Definition and Concept of Femtocell

Femtocells 1.

INTRODUCTION

Mobi Mobile le oper operat ator ors s have have been been sear search chin ing g for for lice licens nsed ed indo indoor or cove overa rage ge

solut olutiions ons

Unfortunately,

the

sinc since e

the the

bulk

of

beg beginn inning ing this

of

wir wireles eless s

opportunity

(i.e.

netw etwor orks ks.. residential

environments) has been beyond the addressable market for cost and oper operat atio iona nall rea easo sons ns.. Thes These e rea easo sons ns has has trig trigge gerred the the desi design gn and and development of new cellular standards such as WiMax (802.16e),the thir third d

gene genera rati tion on

part partne ners rshi hip p

proj projec ect’ t’s( s(3G 3GPP PP’s ’s)H )Hig igh h

spee speed d

pack packet et

access(HSP access(HSPA)and A)and LTE standard standards, s, and3GPP2’s and3GPP2’s EVDO. EVDO. In parallel, parallel, WiFi WiFi mesh mesh networ networks ks ar are e also also being being develo developed ped to provi provide de high-r high-rate ate data data services in a more distributed fashion. Although the Wi-Fi networks will not be able to support the same level of mobility and coverage as the cellular cellular standards, standards, to be competit competitive ive for home and office use, cellular data systems will need to provide service roughly comparable to that offered by Wi-Fi networks.

 The recent technology is femto cell, the main aim of femto cell is to improve coverage and capacity of a mobile network by allowing service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable. A femto cell is a very small base station. so small, infect that can be placed in a customer’s residence. Femto cells are low-power access points that can combine mobile and Internet technologies within the home. The femto cell unit generates a personal mobile phone signal in the home and connects this this to the operat operator’ or’s s netwo network rk throug through h the Inter Internet net.. This This will will allow allow improved coverage coverage and capacity for each user within their home.

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Femtocells

2.

2.1

FEMTOCELLS

DEFINITION AND CONCEPT OF FEMTOCELL

Femtocells are low-power wireless access points that operate in licens licensed ed spectr spectrum um to connec connectt standa standard rd mobile mobile device devices s to a mobile mobile oper perato ator’s r’s

net networ ork k

usi using

reside sident ntia iall

DSL DSL

or

cabl cable e

bro broadb adband and

connections. Concept of femtocell

A femtocell is a very small base station. So small, infect that can be placed in a customer’s residence as shown in figure 1. The femtocell unit unit gene genera rate tes s a pers person onal al mobi mobile le phon phone e sign signal al in the the home home and and connects this to the operator’s network using standard broadband DSL on Cable service and typically supports 2 to 5 mobile phones in a residential setting. This will allow improved coverage and capacity for each user within their home.

Figuer1. Femtocell concept

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Femtocells

2.2 MOTIVATION Befor Before e the develo developme pment nt of femtoc femtocell ells s there there was exist existenc ence e of  other cells such as distributed antenna, microcells.

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Femtocells

Table 1.

Distributed Distrib uted antenna and Microcells Microce lls

But due to their unsatisfactory coverage and capacity, operators are forced to develop femtocell. Femto Solution

Table 2.

Femtocell

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Femtocells

2.3 2.3

Need eed for for femto emtoce celll

  Thir Third-g d-gene enerat ration ion cellul cellular ar techno technolog logy y suffer suffers s from from inadeq inadequat uate e indoor-signal indoor-signal penetration, leading to poor coverage in the environment wher where e cons consum umer ers s spen spend d two-t two-thi hirrds of thei theirr time time.. Poor oor cove covera rage ge 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 it's clear clear more more and and more more consum consumers ers want want to use mobil mobile e 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.

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Femtocells

From a

comp compet etit itiv ive e

pers perspe pect ctiv ive, e, femt femtoc ocel ells ls ar are e

impo import rtan antt

because mobile operators need to seize residential minutes from fixed providers, and respond to emerging VoIP and WiFi offerings.

Impr Improv ovin ing g user user expe experi rienc ence e in the the home home is also also esse essent ntia iall for for reducing churn and gaining marketshare and new revenues. However, high deployment costs ensure that 3G networks rarely extend beyond the regulatory minimum. Usin Using g femt femtoc ocel ells ls solv solves es thes these e prob proble lems ms with with a devi device ce that 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 tran transm smit it powe powers rs,, dram dramat atic ical ally ly incr increa easi sing ng batt batter ery y life life of exis existi ting ng phones, without needing to introduce WiFi enabled handsets.

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Femtocells

2.4 2.4 

Init Initia iall Netw Networ ork k Disc Discov over ery y

 Two initial network access information acquisition procedures

1. If a Femto BS with initial initial access access capability capability is found, MS requests requests and obtains initial network access information through that Femto Cell 2. Else, if only Femto Femto BSs BSs with no initial initial access capabili capability ty are found, found, MS requests and obtains initial network access information (without registration) through Macro BS



Initial access information information gathering 

  The The info inform rmat atio ion n gath gather erin ing g proc proced edur ure e for for netw networ ork k entr entry y applies to the aforementioned initial access cases (1) and (2)



During the initial access, MS transmits the information of  found Femto BSs to the initially accessed BS entity (e.g. Macro/Femto BS managing entity)

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Femtocells 

  The The BS enti entity ty popu popula late tes s a list list of neig neighb hbor or Femto emto cell cells s residing in the vicinity of the MS based on the given extra Femto BS information by the MS



  The The neig neighb hbor or list list,, incl includ udin ing g the the Femto emto Ce Cell lls s and and thei theirr system information, is given to MS, who tries initial network entry to one of the provided Femto Femto BS within the given list

Figure 2. Initial Network Entry to Macro BS-Case (2)

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2.5 2.5

Clas Classi sifi fica cati tion on of femt femtoc ocel ells ls

Since a large number of femtocells can be installed by subscribers, in certain scenarios femtocell access shall be restricted to certain subscribers who are authenticated and authorized for exclusive access and related network service. Additionally, femto BS can provide a mechanism delivering initial access information (e.g. BS ID, frequency, closed group information, NSP, roaming capability) of it’s own and neighboring femto BSs to any MSs in order to facilitate their network discovery/selection and entry procedure to femtocells. Femto BS can be classified into 4 types: 

Based on bearer connection capability 

Open Open femto femto BS : Provi Provides des beare bearerr connec connectiv tivity ity (full (full networ network k services) to any MS

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Femtocells 

Closed femto BS : Only provides bearer connectivity to allowed (identifiable) MSs



Based on initial access information capability 

Initial access able femto BS : Provides Provides initial access information information for any MSs



Initial access unable femto BS : Not allow to provide initial access information information

3.

FEMTOCELL WORKING

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 poin point, t, and and is conn connec ecte ted d via via broa broadb dban and d DSL DSL back back to the the mobi mobile le operator’s network. A femtocell is installed at home and connected to mains power and a standard broadband IP connection (typically DSL) thr through ough to the the mobi mobile le oper operat ator or’s ’s cor core netw networ ork. k. Voice oice call calls, s, text text massages and data services are provided by the same systems.

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Femtocells

Femto emtoce cell lls s oper operat ate e at very very low low ra radi diat atio ion n powe powerr leve levels ls (50 (50 mill milliw iwat atts ts peak peak outp output ut duri during ng a call call,, much much lowe lowerr when when idle idle), ), and and typically have a range of 200 meters. The signals do not travel through wall walls s part partic icul ular arly ly well well,, but but this this is a bene benefi fitt beca becaus use e it allo allows ws the 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 femtoc femtocell ell if permit permitted ted by the mobile mobile operat operator or.. Unlik Unlike e WiF WiFi access access points, 3G Femotcells operate using licensed spectrum and thus must be suppli supplied ed and operat operated ed in conjun conjuncti ction on with with the mobile mobile operat operator or 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 reuse euses s thei theirr exis existi ting ng RN RNC C prod produc ucts ts)) vers versus us UMA, UMA, whic which h has has new, new, cust custom om desi design gned ed syst system ems s ar arch chit itec ecte ted d to hand handle le the the much much larg larger er number of cells and IP connectivity. SIP based solutions may be of  inte interrest est wher where e the the user user want wants s to bypa bypass ss the the netw networ ork k oper operat ator or completely, and is happy to operate in a different way to achieve this.

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Femtocells

Figur igure e 3. 3.

Femto emtoce cell ll wor orki king ng

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Femtocells

4.

SYSTEM ARCHITECTURE

Kineto Wire Wireles less s announ announced ced today today its full full suppor supportt for for the US : Kineto 3GPP 3GPP agr agree eeme ment nt rea each ched ed last last week week on the the Home Home No Node deB B (HNB (HNB)) architec architectur ture e for femtocell femtocell-to-co -to-core re network network connectiv connectivity ity.. Recognizing ecognizing that a standard is needed for the mass-market success of femtocells, Kineto

took

a

lead

role

in

developing

consensus

among

the

contributing companies. Having an agreed architecture marks a major milestone towards the completion of a global 3G femtocell standard. “Develo “Developing ping an industry industry-wid -wide e standard standard re requir quires es a tremend tremendous ous amount of cooperation between vendors and operators, with all parties cont contri ribu buti ting ng thei theirr know knowle ledg dge e and and expe experi rien ence ce to deve develo lop p the the best best poss possib ible le solu soluti tion on,” ,” said said Patri atrick ck Tao, ao, Kine Kineto to’s ’s vice vice pres presid iden entt of  technology. “The femtocell standardization effort within 3GPP provides a great great exampl example e of such such cooper cooperati ation, on, with with the agreed agreed ar archi chitec tectur ture e mer merging ging key attr attrib ibut utes es of the the

3GPP 3GPP UMA/ UMA/GA GANN-ba base sed d

appr approa oach ch

prop propos osed ed by Kine Kineto to with with other other comp compan anie ies’ s’ prop propos osal als s to crea create te an optimize optimized d ar archite chitectur cture e capable capable of supportin supporting g mass-mark mass-market et femtocel femtocelll deployments.”  The agreed 3GPP HNB architecture follows an access network-based approach, leveraging the existing Iu-cs and Iu-ps interfaces into the cor core serv servic ice e netw networ ork. k. The The ar arch chit itec ectu turre defi define nes s two two new new netw networ ork k elemen elements, ts, the HNB (a.k.a (a.k.a.. Femtoce emtocell) ll) and the HNB Gatewa Gateway y (a.k. (a.k.a. a. Femto Femto Gateway). Between these elements is the new Iu-h interface.

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Femtocells •

Home Home No Node deB B (HNB (HNB)) – Co Conn nnec ecte ted d to an exist xistin ing g resid esiden enti tial al broadbandservice, an HNB provides radio coverage for standard 3G handsets within a home. HNBs incorporate the capabilities of  a standard NodeB as well as the radio resource management functions of a standard Radio Network Controller Controller (RNC).

•

HNB Gateway Gateway (HNB-GW): (HNB-GW): Installed Installed within an operator’ operator’s s network, network, the HNB Gateway aggregates traffic from a large number of HNBs back into an existing core service network through the standard Iu-cs and Iu-ps interfaces.

•

Iu-h Interface: Residing between an HNB and an HNB-GW, the Iuh interface includes a new HNB application protocol (HNBAP) for enabling highly-scalable, ad-hoc HNB deployment. The interface also introduces an efficient, scalable method for transporting Iu control signaling over the Internet.

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Femtocells

Figure 4. System Architecture

5.

HANDOVER OPERATION OPERATION

Handover (called handoff in the US) is the process by which a mobile phone switches between different call sites during a phone call, continuing with seamless audio in both directions. One of the most complex aspects of mobile phone systems. Femtocell users need this capability when entering or leaving their home – perhaps a rare use case, but essential nonetheless.

5.1 5.1

Hand Handov over er in in Mob Mobil ile e Phon Phone e syst system ems s

As a person move around when on a call, your mobile phone continuously measures the signal level and quality from nearby cell sites. These measurement reports are streamed to the current active base station, which determines when and where to initiate a handover seq sequen uence. ce.

Com Co mple plex

algor lgorit ithm hms s

are ar e

used used

when when

mak akin ing g

these hese

 judgments, in order to ensure that best use is made of all available capacity while reducing the likelihood of dropping a call during (or by postponing) a handover.

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In the case where connection to the current active cell site is dropped, the system is smart enough to allow the mobile phone to request a new connection on a different cell site and reconnect the call. This typically causes a short break of up to a few seconds in the conversation. If the call cannot be reconnected, then it drops out. 3G systems are slightly more complex because it is possible for a mobile to be actively connected to more than one cell site at the same time time.. This This feat featur ure, e, call called ed soft soft hand handov over er,, allo allows ws the the same same sign signal al transmitted by a mobile phone to be picked up by multiple cell sites and the best quality reception reception selected on a continuous basis.

5.2 5.2

Femto emtoce cell ll Hand Handov over er

Femtoce emtocells lls do not imple implemen mentt soft soft handov handover, er, re regar gardle dless ss of the radio technology used. Instead, all calls are switching instantly to or from the femtocell and the external outdoor cellular network. This is know known n as “har “hard d hand handov over” er” and and woul would d typi typica call lly y not not be audi audibl ble e or noticeable to the caller.  The 2G and 3G systems systems from the same mobile network network co-exist co-exist,, as is very common with GSM and UMTS, and then handover between 2G and 3G can also occur. occur. Operators prefer to use 3G systems because of the the high higher er traf traffi fic c capa capaci city ty and and lowe lowerr cost costs. s. Thei Theirr syst system ems s ar are e therefore configured to automatically select 3G where good reception is available, reverting to 2G when out of coverage – typically either in a rural area or inside building where 3G signals can’t so easily penetrate

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Femtocells

(due to operating at higher frequencies and having fewer 3G call sites thus being further away). Many 3G femtocells are also capable of 2G GSM reception. 2G typically penetrates buildings better than 3G, it allows the femtocell to deter determin mine e where where it is (by (by re readi ading ng the cell cell site site identi identific ficati ation on on its broad broadcas castt channe channel), l), derive derive some some timin timing/c g/cloc lockin king g re refer ferenc ence e (as one input to its timing algorithm), and work out which 2G cell sites might be most appropriate to handover to when a mobile phone leaves the femtocell zone. Presumably, these 2G cell site identifies can then be transm transmitt itted ed to the mobile mobile phone phone as potent potential ial hando handover ver candid candidate ates s (known as the neighbor list), and be measured during any active call in case a handover is requied. 5.3 Optimi Optimizin zing g Hand Handove over r into into a Femt Femtoce ocell ll

  There are potentially three approaches to optimizing handover into a femtocell: 1.

Adding femtocells to the neighbor lists of the outdoor

macro cells: This is unlikely to be as scalable or workable solution.

Although neighbor lists can be quite large, the time taken to scan round many different settings increases proportionally. In dense urban areas, there may potentially be some 100’s of femtocells colleocated with an outdoor macro cell. The mobile phone would not be searching for the most likely cell site to switch over to, and dropped calls would incre increase ase.. Addit Addition ionall ally, y, the comple complex x manage managemen mentt to downlo download ad and maintain vast numbers of femtocell candidates add an overhead to the network operator.

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2.

Addin dding g som some smar smarts ts in into th the mob mobile ile pho phon ne:One of the key

benefits of femtocells is that they work with any standard 3G phone – this is a clear competitive advantage compared with WiFi dual-mode solu soluti tion ons s that that ar are e restr estric icte ted d to spec specif ific ic (and and some someti time mes s mor more expensive) dual mode devices. However, it could be argued that with some some addi additi tion onal al func functi tion onal alit ity y in the the phon phone e itse itself lf,, then then impr improv oved ed handover into the femtocell zone is enabled. For example, the phone could learn about its femtocell zone and the matching external cell site used sed out outside side.. Whe When on a call all in the the exter ternal cel cell sit site it coul could d additionally monitor for the femtocell and switch across to it when in range. 3.

Making the femto toc cell as clever as possible: Ensuring that

any any call calls s abou aboutt to drop dropou outt when when ente enteri ring ng the the femt femtoc ocel elll zone zone ar are e quickly restored as soon as the mobile can detect and lock-on to the femtocell. Parameter selected by the femtocell, such as the cell-ld and pagi paging ng

zone, one,

can can

enc encour ourage

more

rapid pid

iden identi tifi fica cattion. ion.

Som Some

optimization may be required in the mobile network too, but the idea would be to avoid any changes to the mobile phone itself. This is one area where femtocell vendors will be able to differentiate themselves.

6.

DESIGN OF FEMTOCELL

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Femtocells

 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

resul esultt femt femtoc ocell ells s must must be phys physic ical ally ly smal small, l, idea ideall lly y ae aest sthe heti tica call lly y 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 power level than many Wi-F Wi-Fii access access points, points, which can be specified 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. emtocells lls ar are e aimed aimed at delive deliveri ring ng dedica dedicated ted 3G Capacity – Femtoce 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, provi provide de a very very good good benchm benchmark ark in terms terms of perfor performan mance, ce, and and ar are e highly cost effective. Femtocells will be offered for purchase via their Operators. This may be direct or through resellers.

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Femtocells

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 its impact pact on the the fuel uel bil bill. That hat said, aid, fro from an Oper perator ator’’s pers perspe pect ctiv ive, e, this this OPEX OPEX is effe effect ctiv ivel ely y offl offloa oade ded, d, whic which h mak makes the the business case for femtocells even more attractive. Like cabl cable e mode modems ms and and DSL DSL Easy end-user end-user installat installation ion – Lik route outers rs,, femt femtoc ocel ells ls will will be inst instal alle led d by cons consum umer ers s and and acti activa vate ted d 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) (IP) and and flat flat base base-s -sta tati tion on ar arch chit itec ectu turres. es. Back Backha haul ul conn connec ecti tion on 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 than throug through h the IP core. core. This This will will benefi benefitt Operat Operators ors by effect effective ively ly 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.

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Femtocells

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 inst instanc ance e of clos close e pro proximi ximity ty of two two or more more unit units, s, femt femtoc ocel elll with with femtocell. Operators will likely want to launch femtocells on the same channel as their macro cell network for capacity reasons. Handovers

-

Cur Current ent

macr acro

RF

plan planni nin ng

tech echniq niques ues

are ar e

inappropriate for femtocells. Not least because of the sheer potential numbers numbers of femtocell femtocells s and managing managing the neighbor lists that would would be necessary. 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 femt femtoc ocel ell, l, must must be cons consid ider ered ed very very car careful efully ly to ensur ensure e that that the the networks provide the best overall coverage without issue. To illustrate, in macr macro o base based d 3G netw networ orks ks the the over overhe head ad asso associ ciat ated ed with with soft soft-handov handovers ers accoun accounts ts for a signif significa icant nt propo proporti rtion on of RNC proce processi ssing ng capabi capabilit lity y. Unders Understan tandab dably ly then then and in or order der not to exace exacerba rbate te the issu issue, e, grea greatt car care and and soph sophis isti tica cate ted d algo algori rith thms ms ar are e nece necess ssar ary y to overcome these potential issues and ensure that the over-all network quality is not impacted by inefficient handovers and wasted capacity. Given n the requi equirremen ements ts for for low-c ow-cos ostt and and ea easy sy Security - Give installation, the use of the broadband internet as the network interface becomes very easy to understand. However this raises security risks in that hat

broa broadb dba and

inte nternet net

has has

open open

acce ccess. ss.

Ther There e

are

vari variou ous s

approaches to address this issue including the embedding of the Iub

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Femtocells

inte interf rfac ace e with within in the the IP sign signal alin ing g itse itself lf whil while e netw networ ork k secu securi rity ty is managed by the IP security (IPSec) protocol. protocol. World rldwide

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. Produ Products cts will will offer offer suppor supportt for their their re respe specti ctive ve and exist existing ing (3GPP) (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 will suppor supportt exist existing ing handse handsets ts and device devices s furthe furtherr helpin helping g to drive 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 share the same same spectr spectrum um (curr (current ently ly the 2100MH 2100MHz z frequ frequenc ency y band) with the macro network. Operator controlled – Femtocells operate in licensed spectrum

and as such such Ope Opera rato torrs must ust ensu ensurre that that they they com comply with with the the cond condit itio ions ns of that that lice licens nse e and and any any othe otherr cont contrrols ols enfo enforrced ced by a regulator. To these ends femtocells feature client software that enables remote configuration and monitoring via an Operations, Administration,

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Femtocells

Maintenance and Provisioning (OAM&P) system in a similar manner to that used by the macro network. emtoce cell lls s ar are e lik likely ely to New servic services es and and applic applicati ations ons – Femto become an integral part of managing all communications in and out of  the home environment. 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 for a serv servic ices es envi envirronme onment nt on whic which h appl applic icat atio ions ns may may be adde added, d, 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.

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Femtocells

7. BENEFITS OF FEMTOCELLS Due to the substantial benefits, femtocell technology is causing quite a “buzz” in the industry. Research has forecasted that by 2011 ther there will will be 102 millio million n users users of femtoc femtocell ell produ products cts on 32 millio million n access points worldwide. Better coverage and capacity

– Due to short transmit-receive distance •

Lower transmit power

•

Prolong handset life

•

Higher SINR

•

Higher spectral efficiency

Improved macro reliability

– BS can provide better reception for mobile users •

  Tra Traff ffic ic or orig igin inat atin ing g indo indoor ors s can can be abso absorb rbed ed into into femt femtoc ocel elll networks over Ip backbone

Cost Benefit

–

$60,000/year/marcrocell $60,000/year/marcr ocell vs. $200/year/femtocell

Reduced subscriber turnover

– Enhanc Enhanced ed home home cove covera rage ge will will re reduc duce e moti motivat vation ion for for user users s to to switch

Department of Electronics & Communication Engineering K.B.N. College of Engineering, Gulbarga. Page 24

Femtocells

carriers

Capacity benefits of femtocell

–

Reduced distance distance between between sender sender and receiver receiver leads leads to to higher

signal strength [capacity improvement]

–

Lowered

transmit

power

decrease

the

Inter erfferenc ence

for

neighboring cells [capacity improvement] improvement]

–

Femto-AP can devote a larger portion of resource for fewer users. [frequency efficiency]

Department of Electronics & Communication Engineering K.B.N. College of Engineering, Gulbarga. Page 25

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8. DISADVANTAGES DISADVANTAGES AND FUTURE SCOPE

Disadvantages

1.

High price ($300).

2.

Difficult to install. (Cabling, roof access etc)

3.

Depe Depend nden entt on on sig signa nall fr from near neares estt cel celll tow town. n.

4.

Requ equires ires broa broadb dba and conn connec ecti tio on.

5.

Mor More com complex plex to set set up, up, req requi uirres a new/ new/di diff ffer eren entt phone number, more potential for errors.

6.

It does does not not pr provid ovide e goo good d cov cover erag age e in in out outdo door ors. s.

Department of Electronics & Communication Engineering K.B.N. College of Engineering, Gulbarga. Page 26

Femtocells

FUTURE SCOPE By 2012, there will be 36 million shipments with an installed base of 70 million femtocell serving 150 million users

Femtocells by Feature

Figure 5. Market Forecast

Department of Electronics & Communication Engineering K.B.N. College of Engineering, Gulbarga. Page 27

Femtocells

9. APPLICA A PPLICATIONS TIONS 9.1

DSL Modem

  The The step step is to inte integr grat ate e the the femt femtoc ocel elll into into an exist xistin ing g DSL DSL broad broadban band d modem modem design design.. No additi additiona onall exter external nal connec connectio tions ns ar are e needed – the modem will already have power and data connectivity, and usually a list of other standard features too. The femtocell module is hardwired into the modem and can be given priority of voice calls to ensure improved performance.   The The over overal alll cost cost of the the comb combin ined ed unit unit is much much less less than than two two separate boxes, it is the ease of installation and remote management which benefits this option. Many mobile operators have started offering DSL broadband as an additional service, particularly in Europe. If the additional cost of a combined modem/femtocell is acceptable, then this could be shipped to customers c ustomers as part of a package. p ackage.

9.2

Cable Mo Modem

More households in the USA receive their broadband internet service from their cable TV supplier than from the phone company (as is mor more comm common on in Eur Europe ope and and else elsewh wher ere) e).. The The mode modem m can can be separate from the TV Set-top box or a combined unit.   The The larg large e Ca Cabl ble e TV comp compan anie ies s in the the US, US, such such as Co Comc mcas ast, t, prev previo ious usly ly had had agre agreem emen ents ts to resel eselll mobi mobile le serv servic ices es on the the Spri Spritt network. This appears to have been discontinued. Although Cable TV

Department of Electronics & Communication Engineering K.B.N. College of Engineering, Gulbarga. Page 28

Femtocells

companies do own some spectrum (via the Spectrum Co) business, and so could legally launch and operate a rather than traditional mobile phone.

CONCLUSION Femtocell is as an Access Point Base Station—is a small cellular base station, station, typically designed for use in residential or small business envi envirronme onment nts. s. It conn connec ects ts to the the serv servic ice e prov provid ider er’s ’s netw networ ork k via via broadband (such as DSL or cable); current designs typically support 5 to 100 100 mobi mobile le phon phones es in a resid esiden enti tial al sett settin ing. g. A femt femtoc ocel elll allo allows ws service providers to extend service coverage indoors, especially where access would otherwise be limited or unavailable. Unsati tisf sfac acto tory ry http://en.wikipedia.org/wiki/Base_stationUnsa

cove covera rage ge

and and

the increasing number of high-data-rate application are two driving forces for femtocell development Femtoce emtocells lls have have the potent potential ial to provi provide de high-q high-qual uality ity networ network k access to indoor users at low cost  –  improve coverage Provide huge capacity gain  –  Provide From technical standpoint, some challenges shall be overcome  –  New network architecture  –  Interference mitigation  –  Synchronization

Department of Electronics & Communication Engineering K.B.N. College of Engineering, Gulbarga. Page 29

Femtocells

 –  End-to-end QoS support  –  Seamless handover support Femtocells are an alternative way to deliver the benefits of  Fixed Mobile Convergence. Convergence. The distinction is that most FMC architectures requi equirre a new new (dua (duall-mo mode de)) hand handse sett whic which h work works s with with exist xistin ing g home home/e /ent nter erpr pris ise e

Wi-F i-Fi

acce access ss

poin points ts,,

whil while e

a

femt femtoc ocel elll-ba base sed d

deployment will work with existing handsets but requires requires installation of  a new access point.

REFERENCES 1.

http://www http:// www.thinkfe .thinkfemtocell.com mtocell.com/system/ /system/what_are_f what_are_femtoc emtocells.html

2.

http://www http:// www.thinkfe .thinkfemtocell.com mtocell.com/system/ /system/crystalcrystal- frequencyoscillators-in-Femtocells.html

3.

http://www.femtoforum.org

4.

www.google.com

5.

www.lycos.com

Department of Electronics & Communication Engineering K.B.N. College of Engineering, Gulbarga. Page 30