access communication
networks consume significant amount of energy to overcome [2]
fading, distortion, degradation (path loss) obstacles,
interferences TX wirelesschannel RX Jingon Joung Tutorial 2: Energy
Ecient Wireless Communications 5 / 112
8. Green Wireless Communications The energy is mostly consumed
at the transmitter e.g., 80-85% power at base station (BS) in
cellular networks [2] Base Band Module D A C Informationbinarybits
Filter Filter LO LFTPA Attn. control DC control Mixer VGA
Synthethesizer Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 5 / 112
9. Green Wireless Communications 5080% of transmitters power is
consumed at power amplifier (PA) [3] PA input signal output signal
DC Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 5
/ 112
10. References [1]: [McK, 2007] [Fettweis and Zimmermann, 2008]
[Mancuso and Sara Alouf, 2011] [Chatzipapas et al., 2011] [2]:
[Richter et al., 2009] [Baliga et al., 2011] [Vereecken et al.,
2011] [Chatzipapas et al., 2011] [Joung and Sun, 2012] [3]: [Gruber
et al., 2009] [Bogucka and Conti, 2011] [Joung et al., 2012a]
[Joung et al., 2014c] [Joung et al., 2013] Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 6 / 112
11. Green ICT Projects & Consortiums C2Power: Project, EU,
Jan. 2010Dec. 2012 - cognitive radio and cooperative strategies -
power saving in multi-standard wireless devices eWIN, Project, KTH,
Sweden ECOnet: low Energy COnsumption NETworks, EU, Oct. 2010Sept.
2013 - dynamic adaptive technologies G-MC2: Project, Green
Multiuser-MIMO Cooperative Communications, I2 R, Singapore, Jan.
2012Dec. 2014 GREENET: Consortium, green wireless networks, EU
GREENT: Consortium, green terminals for next generation wireless
systems, EU CO2GREEN Project: Spain - cooperative and cognitive
techniques - green wireless communications GreenTouch: Consortium,
architecture, specications and roadmap, since 2010 earth: Project,
Energy Aware Radio and neTwork tecHnologies Green Radio: mobile
virtual center of excellence (VCE) and personal communications, UK
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 7 /
112
12. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 8 / 112
13. Whats Eciency? Eciency: has widely varying meanings in
dierent disciplines refers to the use of resources so as to
maximize the production of goods and services economics is an
important factor in determination of productivity business
describes the extent to which time, eort or cost is well used for
the intended task or purpose wikipedia is the ratio of the energy
developed by a machine, engine, etc., to the energy supplied to it
dictionary Eciency in general valuable resource produced valuable
resource consumed Eciency in communications? Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 9 / 112
14. Whats Eciency? Eciency: has widely varying meanings in
dierent disciplines refers to the use of resources so as to
maximize the production of goods and services economics is an
important factor in determination of productivity business
describes the extent to which time, eort or cost is well used for
the intended task or purpose wikipedia is the ratio of the energy
developed by a machine, engine, etc., to the energy supplied to it
dictionary Eciency in general valuable resource produced valuable
resource consumed Eciency in communications? Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 9 / 112
15. Whats Eciency? Eciency: has widely varying meanings in
dierent disciplines refers to the use of resources so as to
maximize the production of goods and services economics is an
important factor in determination of productivity business
describes the extent to which time, eort or cost is well used for
the intended task or purpose wikipedia is the ratio of the energy
developed by a machine, engine, etc., to the energy supplied to it
dictionary Eciency in general valuable resource produced valuable
resource consumed Eciency in communications? Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 9 / 112
16. Eciency in Communications valuable resource produced in
comm: information, coverage, subscribers, ... valuable resource
consumed in comm: frequency, space, time, power, ... Spectral
Eciency (SE) and Energy Eciency (EE) SE, b/s/Hz: number of reliably
decoded bits per channel use [Cover and Thomas, 2006, Verdu, 2002,
Chen et al., 2011] - Shannon (channel) capacity, data rate
(throughput), goodput EE, b/J: number of reliably decoded bits per
energy - various EEs in communications Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 10 / 112
17. Eciency in Communications valuable resource produced in
comm: information, coverage, subscribers, ... valuable resource
consumed in comm: frequency, space, time, power, ... Spectral
Eciency (SE) and Energy Eciency (EE) SE, b/s/Hz: number of reliably
decoded bits per channel use [Cover and Thomas, 2006, Verdu, 2002,
Chen et al., 2011] - Shannon (channel) capacity, data rate
(throughput), goodput EE, b/J: number of reliably decoded bits per
energy - various EEs in communications Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 10 / 112
18. Eciency in Communications valuable resource produced in
comm: information, coverage, subscribers, ... valuable resource
consumed in comm: frequency, space, time, power, ... Spectral
Eciency (SE) and Energy Eciency (EE) SE, b/s/Hz: number of reliably
decoded bits per channel use [Cover and Thomas, 2006, Verdu, 2002,
Chen et al., 2011] - Shannon (channel) capacity, data rate
(throughput), goodput EE, b/J: number of reliably decoded bits per
energy - various EEs in communications Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 10 / 112
19. Various EEs in Comms. Table 1: Various EEs [Richter et al.,
2009, Tombaz et al., 2011, Hasan et al., 2011, Zhou et al., 2013,
Joung et al., ]. Metric Type Units power usage eciency
facility-level ratio ( 1) data center eciency facility-level %
telecommun. energy e. ratio equipment-level Gbps/W telecommun.
equipment energy e. rating equipment-level log(Gbps/W) energy
consumption rating equipment-level W/Gbps area power consumption
network-level Km2 /W user power consumption network-level users/W
network energy e. with delay eect network-level dB/J pecuniary
eciency network-level bits/$ Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 11 / 112
20. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 12 / 112
21. Theoretical SE-EE Tradeo SE, b/s/Hz EE,b/J Figure 1:
Theoretical SE-EE tradeo. Figure 2: Ideal power consumption. SE =
log2(1 + Pout/2 ): Gaussian signalling, perfectly linear PA [Cover
and Thomas, 2006] EE = SE Pc : ideal power consumption model in
Fig. 2 [Verdu, 2002, Chen et al., 2011] [Pout: transmit power; 2:
noise power; : total bandwidth] Convex and wide (good) tradeo
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 13 /
112
22. Theoretical SE-EE Tradeo SE, b/s/Hz EE,b/J Figure 1:
Theoretical SE-EE tradeo. Pc PPA Pout== Figure 2: Ideal power
consumption. SE = log2(1 + Pout/2 ): Gaussian signalling, perfectly
linear PA [Cover and Thomas, 2006] EE = SE Pc : ideal power
consumption model in Fig. 2 [Verdu, 2002, Chen et al., 2011] [Pout:
transmit power; 2: noise power; : total bandwidth] Convex and wide
(good) tradeo Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 13 / 112
23. Theoretical SE-EE Tradeo SE, b/s/Hz EE,b/J 1 2 ln 2 Figure
1: Theoretical SE-EE tradeo. Pc PPA Pout== Figure 2: Ideal power
consumption. SE = log2(1 + Pout/2 ): Gaussian signalling, perfectly
linear PA [Cover and Thomas, 2006] EE = SE Pc : ideal power
consumption model in Fig. 2 [Verdu, 2002, Chen et al., 2011] [Pout:
transmit power; 2: noise power; : total bandwidth] Convex and wide
(good) tradeo Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 13 / 112
24. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 14 / 112
25. Practical PA Package (a) SM2122-44L (b) SM0822-39 Figure 3:
(a) High power PA with Pmax out = 25 W(44 dBm) and g = 55 dB.
Frequency band 2.1 GHz 2.2 GHz. (b) Low power PA with Pmax out = 8
W and g = 45 dB. PA: a type of electronic amplier - converts a
low-power RF signal into a larger signal of signicant power -
typically, for driving the antenna of a transmitter Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 15 / 112
26. Basic Circuit Model of PA ACRF-drive,Pin DC input, PDC
PAoutput,Pout Power Amplier (PA) Figure 4: Power amplier model with
eld-eect transistor (FET) [Cripps, 2006, Kazimierczuk, 2008].
Transistor is a core semiconductor device: amplies and switches
electronic signals and electrical power changes a voltage or
current: terminals (G,D) to terminals (S,D) Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 16 / 112
27. Basic Circuit Model of PA ACRF-drive,Pin DC input, PDC
PAoutput,Pout gate drainsource transistor RFC DC blocking capacitor
inputnetwork outputnetwork resistor Figure 4: Power amplier model
with eld-eect transistor (FET) [Cripps, 2006, Kazimierczuk, 2008].
Transistor is a core semiconductor device: amplies and switches
electronic signals and electrical power changes a voltage or
current: terminals (G,D) to terminals (S,D) Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 16 / 112
29. Ideal PA Eciency 5 10 15 20 25 30 35 40 45 50 55 5 10 15 20
25 30 35 40 45 50 55 PDC dBm Pout(Pmax)dBm Figure 6: Maximum output
power at linear region versus PA power consumption. between input
and output signals, i.e., Pout/PDC. Jingon Joung Tutorial 2: Energy
Ecient Wireless Communications 18 / 112
30. Linearity Models [Teikari, 2008] Transistor-level
System-level accurate yet difficult to obtain, generalize or
analyze a few parameters obtained from measurements, tractable, and
reasonably accurate PA Linearity Models [23][Vuolevi et al., 2000],
[24][Boumaiza and Ghannouchi, 2003], [25][Gadringer et al., 2005],
[26][Morgan et al., 2006], [27][Kim and Konstantinou, 2001],
[28][Jeruchim et al., 2000] Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 19 / 112
31. Linearity Models [Teikari, 2008] Transistor-level
System-level Memory Memoryless accurate yet difficult to obtain,
generalize or analyze a few parameters obtained from measurements,
tractable, and reasonably accurate a frequency-domain fluctuation
due to the capacitance and Inductance in the circuits and the
thermal fluctuation of the PAs, i.e., an electrical and thermal
memory effects, respectively [23,24] Volterra series model [25]
Wiener, Hammerstein models [26] Memory polynomial [27] previous PA
output signal does not affect the current PA output signal PA
Linearity Models [23][Vuolevi et al., 2000], [24][Boumaiza and
Ghannouchi, 2003], [25][Gadringer et al., 2005], [26][Morgan et
al., 2006], [27][Kim and Konstantinou, 2001], [28][Jeruchim et al.,
2000] Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 19 / 112
32. Linearity Models [Teikari, 2008] Transistor-level
System-level Memory Memoryless Passband Baseband accurate yet
difficult to obtain, generalize or analyze a few parameters
obtained from measurements, tractable, and reasonably accurate a
frequency-domain fluctuation due to the capacitance and Inductance
in the circuits and the thermal fluctuation of the PAs, i.e., an
electrical and thermal memory effects, respectively [23,24]
Volterra series model [25] Wiener, Hammerstein models [26] Memory
polynomial [27] previous PA output signal does not affect the
current PA output signal difficult to do simulation and computation
Nonlinearity of complex baseband frequency approximation is
captured simply [28] PA Linearity Models [23][Vuolevi et al.,
2000], [24][Boumaiza and Ghannouchi, 2003], [25][Gadringer et al.,
2005], [26][Morgan et al., 2006], [27][Kim and Konstantinou, 2001],
[28][Jeruchim et al., 2000] Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 19 / 112
33. Memoryless Baseband PA Models Generic model: simplied
baseband model for tractable analysis Ideal model for analysis: y =
gx, where x and y are PA input and output signals; and g > 0 is
a linear gain. Linear model for analysis [Minko, 1985]: y = gx + n,
where n is the nonlinear distortion that is independent of x and
modeled as Gaussian noise based on Bussgangs theorem [Bussgang,
1952]. Soft limiter model for analysis [Tellado et al., 2003]: y =
(|x|) e2j(|x|) - (): amplitude-dependent gain function - (): phase
shift function (|x|) |x|, if |x| < vsat, vsat, otherwise, (|x|)
0 where vsat is a saturation output amplitude. Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 20 / 112
34. Memoryless Baseband PA Models Generic model: simplied
baseband model for tractable analysis Ideal model for analysis: y =
gx, where x and y are PA input and output signals; and g > 0 is
a linear gain. Linear model for analysis [Minko, 1985]: y = gx + n,
where n is the nonlinear distortion that is independent of x and
modeled as Gaussian noise based on Bussgangs theorem [Bussgang,
1952]. Soft limiter model for analysis [Tellado et al., 2003]: y =
(|x|) e2j(|x|) - (): amplitude-dependent gain function - (): phase
shift function (|x|) |x|, if |x| < vsat, vsat, otherwise, (|x|)
0 where vsat is a saturation output amplitude. Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 20 / 112
35. Memoryless Baseband PA Models Generic model: simplied
baseband model for tractable analysis Ideal model for analysis: y =
gx, where x and y are PA input and output signals; and g > 0 is
a linear gain. Linear model for analysis [Minko, 1985]: y = gx + n,
where n is the nonlinear distortion that is independent of x and
modeled as Gaussian noise based on Bussgangs theorem [Bussgang,
1952]. Soft limiter model for analysis [Tellado et al., 2003]: y =
(|x|) e2j(|x|) - (): amplitude-dependent gain function - (): phase
shift function (|x|) |x|, if |x| < vsat, vsat, otherwise, (|x|)
0 where vsat is a saturation output amplitude. Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 20 / 112
36. Memoryless Baseband PA Models Generic model: simplied
baseband model for tractable analysis Ideal model for analysis: y =
gx, where x and y are PA input and output signals; and g > 0 is
a linear gain. Linear model for analysis [Minko, 1985]: y = gx + n,
where n is the nonlinear distortion that is independent of x and
modeled as Gaussian noise based on Bussgangs theorem [Bussgang,
1952]. Soft limiter model for analysis [Tellado et al., 2003]: y =
(|x|) e2j(|x|) - (): amplitude-dependent gain function - (): phase
shift function (|x|) |x|, if |x| < vsat, vsat, otherwise, (|x|)
0 where vsat is a saturation output amplitude. Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 20 / 112
37. Memoryless Baseband PA Models PA-specic model: accurate
baseband model specied to PA type Saleh model for traveling wave
tube amplier [Saleh, 1981]: (|x|) a1|x| 1 + a2|x|2 ; (|x|) b1|x|2 1
+ b2|x|2 where ai and bi are the distortion coecients Ghorbani
model for FET PA and for low amplitude nonlinearity [Ghorbani and
Sheikhan, 1991]: (|x|) a1|xa2 | 1 + a3|xa2 | + a4|x|; (|x|) b1|xb2
| 1 + b3|xb2 | + b4|x| Rapp model for envelope characteristic of
solid state PA (especially, class-AB) [Rapp, 1991, Falconer et al.,
2000]: (|x|) |x| 1 + |x| vsat 2p 1 2p ; (|x|) 0 where p is a
smoothness factor. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 21 / 112
38. Memoryless Baseband PA Models PA-specic model: accurate
baseband model specied to PA type Saleh model for traveling wave
tube amplier [Saleh, 1981]: (|x|) a1|x| 1 + a2|x|2 ; (|x|) b1|x|2 1
+ b2|x|2 where ai and bi are the distortion coecients Ghorbani
model for FET PA and for low amplitude nonlinearity [Ghorbani and
Sheikhan, 1991]: (|x|) a1|xa2 | 1 + a3|xa2 | + a4|x|; (|x|) b1|xb2
| 1 + b3|xb2 | + b4|x| Rapp model for envelope characteristic of
solid state PA (especially, class-AB) [Rapp, 1991, Falconer et al.,
2000]: (|x|) |x| 1 + |x| vsat 2p 1 2p ; (|x|) 0 where p is a
smoothness factor. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 21 / 112
39. Memoryless Baseband PA Models PA-specic model: accurate
baseband model specied to PA type Saleh model for traveling wave
tube amplier [Saleh, 1981]: (|x|) a1|x| 1 + a2|x|2 ; (|x|) b1|x|2 1
+ b2|x|2 where ai and bi are the distortion coecients Ghorbani
model for FET PA and for low amplitude nonlinearity [Ghorbani and
Sheikhan, 1991]: (|x|) a1|xa2 | 1 + a3|xa2 | + a4|x|; (|x|) b1|xb2
| 1 + b3|xb2 | + b4|x| Rapp model for envelope characteristic of
solid state PA (especially, class-AB) [Rapp, 1991, Falconer et al.,
2000]: (|x|) |x| 1 + |x| vsat 2p 1 2p ; (|x|) 0 where p is a
smoothness factor. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 21 / 112
40. Memoryless Baseband PA Models PA-specic model: accurate
baseband model specied to PA type Saleh model for traveling wave
tube amplier [Saleh, 1981]: (|x|) a1|x| 1 + a2|x|2 ; (|x|) b1|x|2 1
+ b2|x|2 where ai and bi are the distortion coecients Ghorbani
model for FET PA and for low amplitude nonlinearity [Ghorbani and
Sheikhan, 1991]: (|x|) a1|xa2 | 1 + a3|xa2 | + a4|x|; (|x|) b1|xb2
| 1 + b3|xb2 | + b4|x| Rapp model for envelope characteristic of
solid state PA (especially, class-AB) [Rapp, 1991, Falconer et al.,
2000]: (|x|) |x| 1 + |x| vsat 2p 1 2p ; (|x|) 0 where p is a
smoothness factor. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 21 / 112
41. PA Linearity = Nonlinear 0 0.2 0.4 0.6 0.8 0 0.2 0.4 0.6
0.8 1.0 1.2 Ideal model Linearized model (35dB) Soft limiter model
Rapp model (p=10) Rapp model (p=2) Saleh model Ghorbani model p=10
p=2 normalized input signal amplitude, |vin|
normalizedoutputsignalamplitude,|vout| Figure 7: AM/AM distortion
characteristics for various baseband PA models. Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 22 / 112
42. Eciency Models Eciencies of PA [Kazimierczuk, 2008, Raab et
al., 2002] 1 Drain eciency: D Pout PDC 2 Power-added eciency (PAE):
PAE PoutPin PDC = D 1 1 g 3 Overall eciency: O Pout PDC+Pin
Typically D PAE O, Pin PDC, Pin Pout Two important factors Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 23 /
112
43. Eciency Models Eciencies of PA [Kazimierczuk, 2008, Raab et
al., 2002] 1 Drain eciency: D Pout PDC 2 Power-added eciency (PAE):
PAE PoutPin PDC = D 1 1 g 3 Overall eciency: O Pout PDC+Pin
Typically D PAE O, Pin PDC, Pin Pout Two important factors Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 23 /
112
44. Eciency Models Eciencies of PA [Kazimierczuk, 2008, Raab et
al., 2002] 1 Drain eciency: D Pout PDC 2 Power-added eciency (PAE):
PAE PoutPin PDC = D 1 1 g 3 Overall eciency: O Pout PDC+Pin
Typically D PAE O, Pin PDC, Pin Pout Two important factors Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 23 /
112
45. PA Eciency < 100% 5 10 15 20 25 30 35 40 45 50 55 5 10
15 20 25 30 35 40 45 50 55 20% drain efficiency line 30% drain
efficiency line 100% drain efficiency line PAs: 01 GHz PAs: 12 GHz
PAs: 23 GHz PAs: 34 GHz PAs: 45 GHz PDC dBm Pout(Pmax)dBm Figure 8:
Maximum output power (at the linear region) versus PDC. < 100%
[Raab et al., 2003a] Typically between 20% and 30% [Joung et al.,
2012a] Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 24 / 112
46. PA Eciency Drop 0 5 10 15 20 25 28 30 34 40 45 50 0 10 20
30 40 50 60 70 Power-addedeciency(PAE),% Pout dBm SKY65162-70LF
optimal matching Doherty class-AB MAX2840 RF2132 RF2146 SST13LP01
AN10923 Doherty 21180 Figure 9: PAE versus Pout. usually drops
rapidly as the output power decreases [Shirvani et al., 2002] a
peak is achieved at the peak envelope power (PEP) Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 25 / 112
47. PA Classes Table 2: Examples of PA Classes [Raab et al.,
2002, Raab et al., 2003a, Raab et al., 2003b]. Class Linearity
Eciency Utilization Factor Main Applications A high 50% 0.125
millimeter wave (30-100GHz) 4W/30%/Ka-band 250mW/25%/Q-band
200mW/10%/W-band B high 78.5% 0.125 broadband at HF and VHF C 85% -
high-power vacuum-tube Tx D low 100% 0.159 100W to 1kW HF E low
100% 0.098 high-eciency at K-band 16W with 80% eciency at UHF 100mW
with 60% eciency at 10GHz F low very high 50% from 0.125 to 0.159
UHF and microwave (operation) class: amplication method
power-output capability (transistor utilization factor): output
power (# of transistor)(peak drain voltage)(peak drain current)
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 26 /
112
48. Applications of PAs HF VHF UHF L S C X Ku K Ka V W G THF 3M
30M 300M 1G 2G 12G 18G4G 8G 26.5G 40G 110G 300G 3T3G 75G (1-300M)
Comm. Submarines (3-30K) AM broadcasts (153K-26M) Navigation FM
(87.5-108M) TV (54M-890M, VHF, UHF) Weather radio (162M) Aircraft
comm. Land/maritime mobile comm. RFID (ISM band) Shortwave
Broadcasts Citizens' band radio Over-the-horizon radar/comm.
Amateur radio (3G-30G) WLAN 802.11a/ac/ad/n (5G) DBS (10.7G-12.75G)
Satellite comm./TV (C,Ku,Ka) Microwave devices/communications
Modern radars Radio astronomy Amateur radio (30G-300G) LMDS
(26G-29G, 31G-31.3G) WLAN 802.11ad (60G) HIgh-frequency microwave
radio relay MIcrowave remote sensing DIrected-energy weapon
MIllimeter wave scanner Radio astronomy Amateur radio (1T~)
Terahertz imaging Ultrafast molecular dynamics Condensed-matter
physics Terahertz time-domain spectroscopy Terahertz
computing/communications Sub-mm remote sensing Amateur radio
(300M-3G) FRS/GMRS (462M-467M) ZigBee (ISM: 868M,915M,2.4G) Z-Wave
(900M) DECT/Cordless telephone (900M) GPS (1.2,1.5G) GSM
(900M,1.8G) UMTS (2.1G) LTE (698M-3.8G) WLAN (802.11b/g/n/ad 2.4G)
Bluetooth (2.4-2.483.5MHz) BAN/WBAN/BSN (2.36G-2.4G) UWB
(1.6G-10.5G) Modern Cordless telephone (1.9G,2.4G,5.8G) Si LDMOS
GaN-HEMT Si RF CMOS SiGe-HBT, SiGe-BiCMOS GaAs-HBT, GaAs-pHEMT
InP-HBT InP-HEMT, GaAs-mEHMT SiC-MESFET 0 Figure 10: Power amplier
applications over IEEE bands [Joung et al., 2014b]. FET: eld eect
transistor MOSFET: metal oxide semiconductor FET MESFET: metal
epitaxial semiconductor FET DMOS: diued metal oxide semiconductor
LDMOS: laterally DMOS CMOS: complementary metal oxide semicond.
BiCMOS: bipolar CMOS HBT: heterojunction bipolar transistor HEMT:
high electron mobility transistor mHEMT: metamorphic HEMT pHEMT:
pseudomorphic HEMT SiGe: silicon Germanium GaAs: Gallium Arsenide
GaN: Gallium Nitride InP: Indium Phosphide ISM: industrial,
scientic and medical WPAN: wireless personal area network WLAN:
wireless local area network LTE: long term evolution GSM: Global
system for mobile communications UMTS: universal mobile telecommun.
system UWB: ultra-wide band GPS: global positioning system FRS:
family radio service GMRS: general mobile radio service BSN: body
sensor network BAN: body area network WBAN: wireless body area
network DBS: direct-broadcast satellite LMDS: local multipoint
distribution service DECT: digital enhanced cordless telecommun.
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 27 /
112
49. PA in Wireless Communications The LDMOS PA are employed for
many communication equipments. The international technology roadmap
for semiconductors (ITRS) reports that 48 volt LDMOS transistor is
widely used in cellular infrastructure market in 2011 [ITRS, 2011].
The LDMOS can support high output power required for a base station
(BS) in cellular networks. Table 3: Transmit Power of BSs [Auer et
al., 2011, earth, 2015] Type Pmax out back-o average max output
power ISD [m] Macro 54 dBm (250 W) 8 dB 43 dBm (20 W) 1 Km 5 Km
Micro 46 dBm (40 W) 8 dB 38 dBm (6.3 W) 100 m 500 m Pico 33 dBm (2
W) 12 dB 21 dBm (125 mW) 10 m 80 m Femto 29 dBm (800 mW) 12 dB 17
dBm (50 mW) indoor To compensate poor eciency of LDMOS devices in
the low power regime, envelope tracking architecture or Doherty
technique is used for 3G and 4G networks that employs high PAPR
waveform signals. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 28 / 112
50. Previous Studies on the Practical SE-EE Tradeo Practical SE
analysis with PA nonlinearity for multicarrier systems [Tellado et
al., 2003, Zillmann and Fettweis, 2005, Gutman and Wulich, 2012]
Practical SE-EE tradeo conjecture [Chen et al., 2011] Practical
SE-EE tradeo analysis with practical power consumption model
[Heliot et al., 2012, Onireti et al., 2012] Analytical and
numerical quantication of SE-EE tradeo with BOTH nonlinearity and
imperfect eciency of PA [Joung et al., 2012a, Joung et al., 2014c]
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 29 /
112
51. Previous Studies on the Practical SE-EE Tradeo Practical SE
analysis with PA nonlinearity for multicarrier systems [Tellado et
al., 2003, Zillmann and Fettweis, 2005, Gutman and Wulich, 2012]
Practical SE-EE tradeo conjecture [Chen et al., 2011] Practical
SE-EE tradeo analysis with practical power consumption model
[Heliot et al., 2012, Onireti et al., 2012] Analytical and
numerical quantication of SE-EE tradeo with BOTH nonlinearity and
imperfect eciency of PA [Joung et al., 2012a, Joung et al., 2014c]
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 29 /
112
52. Previous Studies on the Practical SE-EE Tradeo Practical SE
analysis with PA nonlinearity for multicarrier systems [Tellado et
al., 2003, Zillmann and Fettweis, 2005, Gutman and Wulich, 2012]
Practical SE-EE tradeo conjecture [Chen et al., 2011] Practical
SE-EE tradeo analysis with practical power consumption model
[Heliot et al., 2012, Onireti et al., 2012] Analytical and
numerical quantication of SE-EE tradeo with BOTH nonlinearity and
imperfect eciency of PA [Joung et al., 2012a, Joung et al., 2014c]
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 29 /
112
53. Practical SE-EE Tradeo SE, b/s/Hz EE,b/J ? Figure 11:
Practical SE-EE tradeo. Pc PPA Pout Figure 12: Practical Power
Consumption. Practical systems power consumption model in Fig. 12
eciency < 100% and PA nonlinearity SE is not a log function
anymore [Joung et al., 2012a, Joung et al., 2014c] Concave, narrow
(bad), and biased tradeo Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 30 / 112
54. Practical SE-EE Tradeo SE, b/s/Hz EE,b/J ? Figure 11:
Practical SE-EE tradeo. Pc PPA Pout Figure 12: Practical Power
Consumption. Practical systems power consumption model in Fig. 12
eciency < 100% and PA nonlinearity SE is not a log function
anymore [Joung et al., 2012a, Joung et al., 2014c] Concave, narrow
(bad), and biased tradeo Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 30 / 112
55. Practical SE-EE Tradeo SE, b/s/Hz EE,b/J Theoretical tradeo
in Fig. 1 Figure 11: Practical SE-EE tradeo. Pc PPA Pout Figure 12:
Practical Power Consumption. Practical systems power consumption
model in Fig. 12 eciency < 100% and PA nonlinearity SE is not a
log function anymore [Joung et al., 2012a, Joung et al., 2014c]
Concave, narrow (bad), and biased tradeo Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 30 / 112
56. Practical SE-EE Tradeo 1 2 ln 2 SE, b/s/Hz EE,b/J PA
ineciency and SE degradation resulting in drop of EE PA
nonlinearity resulting in drop of SE Theoretical SE-EE tradeo
Practical SE-EE tradeo Figure 13: Illustration of SE-EE tradeo. SE
maximization or EE maximization? EE for a single antenna (PA)
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 31 /
112
57. Practical SE-EE Tradeo 1 2 ln 2 SE, b/s/Hz EE,b/J PA
ineciency and SE degradation resulting in drop of EE PA
nonlinearity resulting in drop of SE Theoretical SE-EE tradeo
Practical SE-EE tradeo Figure 13: Illustration of SE-EE tradeo. SE
maximization or EE maximization? EE for a single antenna (PA)
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 31 /
112
58. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 32 / 112
59. Energy Ecient Technologies 5080% of transmitters power is
consumed at power amplifier (PA) Jingon Joung Tutorial 2: Energy
Ecient Wireless Communications 33 / 112
60. Energy Ecient Technologies Device-Level Approach
Transmitter architecture PA package structures Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 33 / 112
61. Energy Ecient Technologies Device-Level Approach
Transmitter architecture PA package structures System-Level
Approach Transceiver signal processing IBO/PAPR/DPD/ Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 33 / 112
62. Energy Ecient Technologies Device-Level Approach
Transmitter architecture PA package structures System-Level
Approach Transceiver signal processing IBO/PAPR/DPD/ Network-Level
Approach Network processing SC/HetNet/CZ/CoMP/CoNap/DTX/ Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 33 /
112
63. EE Tech. [Joung et al., 2014b] Approaches Methods
Improvement Challenges 1. PA Design linear architecture Linearity
(L) high cost, parallel architecture Eciency (E) large form factor
switching architecture (PAS) E envelope tracking (ET) architecture
E PA circuit architecture envelope elimination & restoration
(EER/Kahn) L, E outphasing technique (LINK) L, E Doherty technique
E 2. Signal Design PAPR reduction clipping L, E out-of-band
emission coding additional resource,partial transmit sequence (PTS)
latency, PA input/output selective mapping (SLM) complexity signal
processing tone reservation (TR) tone insertion (TI) Linearlization
feed forward sensitive to PA, feedback additional circuit, digital
predistortion (DPD) complexity 3. Network Design Network
densication E infrastructure, in/out band small cells overhead
signalling, distributed antenna system (DAS) scalability, Ecient
network cooperative communications (relay) handover, topology &
protocol Network protocol interference design by cell zooming
deploying low power PA coordinated multipoint (CoMP) or using PA
on/o cell discontinuous TX/RX (DTX/DRX) coordinated sleep and
napping (CoNap) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 34 / 112
64. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 35 / 112
65. 1. PA Design Architecture: a building block of various
circuits (e.g., multiple PAs, oscillators, mixers, lters, matching
networks, combiners, and circulators) Transmitter Architecture:
direct approach, PA package structures 1 Linear architecture [Raab
et al., 2003c] 2 Corporate architecture [Cripps, 2006] 3 Parallel
architecture [Shirvani et al., 2002, Alc, 2008] 4 Stage bypassing
and gate switching [Raab et al., 2003c, Staudinger, 2000] 5
Envelope elimination and restoration (EER) technique (or Kahn)
[Raab et al., 2003c, Kahn, 1952] 6 Envelope tracking architecture
[Raab et al., 2003c] F 7 Outphasing using linear amplication using
nonlinear components (LINK) [Raab et al., 2003c, Cox, 1974] 8
Doherty technique [Cha et al., 2004, Doherty, 1936, Correia et al.,
2010, Auer et al., 2011, Arnold et al., 2010] F 9 Combined complex
architecture, etc. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 36 / 112
66. 1. PA Design Architecture: a building block of various
circuits (e.g., multiple PAs, oscillators, mixers, lters, matching
networks, combiners, and circulators) Transmitter Architecture:
direct approach, PA package structures 1 Linear architecture [Raab
et al., 2003c] 2 Corporate architecture [Cripps, 2006] 3 Parallel
architecture [Shirvani et al., 2002, Alc, 2008] 4 Stage bypassing
and gate switching [Raab et al., 2003c, Staudinger, 2000] 5
Envelope elimination and restoration (EER) technique (or Kahn)
[Raab et al., 2003c, Kahn, 1952] 6 Envelope tracking architecture
[Raab et al., 2003c] F 7 Outphasing using linear amplication using
nonlinear components (LINK) [Raab et al., 2003c, Cox, 1974] 8
Doherty technique [Cha et al., 2004, Doherty, 1936, Correia et al.,
2010, Auer et al., 2011, Arnold et al., 2010] F 9 Combined complex
architecture, etc. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 36 / 112
67. Transmit Architectures DC A,P gA,P DC A,P gA,P DC + A,P
gA,P DC A,P gA,P A,P gA,P E-Det. A A,P A,P gA,P E-Det. A P DC + A,P
gA,P P1 P2 DC + A,P gA,P DC : DC power supply : PA A: amplitude
information P: phase information g: gain: RF-drive input : RF
output : delay+ : combiner (a) (b1) (d) (e) (b2) (c) (f) (g) SCS
limitter DC DC/DC Figure 14: Various transmit architectures: a)
Linear architecture. b) Parallel architecture. c) Switching
architecture. d) Envelope tracking (ET) architecture. e) EER
technique (or Kahn). f) Outphasing technique. g) Doherty technique
(DT). ET: DC power is controlled by the envelope of the RF input
signal DT: Class-B (carrier or main PA) + Class-C (peaking or
auxiliary PA) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 37 / 112
68. Key Points Table 4: Eciency, costs and environmental impact
of a 20,000-base-station network with dierent power amplier
technologies [Mancuso and Sara Alouf, 2011]. Traditional technology
Doherty technology Envelope tracking PA eciency 15 % 25 % 45 %
Power consumption 51.7 MW 27.2 MW 16.1 MW CO2 emission 194,600 tons
102,400 tons 60,800 tons Power cost 54.3 MM$ 28.6 MM$ 17.0 MM$
Challenges: Nonlinearity and ineciency are fundamental and
inevitable. mathematical model: modeling and empirical evaluation,
i.e., simulated-annealing-based custom computer-aided design high
manufacturing cost large form factor wide dynamic range with high
eciency advanced materials and metamaterials Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 38 / 112
69. Key Points Table 4: Eciency, costs and environmental impact
of a 20,000-base-station network with dierent power amplier
technologies [Mancuso and Sara Alouf, 2011]. Traditional technology
Doherty technology Envelope tracking PA eciency 15 % 25 % 45 %
Power consumption 51.7 MW 27.2 MW 16.1 MW CO2 emission 194,600 tons
102,400 tons 60,800 tons Power cost 54.3 MM$ 28.6 MM$ 17.0 MM$
Challenges: Nonlinearity and ineciency are fundamental and
inevitable. mathematical model: modeling and empirical evaluation,
i.e., simulated-annealing-based custom computer-aided design high
manufacturing cost large form factor wide dynamic range with high
eciency advanced materials and metamaterials Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 38 / 112
70. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 39 / 112
71. 2. Signal Design Transceiver Signal Processing: knowledge
of the signal properties 1 Input backo (IBO) [Kowlgi and Berland,
2011] - Reducing the transmit power to suciently below its peak
output power - Broadband signal having a high peak-to-average power
ratio (PAPR), e.g., 8 to 13 dB PAPR for ODFM signals [Kowlgi and
Berland, 2011], requires high IBO - High IBO reduces the PA eciency
2 PAPR reduction methods [Jiang and Wu, 2008] Clipping/ coding/
partial transmission sequence and selective mapping/ nonlinear
companding transform/ tone reservation and tone injection 3
Linearization [Pothecary, 1999, Kenington, 2000] To mitigate the
nonlinearity of PAs in the low power regime, various linearization
methods such as feedforward/ feedback/ predistortion 4 Active
antenna systems (reducing feeder loss) 5 SE improving system
design: large (massive) MIMO, 3D MIMO, etc. 6 Combined complex
architecture Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 40 / 112
72. 2. Signal Design Transceiver Signal Processing: knowledge
of the signal properties 1 Input backo (IBO) [Kowlgi and Berland,
2011] - Reducing the transmit power to suciently below its peak
output power - Broadband signal having a high peak-to-average power
ratio (PAPR), e.g., 8 to 13 dB PAPR for ODFM signals [Kowlgi and
Berland, 2011], requires high IBO - High IBO reduces the PA eciency
2 PAPR reduction methods [Jiang and Wu, 2008] Clipping/ coding/
partial transmission sequence and selective mapping/ nonlinear
companding transform/ tone reservation and tone injection 3
Linearization [Pothecary, 1999, Kenington, 2000] To mitigate the
nonlinearity of PAs in the low power regime, various linearization
methods such as feedforward/ feedback/ predistortion 4 Active
antenna systems (reducing feeder loss) 5 SE improving system
design: large (massive) MIMO, 3D MIMO, etc. 6 Combined complex
architecture Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 40 / 112
73. 2. Signal Design Transceiver Signal Processing: knowledge
of the signal properties 1 Input backo (IBO) [Kowlgi and Berland,
2011] - Reducing the transmit power to suciently below its peak
output power - Broadband signal having a high peak-to-average power
ratio (PAPR), e.g., 8 to 13 dB PAPR for ODFM signals [Kowlgi and
Berland, 2011], requires high IBO - High IBO reduces the PA eciency
2 PAPR reduction methods [Jiang and Wu, 2008] Clipping/ coding/
partial transmission sequence and selective mapping/ nonlinear
companding transform/ tone reservation and tone injection 3
Linearization [Pothecary, 1999, Kenington, 2000] To mitigate the
nonlinearity of PAs in the low power regime, various linearization
methods such as feedforward/ feedback/ predistortion 4 Active
antenna systems (reducing feeder loss) 5 SE improving system
design: large (massive) MIMO, 3D MIMO, etc. 6 Combined complex
architecture Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 40 / 112
74. 2. Signal Design Transceiver Signal Processing: knowledge
of the signal properties 1 Input backo (IBO) [Kowlgi and Berland,
2011] - Reducing the transmit power to suciently below its peak
output power - Broadband signal having a high peak-to-average power
ratio (PAPR), e.g., 8 to 13 dB PAPR for ODFM signals [Kowlgi and
Berland, 2011], requires high IBO - High IBO reduces the PA eciency
2 PAPR reduction methods [Jiang and Wu, 2008] Clipping/ coding/
partial transmission sequence and selective mapping/ nonlinear
companding transform/ tone reservation and tone injection 3
Linearization [Pothecary, 1999, Kenington, 2000] To mitigate the
nonlinearity of PAs in the low power regime, various linearization
methods such as feedforward/ feedback/ predistortion 4 Active
antenna systems (reducing feeder loss) 5 SE improving system
design: large (massive) MIMO, 3D MIMO, etc. 6 Combined complex
architecture Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 40 / 112
75. Key Points Impact: avoidance/compensation of the adverse
impact of PA nonlinearity Cost: - PA eciency reduction (high power
consumption) for input back o - out-of-band radiation increase for
signal clipping - SE reduction for side information - additional
computational complexity (see e.g., parameter optimization and
multiple candidate sequence generation [Rahmatallah and Mohan,
2013]) - additional analog circuits Challenges: hardware capability
limitation high sensitivity to PA status additional resource
requirement additional circuits tradeo between: linearity and
eciency; SE and EE Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 41 / 112
76. Key Points Impact: avoidance/compensation of the adverse
impact of PA nonlinearity Cost: - PA eciency reduction (high power
consumption) for input back o - out-of-band radiation increase for
signal clipping - SE reduction for side information - additional
computational complexity (see e.g., parameter optimization and
multiple candidate sequence generation [Rahmatallah and Mohan,
2013]) - additional analog circuits Challenges: hardware capability
limitation high sensitivity to PA status additional resource
requirement additional circuits tradeo between: linearity and
eciency; SE and EE Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 41 / 112
77. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 42 / 112
78. 3. Network Design Network Processing: using small power
PA/reducing PA activation time 1 Network densication - in/out band
small cell, inter-cell interference coordination (ICIC),
heterogeneous network (HetNet) [Chen et al., 2011, Richter et al.,
2009] - DAS [Choi and Andrews, 2007, Joung and Sun, 2013, Joung et
al., 2014a] - relay [Joung and Sun, 2012, Yang et al., 2009] Figure
15: Example of network densication. Jingon Joung Tutorial 2: Energy
Ecient Wireless Communications 43 / 112
79. 3. Network Design Network Processing: using small power
PA/reducing PA activation time 1 Network densication - in/out band
small cell, inter-cell interference coordination (ICIC),
heterogeneous network (HetNet) [Chen et al., 2011, Richter et al.,
2009] - DAS [Choi and Andrews, 2007, Joung and Sun, 2013, Joung et
al., 2014a] - relay [Joung and Sun, 2012, Yang et al., 2009]
carrier frequency 1 carrier frequency 2 joint processing cross-tier
interference intra-tier interference in-band small cell coverage
out-band small cell coverage cooperative communication region Macro
BS coverage usermacro BS small BS relay AP/RRH Figure 15: Example
of network densication. Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 43 / 112
80. Network Design 1 Network densication 2 Network protocol
design - Cell zooming [Niu et al., 2010] - CoMP [Han et al., 2011]
- DTX/CoNap [Frenger et al., 2011, 3GPP, TR 25.927 V11.0.0, 2012,
Adachi et al., 2012, Adachi et al., 2013, Shirvani et al., 2002]
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 44 /
112
81. Network Design 1 Network densication 2 Network protocol
design - Cell zooming [Niu et al., 2010] deactivated BS deactivated
BSactive BS - CoMP [Han et al., 2011] - DTX/CoNap [Frenger et al.,
2011, 3GPP, TR 25.927 V11.0.0, 2012, Adachi et al., 2012, Adachi et
al., 2013, Shirvani et al., 2002] Jingon Joung Tutorial 2: Energy
Ecient Wireless Communications 44 / 112
82. Network Design 1 Network densication 2 Network protocol
design - Cell zooming [Niu et al., 2010] deactivated BS deactivated
BSactive BS - CoMP [Han et al., 2011] deactivated BS active
BSactive BS - DTX/CoNap [Frenger et al., 2011, 3GPP, TR 25.927
V11.0.0, 2012, Adachi et al., 2012, Adachi et al., 2013, Shirvani
et al., 2002] Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 44 / 112
83. Network Design 1 Network densication 2 Network protocol
design - Cell zooming [Niu et al., 2010] deactivated BS deactivated
BSactive BS - CoMP [Han et al., 2011] deactivated BS active
BSactive BS - DTX/CoNap [Frenger et al., 2011, 3GPP, TR 25.927
V11.0.0, 2012, Adachi et al., 2012, Adachi et al., 2013, Shirvani
et al., 2002] fre q u e n c y P A c a n b e tu rn e d o ff P A is o
p e ra tin g in h ig h e ffic ie n c y T ra n s m it p o w e r
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 44 /
112
84. Key Points Requirements for cell densication: cross-tier
interference management - cell range expansion [Damnjanovic et al.,
2011] and eICIC [Kosta et al., 2013] in 3GPP - optimization of
beamforming and radio resource management [Joung et al., 2012b,
Joung et al., 2012c] Requirements for network protocol design:
cooperation or coordination among dierent nodes - decide how often
the cooperation/coordination performs PA on and o to balance the
system performance and the power saving - optimization of the radio
resource allocation Challenges: high infrastructure cost overhead
signalling and frequent handover network (backbone) overhead
scalability to already-deployed networks Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 45 / 112
85. Key Points Requirements for cell densication: cross-tier
interference management - cell range expansion [Damnjanovic et al.,
2011] and eICIC [Kosta et al., 2013] in 3GPP - optimization of
beamforming and radio resource management [Joung et al., 2012b,
Joung et al., 2012c] Requirements for network protocol design:
cooperation or coordination among dierent nodes - decide how often
the cooperation/coordination performs PA on and o to balance the
system performance and the power saving - optimization of the radio
resource allocation Challenges: high infrastructure cost overhead
signalling and frequent handover network (backbone) overhead
scalability to already-deployed networks Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 45 / 112
86. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 46 / 112
87. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 47 / 112
88. System Model x y IDFTF addCPP/SDAC ADCS/PremoveCP DFTFH x
PA LPA() {h0, , hL1} w z y Figure 16: An OFDM system with a
nonlinear memoryless PA [Joung et al., 2014c]. x = [x0, , xN1] T
CN(0, Pin): OFDM symbol consisting of N complex-valued data symbols
x = [x0, , xN1]T = F x: time domain signal vector Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 48 / 112
89. Signal Model F : N-by-N unitary IDFT matrix wt = LPA(xt):
PA output signal, w = [w0, , wN+NCP1]T xt = atejt : at |xt|, t is
the phase of xt (0 t < 2) wt = btejt : bt |wt| {h0, h1, , hL1}:
L-tap multipath channel Yt = ht wt + zt: received signal - perfect
timing synchronization - the CP is removed - indices are shifted to
start from 0 - zt CN(0, 2 z ): AWGN - yt rtej : rt and t represent
the amplitude and phase of Yt - y = [Y0, , YN1]T : vector
representation y = [y0, , yN1]T = F H y: frequency domain signal
vector after DFT of y Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 49 / 112
90. Assumptions A1: {xn} are i.i.d. with distribution x CN(0,
Pin) A2: Soft limiter model for PA input/ouput power: LPA(at) =
gat, if at < amax bmax, if at amax - amax Pmax in and bmax Pmax
out - Linearity in low power regime can be obtained with
linearization techniques (e.g., feedforward, feedback, and
predistortion) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 50 / 112
91. Assumptions A1: {xn} are i.i.d. with distribution x CN(0,
Pin) A2: Soft limiter model for PA input/ouput power: LPA(at) =
gat, if at < amax bmax, if at amax - amax Pmax in and bmax Pmax
out - Linearity in low power regime can be obtained with
linearization techniques (e.g., feedforward, feedback, and
predistortion) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 50 / 112
92. Mutual Information (MI) in Flat Fading Channels (L = 1)
Achievable rate averaged over N transmissions is given by I(X; Y
)/N (a) = I(X; Y )/N (a) Unitary transform (IDFT) (b) = N1 t=0
I(Xt; Yt)/N (b) independency in time domain (c) = I(X; Y ) = H(Y )
H(Y |X) (c) identical MI over t (d) = H(Y ) log2 e2 z [b/s] (d) H(Y
|X) = H(N) = log2 e2 z The entropy of Y is given by [Cover and
Thomas, 2006] H(Y ) = y fY (y) log2 fY (y)dy Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 51 / 112
93. Mutual Information (MI) in Flat Fading Channels (L = 1)
Achievable rate averaged over N transmissions is given by I(X; Y
)/N (a) = I(X; Y )/N (a) Unitary transform (IDFT) (b) = N1 t=0
I(Xt; Yt)/N (b) independency in time domain (c) = I(X; Y ) = H(Y )
H(Y |X) (c) identical MI over t (d) = H(Y ) log2 e2 z [b/s] (d) H(Y
|X) = H(N) = log2 e2 z The entropy of Y is given by [Cover and
Thomas, 2006] H(Y ) = y fY (y) log2 fY (y)dy Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 51 / 112
94. Mutual Information (MI) in Flat Fading Channels (L = 1)
Achievable rate averaged over N transmissions is given by I(X; Y
)/N (a) = I(X; Y )/N (a) Unitary transform (IDFT) (b) = N1 t=0
I(Xt; Yt)/N (b) independency in time domain (c) = I(X; Y ) = H(Y )
H(Y |X) (c) identical MI over t (d) = H(Y ) log2 e2 z [b/s] (d) H(Y
|X) = H(N) = log2 e2 z The entropy of Y is given by [Cover and
Thomas, 2006] H(Y ) = y fY (y) log2 fY (y)dy Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 51 / 112
95. Mutual Information (MI) in Flat Fading Channels (L = 1)
Achievable rate averaged over N transmissions is given by I(X; Y
)/N (a) = I(X; Y )/N (a) Unitary transform (IDFT) (b) = N1 t=0
I(Xt; Yt)/N (b) independency in time domain (c) = I(X; Y ) = H(Y )
H(Y |X) (c) identical MI over t (d) = H(Y ) log2 e2 z [b/s] (d) H(Y
|X) = H(N) = log2 e2 z The entropy of Y is given by [Cover and
Thomas, 2006] H(Y ) = y fY (y) log2 fY (y)dy Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 51 / 112
96. Mutual Information (MI) in Flat Fading Channels (L = 1)
Achievable rate averaged over N transmissions is given by I(X; Y
)/N (a) = I(X; Y )/N (a) Unitary transform (IDFT) (b) = N1 t=0
I(Xt; Yt)/N (b) independency in time domain (c) = I(X; Y ) = H(Y )
H(Y |X) (c) identical MI over t (d) = H(Y ) log2 e2 z [b/s] (d) H(Y
|X) = H(N) = log2 e2 z The entropy of Y is given by [Cover and
Thomas, 2006] H(Y ) = y fY (y) log2 fY (y)dy Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 51 / 112
97. Entropy H(y) in Flat Fading Ch. Dene S as a binary random
variable denoting the clipping at the PA: S = 0, if A amax 1,
otherwise The pdf of y can be rewritten as fY (y) = fY (y, S = 0) +
fY (y, S = 1) A closed-form expression of fY (y, S = 0) and fY (y,
S = 1) (see [Joung et al., 2014c] for the proof): fY (y, S = 0) =
N0(y) 1 Q1 (y), max fY (y, S = 1) = N1(y) exp a2 max Pin 2bmaxyRe 2
z I0 2bmax|y| 2 z - N0(y): pdf of CN 0, gPin + 2 z , N1(y): pdf of
CN bmax, 2 z - Q1(, ): Marcum-Q-function [Papoulis and Pillai,
2002] with parameters max 2(gPin+2 z) gPin bmax and (y)
8gPin(gPin+2 z) 4 z |y|2 - yRe: real part of y - I0(): modied
Bessel function of rst kind Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 52 / 112
98. Entropy H(y) in Flat Fading Ch. Dene S as a binary random
variable denoting the clipping at the PA: S = 0, if A amax 1,
otherwise The pdf of y can be rewritten as fY (y) = fY (y, S = 0) +
fY (y, S = 1) A closed-form expression of fY (y, S = 0) and fY (y,
S = 1) (see [Joung et al., 2014c] for the proof): fY (y, S = 0) =
N0(y) 1 Q1 (y), max fY (y, S = 1) = N1(y) exp a2 max Pin 2bmaxyRe 2
z I0 2bmax|y| 2 z - N0(y): pdf of CN 0, gPin + 2 z , N1(y): pdf of
CN bmax, 2 z - Q1(, ): Marcum-Q-function [Papoulis and Pillai,
2002] with parameters max 2(gPin+2 z) gPin bmax and (y)
8gPin(gPin+2 z) 4 z |y|2 - yRe: real part of y - I0(): modied
Bessel function of rst kind Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 52 / 112
99. Entropy H(y) in Flat Fading Ch. Dene S as a binary random
variable denoting the clipping at the PA: S = 0, if A amax 1,
otherwise The pdf of y can be rewritten as fY (y) = fY (y, S = 0) +
fY (y, S = 1) A closed-form expression of fY (y, S = 0) and fY (y,
S = 1) (see [Joung et al., 2014c] for the proof): fY (y, S = 0) =
N0(y) 1 Q1 (y), max fY (y, S = 1) = N1(y) exp a2 max Pin 2bmaxyRe 2
z I0 2bmax|y| 2 z - N0(y): pdf of CN 0, gPin + 2 z , N1(y): pdf of
CN bmax, 2 z - Q1(, ): Marcum-Q-function [Papoulis and Pillai,
2002] with parameters max 2(gPin+2 z) gPin bmax and (y)
8gPin(gPin+2 z) 4 z |y|2 - yRe: real part of y - I0(): modied
Bessel function of rst kind Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 52 / 112
100. Analytical Results on SE SE() = H(Y ) log2 e2 z = y s=0,1
fY (y, S = s) log2 s=0,1 fY (y, S = s) dy log2 e2 z If the PA is
perfectly linear, i.e., bmax and thus amax fY (y, S = 0) = N0(y) 1
Q1 (y), max = N0(y) fY (y, S = 1) = N1(y) exp a2 max Pin 2bmaxyRe 2
z I0 2bmax|y| 2 z = 0 SEideal () = log2 (1 + ) Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 53 / 112
101. Analytical Results on SE SE() = H(Y ) log2 e2 z = y s=0,1
fY (y, S = s) log2 s=0,1 fY (y, S = s) dy log2 e2 z If the PA is
perfectly linear, i.e., bmax and thus amax fY (y, S = 0) = N0(y) 1
Q1 (y), max = N0(y) fY (y, S = 1) = N1(y) exp a2 max Pin 2bmaxyRe 2
z I0 2bmax|y| 2 z = 0 SEideal () = log2 (1 + ) Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 53 / 112
102. Analytical Results on SE SE() = H(Y ) log2 e2 z = y s=0,1
fY (y, S = s) log2 s=0,1 fY (y, S = s) dy log2 e2 z If the PA is
perfectly linear, i.e., bmax and thus amax fY (y, S = 0) = N0(y) 1
Q1 (y), max = N0(y) fY (y, S = 1) = N1(y) exp a2 max Pin 2bmaxyRe 2
z I0 2bmax|y| 2 z = 0 SEideal () = log2 (1 + ) Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 53 / 112
103. Analytical Results on SE If PA input power is low, i.e., 1
fY (y, S = 0) = N0(y) 1 Q1 (y), max N0(y) fY (y, S = 1) = N1(y) exp
a2 max Pin 2bmaxyRe 2 z I0 2bmax|y| 2 z N1(y) SEIBO () log2 (1 + )
+ e 1 log2 2 z e1 1 log2 2 z Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 54 / 112
104. Analytical Results on SE If PA input power is low, i.e., 1
fY (y, S = 0) = N0(y) 1 Q1 (y), max N0(y) fY (y, S = 1) = N1(y) exp
a2 max Pin 2bmaxyRe 2 z I0 2bmax|y| 2 z N1(y) SEIBO () log2 (1 + )
+ e 1 log2 2 z e1 1 log2 2 z Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 54 / 112
105. Analytical Results on SE If PA input power is low, i.e., 1
fY (y, S = 0) = N0(y) 1 Q1 (y), max N0(y) fY (y, S = 1) = N1(y) exp
a2 max Pin 2bmaxyRe 2 z I0 2bmax|y| 2 z N1(y) SEIBO () log2 (1 + )
+ e 1 log2 2 z e1 1 log2 2 z Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 54 / 112
106. Analytical Results on SE Theorem 1. The approximated SE,
SEIBO (), is a concave function over max 0, 1 ln 2 z < 1 2 .
Theorem 2. The SE-aware optimal power loading factor SE which
maximizes SEIBO () is obtained by the solution of the following
equality: 1 + = e1 2 1 + 1 ln e2 z Proposition 3. A closed form
approximation of SE is given by SE SE 1 W 1 ln(e2 z ) where W()
denotes the Lambert W function [Chapeau-Blondeau and Monir, 2002]
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 55 /
112
107. Analytical Results on SE Theorem 1. The approximated SE,
SEIBO (), is a concave function over max 0, 1 ln 2 z < 1 2 .
Theorem 2. The SE-aware optimal power loading factor SE which
maximizes SEIBO () is obtained by the solution of the following
equality: 1 + = e1 2 1 + 1 ln e2 z Proposition 3. A closed form
approximation of SE is given by SE SE 1 W 1 ln(e2 z ) where W()
denotes the Lambert W function [Chapeau-Blondeau and Monir, 2002]
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 55 /
112
108. Numerical Results on SE Bandwidth: = 10 MHz Channel
attenuation: G 128 + 10 log10 (d ) [LTE, 2011] - G = 5 dB: TRx
feeder loss + antenna gains - d = 200 m: distance between Tx and Rx
- = 3.76: path loss exponent AWGN: 2 z = 174 dBm / Hz PA:
SM2122-44L Pmax out = 25 W g = 55 dB 0 0.2 0.4 0.6 0.8 1 0 2 4 6 8
10 12 14 16 18 Power loading factor, SE(),b/s/Hz SEideal () SE()
SEIBO () SE( SE) : ideal SE with an ideal PA : practical SE with a
practical PA : approximated SE : optimal SE Figure 17: SE
evaluation results. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 56 / 112
109. Power Consumption And Losses Power Amplifier (PA) Module
DC Power Supply (PS) Module Base Band (BB) Module Radio Frequency
(RF) Module (except PA) Active Cooler and Battery Back up (CB)
Module (if present) PBB PRF PPA PCB Pin Pout loss loss loss loss
Figure 18: Block diagram for system power consumption [Auer et al.,
2011, Arnold et al., 2010, Deruyck et al., 2010, Deruyck et al.,
2011, Kumar and Gurugubelli, 2011]. Px (1 + CPS)(1 + CCB)(PBB +
PRF) CPS: power supply coecient between 0.1 and 0.15 CCB: active
cooler and battery coecient less than 0.4 Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 57 / 112
110. PA-Dependent Nonlinear Power Consumption Model
PA-dependent nonlinear power consumption model (0 < 1): Pc() =
Px + c c1 + c2 Pmax out - c: power loading-dependent scaling
coecient - -way Doherty PA [Raab, 1987] (for class-A and B, = 1)
(c1, c2) = 4 (2, 0) , 0 < 1, (0, 1) , 0 < 1 2 , (1, + 1) , 1
2 < 1. Ideal power consumption model with ideal PA (100%
eciency): Pideal c () = Px + c 1 g1 Pmax out Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 58 / 112
111. PA-Dependent Nonlinear Power Consumption Model
PA-dependent nonlinear power consumption model (0 < 1): Pc() =
Px + c c1 + c2 Pmax out - c: power loading-dependent scaling
coecient - -way Doherty PA [Raab, 1987] (for class-A and B, = 1)
(c1, c2) = 4 (2, 0) , 0 < 1, (0, 1) , 0 < 1 2 , (1, + 1) , 1
2 < 1. Ideal power consumption model with ideal PA (100%
eciency): Pideal c () = Px + c 1 g1 Pmax out Jingon Joung Tutorial
2: Energy Ecient Wireless Communications 58 / 112
112. Power Consumption 0 0.2 0.4 0.6 0.8 1 60 90 120 150 180
210 240 Power loading factor, Powerconsumption,Pc(),W idle mode
linear model nonlinear model with class B PA nonlinear model with
2-way Doherty PA model with ideal PA Figure 19: Power consumption
of microcell base station with Px = 130 W and c = 4.7 4 . Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 59 /
112
113. Analytical Results on EE Practical EE EE() = SE() Pc()
Ideal EE with a perfectly linear and ecient PA EEideal () SEideal
() Pideal c () PA-dependent EE with a perfectly linear PA EElinear
() SEideal () Pc() Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 60 / 112
114. Analytical Results on EE Practical EE EE() = SE() Pc()
Ideal EE with a perfectly linear and ecient PA EEideal () SEideal
() Pideal c () PA-dependent EE with a perfectly linear PA EElinear
() SEideal () Pc() Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 60 / 112
115. Analytical Results on EE Practical EE EE() = SE() Pc()
Ideal EE with a perfectly linear and ecient PA EEideal () SEideal
() Pideal c () PA-dependent EE with a perfectly linear PA EElinear
() SEideal () Pc() Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 60 / 112
116. Analytical Results on EE Theorem 4. EElinear () is a
piecewise quasi-concave function over v + 1 + v2 2 /2 , where v =
Pmax out c0c2/(P0 + Pmax out c0c1). Specically, EElinear () is
quasi-concave over 1/2 and also over 1/2 < 1. Theorem 5.
Assuming EE , EE equals either [ 1 ] 1/2 or [ 2 ]1 1/2,, where 1
and 2 are the solutions of EElinear () = 0 with given (c1, c2).
Proposition 6. A closed form approximation of EE, denoted by EE,
equals either [ 1 ] 1/2 or [ 2 ]1 1/2,, where i (i {1, 2})
approximates i and is given by EE = i i = 1 exp 2 + 2W ev , i = 1
or 2. where W() > 0 as ev > 0, so that W() is unique. Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 61 /
112
117. Analytical Results on EE Theorem 4. EElinear () is a
piecewise quasi-concave function over v + 1 + v2 2 /2 , where v =
Pmax out c0c2/(P0 + Pmax out c0c1). Specically, EElinear () is
quasi-concave over 1/2 and also over 1/2 < 1. Theorem 5.
Assuming EE , EE equals either [ 1 ] 1/2 or [ 2 ]1 1/2,, where 1
and 2 are the solutions of EElinear () = 0 with given (c1, c2).
Proposition 6. A closed form approximation of EE, denoted by EE,
equals either [ 1 ] 1/2 or [ 2 ]1 1/2,, where i (i {1, 2})
approximates i and is given by EE = i i = 1 exp 2 + 2W ev , i = 1
or 2. where W() > 0 as ev > 0, so that W() is unique. Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 61 /
112
118. Numerical Results on EE 0 0.2 0.4 0.6 0.8 1 0 0.5 1.0 1.5
2.0 2.5 Power loading factor, EE(),Mb/J EElinear ( EE); EE( EE); EE
in Prop. 6 EElinear () EEideal () EE(): 2-way Doherty PA EE():
class-B PA EE(): class-A PA Figure 20: EE evaluation with Px = 130
W and c = 4.7. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 62 / 112
119. Practical SE-EE Tradeo 0 2 4 6 8 10 12 14 16 18 0 0.5 1.0
1.5 2.0 2.5 SE(), b/s/Hz EE(),Mb/J SE-EE tradeo with PAlow SE-EE
tradeo with PAhigh : (SE( SE), EE( SE)) : (SE( EE), EE( EE)) Fig.
24 Figure 21: SE-EE tradeo with 2-way Doherty PAs. PAlow with Pmax
out = 25 W and g = 55 dB, and PAhigh with Pmax out = 100 W and g =
50 dB. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 63 / 112
120. PA Switching (PAS) Method SE EE Low power PA, PA-1 SE EE
High power PA, PA-2 Figure 22: Illustration of PAS Concept. Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 64 /
112
121. PA Switching (PAS) Method SE EE Low power PA, PA-1 SE EE
High power PA, PA-2 SE EE PA switching Figure 22: Illustration of
PAS Concept. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 64 / 112
122. PAS for FDD/TDD Frame switching time frame k 1, PA-1 frame
k, PA-1 frame k + 1, PA-2 time (a) FDD Systems switching time DL
frame, PA-1 UL frame DL frame, PA-2 UL frame length + TTG + RTG
> time TTG RTG (b) TDD Systems Figure 23: Illustration of PA
switching between PA-1 and PA-2. K: frame number; T: frame length;
: switching time Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 65 / 112
123. SE and EE of PAS SEs(, ) = kT SE 1() + (K k)T SE 2() KT +
EEs(, ) = KT SEs(, ) kT P1 c () + (K k)T P2 c () = k K is PA time
sharing factor. Switch power consumption is ignored as it is
relatively negligible compared to Pi c (). FDD: > 0 unless there
is switching. TDD: < 1 ms and UL frame length (10 ms) [LTE,
2011]; PAs can be switched between consecutive DL frames while
receiving UL frame, without consuming any switching time overhead,
i.e., = 0. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 66 / 112
124. SE-EE Tradeo of PAS = 10 s, LS = 1 dB, T = 10 ms, and K =
20 A B(D) : EE 210%(41%) SE 12% A C(E) : EE 323%(69%) SE 15% 14.0
14.5 15.0 15.5 16.0 16.5 17.0 17.5 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
2.0 2.2 SE(), b/s/Hz EE(),Mb/J GS = 0 dB, = 0 s, ideal GS = 1 dB, =
0 s, TDD GS = 1 dB, = 10 s, FDD GS = 1 dB, = 1 ms, FDD A DE B C
SE-EE tradeo with PAhigh Figure 24: SE-EE tradeo. Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 67 / 112
125. TAS-MRC Syst. with Partial CSIT x z1 z2 y1 MRC x y2 Ah2
Ah1S1 M +1 feedback for S1 and PC PC power contorl 1 2 : high-power
main power ampliers Figure 25: A transmit antenna selection with
maximum ratio combining system. Switch S1 selects a transmit
antenna Switch S2 selects a PA [Joung et al., 2013] Pmax out :
maximum output power of TX subject to regulatory constraints mPmax
out : Maximum output power of PA m 0 < 1 < 2 < < M+1 =
1 Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 68
/ 112
126. TAS-MRC Syst. with Partial CSIT x z1 z2 y1 MRC x y2 Ah2
Ah1S1S2 o mode M +1 M 1 ... feedback for S1 and S2 0 M + 1 M 1 1 2
: high-power main power ampliers : low-power auxiliary power
ampliers Figure 25: A transmit antenna selection with maximum ratio
combining system. Switch S1 selects a transmit antenna Switch S2
selects a PA [Joung et al., 2013] Pmax out : maximum output power
of TX subject to regulatory constraints mPmax out : Maximum output
power of PA m 0 < 1 < 2 < < M+1 = 1 Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 68 / 112
127. PA Switching Probability A switching probability for given
target rate R b/s/Hz fm = Pr(Rm1 < R Rm) = (m1 m) (m1 + m 2) by
using order statistics [David, 1970, Proakis and Salehi, 2007] - m
2R 1 2 m + 1 e(2R 1)2 m - 2 m 2 z AmP max out , where 2 z is
variance of AWGN - 0 = 0 and M+2 = 1 EE of the proposed TAS-MRC
systems for the given R EETAS MRC = R(1 fM+2) M+2 m=1 PTx,mfm -
PTx,m 100cmP max out (m) + Px, if m = 1, . . . , M + 1, Px, if m =
M + 2 (o-mode) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 69 / 112
128. PA Switching Probability A switching probability for given
target rate R b/s/Hz fm = Pr(Rm1 < R Rm) = (m1 m) (m1 + m 2) by
using order statistics [David, 1970, Proakis and Salehi, 2007] - m
2R 1 2 m + 1 e(2R 1)2 m - 2 m 2 z AmP max out , where 2 z is
variance of AWGN - 0 = 0 and M+2 = 1 EE of the proposed TAS-MRC
systems for the given R EETAS MRC = R(1 fM+2) M+2 m=1 PTx,mfm -
PTx,m 100cmP max out (m) + Px, if m = 1, . . . , M + 1, Px, if m =
M + 2 (o-mode) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 69 / 112
129. PA Output Power (Pout W) and Eciency (%) Table 5: Proposed
PAS TAS-MRC with M = 2. PAS m PA Pout W % FB s1 s2 fm Auxiliary PA
1 PA1 0.63 W 55% 110/1 1/2 1 f1 2 PA2 2.5 W 43% 010/1 1/2 2 f2 Main
PA 3 PA3 10 W 60% 100/1 1/2 3 f3 o-mode 4 o-mode 0 0 000 0 f4 Table
6: Conventional TAS-MRC System with Power Control. Level l PA Pout
W % feedback s1 fpow l P1 1 PA3 0.63 W 9% 110/1 1/2 fpow 1 P2 2 PA3
2.5 W 32% 010/1 1/2 fpow 2 P3 3 PA3 10 W 60% 100/1 1/2 fpow 3 P4 4
o-mode 0 0 000 fpow 4 Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 70 / 112
135. EE Comparison Simulation Environments PA1(0.63 W, 55%),
PA2(2.5 W, 43%), PA3(10 W, 60%) 8 dB IBO Switch insertion loss: GS
= 0 dB for S1, GS = 1 dB for S2 Channel attenuation: A dB = G 128 +
10 log10(d) [LTE, 2011] G = 5 dB, d = 0.6 km, = 3.76 2 = 174 dBm /
Hz, = 10 MHz, Px = 40 W and c = 4.7 [Joung et al., 2014c] 0 1 2 3 4
5 6 7 8 9 10 11 12 13 14 15 0 0.2 0.4 0.6 0.8 1.0 1.2 R b/s/Hz
Energyeciency(EE)Mb/J no power control Figure 27: EE comparison.
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 72 /
112
136. EE Comparison Simulation Environments PA1(0.63 W, 55%),
PA2(2.5 W, 43%), PA3(10 W, 60%) 8 dB IBO Switch insertion loss: GS
= 0 dB for S1, GS = 1 dB for S2 Channel attenuation: A dB = G 128 +
10 log10(d) [LTE, 2011] G = 5 dB, d = 0.6 km, = 3.76 2 = 174 dBm /
Hz, = 10 MHz, Px = 40 W and c = 4.7 [Joung et al., 2014c] 0 1 2 3 4
5 6 7 8 9 10 11 12 13 14 15 0 0.2 0.4 0.6 0.8 1.0 1.2 R b/s/Hz
Energyeciency(EE)Mb/J 1-bit FB for o-mode o-mode gain Figure 27: EE
comparison. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 72 / 112
137. EE Comparison Simulation Environments PA1(0.63 W, 55%),
PA2(2.5 W, 43%), PA3(10 W, 60%) 8 dB IBO Switch insertion loss: GS
= 0 dB for S1, GS = 1 dB for S2 Channel attenuation: A dB = G 128 +
10 log10(d) [LTE, 2011] G = 5 dB, d = 0.6 km, = 3.76 2 = 174 dBm /
Hz, = 10 MHz, Px = 40 W and c = 4.7 [Joung et al., 2014c] 0 1 2 3 4
5 6 7 8 9 10 11 12 13 14 15 0 0.2 0.4 0.6 0.8 1.0 1.2 R b/s/Hz
Energyeciency(EE)Mb/J 2-bit FB for Pow Ctrl o-mode power control
gain gain Figure 27: EE comparison. Jingon Joung Tutorial 2: Energy
Ecient Wireless Communications 72 / 112
138. EE Comparison Simulation Environments PA1(0.63 W, 55%),
PA2(2.5 W, 43%), PA3(10 W, 60%) 8 dB IBO Switch insertion loss: GS
= 0 dB for S1, GS = 1 dB for S2 Channel attenuation: A dB = G 128 +
10 log10(d) [LTE, 2011] G = 5 dB, d = 0.6 km, = 3.76 2 = 174 dBm /
Hz, = 10 MHz, Px = 40 W and c = 4.7 [Joung et al., 2014c] 0 1 2 3 4
5 6 7 8 9 10 11 12 13 14 15 0 0.2 0.4 0.6 0.8 1.0 1.2 R b/s/Hz
Energyeciency(EE)Mb/J 2-bit FB for Pow Ctrl 2-bit FB for PAS Figure
27: EE comparison. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 72 / 112
139. MIMO Syst. with Partial CSIT x2 x1 z2 z1 y2 y1 MRC/MIMO x2
x1 Ah2 Ah1 M +1 M +1 Ant.2 Ant.1 : high-power main power ampliers
PC PC power contorl feedback for PC Figure 28: PAS MIMO system
model with two main PA and M auxiliary PAs. Switch S0 selects a
communication mode Switch S1 selects a PA [Joung et al., 2014d]
mPmax out : Maximum output power of PA m {1, , M + 1} 0 < 1 <
< M < M+1 = 1 2Pmax out : maximum output power of TX subject
to regulatory constraints Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 73 / 112
140. MIMO Syst. with Partial CSIT x2 x1 z2 z1 y2 y1 MRC/MIMO x2
x1 Ah2 Ah1S0 S1 M +1 M +1 M 1 Ant.2 Ant.1 0 0 M + 1 M 1 1 :
high-power main power ampliers : low-power auxiliary power ampliers
feedback for S1 and S2 ... o-mode Figure 28: PAS MIMO system model
with two main PA and M auxiliary PAs. Switch S0 selects a
communication mode Switch S1 selects a PA [Joung et al., 2014d]
mPmax out : Maximum output power of PA m {1, , M + 1} 0 < 1 <
< M < M+1 = 1 2Pmax out : maximum output power of TX subject
to regulatory constraints Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 73 / 112
141. Commun. Mode Selection Prob. A switching probability for
given target rate R b/s/Hz - PAS-MRC mode: fm = fU (2R 1)2 m u <
(2R 1)2 m1 , m = {1, , M} = m m1 where m 1 + 2R 1 2 m e(2R 1)2 m .
- O-mode: fM+3 fC(x < R|2 M+1) = FC(R|2 M+1) FC(x|2 M+1)= 0 ex
1+ x 22 M+1 j2u ln 2 dx 0 x2 ex 1+ x 22 M+1 j2u ln 2 dx 0 xex 1+ x
22 M+1 j2u ln 2 dx 2 1 ej2ux j2u du. - MIMO mode: fM+2 = 1 M+1 m=1
fm fM+3 Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 74 / 112
142. EE Analysis EE can be derived as EEPAS MIMO = R(1fM+3) M+3
m=1 PTx,mfm . - Numerator represents system throughput over
bandwidth Hz and given target rate R - Denominator is total power
consumption with model dened as [Joung et al., 2013, Heliot et al.,
2012]: PTx,m = Pant,m + Psp1 + Px, if m = 1, , M + 1, 2Pant,m +
Psp1 + Px, if m = M + 2, Px, if m = M + 3 + Pant,m: power
consumption that is proportional to the number of transmit antennas
NT [Xu et al., 2011], as Pant,m = cmP max out (m) + Pcc + Psp2 + c:
a system dependent power loss coecient which can be empirically
measured and obtained + (m): a PA eciency that depends on the input
power (or equivalently PA output power) + Pcc and Psp2 are the RF
circuit and signal processing related power consumptions per
bandwidth, respectively, which are proportional to NT + 4 = 3 +
Psp1: a sig. proc.g related power consumption which is independent
of NT + Px: a xed power consumption, for power supply and cooling
system, which is independent of P max out , NT , and Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 75 / 112
143. PA Output Power (Pout W) and Eciency (%) Table 7: Proposed
PAS MIMO with M = 2. Comm. Mode m PA Pout W % FB s0 s1 fm PAS-MRC 1
PA1 0.63 W 55% 00 0 1 f1 2 PA2 2.5 W 43% 01 0 2 f2 3 PA3 10 W 60%
10 0 3 f3 MIMO 4 two PA3s 2 10 W 60% 11 1 3 f4 o-mode 5 PA4 0 0
null 0 0 f5 Table 8: Conventional MIMO System with Power Control.
Level l PA Ptotal out W % feedback fpow l P1 1 PAa 3, PAb 3 2 0.315
W 5% 00 fpow 1 P2 2 PAa 3, PAb 3 2 1.25 W 15.5% 01 fpow 2 P3 3 PAa
3, PAb 3 2 5 W 32% 10 fpow 3 P4 4 PAa 3, PAb 3 2 10 W 60% 11 fpow 4
P5 5 o 0 0 null fpow 5 Jingon Joung Tutorial 2: Energy Ecient
Wireless Communications 76 / 112
144. Mode Switching Probability 0 2 4 6 8 10 12 14 16 18 20 22
24 0 0.2 0.4 0.6 0.8 1.0 Target rate, R b/s/Hz Probability,fm m =
1, PA1: 0.63 W m = 2 m = 3 m = 4 PA2 2.5 W PA3 10 W PA3+PA3 2 10 W
m = 5, PA4: o-mode (a) 0 2 4 6 8 10 12 14 16 18 20 22 24 0 0.2 0.4
0.6 0.8 1.0 Target rate, R b/s/HzProbability,fpow l l = 5, P5:
o-model = 1, P1: 2 0.315 W l = 2, P2 2 1.25 W l = 3, P3 2 5 W l =
4, P4 2 10 W (b) Figure 29: Probabilities. (a) fm of PAS. (b) fpow
l of power control. Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 77 / 112
145. EE Comparison Simulation Environments Switch insertion
loss: GS = 0 dB for S0, GS = 0 dB for S1 2 = 174 dBm/ Hz, = 5 MHz,
with 512 FFT size (300 subcarriers) Px = 36.4 W, c = 2.63, Pcc =
66.4 W, Px = 36.4 W, Psp1 = 1.28 W / Hz, Psp2 = 3.32 W / Hz 0 2 4 6
8 10 12 14 16 18 20 22 24 0 0.05 0.10 0.15 0.20 0.25 Target rate, R
b/s/Hz Energyeciency(EE)Mb/J Conventional MIMO w/o Pow Ctrl. Figure
30: EE comparison of the proposed MIMO-MRC with PAS and the
conventional MIMO w/ or w/o Pow Ctrl. Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 78 / 112
146. EE Comparison Simulation Environments Switch insertion
loss: GS = 0 dB for S0, GS = 0 dB for S1 2 = 174 dBm/ Hz, = 5 MHz,
with 512 FFT size (300 subcarriers) Px = 36.4 W, c = 2.63, Pcc =
66.4 W, Px = 36.4 W, Psp1 = 1.28 W / Hz, Psp2 = 3.32 W / Hz 0 2 4 6
8 10 12 14 16 18 20 22 24 0 0.05 0.10 0.15 0.20 0.25 Target rate, R
b/s/Hz Energyeciency(EE)Mb/J Conventional MIMO w/ Pow Ctrl. Figure
30: EE comparison of the proposed MIMO-MRC with PAS and the
conventional MIMO w/ or w/o Pow Ctrl. Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 78 / 112
147. EE Comparison Simulation Environments Switch insertion
loss: GS = 0 dB for S0, GS = 0 dB for S1 2 = 174 dBm/ Hz, = 5 MHz,
with 512 FFT size (300 subcarriers) Px = 36.4 W, c = 2.63, Pcc =
66.4 W, Px = 36.4 W, Psp1 = 1.28 W / Hz, Psp2 = 3.32 W / Hz 0 2 4 6
8 10 12 14 16 18 20 22 24 0 0.05 0.10 0.15 0.20 0.25 Target rate, R
b/s/Hz Energyeciency(EE)Mb/J Conventional MIMO w/ Pow Ctrl.
Proposed MIMO w/ PAS Figure 30: EE comparison of the proposed
MIMO-MRC with PAS and the conventional MIMO w/ or w/o Pow Ctrl.
Jingon Joung Tutorial 2: Energy Ecient Wireless Communications 78 /
112
148. Index 1 Introduction and Background (35 min, 24 pages)
Green Wireless Communications Eciency in Communications Theoretical
Spectral Eciency (SE) Energy Eciency (EE) Tradeo Practical SE-EE
Tradeo 2 Technologies for Energy Eciency (20 min, 11 pages)
Device-Level Approach System-Level Approach Network-Level Approach
3 Review (30 min, 60 pages) PA Switching/Selection (PAS) Method
Large-scale Distributed-Antenna Systems (L-DAS) 4 Conclusion and
QnA (5 min, 3 page) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 79 / 112
149. System Model [Joung et al., 2014a] BBU deactivated DA user
equipment SISO MISO MU-MIMO activated DA optical fibre large-scale
distributed antennas (DAs) cellular communication networks Jingon
Joung Tutorial 2: Energy Ecient Wireless Communications 80 /
112
150. EE Model of L-DAS EE (S, W, P ) System throughput per unit
time Total power consumption System throughput: R(S, W, P ) = uU
log2 (1 + SINRu(S, W, P )) SINRu(S, W, P ) = |hr u(sc uwc u)|2 puu
U u=1,u=u hr u sc u wc u 2 puu +2 Total power consumption: C(S, W,
P ) = f(S, W, P ) + g(S, W ) f(): TPD (transmit power dependent)
term g(): TPI (transmit power independent) term Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 81 / 112
151. EE Model of L-DAS EE (S, W, P ) System throughput per unit
time Total power consumption System throughput: R(S, W, P ) = uU
log2 (1 + SINRu(S, W, P )) SINRu(S, W, P ) = |hr u(sc uwc u)|2 puu
U u=1,u=u hr u sc u wc u 2 puu +2 Total power consumption: C(S, W,
P ) = f(S, W, P ) + g(S, W ) f(): TPD (transmit power dependent)
term g(): TPI (transmit power independent) term Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 81 / 112
152. EE Model of L-DAS EE (S, W, P ) System throughput per unit
time Total power consumption System throughput: R(S, W, P ) = uU
log2 (1 + SINRu(S, W, P )) SINRu(S, W, P ) = |hr u(sc uwc u)|2 puu
U u=1,u=u hr u sc u wc u 2 puu +2 Total power consumption: C(S, W,
P ) = f(S, W, P ) + g(S, W ) f(): TPD (transmit power dependent)
term g(): TPI (transmit power independent) term Jingon Joung
Tutorial 2: Energy Ecient Wireless Communications 81 / 112
153. Power Consumption Model: TPD ASIC, FPGA, DSP Examples:
-digital up converter -digital predistorter -scrambling -CRC check
-conv. encoder -interleaver -modulation -IFFT -CP insertion
-parallel-to-serial eRF module oRF module oRF module eRF module
Examples: -O/E converter Examples: -E/O converter -laser -driver
-modulator Examples: -D/A converter -filters -synthesizer Examples:
-VGA -driver -PA Examples: -AC/DC -DC/DC -active cooler ... ... ...
... ... ... baseband module mth RF module at BBU baseband unit
(BBU) mth distributed antenna (DA) port 1st Ant. mth Ant. Mth Ant.
1 m M ber Psp1, Psp2, Psig (TPI) Pcc1,m (TPI) Pcc2,m (TPI)Pcc2,m
(TPI) Px (TPI) Ptx,m (TPD) TPD term f(S, W, P ) = mM c m (S W )P (S
W )H mm eRF (electric RF) oRF (optical RF) Jingon Joung Tutorial 2:
Energy Ecient Wireless Communications 82 / 112
154. Power Consumption Model: TPI TPI term g(S, W ) = grf(S) +
gbb(W ) + gnet(M) + Px grf(S) = mM Pcc1,m + Pcc2,m uU Ru maxu smu
gbb(W ) = Psp1 [dim(W )]+1 + Psp2 gnet(M) = MPsig Pcc1: eRF Pcc2:
per unit-bit-and-second of oRF Ru: target rate of user u 0: implies
overhead power consumption of MU processing compared to SU-MIMO Px:
xed power consumption (e.g., pow supply, AC/DC, DC/DC, and cooling
system) Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 83 / 112
155. EE of L-DAS EE (S, W, P ) = uU log2 1 + |hr u (sc u wc u)|
2 puu U u=1,u=u |hr u (sc u wc u )|2 puu + 2 mM c m (S W )P (S W )H
mm + mM Pcc1,m + Pcc2,m uU Ru max u smu + Psp1 [dim(W )] +1 + Psp2
+ MPsig Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 84 / 112
156. Original Problem Formulation Po: original problem max
{S,W,P } EE (S, W, P ) s.t. (S W )P (S W )H mm Pm, m M, Ru(S, W, P
) Ru, u U, pu1u2 = 0, u1 = u2 U, smu {0, 1}, m M, u U objective
function: EE per-ant pow constraints with max-output pow Pm
per-user rate constraints with a target rate Ru diagonal structure
of P DA selection Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 85 / 112
160. Original Problem Formulation Po: original problem max
{S,W,P } EE (S, W, P ) s.t. (S W )P (S W )H mm Pm, m M, Ru(S, W, P
) Ru, u U, pu1u2 = 0, u1 = u2 U, smu {0, 1}, m M, u U objective
function: EE per-ant pow constraints with max-output pow Pm
per-user rate constraints with a target rate Ru diagonal structure
of P DA selection Jingon Joung Tutorial 2: Energy Ecient Wireless
Communications 85 / 112