06-09-2016, 11:41 AM
1453210360-fppt.pdf (Size: 804.95 KB / Downloads: 40)
Evolution of femtocell
The first interest in femto cells started around 2002 when a group of
engineers at Motorola were investigating possible new applications and
methodologies that could be used with mobile communications.
Further after 2yrs. In 2004 more attention was given to this technology and it
was enhanced further.
What is a Femtocell?
Mobile cellular and 3G networks normally ften suffer from poor penetration
and reception in certain areas, like indoors. This decreases the quality of
voice and video communication and slows down high-speed services. A
femtocell is a small device that is used to improve wireless coverage over a
small area, mostly indoor. It is a small cellular base station, also called a
wireless access point that connects to a broadband Internet connection and
broadcasts it into radio waves in its area of coverage. As a result, mobile
handsets can handle phone calls through the femtocell, via the broadband
Internet connection.
The name femtocell has the prefix 'femto', meaning a very small cell (area of
network coverage). Small is rather a big word here, because femto denotes a
division that is mathematically represented by 10 raised to the power of -15,
or a quadrillionth. In plain English, it is one divided by a figure with fifteen
zeros. Well, close to infinitely small.
Femtocell Definition
Femtocell is a small cellular base station, designed for use in residential or
enterprise.It connects to the service provider’s network via broadband. It
supports 2 to 5 mobile.It allows service providers to extend service coverage
indoors.
Need of femtocell
Mobile cellular and 3G networks normally often suffer from poor penetration
and reception in certain areas, like indoors. This decreases the quality of
voice and video communication. It slows down high-speed services.
Problem-3G Coverage Issues:
• 3G cells are smaller by virtue of supporting higher data rates
• 3G infrastructure needs to Proliferate
• Femtocells are a vehicle for expanding 3G coverage and improving
indoor coverage
• Infrastructure must evolve to support millions of small cells
Third-generation cellular technology suffers from inadequate indoor-signal
penetration, leading to poor coverage in the environment where consumers
spend two-thirds of their time. Poor coverage diminishes the quality of voice
and video applications, and slows down high-speed data services To keep
customers satisfied, 3G carriers have increased capacity by building
additional microcell sites. This strategy is becoming much less attractive.
Site acquisition costs are exorbitant and continue to mount as space on
viable towers and buildings fills up, landlords exact high rents and regulators
impose onerous permit requirements. Public opposition to the building of
large-scale base stations is increasingly common.
Acquiring a site is only half the battle: Sophisticated base station equipment
must then be purchased, installed, insured, operated and maintained. The
net present value of a cell site in the U.K. is estimated to be $500,000.
Carriers thus face a serious dilemma. Well it's clear more and more
consumers want to use mobile phones in the home, even when there’s a
fixed line available. Friends and family usually call a mobile number first, and
it’s where messages and contact lists are stored. However, it is often the
case that providing full or even adequate mobile residential coverage is a
significant challenge for operators.
From a competitive perspective, femtocells are important because mobile
operators need to seize residential minutes from fixed providers, and
respond to emerging VoIP and WiFi offerings. Improving user experience in
the home is also essential for reducing churn and gaining marketshare and
new revenues. However, high deployment costs ensure that 3G networks
rarely extend beyond the regulatory minimum. Using femtocells solves these
problems with a device that employs power and backhaul via the user’s
existing resources. It also enables capacity equivalent to a full 3G network
sector at very low transmit powers, dramatically increasing battery life of
existing phones, without needing to introduce WiFi enabled handsets.
• Indoor cellular coverage
• Can “talk” with any handset device
• Low cost backhauling
• More than 50% voice calls and more than 70% data traffic are
originated indoor
• The 3Cs--coverage, churn and capacity--are stifling 3G adoption.
• Femtocells produce cost savings as well for the carriers. Consumer's
home in essence becomes a cell site and there is no site acquisition
costs involved.
• Electricity bills can be minimized.
• Unlimited mobile minutes for a fixed monthly fee.
Other solutions:
• Repeaters
• Dual Mode WiFi
• Femtocells
Why Femtocell?
The 3Cs--coverage, churn and capacity--are stifling 3G adoption. Femtocells
produce cost savings as well for the carriers. Consumer's home in essence
becomes a cell site and there is no site acquisition costs involved. Electricity
bills can be minimized. Unlimited mobile minutes for a fixed monthly fee. The
call charges can also be reduced based on which subscriber we are using.
Provides better coverage and also prolonged battery life compared to others.
Portable and easy to install and use.
Speed:
• 2.5 G
The femtocell will be 2G GSM technology, supporting data services through
GPRS and EDGE which typically offer up to 384kbit/s.
• 3G UMTS
Femtocells add network capacity and make it possible to deliver 7.2 Mbps
and 14.4 Mbps data rates to consumers in indoor environments.
Working of Femtocell
Femtocells from part of the mobile operation’s network, although they are
located at home or in the business. Most of the functionality of a completer
3G cell site has been miniaturized onto a chip, which look and operates like a
WiFi access point, and is connected via broadband DSL back to the mobile
operator’s network. A femtocell is installed at home and connected to mains
power and a standard broadband IP connection (typically DSL) through to the
mobile operator’s core network. Voice calls, text massages and data services
are provided by the same systems.
Femtocells operate at very low radiation power levels (50 milliwatts peak
output during a call, much lower when idle), and typically have a range of
200 meters. The signals do not travel through walls particularly well, but this
is a benefit because it allows the frequency to be reused for other calls in
nearby building. Where users walk outside or out of range, calls are
automatically handed over to the external mobile network. Any standard 3G
phone can be used on the femtocell if permitted by the mobile operator.
Unlike WiFi access points, 3G Femotcells operate using licensed spectrum
and thus must be supplied and operated in conjunction with the mobile
operator Figure 1 shows working of femtocell.
The battle is most likely to be between the modified 3G RAN (which some
RAN Network vendors are keen to promote because it reuses their existing
RNC products) versus UMA, which has new, custom designed systems
architected to handle the much larger number of cells and IP connectivity.
SIP based solutions may be of interest where the user wants to bypass the
network operator
When registered handsets enter the range of a femtocell, handing over to
the femtocell network is done automatically, such that calls are channeled
through the broadband connection. One femtocell can support up to 5 mobile
handsets.
Femtocell technology, which is another block in the Fixed-Mobile
Convergence concept, is still in its early days and it is receiving fierce
competition from UMA and Wi-Fi technologies. For instance, one might ask
why invest in femtocells when a cheap Wi-Fi router can do the work with a
Wi-Fi supporting handset, given that handsets supporting Wi-Fi are becoming
more common and are being shipped by hundreds of millions.
Design of Femtocell
The following are the key features that are to be considered as the
characteristics of femtocell in the design of femtocell.
Low-impact – Space may be limited for some households. As a result
femtocells must be physically small, ideally aesthetically pleasing and easy
to position. Furthermore, they should also be silent in operation, generate
low levels of heat output and inexpensive to run in terms of on-going
[electricity] cost.
Low RF power – The transmit RF power output of femtocells is low; between
10 and 100 milli-watts. Put in perspective, this is a lower power level than
many Wi-Fi access points, which can be specified up to 1 Watt of output
power. Additionally, by being close to the femtocell the 3G handset is itself
able to transmit at lower power levels than it might otherwise have to when
on the macro network.
Capacity – Femtocells are aimed at delivering dedicated 3G coverage to a
household and in doing so can provide a very good enduser experience
within the home environment. As a result, femtocells have a design
“capacity” of up to 6 end-user.
Low-cost – There is significant competition for access solutions in the home
space. Wi-Fi is commonplace, easy to install/configure, provide a very good
benchmark in terms of performance, and are highly cost effective.
Femtocells will be offered for purchase via their Operators. This may be
direct or through resellers.
Energy offset - Low-power consumption – Clearly if the end-user is to foot
the bill for the electrical energy consumed by the femtocell base-station then
this figure must be low enough not to raise concerns as to its impact on the
fuel bill. That said, from an Operator’s perspective, this OPEX is effectively
offloaded, which makes the business case for femtocells even more
attractive.
Easy end-user installation – Like cable modems and DSL routers,
femtocells will be installed by consumers and activated through service
providers. This means that the Operator no longer has to employ installation
teams or have a truck-roll every time a new femtocell is “deployed”. From
the end-user perspective the unit must be a simple “plug and play”
installation with a minimal amount of intervention required.
Backhaul via broadband – Femtocells utilize Internet protocol (IP) and flat
base-station architectures. Backhaul connection to Operator networks will be
through wired broadband Internet service existing in the home such as DSL,
cable, or fiber optics as available. There are no connections required to the
wider cellular network other than through the IP core. This will benefit
Operators by effectively offloading traffic that would otherwise be on the
macro-layer directly onto the internet from the femtocell; this not only
reduces the load on the core network but also lowers the cost of delivering
wireless traffic when compared to the macro network.
Interference - The use of femtocells in spectrum also currently used by the
macro layer may, if not managed correctly, give rise to issues with
interference between cells; macro with femtocell and in the instance of close
proximity of two or more units, femtocell with femtocell. Operators will likely
want to launch femtocells on the same channel as their macro cell network
for capacity reasons.
Handovers - Current macro RF planning techniques are inappropriate for
femtocells. Not least because of the sheer potential numbers of femtocells
and managing the neighbor lists that would be necessary. Also the potential
to “ping-pong” between layers, especially as an end-user moves around the
home and enters into areas where the signal strength from the macro-cell is
greater than that of the femtocell, must be considered very carefully to
ensure that the networks provide the best overall coverage without issue. To
illustrate, in macro based 3G networks the overhead associated with
softhandovers accounts for a significant proportion of RNC processing
capability. Understandably then and in order not to exacerbate the issue,
great care and sophisticated algorithms are necessary to overcome these
potential issues and ensure that the over-all network quality is not impacted
by inefficient handovers and wasted capacity.
Security - Given the requirements for low-cost and easy installation, the use
of the broadband internet as the network interface becomes very easy to
understand. However this raises security risks in that broadband internet has
open access. There are various approaches to address this issue including
the embedding of the Iub interface within the IP signaling itself while network
security is managed by the IP security (IPSec) protocol.
Worldwide cellular network standards support – Understandably
femtocell products are likely to appeal to many endusers around the world.
As a result differing models will be developed and offered to satisfy the
various needs from the different regions. Products will offer support for their
respective and existing (3GPP) UMTS and (3GPP2) CDMA standards, as well
as emerging standards such as WiMAX, UMB and LTE.
Support for existing 3G handsets and devices –Support for existing
handsets and devices is a very important consideration for the end-user and
Operator alike, not least because of the cost of changing devices if that were
necessary. In each technology market, femtocells will support existing
handsets and devices further helping to drive uptake of 3G services and
femtocells in particular.
Operation (transmit/receive) in Operator-owned spectrum–
Femtocells operate in licensed spectrum owned by Operators and may share
the same spectrum (currently the 2100MHz frequency band) with the macro
network.
Operator controlled – Femtocells operate in licensed spectrum and as such
Operators must ensure that they comply with the conditions of that license
and any other controls enforced by a regulator. To these ends femtocells
feature client software that enables remote configuration and monitoring via
an Operations, Administration, Femtocells Maintenance and Provisioning
(OAM&P) system in a similar manner to that used by the macro network.
New services and applications – Femtocells are likely to become an
integral part of managing all communications in and out of the home
environment. Femtocells enable Operators to cost-effectively offer in-home
pricing and integrate mobile services into triple-play / quad-play service
offerings. Femtocell architectures include provision for a services
environment on which applications may be added, thereby facilitating new
revenue opportunities.
Service Assurance – Remote Management to enable an operator to provide
the end-user quality of service at the edge of the network.