The document summarizes key aspects of energy efficient wireless access networks, comparing LTE and LTE-Advanced technologies. It begins with an overview of cellular generations from 1G to 4G. It then discusses energy efficiency in wireless access networks and base station power consumption models. The document analyzes how LTE-Advanced functionalities like carrier aggregation, heterogeneous deployments, and MIMO can improve energy efficiency over LTE. It finds that carrier aggregation and MIMO in LTE-Advanced can increase network energy efficiency by up to 400% and 450% respectively. The document concludes that future networks should implement LTE-Advanced for better energy efficiency compared to LTE.

1. INDIAN INSTITUTE OF TECHNOLOGY ROORKEE
Seminar Presentation
On
Energy-Efficient Wireless Access Networks:
LTE and LTE-Advanced
Under the Guidance of
Dr. Meenakshi Rawat
Presented by :
Rajnish Kumar Singh(15531014)
M.Tech , Communication Systems

2. 2
Outline
• Brief overview of cellular generations
• Energy Efficiency in Wireless Access Networks
• Base Stations’s power consumption model
• LTE Advanced Functionalities
• Carrier Aggregation
• Heterogeneous Deployments(macrocell and femtocell)
• MIMO (Multiple Input Multiple Output)
• Conclusion
• Research Gaps
• Future work
• References

3. 3
Brief overview of cellular generations
First Generations Cellular Networks(1G)
• Introduced in 1980’s, Speed was upto 2.4kbps
• Used Analog radio Signal for voice services
• Used Circuit Switched technology
• Used FDMA for transmission
• Cellular Standard:
AMPS: Developed by Bell Labs ,
First launched in USA
• Drawbacks: Poor Voice Quality
No Security
Limited Capacity
Poor Handoff Reliability

4. 4
Brief overview of cellular generations(cont.)
Second Generations Cellular Networks(2G)
• Uses Digital signals for voice transmission
• It’s data speed was upto 64kbps and Bandwidth
range of 30-200Khz
• Introduced facility of SMS(Short Message Service)
• Main cellular standards:
1) GSM -TDMA based
Today accounts for over 80% of all subscribers in the world
2) IS-95 –CDMA based
• Drawback: Limited speed

5. 5
Brief overview of cellular generations(cont.)
Third Generations Cellular Networks(3G)
• Data Transmission speed increased to 2Mbps
• Increased its bandwidth (15-20 Mhz) and data transfer rates
for High speed internet services like video calling,MMS
• Uses Packet switching for data transmission and
circuit switching for voice call transmission
• Based on spread spectrum radio transmission technology
• Drawbacks:
1) Costly compared to 2G
2) High Bandwidth requirement leading to high power
consumption resulting in reduced battery life

6. 6
Brief overview of cellular generations(cont.)
Fourth Generations Cellular Networks(4G)
• Basically an extension in 3G technology
• All Internet Protocol (IP) packet based communication
• High speed (100Mbps-1Gbps )and high capacity
• OFDMA multi -carrier transmission
• Multiple-input multiple-output (MIMO) communications
• Standards:
1) LTE- Long Term Evolution(release 8)
2) LTE Advanced- standardized by the 3GPP (release 10)

7. 7
Energy Efficient Wireless Access Networks
Introduction
• Recent years have seen a tremendous increase in the number of
mobile users.
• This growth has affected wireless access networks (WANs), which
are already large energy consumers within the information
communication technology (ICT) domain.
• Base stations account for up to 90 percent of a WAN’s power
consumption.
• A thorough study of a base station’s power consumption can help us
to develop guidelines for reducing these networks’ power
consumption.
• Hence there is a need of energy efficient wireless access networks.
• Hence Comparison between LTE(release 8/9) networks and LTE
Advanced (release 10) is done

8. 8
Energy Efficiency in Wireless Access Networks
• Which base station type is most energy efficient (EE) ?
• Different performance parameters: (bandwidth, coverage, served
users, and so on).
• Here it defines energy efficiency EE (∈ [0, ∞[) (in (km2 .Mbps)/W
as EE =
π.R2.B.U
Pel
Where
Pel : the base station’s power consumption(in watts)
R : is the range (in km)
B: is the physical bit rate by the base station (in Mbps)
U :is the number of served users
• The higher the EE, the more energy efficient the base station is.

9. 9
Base Stations’s power consumption model
Base Stations Types:
• Macrocell : Bigger than the
base station of Femtocell ,
serves more users and has
higher Range
• Femtocell :is much smaller
than a macrocell base station
and is comparable to the base
station of a Wi-Fi access point

10. 10
LTE-Advanced functionalities
• LTE-Advanced introduces three new functionalities:
1) Carrier aggregation
2)Heterogeneous networks
3)Extended (MIMO) support -multiple-input, multiple output
• Note:The first two releases (release 8/9) are known as LTE.
Release 10, is also known as LTE-Advanced.
• It supports bandwidths roughly upto 20 MHZ(in both versions)
• Note:
This bandwidth can be further extended in LTE-Advanced by carrier
aggregation, which lets the base station transmit multiple LTE
carriers, each with a bandwidth of up to 20 MHz.
• LTE-Advanced enhances support for MIMO up to eight transmit
antennas.

11. 11
Carrier Aggregation
• Carrier aggregation is used in LTE-Advanced in order to increase
the bandwidth, and thereby increase the bit rate.
=>hence increasing EE(Energy Efficiency)
• We investigate how adding carrier aggregation
influences energy efficiency.
• To obtain the results in the following figure , we determine
the power consumption, range, and bit rate as discussed earlier.
• The number of served users is fixed.
• Channel bandwidth 5 MHz
• We then calculate EE for both macrocell and femtocell

12. 12
Results (LTE & LTE Adv.) –carrier aggregation
Figure 2. Energy efficiency of LTE and LTE-Advanced in a 5-MHz channel. The figure
compares the energy efficiency when aggregating no carriers (LTE) and when aggregating
two or five carriers (LTE-Advanced) for different modulation schemes and coding rates and
for both a macrocell and a femtocell base station. (CA = carrier aggregation; QAM =
quadrature amplitude modulation; QPSK = quadrature phase shift keying) [3]

13. 13
Curve Notes for carrier aggregation
• Carrier Aggregation increases the EE(Energy Efficiency)
• Higher modulation scheme or coding rate results in lower EE
because a higher modulation scheme and coding rate lead to a
shorter range for a higher bit rate.(EE R2)
• Introducing carrer aggregation has little impact on base station’s
power consumption( i.e extra power consumed is negligible)
• With carrer aggregation, we can obtain high bit rates with a lower
modulation scheme

14. 14
Heterogeneous Deployments
• We might think that a femtocell base station is less energy efficient
than a macrocell basestation. However, this isn’t always the case.
• Following figure compares the energy efficiency of LTE-Advanced
macrocell and femtocell base stations as a function of attainable bit
rates.

15. 15
Results of Heterogeneous Deployments
Figure 3. Comparison of the energy efficiency of an LTE-Advanced
macrocell and femtocell base station for different bit rates [3]

16. 16
Curve Notes Heterogeneous Deployments
• Which base station type is most energy efficient?
• For bit rate >20 Mbps, the macrocell base station is the most
energy efficient
due to its longer range and higher number of served users (despite
its higher power consumption)
• For bit rate 5 to 20 Mbps- Ambiguous
• For bit rate < 5 Mbps, femtocell is more Energy Efficient

17. 17
MIMO
• MIMO is used to increase the overall bit rate through transmission
of two (or more) different data streams on two (or more) different
antennas
=>hence increasing EE(Energy Efficiency)
• A major change in LTE-Advanced is the introduction of 8x8 MIMO
in the DL and 4x4 in the UL
• Now we consider the influence of spatial diversity on energy
efficiency for different MIMO modes in both macrocell and
femtocell base stations assuming a bit rate of 2.8 Mbps in a 5-MHz
channel
• We use single-input, single-output (SISO)— that is, only one
transmitting and one receiving antenna— as a reference scenario

18. 18
Results for MIMO
Figure 4. Influence of spatial diversity on energy efficiency for different MIMO modes using
1/3 QPSK in a 5-MHz channel. (Percentages on the right side of each bar show the
improvement compared to single-input, single-output [SISO]; the numbers at the top of
each bar indicate the EE-values.) [3]

19. 19
Curve Results for MIMO
• Shows that more the transmitting and receiving antennas, the
higher the EE.
• For the macrocell base station -
EE increases upto 433 % when using 8×8 MIMO
• For the macrocell base station-
EE increases upto 454.6 % when using 8×8 MIMO

20. 20
Conclusion
• Hence power consumption model for both LTE and LTE-Advanced
macrocell and femtocell base stations, as well as a suitable energy-
efficiency measures were discussed
• We saw that LTE-Advanced’s carrier aggregation and MIMO
improve networks’ energy efficiency up to 400 and 450 percent,
respectively.
=> which proved that LTE-Advanced (release 10) is more
energy-efficient than LTE (release 8/9)
• Future networks should implement LTE-Advanced, which will
improve energy efficiency better than LTE

21. 21
Research gap
• We will need a good estimation of the needed bit rate, coverage, and
number of served users to determine which base station type is most
suitable in each network location to reduce the network's power
consumption.
• We saw that, in some cases the macrocell base station is most energy
efficient , while in other cases the femtocell base station is most
energy efficient.
• It didn’t discussed the combination of both type of cells
(Since user demand varies over time, both base station types are
needed to be deployed in the network)
.

22. 22
Future Work
• Since user demand varies over time, both base station types must be
deployed in the network, with the optimal combination resulting in a
more energy-efficient network.
• We can find this optimal combination by -
1) placing macrocell base stations to cover the area first,then
2) femtocell base stations to provide coverage in the coverage holes.
3) hence we can extend the macrocell base station’s capacity as
needed using femtocell base stations
• LTE-Advanced also adds enhanced support for relaying, which can
probably also improve energy efficiency
• Study how the features investigated here will perform in terms of
energy efficiency when applied on an actual network.
• Future networks can benefit from MIMO, which currently has only
limited deployment.

23. 23
Main References
[1] S. CHEN and M. Deruyck ,“The Development of TD-SCDMA
3G to TD-LTE-Advanced 4G From 1998 To 2013”, Wireless
Communications, IEEE vol. 21, no. 6, 2014, pp.167-176
[2] V. K. Garg, “Wireless Network Evolution: 2G to 3G”, Prentice
Hall
[3] Margot Deruyck, E. Dahlman Wout Joseph, Bart Lannoo, Didier
Colle and LucMartens, Designing Energy-
Efficient Wireless Access Networks: LTE and LTE Advanced, IEEE
Internet Computing, IEEE, vol. 23, no. 4, 2013, pp. 39-45
[4] E. Dahlman, S. Parkvall and J. Sko, 4G LTE/LTE-Advanced for
Mobile Broadband,Academic Press.
[5] J. Baliga et al. and Idquo,Energy Consumption in Wired and
Wireless Access Networks, IEEE Comm., vol. 49, no. 6, 2011, pp.
70-77.

24. 24
End of seminar
THANK YOU