what is a femtocell?

courageouscellistAI and Robotics

Oct 29, 2013 (3 years and 9 months ago)

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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

Key
requirements
for co
-
channel deployment of femtocells

Auto
-
Configuration


I渠t桥 摯d湬i湫:

Maim畭 Tra湳mit P潷er 桡s t漠扥
捯湦i杵ged


In the uplink:

User
-
equipment’s power has to be
limited

Public Access


Preve湴s e捥ssive i湴erfere湣n 扥twee渠UEs l潣ate搠
捬潳e t漠a 灲ivate 潷湥搠femt潣ells w潲ki湧ni渠t桥
same fre煵q湣n ra湧n.


䅬s漠灲eve湴s str潮朠
摯d湬i湫 i湴erfere湣n

捲eate搠
批 UEs 湯n 捯湮n捴e搠t漠湥ar femt潣ells.

Features of femtocells

INTEROPERABILITY



Transparent access



Sta湤nr搠i湴erfa捥s

SCALABILITY


Integration into the core without
decreasing the performance of the
macrocell

POWER CONTROL



In the Downlink:
Ensure a constant radius.



I渠t桥 U灬i湫:
l潷 灲e 摥fi湡扬e im灡捴 t漠
ma捲潣ells

2.Network architecture and
Performance

Event

Why?

Drop

in

the

macrocell

throughput

caused

by

the

increase

of

active

femtocells

from

10

to

100

is

minimal

1.
Low

transmit

power

of

the

femtocells

in

the

downlink


2.
Wall

separation

Theoretically

achievable

femtocell

throughput

is

very

high

as

the

deployments

are

indoors



high

SIRs

1.
Small

distance

to

the

femtocell

(Indoors)

2.
Wall

separation

Increasing

the

number

of

femtocells

from

10

to

100

does

not

change

the

downlink

throughput

of

the

femtocells

1.
Small

size

of

each

cell


2.
Wall

separation

CDF of downlink throughputs for
locations within the central macrocell [1]

DOWNLINK:

2.Network architecture and
Performance

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



hi杨

卉Rs

1.
High

signal

to

interference

ratios

due

to

the

small

distance

to

the

femtocell


2.
Wall

separation
.

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



per景rman捥



the

femtocell

reduced

but

not

significantly

The

SIR

can

drop

up

to

10

dB,

resulting

in

a

reduction

in

uplink

throughput
.

CDF of uplink throughputs for locations
within the central macrocell [1]

UPLINK:

2.Network architecture and
Performance

Interference Management

Interference Management 3G

Femtocells


Planned deployment


Fre煵q湣n/C潤o re畳e


UNP䱁LNED DEP䱏YMENT !!!

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]

PROBLEM

Macrocell and femtocells are working in the same
frequency range



Co
-
Channel Interference (CCI)


3.Financial Analysis of a Pico
-
Cellular Home Network Deployment

Wireless Network Evolution

Overview

of

macro
-
cellular

underlay

network

with

femto
-
cellular

home

base

station

overlay

deployment

[
3
]
.

From a NETWORK OPERATOR POINT
OF VIEW

Time Terms



Short Term


䱯湧LTerm

Expense Terms


Operational
Expenditure


Ca灩tal E灥湤nt畲e

Evaluation Scenario

Deployments to be considered …

Femto
-
cellular deployment


Randomly placed

Macro
-
cellular deployment


Best
-
case scenario

3.Financial Analysis of a Pico
-
Cellular Home Network Deployment

Economic Models

Macrocell case

Home
-
Cell Case

Capital Expenditure (
CapEx
)


Cost per base station


C潲e UMTS


C潲e 灡pket r潵oers


N漠e煵q灭e湴 捯sts


N漠I湳tallati潮o捯sts

Operational Expenditure (
OpEX
)


Cost of maintenance


Site r畮湩湧 捯cts


Ba捫桡畬 捯cts





mai湴e湡湣n 捯sts


HOME BROADBAND
WOULD

BE SUBSIDIZED BY
THE OPERATOR!!

3.Financial Analysis of a Pico
-
Cellular Home Network Deployment

Impact Analysis

Event

Reason

Small fraction of HBS
achieve a full coverage


Randomly distributed
HBS

Fractional user coverage for different
operator market share
[3].

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
.


3.Financial Analysis of a Pico
-
Cellular 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

Network costs for an operator with
40% market share and 64 user per
macrocell [3].

Characteristic

Point
:


Total

network

cost

minimize

at

30
%

HBS



UMB and LTE

OFDMA based





Higher spectral efficiencies




Low latency




High peak data rate




All
-
IP






Key feature for FEMTOCELL deployments


4. UMB and LTE for Femtocells



New generation femtocells

Higher order modulations






Improve self
-
configuration






Improve self
-
provisioning






Improve self
-
optimization






Mobile operators may
choose to introduce islands of
4G in an ocean of 3G



5.Conclusions

1.
Network architecture, Performance and Interference Management


Performance analysis














Macrocell
Performance

Femtocell
Performance

Downlink

(from 10 to 100 HBS)


Unchanged
throughput


Hig栠t桥潲eti捡l
畮捨c湧e搠
t桲潵o桰畴

Uplink

(from 10 to 100 HBS)



Unchanged
throughput


Perf潲ma湣n
affe捴e搠扵t
t桲潵o桰畴 still
g潯o


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

2.
Financial Analysis of a Pico
-
Cellular Home Network Deployment


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)



3.
UMB and LTE for Femtocells


New generation flat, low cost architectures


Hybrid mobile network


New broadband experience for the users


6.References

[
1
]


H
.

Claussen
.
,

“Performance

of

Micro
-

and

co
-
Channel


Femtocells

in

Hierarchical

Cell

Structure”,

in
:

Proceedings


18
th


Annual

IEEE

International

Symposium

on

Personal,


Indoor

and


Mobile

Radio

Communications

(PIMRC’
07
),


2007
.

[
2
]


V
.

Chandrasekhar

and

J
.
G
.

Andrews
.
,

“Uplink

Capacity


and


Interference

Avoidance

for

Two
-
Tier

Cellular


Networks”

in
:


Proceedings

IEEE

GLOBECOM,

2007
.

[
3
]


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
.

[
4
]


Qualcomm
.
,

“Femtocells

and

WLAN

Complement

3
G

and


Beyond”,

December

2007
.




Many
thanks for
your
attention