Admission Control Algorithms Integrated with Pricing for Revenue Optimization with QoS Guarantees in Mobile Wireless Networks

Transcription

1 Admissio Cotrol Algoritms Itegrated wit Pricig for Reveue Optimizatio wit QoS Guaratees i Mobile Wireless Networks Nares Verma ad Ig-Ray Ce Computer Sciece Departmet Virgiia Tec {averma, irce}@vt.edu ABSTRACT: We propose ad aalyze call admissio cotrol algoritms itegrated wit pricig for reveue optimizatio wit QoS guaratee to serve multiple service classes i mobile wireless etworks. Traditioal admissio cotrol algoritms make acceptace decisio for ew ad adoff calls to satisfy certai QoS costraits suc as te droppig probability of adoff calls ad te blockig probability of ew calls beig lower ta a pre-specified tresold. We aalyze a class of partitioig ad tresold-based admissio cotrol algoritms tat make acceptace/rejectio decisio ot oly to satisfy QoS requiremets but also to optimize te reveue of te system, takig ito accout prices ad arrival/departure iformatio of service calls. We sow tat for a carge-by-time pricig sceme, tere exist optimal resource allocatio settigs uder wic te partitioig ad tresold-based admissio cotrol algoritm would produce te maximum reveue obtaiable by te system witout sacrificig QoS requiremets. Furter, te tresold-based admissio cotrol algoritm outperforms te partitioig-based couterpart at optimizig settigs over a wide rage of iput parameters caracterizig te operatig eviromet ad service workload coditios. Metods for utilizig of te aalysis results for real-time admissio cotrol for reveue optimizatio wit QoS guaratee are described wit umerical data give to demostrate te applicability. I. Itroductio Next geeratio wireless etworks will carry real-time multimedia services suc as video ad audio ad oreal-time services suc as images ad files. Icreasig demads from idividuals ad busiesses wit differet profiles expect a flexible ad forgivig etwork tat ca easily adapt to teir eeds ad growig populatio witout compromisig te QoS, wile tey are travelig away from office or ome. Two of te most importat QoS measures i cellular etworks are percetages of ew ad adoff calls blocked due to uavailability of caels. Mobile users i a cellular etwork establis a coectio troug teir local base statio. A base statio may support oly a limited amout of coectios (cael assiged) simultaeously due to badwidt limitatios. Hadoff occurs we a ogoig coectio leaves te curret cell ad eters ito aoter cell. Tus a ogoig, icomig coectio may be dropped durig a adoff if tere is isufficiet badwidt i te ew cell to support it. We ca reduce te adoff call drop probability by rejectig ew coectio requests. Reducig adoff call drop probability could result i a icrease i te ew call blockig probability. As a result, tere is a tradeoff betwee te adoff ad ew call blockig probabilities. I te past, sigle class of traffic, suc as voice (realtime), as bee studied extesively. Te Guard cael algoritm [] assigs a iger priority to adoff calls were a fixed umber of caels are reserved for adoff requests. Hog ad Rappaport [] proposed a cutoff tresold algoritm wit o distictio made iitially betwee ew ad adoff calls wic are treated equally o a FCFS basis for cael allocatio util a predetermied cael tresold is reaced. We te tresold is reaced, ew calls are blocked (cutoff), allowig oly adoff calls. I [3] tey proposed a priority orieted algoritm were queuig of adoff calls is allowed. Gueri i [4] demostrated queuig of bot ew ad adoff calls improves cael utilizatio wile reducig te call blockig probabilities. Most of te above researc metods focus o voice-based cellular systems. Y. Fag i [5] preseted a tiig algoritm wic supports multiple types of services by calculatig te call admissio probability based o te priority ad te curret traffic situatio. We etwork approaces cogestio, calls admissio are trottled based o te priority levels of calls: lower priority calls are blocked ad ece tied to allow iger priority calls. Wag, Zeg ad Agarwal [6] caracterized traffic ito real-time ad o-real time traffic ad divided te caels i eac cell ito tree parts: for ew ad adoff real-time calls, for ew ad adoff o-real-time calls, ad for overflow of real-time ad o-real-time service adoff request from first two groups of caels, were real-time adoff service request are give iger priority ta oreal-time service requests. Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE

2 Li, Li ad Caso [7] proposed a ybrid cutoff priority algoritm for multimedia services. Idividual services ca be assiged a differet cutoff tresold i wic iger priority is give to adoffs, ad lower priorities are served if eoug caels are available. Eac service class is caracterized by its QoS requiremets i terms of umber of caels eeded. A badwidt reservatio ad recofiguratio mecaism wic facilitates adoff process for multiple service classes was proposed i [8]. I geeral tese algoritms make acceptace decisio for ew ad ad off calls to satisfy Quality of Service (QoS) requiremets suc tat te droppig probability of adoff calls ad te blockig probability of ew calls are lower ta pre-specified tresolds. I tis paper, we propose ad aalyze a class of partitioig ad tresold-based admissio cotrol algoritms tat make acceptace/rejectio decisio ot oly to satisfy QoS requiremets but also to optimize te reveue of te system based o carge-by-time pricig algoritms defied by te service provider. By partitioig we mea a umber of caels are specifically reserved to serve adoff (or ew) calls of a particular service type ad calls from oter service types would ot use te reserved caels. By tresoldbased we mea adoff (or ew) calls of a service type are give a tresold ad as log as te tresold is ot reaced ad tere are still caels available i te cell, adoff (or ew) calls of tat service type ca be admitted. Compared wit partitioig algoritms, tresold-based algoritms ave a ieret multiplexig property tat results i a large sared partitio to be opeed to accommodate multiple service classes as log as te tresolds are ot reaced. Tese algoritms i geeral support ay umber of service classes, eac of wic ca ave its ow QoS requiremets i terms of umber of caels eeded, legt of coectio ad cutoff priority employed. Our work is differet from previous oes i tat we develop tese partitioig ad tresold-based algoritms to target real-time admissio cotrol for reveue optimizatio wit QoS guaratees. Te goal of reveue optimizatio wit QoS guaratees is acieved by itegratig pricig wit call admissio cotrol to meet QoS requiremets. We do ot deal wit dyamic pricig as i [9] because we believe dyamic pricig (cagig te carge rate dyamically) is perturbig wit little acceptace i user or provider commuities. Rater we itegrate a static carge-by-time pricig algoritm wit admissio cotrol to maximize te reveue received subject to te costraits tat system imposed QoS requiremets are satisfied. II. System Model A cellular etwork is modeled by a flat arcitecture i wic cells are coected cosecutively. I te ceter of eac cell, oe base statio is allocated to provide etwork services to mobile osts i te cell. We assume tere exists a umber of distict service class S, S,, S. eac caracterized by te service type attribute. For example, te service types ca be real-time ad o-real time. Furter, tere are adoff ad ew calls for eac service type wit adoff calls avig a iger priority ta ew calls. Eac service type, oter ta requirig a umber of badwidt caels for te itrisic badwidt QoS requiremet, ca possibly impose a system-wide QoS requiremet. For example, te QoS requiremet may be tat te adoff call drop probability of a service type be less ta 5%. Users are more muc dissatisfied we adoff calls are dropped ta ew calls beig blocked. Assume tat for eac service class, say i, a QoS costrait exists o te adoff call blockig probability B i t. From te perspective of a sigle cell, eac service class is caracterized by its arrival rate (icludig for ew service coectios iitiated by mobile users i te cell ad for adoff service coectios from eigbor cells), ad departure rate (of leavig te cell). Let i deote te arrival rate of ew calls of service class i ad i be te correspodig departure rate. Similarly, let i deote te arrival rate of adoff calls of service class i ad i be te correspodig departure rate. Tese parameters ca be determied by ispectig statistics collected by te base statio i te cell ad by cosultig wit base statios of eigbor cells. Witout loss of geerality we assume tat a cell as C caels were C ca vary depedig o te amout of badwidt available i te cell. We service class i eters a adoff area from a eigborig cell, a adoff call request is geerated. Eac call as its specific QoS badwidt requiremet dictated by its service traffic type attribute. Assume tat a service call of service class i (regardless of adoff or ew) requires k i caels. From te perspective of a cellular etwork service provider, eac service class also as a price associated wit it suc tat te system receives some reveue correspodig to te price associated we te service is redered. Te service provider would like to maximize te total reveue obtaied by te system by meas of optimal pricig for service classes ad performig admissio cotrol fuctios subject to te badwidt resources available i te system. Te system acieves total reveue maximizatio i a distributed maer by maximizig eac idividual cell s reveue. Tat is, eac cell makes admissio cotrol decisios for ew ad adoff call requests takig ito cosideratio te price rate iformatio of tese service calls, so as to maximize Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE

3 te reveue received from servicig ew ad adoff calls i te cell. Te total reveue obtaied by te system is ieretly related to te pricig algoritm employed by te service provider. Wile may pricig algoritms exist [9] te most prevalet wit geeral public acceptace to date is te price-rate sceme by wic a user is carged by te amout of time i service. We assume tat suc a pricerate pricig sceme is adopted by te service provider suc tat a call of service class i is associated wit a carge-rate v i per time uit. Tat is, if a call of service class i is admitted ito a cell, ad subsequetly aded off to te ext cell or termiated i te cell, a reward of v i multiplied wit te amout of time te service is redered i te cell will be eared by te system. We cojecture tat tere exists a optimal way to assig proper values v i to all service classes suc tat te reward obtaied by te system is maximized wile satisfyig some system imposed QoS costraits. III. Admissio Cotrol for Reveue Optimizatio wit QoS Guaratee I tis sectio we develop admissio cotrol algoritms itegrated wit pricig for reveue optimizatio wit QoS guaratee i wireless mobile eviromets. For ease of presetatio we assume tat tere are two service types, class (ig-priority) ad class (low-priority), distiguised primarily by teir traffic type, i.e., real-time ad o-real-time respectively. Tese algoritms ca be easily applied to te case i wic more ta two service classes exist. 3. Partitioig Admissio Cotrol A partitioig call admissio cotrol policy divides te total umber of caels i a cell ito fixed partitios wit eac partitio specifically reserved to serve a service class (real-time vs. o-real-time) ad call type (ew vs. adoff). Tus for our example system tere exist four partitios: ig-priority adoff calls, ig-priority ew calls, low-priority adoff calls, ad low priority ew calls, as illustrated i Figure. By partitioig ere we mea tat a fixed umber of caels is allocated to a specific service type ad a call type ad it caot be used or sared by oters. I calculatig te expected reveue we assume tat we ave a priori kowledge of te arrival rate of calls ad te service class to wic it belogs. Tis kowledge is essetial to justify te admissio of a call i to a cell i order to maximize te reveue of a cell at ay give poit of time. We also assume te etwork service provider as specified te desired tresold blockig probability for adoff calls for differet service classes as te QoS costraits to be satisfied. Wit te sceario of two service types, te followig are te iput parameters to a cell:, µ,,, µ,,, µ,,, µ,, k, k, B t, ad B t were B t is te tresold blockig probability of class adoff calls ad B t is te tresold blockig probability of class adoff calls. Uder tis partitioig admissio cotrol algoritm, te total umber of cael C is divided ito *k, *k, *k, *k ad caels for ig-priority adoff calls, ig-priority ew calls, low-priority adoff calls, ad low priority ew calls respectively as sow i Figure, subject to te costraits tat: k C, k C, k C, k C; () k + k + k + k = C; () Te QoS costraits to be satisfied are te blockig probability of adoff calls for bot class ad calls. Tat is, we like to partitio C caels suc tat te followig QoS costraits are satisfied: B < B t (3) B < B t (4) Te reveue tat a call successfully termiated or adedoff brigs to te cell is calculated by te product of te call s price rate parameter v i wit te duratio of te call i te cell. Specifically suppose a partitioig admissio cotrol algoritm results i N, N, N, ad N igpriority adoff calls, ig-priority ew calls, low-priority adoff calls, ad low priority ew calls, respectively, successfully termiated or aded off per uit time i te cell. Te te cell will receive te followig reveue per uit time due to te deploymet of te partitioig admissio cotrol algoritm: Figure : Partitioig Admissio Cotrol. N v N v N v N v (5) Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE

4 Tus we eed to idetify te best partitioig admissio cotrol policy tat maximizes te cell s reveue subject to te imposed QoS costraits i terms of Coditios 3 ad 4 listed above beig satisfied Modelig ad Aalysis of Partitioig Admissio Cotrol Uder te partitioig algoritm, if a ew ig-priority (i.e., class ) call arrives at a cell ad all te caels allocated to serve ig-priority ew calls are used up, te te call is rejected. Similar reasoig applies to oter service classes too. No sarig is allowed amog multiple partitios tat exist. I tis case te system beaves as if it is maagig four cocurret queues: a M/M/ / queue to serve ew ig-priority ew calls i a cell wit arrival rate, service rate µ, ad te umber of caels allocated beig, a M/M/ / queue to serve ig-priority adoff calls wit arrival rate, service rate µ, ad te umber of caels allocated beig, a M/M/ / queue to serve low-priority ew calls wit arrival rate, service rate µ, ad te umber of caels, ad a M/M/ / queue to serve lowpriority adoff calls wit arrival rate, service rate µ, ad te umber of caels beig. Te call droppig probabilities for adoff calls for various service classes (i.e., B ad B ) ca be determied easily by te probability tat te partitio allocated to serve te adoff calls is full. We ca calculate te reveue geerated per uit time by te partitio reserved to serve oly ig-priority adoff calls by associatig a reward of i * v for state i i te M/M/ / queue. Te same way applies to oter partitios. Specifically, we ca compute te reveue per uit time to te cell by: R = R + R + R + R (6) were R, R, R, ad R stad for te reveues geerated per uit time due to ig-priority adoff calls, ig-priority ew calls, low-priority adoff calls, ad low-priority ew calls, respectively, as give by (oly R is sow below sice expressios for oters are similar): R i i! i (7) j j j! j A partitioig solutio is legitimate if B ad B satisfy Coditios 3 ad 4. A partitioig admissio cotrol itegrated wit pricig for reveue optimizatio wit QoS guaratee aims to fid te optimal set (,,, ) tat will yield te maximum reveue obtaied amog all legitimate solutios. 3. Tresold-Based Admissio Cotrol I te tresold-based admissio cotrol algoritm, we select a tresold C T to separate class from class based o te service type, i.e., real-time vs. o-real time. Te meaig of te tresold is tat we te umber of caels used i te cell exceeds C T te ew or adoff calls from service class (low-priority) will ot be admitted. Witi eac service class, we furter create tresolds to differetiate adoff from ew calls suc tat C is te tresold for class ig-priority adoff calls; C is te tresold for class ig-priority ew calls; C is te tresold for class low-priority adoff calls; ad C is te tresold for class low-priority ew calls. Figure : Tresold-based Admissio Cotrol. Figure illustrates te tresold-based admissio cotrol algoritm. Sice we give adoff calls a iger priority ta ew calls, te followig additioal coditios must also be satisfied: C C T, C > C T (8) C C T, C C T (9) A tresold-based admissio cotrol itegrated wit pricig for reveue optimizatio wit QoS guaratees tus aims to fid te optimal set (C, C, C, C ) satisfyig Coditios 8 ad 9 tat would yield te igest reveue wile satisfyig te QoS costraits specified by coditios 3 ad Modelig ad Aalysis of Tresold-based Admissio Cotrol We aalyze te tresold-based admissio cotrol algoritm by usig a SPN model. A SPN model is used rater ta a Markov model because of te Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE

5 iterdepedecy betwee tresolds assiged to adoff ad ew calls of various service classes. Te SPN model adopts te idea from [7] ad is geerically applicable to multiple service classes. Figure 3 sows a SPN model for te tresold-based admissio cotrol wit two service classes. B rate( E ) were rate(e i ) is calculated by fidig te expected value of a radom variable X defied as X= i if E i is eabled; 0 oterwise. A legitimate solutio from a tresold admissio cotrol algoritm must geerate B ad B to satisfy te QoS costraits specified by coditios 3 ad 4 discussed earlier. We compute te reveue geerated per uit time from te tresold-based admissio cotrol algoritm to te cell by: R=TR +TR +TR +TR (0) Here TR, TR, TR, ad TR stad for te reveues geerated per uit time due to ig-priority adoff calls, ig-priority ew calls, low-priority adoff calls, ad low-priority ew calls, respectively, give by: Figure 3: A SPN Model for Tresold-based Admissio Cotrol wit two Service Classes. Te trasitios ad places sow i Figure 3 are described as follows. For trasitios, E i models ew call arrivals of service class i at rate i.; E i models adoff call arrivals of service class i at rate i ; S i models service of ew calls of service class i wit a service rate of M(UC i ) multiplied wit µ i were M(UC i ) stads for te umber of tokes i place UC i.; ad S i models service of adoff calls of service class i wit a service rate of M(UC i ) multiplied wit µ i were M(UC i ) stads for te umber of tokes i place UC i. For places, UC models te executio state of service class ew call; UC models te executio state of service class adoff calls; UC models te executio state of service class ew calls; ad UC models te executio state of service class adoff calls. Te eablig predicate of E is (M(UC) * k ) + k + M(UC) * k <= C. Te eablig predicate of E is (M(UC) * k ) + k + M(UC) * k <= C. Te eablig predicate of E is (M(UC) * k ) + k + M(UC) * k <= C. Te eablig predicate of E is (M(UC) * k ) + k + M(UC) * k <= C were M(UC) = M(UC ) + M(UC ); M(UC) = M(UC ) + M(UC ) ad UC = M(UC) + M(UC). Te blockig probability B ad B are calculated from te SPN model by: B rate( E ) TR i = (- B i ) i v i / µ i, () TR i = (- B i ) i v i / µ i. () IV. Aalysis I tis sectio we report umerical data obtaied from applyig Equatios 6 ad 7 derived for partitioig admissio cotrol wit QoS guaratee ad Equatios 0,, for tresold-based admissio cotrol to aalyze ad compare performace of partitioig ad tresoldbased algoritms. Te cargig rate model is based o te popular carge-by-time sceme for wic a call is carged by time wit a fixed rate per time uit. Te aalysis cosiders two classes wit class (real-time) demadig more resources ta class (o-real-time), so class as a iger cargig rate per uit time ad a more striget tresold o te adoff call blockig probability ta class. Te default parameter values used are =3.5; µ = 0.8; =50; =.0; µ = 0.7; =50; =8.0; µ = 0.8; = 0; = 7.0; µ = 0.7; = =0; k =4; k =; B t=0.05; ad B t=0.5. We vary te values of some of tese model parameters, suc as te arrival ad departure rates of ew/adoff calls for differet classes ad tresold blockig probabilities, to aalyze teir effects o te maximum reveue obtaiable subject to te QoS costraits specified i terms of Coditios 3 ad 4 beig satisfied. 4. Partitioig Admissio Cotrol Figure 4 sows te maximum reveue obtaiable per time uit by a cell executig te partitioig algoritm at Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE

6 optimizig (,,, ) for reveue optimizatio as a fuctio of ad for te case we bot QoS costraits as specified by Coditios 3 ad 4 are satisfied. It sows tat iitially te maximum reveue obtaiable icreases as eiter or icreases. As furter icreases, te system teds to reserve more resources to serve ig-priority adoff calls to satisfy te tresold blockig probability requiremet for igpriority adoff calls, tus decreasig te maximum reveue obtaiable sice may ig-priority ew calls, ad low-priority calls (bot ew ad adoff) will be rejected. Fially, we is very ig (e.g., > 5, ot sow i te diagram), we ave observed tat o legitimate solutio from te partitioig algoritm exists tat ca adle te ig workload wile still satisfyig te QoS requiremets imposed by coditios 3 ad 4. Reveue/Time Hig-Priority Had off Call Arrival Rate ( ) = 3.5 = 4.5 = 5.5 Figure 4: Maximum reveue obtaiable via Partitioig admissio cotrol wit QoS. Figure 4 reveals tat uder te eviromet settig tested we te ig-priority adoff arrival rate ( ) is betwee to 4, te reveue obtaied by te cell is maximized wile satisfyig bot QoS costraits as imposed by Coditio 3 ad 4, wit te maximum poit movig toward rigt as te ig-priority ew call arrival rate ( ) icreases. From te above result, we see tat a cell may eed to reduce te maximum reveue obtaiable i order to satisfy te QoS costraits. To examie te effect of QoS costraits, Figure 5 sows te maximum reveue obtaiable per time uit by a cell executig te partitioig algoritm at optimizig (,,, ) for reveue optimizatio uder tree QoS-costrait scearios, amely, o QoS costraits (top curve), wit QoS costraits specified by bot coditios 3 ad 4 (bottom curve, as i Figure 5) ad wit partial QoS costraits specified by eiter coditio 3 or 4 (two middle curves), uder te case we te ig-priority ew call arrival Rate = 3.5. I Figure 5 we sow te maximum reveue obtaiable as a fuctio of wile fixig all oter parameters to aalyze te effect of. We see from Figure 5 tat we o QoS costraits are required (te top curve), te cell experieces icreasig reveue as te ig-priority adoff call arrival rate icreases at te expese of QoS ad user satisfactio. Tis is i cotrast to te case we bot QoS coditios 3 ad 4 are required were te maximum reveue icreases iitially as icreases ad te drops as icreases furter, resultig i a cocave curve. As explaied earlier, te reaso is tat we bot QoS costraits are required, te system must reserve more system resources to serve adoff calls to satisfy tese QoS costraits. As a result, ew calls are blocked wit a ig probability, tus causig te reveue obtaied dropped as icreases. Reveue/Time Hig-Priority Had Off Call Arrival Rate ( ) No Costraits Wit Costraits Class Costrait Oly Class Costraits Oly Figure 5: Maximum Reveue uder Partitioig Admissio Cotrol for Tree QoS-costrait Scearios. We also observe te same tred we oly QoS coditio 3 is required. I tis case, te system reserves muc of te resources to serve ig-priority adoff calls, resultig i a decrease i te maximum reveue obtaiable sice may ig-priority ew calls, ad low-priority calls (bot ew ad adoff) will be rejected as icreases. Furter we te workload is ig ( > 5), te system o loger ca fid a legitimate solutio to satisfy te QoS costraits specified by coditios 3 ad 4. I tis case, te system maager may coose to relax coditio 4 (middle two curves) or relax bot coditios 3 ad 4 (te top curve) wile still maximizig te reveue obtaiable at optimizig (,,, ) for reveue optimizatio, depedig o te maximum allowable workload idetified i Figure 5. Figure 6 illustrates te effect of B t (te ig-priority adoff call droppig probability tresold as specified i coditio 3) o te maximum reveue obtaiable by te cell. As B t icreases, te partitioig algoritm as more flexibility to reserve system resources to serve igpriority adoff calls witout violatig QoS coditio 3, tus allowig more ig-priority ew calls, ad lowpriority calls (bot ew ad adoff) to be admitted ad served, resultig i a icrease of te reveue as B t Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE

7 icreases util a maximum reveue is obtaied as limited by te resource costraits, ot due to B t. Reveue/Time Class : = 3.5, = Tresold Blockig Probability of Hig-Prioirty Hadoff Calls B t Figure 6: Reveue obtaiable via Partitioig Admissio Cotrol as a fuctio of B t. Reveue/Time Hig-Priority Had off Call Arrival Rate ( ) = 3.5 = 4.5 Figure 7: Maximum Reveue obtaiable via Tresold Admissio Cotrol wit QoS. 4. Tresold-based Admissio Cotrol I tis sectio, we report performace of tresold-based admissio cotrol. Figure 7 summaries te maximum reveue obtaiable per time uit by a cell executig te tresold algoritm at optimizig (C, C, C, C ) for reveue optimizatio as a fuctio of ad for te case we bot QoS costraits specified by Coditios 3 ad 4 are imposed. It sows tat iitially te reveue obtaiable icreases as eiter or icreases. As furter icreases, te system teds to reserve more resources to serve ig-priority adoff calls, tus tryig to maximize reveue obtaiable by allowig ig-priority ew calls at te cost of blockig low-priority calls (bot ew ad adoff) calls. Fially, we is very ig (e.g., > 4), te resources required grows suc tat o legitimate solutio from te tresold algoritm exists tat ca adle te ig workload wile still satisfyig te imposed QoS requiremets imposed by Coditios 3 ad 4. I tis extreme case, te system ca relax te QoS costraits to maximize te reveue obtaiable by te cell, by icreasig te blockig probability (b ) for igpriority adoff call ad decreasig te blockig probability (b ) for low-priority adoff calls. 4.3 Performace Compariso I tis sectio, we compare partitioig admissio cotrol vs. tresold-based admissio cotrol algoritms ead-toead uder te same set of parameter coditios. Figure 8 compares te maximum reveue obtaiable per time uit by a cell executig te partitioig algoritm at optimizig (,,, ) vs. te tresold algoritm at optimizig (C, C, C, C ) settigs. We see from Figure 8 tat we te ig-priority adoff arrival rate < 4, tresold-based admissio cotrol is able to obtai iger reveue ta partitioig admissio cotrol wile satisfyig QoS costraits imposed. However, Figure 8 sows tat as te workload icreases suc as we te ig-priority arrival rate exceeds to pass a tresold ( > 4), tresold-based admissio cotrol fails to fid a legitimate (C, C, C, C ) solutio, wile partitioig admissio cotrol is still able to fid a legitimate (,,, ) solutio to satisfy te QoS costraits as imposed by coditio 3 ad 4. Te reaso is tat te partitioig algoritm reserves desigated partitios for distict service classes so eac class is less sesitive to te arrivals of oter classes oce partitioed resources are reserved to satisfy Coditios 3 ad 4, wile te tresold-based algoritm i effect teds to ope a large sared partitio to serve multiple classes due to its ieret resource multiplexig property, tus makig eac class sesitive to arrivals of oter classes ad difficult to satisfy QoS Coditios 3 ad 4. Note tat, owever, te ieret multiplexig property of te tresold-based algoritm teds to accommodate more calls ad tus produce iger maximum reveue compared wit te partitioig algoritm for te case we a legitimate solutio exists. Reveue/Time Hig-Priority Had off Call Arrival Rate ( ) Partitioig Tresold-based Figure 8: Compariso of Maximum Reveue obtaiable by Partitioig Admissio Cotrol vs. Tresold-based Admissio Cotrol. Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE

8 V. Applicability ad Summary I tis paper we ave proposed ad aalyzed te desig cocept for te itegratio of pricig wit admissio cotrol algoritms wit QoS guaratees i a cellular wireless etwork. Te desig cocept is based o te idea tat a admissio cotrol algoritm i decidig wic calls to admit sould cosider ot oly te QoS costraits imposed by te system, but also te reveue tat te admissio of suc a call will brig to te system. I illustratig our cocept we assume tat a carge-bytime pricig sceme is beig used by te service provider were a user is carged by te amout of time i service by te service provider. Two admissio cotrol algoritms for adlig multiple classes of traffic were proposed, amely, partitioig ad tresold-based, wit te itetio of maximizig reveue geerated by a cell wile still satisfyig te QoS costraits imposed by te system for distict service classes. Te proposed scemes are very geeral i tat eac type of traffic ca request differet QoS i terms of a variety of system parameters. Bot scemes are flexible ad adapt to te cagig traffic load experieced by te cell. Our aalysis results idicated tat at optimizig coditios te tresoldbased admissio cotrol algoritm ca geerate iger reveue wit QoS guaratee ta te partitioig admissio cotrol algoritm. However, te partitioig admissio cotrol algoritm is able to sustai a eavier workload ta te tresold-based couterpart witout violatig QoS costraits because i te partitioig algoritm eac service class as its ow desigated partitio, tus makig eac class less sesitive to arrivals of oter classes i eavy-load situatios. To apply te results obtaied i te paper, a cell ca dyamically moitor te traffic of service classes to obtai values of arrival ad departure rates of ew/adoff calls of various service classes periodically ad perform a simple table look up at rutime to obtai te optimal (,,, ) uder partitioig, or (C, C, C, C ) uder tresold-based for reveue optimizatio wit QoS guaratees. I cases te cell experieces a eavy-load situatio tat goes beyod te cell s capacity to satisfy te imposed QoS costraits as avig bee idetified i te paper, te cell ca cosider adoptig te partial-qos-costrait or o-qos-costrait partitioig or tresold-based scemes to effectively tradeoff QoS for reveue optimizatio. Refereces [] Y. B. Li ad I. Clamtac, Wireless ad Mobile Network Arcitecture, pp , Jo Reiley ad Sos, Ic., 00. [] D. Hog ad S. S. Rappaport, Priority Orieted Cael Access Foe Cellular Systems Servig Veicular Ad Portable Radio Telepoes, IEEE Proceedigs Trasactios o Veicular Tecology, Vol. 36, Part I, No. 5. October 989. [3] D. Hog ad S. S. Rappaport, Traffic Model ad Performace Aalysis for Cellular Mobile Radio Telepoe Systems wit Prioritized Ad No-Prioritized Hadoff Procedures, IEEE Trasactios o Veicular Tecology, Vol. VT35. No.3, August 986. [4] R. Gueri, Queuig-Blockig System wit Two Arrival Streams ad Guarded Caels, IEEE Trasactios o Commuicatio, Vol. 36, pp , February 988. [5] Y. Fag, Tiig Algoritms for Call Admissio Cotrol i Wireless Networks, IEEE Trasactios o Computers, Vol. 5, No. 5, pp , May 003. [6] J. Wag, Q. Zeg ad D.P. Agrawal, Performace Aalysis of a Preemptive ad Priority Reservatio Hadoff Algoritm for Itegrated Service-Based Wireless Mobile Networks, IEEE Trasactios o Mobile Computig, Vol., No., pp , Jauary-Marc 003. [7] B. Li, C. Li, ad S.T. Caso, Aalysis of a Hybrid Cutoff Priority Algoritm for Multiple Classes of Traffic i Multimedia Wireless Networks, Wireless Networks, Vol. 4, pp , 998. [8] J. Ye, J. Hou, ad S. Papavassilliou, A Compreesive Resource Maagemet for Next Geeratio Wireless Networks, IEEE Trasactios o Mobile Computig, Vol., No. 4, pp , October-December 00. [9] N.J. Keo ad G. Aadaligam, "Optimal pricig for multiple services i telecommuicatios etworks offerig quality-of-service guaratees," IEEE/ACM Tras. o Networkig, Vol., No., Feb. 003, pp [0] J. Hou, J. Yag ad S. Papavassiliou, Itegratio of pricig wit call admissio cotrol to meet QoS requiremets i cellular etworks, IEEE Tras. o Parallel ad Distributed Systems, Vol. 3, No. 9, pp , Sept. 00. Ackowledgemet Tis researc work was supported by a Natioal Sciece Foudatio IGERT grat # Proceedigs of te Tet Iteratioal Coferece o Parallel ad Distributed Systems (ICPADS 04) /04 $ 0.00 IEEE