Transcript Diapositiva 1 - Vienna University of Technology

Arrate Alonso Gómez (e0728412)
Mobile Communications Seminar
Overview
1. Introduction
2. Network architecture, Performance and Interference
Management
3. Financial Analysis of a Pico-Cellular Home Network
Deployment
4. UMB and LTE for Femtocells
5. Conclusions
1. Introduction





WHAT IS A FEMTOCELL?
Small cellular base station
Limited transmission power
Limited user support to 8
users
Plug & Play
Extension of the operators
cellular networks
2.Network architecture and
Performance
Features of femtocells
INTEROPERABILITY

Transparent
access of femtocells
Key
requirements for co-channel
deployment

Auto-Configuration
Public Access
SCALABILITY

POWER CONTROL


Standard interfaces
 In the downlink: Maximum Transmit Power has to be
Integration
into the core without
configured
decreasing
of the
 In the
the performance
uplink: User-equipment’s
power has to be
macrocelllimited
In the
a constant
radius.
 Downlink:
PreventsEnsure
excessive
interference
between UEs located
In the Uplink:
definable
to working in the
close low
to apre
private
ownedimpact
femtocells
macrocells
same frequency range.
 Also prevents strong downlink interference created
by UEs not connected to near femtocells.
2.Network architecture and
Performance
DOWNLINK:
Event
Why?
Drop in the macrocell
throughput caused by
the increase of active
femtocells from 10 to 100
is minimal
1.
Theoretically achievable
femtocell throughput is
very
high
as
the
deployments are indoors
 high SIRs
1.
2.
Small distance to the
femtocell (Indoors)
Wall separation
Increasing the number
of femtocells from 10 to
100 does not change the
downlink throughput of
the femtocells
1.
2.
Small size of each cell
Wall separation
2.
Low transmit power of
the femtocells in the
downlink
Wall separation
CDF of downlink throughputs for
locations within the central macrocell [1]
2.Network architecture and
Performance
UPLINK:
Event
Why?
Drop in the macrocell
throughput caused by the
increase of active femtocells
from 10 to 100 is minimal
Fast power control in the
uplink for femtocells of UEs
Theoretically
achievable
femtocell throughput is very
high as the deployments are
indoors  high SIRs
1.
Increasing the number of
femtocells from 10 to 100 in
the same macrocell sector,
reduces
the
maximum
allowed interference per UE is
reduced by a factor of 10 
performance of the femtocell
reduced but not significantly
The SIR can drop up to 10 dB,
resulting in a reduction in
uplink throughput.
2.
High signal to interference
ratios due to the small
distance to the femtocell
Wall separation.
CDF of uplink throughputs for locations
within the central macrocell [1]
2.Network architecture and
Performance
Interference Management
Interference Management 3G
Femtocells



Planned deployment
Frequency/Code reuse
UNPLANNED DEPLOYMENT !!!
PROBLEM
Macrocell and femtocells are working in the same
frequency range
 Co-Channel Interference (CCI)
SOLUTION : TWO-TIER NETWORK
1. Deployment in separate carriers (Split RF
Spectrum)
2. Intelligent algorithms at femtocells (Shared RF
Spectrum)
A femtocell based two-tier CDMA
network [2]
3.Financial Analysis of a PicoCellular Home Network Deployment
Wireless Network Evolution
From a NETWORK OPERATOR POINT OF VIEW
Time Terms


Short Term
Long Term
Expense Terms

Operational
Expenditure
Capital Expenditure

Evaluation Scenario
Deployments to be considered …
Femto-cellular deployment

Randomly placed
Macro-cellular deployment

Best-case scenario
Overview of macro-cellular underlay
network with femto-cellular home
base station overlay deployment [3].
3.Financial Analysis of a PicoCellular Home Network Deployment
Economic Models
Macrocell case
Home-Cell Case
Capital Expenditure (CapEx)



Cost per base station
Core UMTS
Core packet routers


No equipment costs
No Installation costs
Operational Expenditure (OpEX)



Cost of maintenance
Site running costs
Backhaul costs

No maintenance costs
HOME BROADBAND
WOULD BE SUBSIDIZED BY
THE OPERATOR!!
3.Financial Analysis of a PicoCellular Home Network Deployment
Impact Analysis
Event
Reason
Small fraction of HBS
achieve a full coverage

Randomly distributed
HBS
EXAMPLE:
Operator with 40% market share and in
which 20% of its customers have home
base stations deployed, those home base
stations alone will satisfy approximately
80% of the total demand.
Fractional user coverage for different
operator market share [3].
3.Financial Analysis of a PicoCellular Home Network Deployment
Impact Analysis
Event
Reason
Home Network CapEx and
OpEx similar

Both very low for the
savings applied to both
Macro cellular Network OpEx
dominate the total annual
costs.

OpEx are the most
expensive cost due to
its periodicity.
Macrocellular costs decrease
quickly with low percentage of
HBS

High user coverage
achievable with a
relatively small fraction
of HBS
Characteristic Point:
Total network cost minimize at 30% HBS
Network costs for an operator with
40% market share and 64 user per
macrocell [3].
4. UMB and LTE for Femtocells
• UMB and LTE
OFDMA based
Higher spectral efficiencies
Low latency
High peak data rate
All-IP
Key feature for FEMTOCELL deployments
• New generation femtocells
•„ Mobile operators may
choose to introduce islands of
4G in an ocean of 3G“
Higher order modulations
Improve self-configuration
Improve self-provisioning
Improve self-optimization
5.Conclusions
1.
Network architecture, Performance and Interference Management
Performance analysis


Macrocell
Performance
Femtocell
Performance
Downlink
(from 10 to 100 HBS)

Unchanged
throughput

High theoretical
unchanged
throughput
Uplink
(from 10 to 100 HBS)

Unchanged
throughput

Performance
affected but
throughput still
good
CCI Management
Normal case: None overpopulated area, no CCI to be taken into account.
Worst case: Femto cell overpopulated urban area
Solution: Two-tier layer with shared RF spectrum and TH-CDMA physical layer
(7x improvement).
5.Conclusions
Financial Analysis of a Pico-Cellular Home Network Deployment
2.
3.

Macrocell coverage less economically viable with higher demand

Deploying HBS with small fraction of users is finantially a better chance and
also better RF performance.

Femtocells not only a good solution for users but also for vendors (more
service for nearly any investments)
UMB and LTE for Femtocells

New generation flat, low cost architectures

Hybrid mobile network

New broadband experience for the users
6.References
[1]
[2]
[3]
[4]
H. Claussen., “Performance of Micro- and co-Channel
Femtocells in Hierarchical Cell Structure”, in: Proceedings
18th
Annual IEEE International Symposium on Personal, Indoor
and
Mobile Radio Communications (PIMRC’07), 2007.
V. Chandrasekhar and J.G. Andrews., “Uplink Capacity
and
Interference Avoidance for Two-Tier Cellular
Networks” in:
Proceedings IEEE GLOBECOM, 2007.
H. Claussen and L.T.W. Ho and L.G. Samuel., “Financial
Analysis of a Pico-Cellular Home Network Deployment”,
in:
Proceedings International Conference on
Communications (ICC),
2007.
Qualcomm., “Femtocells and WLAN Complement 3G and
Beyond”, December 2007.
Many
thanks for
your
attention