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valuation of Signaling Mechanisms to Incorporate Wireless LANHotspots into 3G !G Mo"ile S#stems

$% Scot &ans"ottom' (rac# Mann' an) Nathaniel $% *avis ' I+,ra)le# *epartment of Electrical an) -omputer Engineering

+irginia .ol#technic Institute an) State /niversit#

E0mail1 2rans"ottom' tmann' n)avis34vt%e)u

A"stractRecent research supports the eventual convergence of wirelessLAN (WLAN) and cellular systems in order to achieve theIMT !""" (#$) re%uirement for !M&ps indoor capacities'even more for $ systems The future trend is toward I*

&ased signaling' however current cellular systems employ ++,signaling in the control plane The WLAN access point can &eenhanced to either incorporate or supplant the transmissionand pac-et data capa&ilities in the cellular networ- .urcurrent research uses .*N/T0 to model these control planecommunications We present an enhanced WLAN access point

that includes 11+, &ased channels on the wire line side forcontrol signaling within a #$ system This is the foundationto allow us to identify signaling mechanisms that leverage thecapa&ilities of WLAN while supporting cellular service

provisioning and accounta&ility re%uirements for current andfuture systems

Section I1 Intro)uct ionThe origins of the wireless industry focused on providingvoice communications to the outdoor' traveling userTechnological advances have increased the coverage and the%uality of that service Mo&ile systems are still %uite limitedin their a&ility to provide %uality coverage inside &uildings

The a&ility to provide %uality coverage in 2hotspots3 (indoorlocations with high concentrations of potential customers' e g 'office &uilding and airports) would increase the potential formo&ile systems to compete directly with infrastructure &asedcommunications systems The Third $eneration *artnership*ro4ect (#$**) is one of the primary standards &odiesdeveloping the standards for Third $eneration (#$) mo&ilecellular systems Much of their wor- focuses on addressingthe convergence of voice and data communications

WLAN technologies are currently capa&le of providing highcapacity LAN coverage within a limited area' such as within a

&uilding This capacity can &oth support a high concentrationof users and allow the potentially limited cellular capacity to

&e reserved for voice traffic 5or these reasons' the #$**group +A6 (+ervices and +ystem Aspects) has pu&lished afeasi&ility study and &egun development of proposedstandards supporting the Interwor-ing of #$** systems withWLAN systems 7!8 The study identifies si9 scenarios withthe potential to integrate the two systems We present thesescenarios in +ection II

The main goal of this paper is to descri&e our approach formodeling the integrated #$ and WLAN networ- .ur currentmodel addresses the #$** proposed scenario :! supportingauthentication' access control' and &illing functions for a clientcapa&le of using WLAN to gain high capacity networ- accessThis simulation environment is to &e the foundation for futurewor-s in the comparison and evaluation of mechanisms tosupport even tighter integration of #$ and WLAN systems

This paper is organi;ed as follows In +ection II' we provide

some insights into the

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data services (*+) are &ased on the ! >$ $+M *ac-et Radio+ervice ($*R+) framewor- 5igure 6 presents the pac-etdomain components in the

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&etween stations' forming an independent @++ comprised of agroup of stations' operating on the same radio fre%uencyThe I/// E"! 66 MA1 standard defines three &asic accessmechanisms the mandatory &asic method &ased on a versionof 1+MAD1A (1arrier +ense Multiple Access with 1ollisionAvoidance)' an optional method avoiding the hidden terminal

pro&lem' and finally a contention free polling method fortime &ounded service The first two methods are implementedin the distri&uted coordination function (B15)' and the thirdmethod' called the point coordination function (*15)' is usedin the infrastructure @++

3GPP Standardization EffortsAs previously stated' #$** standards continue to evolve .neof the #$** stated goals is to support data rates of up to!M&ps in the indoor environment 768 This re%uirement isstated for the #$** system' and is not &ased upon theintegration of WLAN

The #$** +A6' TR !! F# 7!8' presents their current wor- ondefining standards for the integration of #$ and WLANsystems The most significant result of their current wor- isan initial definition of potential levels of Interwor-ingre%uirements for #$** and WLAN systems Ta&le 6 presentsthe G scenarios e9actly as stated in 7!8 The scenarios range inInterwor-ing from two completely disparate systemsconnected only through offline &illing and support servicesand su&se%uently progress to a completely seamlessintegration of the two systems There is very limited

information presented &eyond the &asic ta9onomy for any ofthe scenarios with the e9ception of scenario :! +cenario :!defines Interwor-ing to consist of sharing the #$** providedmechanisms for access control (authentication andauthori;ation) and for the charging or &illing functionalityWe eventually desire to simulate each of the scenarios in thesystem to identify cost and &enefits for each This will allowus to compare the options and potentially identify the &estoperating point for a set of parameters

Scenarios*

Ser ice andoperationalCapa+ilities*

Scenario ,*CommonBillin! andCustomerCare

Scenario -*.")) s#stem+asedAccessControl andC/ar!in!

Scenario .*Access to.")) s#stem)S +asedser ices

Scenario 0*Ser icecontinuit#

Scenario 1*Seamlessser ices

Scenario 2*Access to.")) s#stemCS +asedser ices

Common +illin!3 3 3 3 3 3Common customer

care 3 3 3 3 3 3.")) s#stem +asedAccess Control 3 3 3 3 3.")) +ased AccessC/ar!in! 3 3 3 3 3Access to ."))s#stem )S +asedser ices 4rom 5'AN

3 3 3 3

Ser ice Continuit# 3 3 3Seamless Ser iceContinuit# 3 3Access to ."))s#stem CS +asedser ices wit/seamless mo+ilit#

3

Ta&le 6 +cenarios for Interwor-ing #$** and WLAN

Section III1 Simulat ion Metho)olog#.ur current wor- is focused on esta&lishing the foundation forfuture study of the interwor-ing of

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allow for the esta&lishment and initiali;ation of the ATMcircuits The *MM in ) ma-es the state transition fromDETACHED to C NNECT upon successful authenticationinto the

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simulate with this model' the simulation log stated that therewas a mismatch &etween the num&er of rows in the I* AddressInformation Ta&le and the num&er I* interfaces .nce wedetermined that the num&er of I* interfaces was set in theinitial declaration of the node and we located 5A IB #G 7E8'we attempted to follow the prescri&ed process without successIn addition to limited understanding of modeler processes' thee9isting models for &oth > to > has reduced theaverage num&er of B1C channels in use &y appro9imatelyG"O It is possi&le to reallocate these unused B1C channelsto voice services or to additional pac-et data services Wetherefore assert that these results could allow the provider togenerate additional revenue

5igure 66 Active B1C 1hannels.ne might %uestion why the reduction was only G"O' and theresults in 5igure 6! offer that insight There were " %ueuedre%uests for service in the case of service augmented &yWLAN' while the heavily loaded system using strictly

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5igure 6! ueued Re%uests (Belayed or Benied +ervice)

Section +I1 -onclusions an) =uture Wor>

Wireless LAN is a useful enhancement to mo&ile wirelesssystems' rather than a competitor WLAN addresses theindoor capacity limitations of mo&ile wireless Incorporationof WLAN capa&ilities to support indoor' high concentrationre%uirements allows