MAC Protocol for Supporting QoS in All-IP HiperLAN2

Transcription

1 MAC Potocol fo Suppoting QoS in All-IP HipeLAN Chistos E. Politis, Rahim Tafazolli Univesity of Suey Cente fo Communication Systems Reseach Guildfod, GU 7XH, Suey, UK Tel.: , FAX: Abstact -- The demand fo high-speed Intenet access and the emegence of multimedia applications ae leading towads a new aea of boadband wieless netwoks. This pape focuses on HipeLAN ai-inteface standad based on an all-ip netwok achitectue. An appopiate QoS famewok is poposed, based on which, classification and scheduling mechanisms of taffic classes ae investigated. These could be consideed as potential enhancements and compliments to the MAC potocol of HipeLAN fo poviding end-to-end QoS. I. INTRODUCTION HipeLAN (HIgh PERfomance LAN) opeates in the unlicensed 5 GHz fequency band, which has been allocated fo wieless LANs. HipeLAN (H) systems can be deployed in offices, classooms, homes, factoies, hot spot aeas and potentially wheeve adio tansmission is an efficient altenative o a complement to wied technology. In contast to the IEEE 80. wieless Ethenet technology, H is connection oiented. Connections can be assigned diffeent levels of Quality of Sevice (QoS). This QoS suppot allows fo the tansmission of a pot poui of technologies and sevices, e.g. voice, data, video at vey high bit ates (>0 Mb/s). The ETSI (Euopean Telecommunications Standads Institute) HipeLAN achitectue compises of the Physical (PHY) laye, the Data Link Contol (DLC) laye and the Convegence Laye (CL). The Convegence laye pefoms specific functions between the DLC laye and the netwok laye. These functions ae intoduced, in ode to povide connectivity between the PHY, DLC layes of the H and the othe access netwoks, such as IP, ATM and UMTS. The physical laye of HipeLAN is based on the signal modulation Othogonal Fequency Division Multiplexing (OFDM) with seveal sub-caies and fowad eo coection schemes, which can suppot vaiety of channel configuations []. The DLC/MAC laye is pesented in details in section II. The H Convegence laye, functions as an adapte between the DLC and highe layes (e.g. IP, application layes). Two types of CLs have been specified by ETSI BRAN (Boadband Radio Access Netwoks), a ATMcell based CL and a packet based CL. This pape mainly focuses on the packet based CL, which offes sevices to highe layes (HL) that use packets o fames of vaiable size o fixed size (e.g. Ethenet and/o the IP suite). The packet based CL is divided into two main pats, a common pat and a sevice specific pat, which consists of seveal Sevice Specific Convegence Sub-layes (SSCS). The use plane of the common pat is futhe subdivided into the Common Pat Convegence Sublaye (CPCS) and the Segmentation and Reassembly (SAR) sublaye (Fig. ) [3]. The CL has two main functions, adapting the sevice equest fom HLs to the sevice offeed by the DLC laye and secondly to adjust the HL vaiable size packets to the DLC SDU (Sevice Data Unit) fixed size. C L (S S C S ) S eg m e n ta tio n a n d R e -a ss e m b ly (S A R ) C L (C P C S ) DLC Ctl SAP DLC Use SAP D L C Contol Plane RLC Highe Fig.. HipeLAN potocol stack (Access Point and Mobile Teminal). In the H cellula system, the AP (Access Point) is the contolle fo each fomed adio cell that coves cetain geogaphical aeas. H suppots tansmission in the uplink (UL), downlink (DL) as well as diect link (DiL) - fo ad hoc configuation. II. H MAC PROTOCOL M A C Layes IP Sevice Specific Convegence Sublaye (SSCS) RRC AC DCC SAP: Sevice Access Point RRC: Radio Resouce Contol P H Y (O F D M ) Use Plane C o m m o n P a t P a c ke t-b as e d C L (C P C S ) The H DLC laye consists of the Medium Access Contol (MAC) function, the Eo Contol (EC) function and the Radio Link Contol (RLC) function. It is divided into the use data tanspot functions and the contol functions. Fo the H, a centally contolled DLC laye is selected, in othe wods the access point decides how the esouces ae allocated in a MAC fame. The MAC potocol is a centally scheduled TDMA/TDD (Time Division Multiple Access/Time Division Duplex) scheme. Each MAC fame has a fix duation of ms and consists of seveal phases. Impotant entities of the MAC fame ae the logical and tanspot channels. A logical channel is a geneic tem EC AC: Association Contol DCC: DLC Connection Contol

2 fo any distinct data path and it is mapped onto diffeent tanspot channels. The tanspot channels ae the basic elements that constuct the PDU (Potocol Data Unit) tains. Tanspot channels descibe the basic message fomat. The MAC decomposition to its child entities is bullet-listed hee and a visual epesentation is shown in Fig. []. ΠBoadcast phase: This phase caies the BCCH (Boadcast Contol CHannel) and the FCCH (Fame Contol CHannel), which ae mapped onto the BCH (Boadcast CHannel) and FCH (Fame CHannel) espectively. The BCH tansmits contol infomation in each MAC fame and to all MTs (Mobile Teminals). The FCH caies an exact desciption of how the cuent MAC esouces have been allocated to the UL/DL. This phase also includes the ACH (Access feedback CHannel), which povides infomation on access attempts made by MTs in the RCH (Random access CHannel) of the pevious MAC fame. ΠDownlink phase: It consists of SCH (Shot CHannels) and LCH (Long CHannels). Duing this phase, contol infomation and use data ae tansmitted fom the AP to MTs. The infomation is assembled in goups of vaiable length, called cell tains. Each cell tain is unique fo a coespondent MT. ΠUplink phase: In this phase (same stuctue as DL), contol infomation and use data ae tansmitted fom the MTs to the AP. ΠRandom Access phase: This phase caies the RCHs. The DL, UL phases consist of two types of DLC PDUs (see Fig. ): long PDUs (LCH) and shot PDUs (SCH). The LCH PDUs cay mainly the payload of the connections. Thei size is 54 bytes, wheeby 48 bytes ae allocated fo the payload and the est (6 bytes) ae used fo DLC heades. At the same time, the SCH PDUs contain geneally contol data (e.g. ARQ) and thei size is 9 bytes. SCH PDUs ae also used by MTs to equest esouces (RR) fo a paticula connection in the next MAC fame. The RR can eithe be tansmitted duing the UL phase in SCH PDUs o in the RCH in competition with othe MTs. The stuctue of each cell tain is cached in the FCH, which seves as a diectoy fo UL and DL phases. The FCH PDU caies a list of Resouce Gant Infomation Elements (RG-IE), each defining a cell tain of one MT, eithe UL o DL. The RG-IE is oganized in blocks of 8 bytes. The block consists of the IE addessing the paticula MT by its MAC-id and detemining the location of the cell tain within the MAC fame by the stat pointe field. The FCH PDUs ae segmented in goups of constant length each potected individually by a CRC (Cyclic Redundancy Check), in ode fo the eceive to decode ealy the elevant infomation contained in them. In the following sections, the enhancements to H MAC potocol ae poposed fo suppoting vaious IP taffic types and sevice classes, whilst poviding end-to-end QoS. Fig.. MAC fame fo HipeLAN. A small intoduction to the H CL fo IP follows. A. IP Suppot Boadcast Phase BCCH BCCH FCCH FCCHN BCH FCH ACH Boadcast Data MAC Fame ( ms) Vaying bodes Downlink (DL) Phase Uplink (UL) Phase DL DLK UL ULK DL, UL contol & use data Random Access Phase BCCH: Boadcast Contol CHannel ACH: Access feedback CHannel DL: Downlink Contol & Use Data FCCH: Fame Contol CHannel SCH: Shot tanspot CHannel RCH: Random Access CHanne BCH: Boadcast CHannel LCH: Long tanspot Channel RR: Resouce Request FCH: Fame CHannel UL: Uplink Contol & Use data RG: Resouce Gand The H Convegence laye functions as an adapte between the DLC and highe layes (e.g. netwok laye- IP). Hee, IP packets ae tansfeed to the CL laye though the CL Sevice Access Point (SAP). At this point, packets ae stamped with infomation about thei length, souce and destination addesses and thei QoS paametes. The taget of the addess management function in the H convegence laye is to maintain a mapping between the local link laye addesses and the addesses sent by the IP wieless inteface. This can be accomplished by using othe wieless intefaces addesses (i.e. IEEE80.b) as static hadwae addesses [4]. At the same time, implementing end-to-end QoS equies coopeation at all potocol levels, howeve in this pape the mapping of the IP (Netwok) laye QoS to the DLC QoS is the main objective. The DLC entity of inteest is the MAC one. Thus, suitable QoS techniques ae intoduced fo the management of the scace adio esouces. This appoach is pesented in the est of this pape, examining effective classification and scheduling algoithms. III. QOS SUPPORT AND SCHEDULING The basic way to povide QoS is by giving one use pioity ove anothe, and/o to contol the bandwidth usage of cetain uses so that a pe-assigned QoS can be assued. Futhemoe, in ode to suppot the vaiety of sevices, it is necessay to develop a QoS mechanism/famewok that can suppot multiple sevices and taffic classes. These taffic classes will classify packet steams accoding to thei eal-time needs. Fou taffic classes ae selected, in close elation to the UMTS QoS Classes defined in [0] and used in [5, 6], the following: ΠConvesational, ΠSteaming, ΠInteactive, ΠBackgound. RCH RCHN Random Access Data SCH SCH LCH LCH SCH LCH

3 The main distinguishing facto between these QoS classes is how delay sensitive the taffic is: Convesational class is meant fo taffic which is vey delay sensitive while Backgound class is the most delay insensitive taffic class. Convesational and Steaming classes ae mainly intended to be used to cay eal-time taffic flows. The main divide between them is how delay sensitive the taffic is. Futhemoe, Convesational class suppots mainly bi-diectional taffic with uplink and downlink QoS povisioning. Examples of Convesational eal-time sevices ae, video telephony o voice ove IP. Inteactive and Backgound classes ae mainly used by taditional Intenet applications like WWW, , Telnet and FTP. The main diffeence between Inteactive and Backgound class is that Inteactive class is mainly used by inteactive applications, e.g. inteactive o inteactive Web bowsing, while Backgound class is used fo backgound taffic. Taffic in the Inteactive class has highe pioity in scheduling than Backgound class taffic, so backgound applications use tansmission esouces only when inteactive applications do not need them. This is vey impotant in wieless envionment whee the bandwidth is low compaed to fixed netwoks. At the same time, thee ae two commonly used models fo end-to-end quality of sevice (ete-qos), which ae integated sevices (IntSev) and diffeentiated sevices (DiffSev). In this study, as it is shown in Fig. 3, two sevice models ae suppoted, the IntSev model and the DiffSev model. While, best effot taffic (backgound BE) is injected in both domains. In the Integated Sevices domain [7, 8, 9], netwok esouces ae explicitly identified and eseved pe flow. Each netwok node classifies incoming packets and uses the esevations to povide QoS. While in the Diffeentiated Sevices domain [0], the esouces ae eseved pe aggegate of flows. The taffic is diffeentiated into a set of classes; while the netwok nodes povide pioity-based teatment based on these classes (see Fig. 3). Nevetheless, the QoS mechanism must obey cetain ules, accoding to selected QoS metics. Then, the evised stuctue of MAC potocol should adapt these metics, in ode to establish adio links with specified QoS. The metics can be expessed as a set of paametes, such as delay, jitte, PDU Eo Rate (PER) and thoughput. Depending on the amount of taffic to be deliveed on the adio channel, QoS contacts assigned by highe layes have to be classified, pioitised and handled at the MAC laye (by the classifie & schedule). The enhancements in the H MAC potocol ae intoduced in thee nodal points and fo two sevice models (Fig. 3). In the fist domain, the taffic is classified ( st point) by souce and destination addess, type of sevice (ToS) o/and othe fields (pe flow teatment). Then, two queuing ( nd point) and a scheduling (3 d point) schemes ae used, namely the Weighted Fai Queuing (WFQ) and the Class-Based Queuing (CBQ). Concuently, a eseved path, which is RSVP (Resouce Resevation Potocol) enhanced, is intoduced in the IntSev domain. This will mainly suppot convesational and steaming taffic classes and multimedia sevices (e.g., VoIP, video confeencing), while backgound BE taffic will be also allowed to flow. On the othe hand, in the DiffSev domain the classification will be handled by the ToS pe aggegate in the H AP, the est focal points will emain the same. Next, a bief intoduction to WFQ and CBQ algoithms ae given. Weighted fai queuing [] pioitises taffic flows while ensuing that lowe pioity flows eceive an acceptable level of sevice. Taffic is classified and put into queues that ae assigned elative weights/pioities. The queues ae seviced on a ound-obin basis and the amount of data emoved fom each queue is in popotion to the elative weight of the queue. Highe pioity queues get a lage potion of the bandwidth, but even the lowest pioity queue always eceives some bandwidth. This is an impotant featue in the bandwidth limited wieless envionments. Class-based queuing [] goes beyond pioitisation by poviding assued bandwidth to taffic flows. Taffic is fist classified and put into queues. Each queue is assigned a numbe of bytes that will be fowaded each time the queue is seviced. The queues ae seviced on a ound-obin basis and the assigned amount of data is fowaded fom each queue. Each taffic class is theefoe allocated a pecentage of bandwidth on the outbound link and may bust above thei allocated bandwidth if othe taffic classes ae not using the bandwidth. These chaacteistics make this algoithm less fai in distibuting the esouces in bandwidth and intefeence limited envionments and when it seves multimedia o mixed taffic applications. Reseved Bandwidth (RSVP Enhanced) Pioity/Best Effot path IntSev Domain Taffic classified by ToS o CoS, souce and destination addess pe flow (IntSev). Incoming Taffic Taffic classified by ToS pe aggegate (DiffSev). Backgound BE in both domains DiffSev Domain Classifie () Fig. 3. QoS Povisioning fo all-ip HipeLAN. IV. SIMULATION MODELS AND PERFORMANCE ANALYSIS This study is pefomed and suppoted by means of compute simulations, with each simulation expeiment consisting of a netwok scenaio with vaiables {x =Load=5, y =QoS mechanism=} and a taffic scenaio with vaiables {x =Domain=, y =Sevice=3}. Oveall sixty expeiments wee pefomed, giving the sequence of esults shown in subsection IV-D. () x/y xn/yn xx/yy Xx/Yy = Link Utilization Ratio (CBQ) Schedule (3) Tansmit Queue Weighted Scheduling Class Queues (CBQ) CBQ: Allocate configued popotion of BW (), (), (3): Nodal Points o Flow Queues (WFQ) WFQ: Allocate fai popotion of link BW

4 A. Netwok Related Aspects The netwok topology consists of a wieless and a wied pat. The wied pat is using full duplex links (0Base-T, 00Base-T o PPP-DSX) inteconnecting high pefomance gateway outes with multimedia seves/clients. The wieless pat (H) can suppot data ates up to Mb/s. In ode to model the wieless channel chaacteistics, a Gilbet model [3] was incopoated to intoduce busty bit eos in the tansmitted packets. Fig. 4. Simulation scenaio Netwok scenaios ae also consideed with the fou afoementioned classes of sevice, wheeby each CoS is epesented by a sepaate output queue in the access point. At the same time, single taffic types ae consideed, in netwok topologies with single and multiple taffic classes [4]. As it can be seen fom Fig. 4, one o many taffic souces ae identified (geneating taffic of a given type) as the oiginating souce and a numbe of mobile uses (fom to 0) as the taget souces. The classifying-queuing-scheduling is pefomed at the access point. Then, a numbe of QoS paametes can be measued, including the end-to-end delay, the thoughput of a given system load and fo vaious classes and sevices, at the two sevice domains. B. Taffic Geneation Related Aspects In ode to poduce meaningful esults, paticula attention is paid to the model(s) used in geneating each type of taffic. This pape is only limited to voice, video and data/http taffic (the latte eceiving both best effot backgound and inteactive). Voice. Thee ae vaious ways to encode voice signals (e.g. PCM fo G.7, G.79, G.73., GSM, etc.). In this study, IP telephony and silence suppessed with the G.79 encode scheme (silence) has been used. The voice taffic that entes the gateway outes can be modelled by an on-off model with exponentially distibuted ON and OFF peiods (which is equivalent to a two state Makov Modulated Deteministic Pocess with one silent state). The talk sput inteval (ON) set to be 0.4 sec and the silence inteval (OFF) is 0.6 sec [5,7]. The on-off taffic souce model can be descibed by the paametes (0'5P W on ) as follows: MDR =, t on = a, a m = T T ( a + b ) and ( a + b ) β = () a Whee, MDR is the Maximum Data Rate, a and b ae the tansition ates, i.e. a is the invese of the mean bust duation, b is the invese of the mean silence duation, m is the mean data ate, is the bustiness and t on is the aveage bust duation. Finally, T is the constant inteaival time in milliseconds. Futhemoe, it is assumed that when the souce is in the ON state fixed-size packets ae geneated at a constant inteval. On the othe hand, no packets ae tansmitted when the souce is OFF. Video. The chaacteistics of encoded video vay enomously with the content, the video compession scheme and the video encoding contol scheme. At the same time, video taffic models ange fom classical models based on Poisson aival pocesses to sophisticated models like autoegessive pocesses, Makov chains and self-simila models. Fo the needs of this wok, two diffeent standads wee initially selected, the MPEG- and the ITU H.63 standad. Howeve, due to the high bit ate equiement of the MPEG steams that sustains the quality of playback and the limited numbe of clips that they wee deived fom, made them unsuitable fo the wieless medium [5]. Fo these easons, eal data steams fom videoconfeence employing H.63 wee eventually used. Data. Data application taffic (web, telnet, ftp, smtp) foms the majoity of the Intenet taffic, with web taffic epesenting moe than 80%. In these seies of simulations, http taffic (i.e. web taffic) is consideed. It is modelled by a succession of exponentially distibuted connections gouped in Paeto distibuted busts [6]. These Paeto distibuted busts, which ae hypebolic ove thei entie ange, have a pobability density function (pdf) given by, α α p ( x ) = α β x fo α β > 0, x > β, () while thei cumulative distibutive function (cdf) is given by, β P [ X ) x a x ] = ( fo α β > 0, x > β, (3) whee, ae the location paamete and the shape paamete of the distibution espectively. Finally thei mean value, is given by, α β µ =, a > (4) α Each data use epesents a high-speed best effot data tansfe, while no explicit delay bounds applied.

5 C. Pefomance Related Aspects In ode to evaluate the pefomance of the system, we have selected a numbe of QoS metics. These metics can povide a clea idea of the system pefomance, the taffic equiements and the status of the QoS contacts. At the same time, packet loss may be due to, in the case of eal time applications, the end-toend delay (ete-delay) became lage than the specified maximum delay equiements. Hence, it is impotant to deive the pobability that the ete-delay D ETE exceeds a theshold D THR, P (D ETE > D THR ). Since packet loss may be toleable up to a given maximum delay D (max), then the compaison between P (D ETE > D THR ) and D (max) sets the gounds on whethe an application can be accepted o not. The pincipal equiement fo eal-time voice and video communication is the bounded delay; if eithe voice o video samples ae not deliveed to the eceive on time, then they will have to be discaded. Following ITU-T ecommendation G.4 [8], we conside a 00ms ete-delay fo VoIP (Voice ove IP) taffic, fom which we allocate 0 ms bound fo netwok delay, D NET. Futhemoe, accoding to IEEE 80.D ecommendation [9], we conside an ete-delay equiement of 00ms fo video taffic, fom which we allocate a D NET = 00ms bound fo netwok delay. In equation 5, the conditions fo delays bounds ae mathematically given: P{ ( D = i= = DETE(vo) < DTHR(vo) ) U P(D) i whee D ETE(vo) ( D = D = D+ i= s THR(vo) d + and fo video the delay conditions ae: P {( D = D = j P ( D ) j ETE(vi) < D THR(vi) ) U ( D = D i < D j= s THR(vi) j ( max) P + T D ( max ) )} = (5a) )} = (5b) TABLE I Delay Requiements fo Voice and Video Taffic Delay Requiements D NET D THR Pioities and Classes (ms) (ms) (ms) D (max) Convesational RT {} Steaming RT {} Inteactive BE {3} BE BE - Backgound BE {4} BE BE - These conditions/equiements can be seen in Table I. D, d i, P j, T ae delay components namely duation of the time sequence, time to send/eceive a packet to/fom the netwok, time elapsed between the sound sequence and the time the packet sent/eceived to/by the netwok and the tansmission delay espectively. It must be stated that the maximum delay bounds (D (max) ) ae fo FFS [0]. Fo http taffic, the bustiness is in the ode of hundeds. Fo this type of taffic, thoughput is a moe appopiate QoS metic than ETE delay and jittes. The thoughput is defined as the ate (in bits/sec) of data packets aiving at the MT. Finally, in this pape, we have set the guaanteed bitate to 04kb/s and the maximum bitate to 6 (o ) Mb/s. D. Numeical Results In this section, we investigate the behaviou of the H QoS mechanism, when each taffic type flows alone in the netwok and in two diffeent domains: the IntSev and the DiffSev domain. Data. In this scenaio, multiple http souces ae multiplexed into the same output queue (see Fig. 4.). They ae given diffeent pioity accoding to thei CoS/ToS classification (inteactive o backgound BE). The esults fo the system thoughput fo both domains ae shown in Fig.5. In Fig.5a. and fo 80% load (i.e. 6 uses), the WFQ algoithm gives 5kb/s incease in the system thoughput, while in Fig.5b. the absolute incease between the two algoithms emains the same, but the enhanced domain (RSVP) povides a slight impovement (5-8kb/s). Theefoe, in this case the domains behave in an analogous manne towads http taffic. It must be noted, that fo low load (4-8 uses) in both domains, the pefomance of the CBQ algoithm is almost the same with that of WFQ. Finally, the pefomance of the system has not been significantly impoved in the IntSev domain, as it was expected, due to stand-alone http taffic. Voice. The same expeiment is epeated fo voice steams. The pioities ae given hee accoding to ToS (VoIP and backgound BE taffic) and CoS (Convesational, Backgound). As, it can be seen fom Fig.6a. the lowe delay bounds ae kept fo both algoithms and domains. Fo an 80% load the WFQ algoithm offes a bette pefomance in the ode of 4ms fo IntSev and 6 ms fo DiffSev. The pefomance of both algoithms emains stictly between the delay bounds/thesholds, even in a congested H netwok. Moeove, the RSVP-enabled domain povides a significant impovement to the oveall system pefomance, with the dawback being the inceased contol and signalling load (scalability). This is since RSVP is based on soft states, each connection needs peiodic signalling activity, so the wok equied fo the same amount of steams is much highe. Video. In this last scenaio, multiple multiplexed video steams ae injected into the netwok. Again the pioities ae given accoding to ToS (VidConf and backgound BE taffic) and CoS (Steaming, Backgound). As expected, the esulting delay behaviou is mostly influenced by the encoding contol scheme. Again fo both algoithms and domains the delay equiements wee well peseved. In Fig. 7 and fo an 80% load the DiffSev WFQ gives a 0ms impovement to the system pefomance, while this absolute diffeence is maintained fo all the specified load conditions.

6 In the IntSev domain the CBQ dops the (algoithms) maginal diffeence to appoximately 5ms. The RSVP deployment povides, as fo the voice case, an impovement in the ode of 30 to 35ms. It must be stated that both algoithms and domains behave well in all kinds of taffic loads, howeve the maximum (and maybe the theshold) delay bounds should be futhe investigated fo multimedia taffic and eal-time sevices. V. CONCLUSIONS The H standad is not cuently consideing IP QoS. In ode to fill in this gap, we set up a QoS famewok with espect to the investigation of MAC classifies and schedules fo suppoting diect IP taffic in diffeent sevice domains. The H MAC potocol was built and simulated, and the afoementioned appopiate enhancements wee intoduced. These modifications could be consideed as possible enhancements to the H MAC potocol fo an IP-based HipeLAN. This pape suggested the mapping of the highe layes QoS to the DLC/MAC laye QoS. This was pefomed by investigating vaious taffic types and classes in thee nodal points (classifying, queuing and scheduling) and fo two-sevice domains (IntSev, DiffSev) unde diffeent netwok loads and topologies. Futhemoe, diffeent QoS metics (paametes) wee consideed, in ode to allow fo IP connections accoding to thei specified QoS equiements/contacts. Two nodal algoithms wee selected: WFQ and CBQ and adjusted to the HipeLAN MAC potocol. In the IntSev domain, RSVP signalling was used. The pefomance evaluation fo thee types of sevices, namely VoIP, video confeencing and HTTP wee shown. The WFQ fo both domains and fo all taffic types gives a bette pefomance than CBQ, while the IntSev domain poves its supeioity (fo eal-time sevices) against DiffSev, with the dawback being that of scalability. Futhemoe, both (WFQ & CBQ) algoithms wee shown to be able to suppot the specified QoS contacts, in tems of thoughput and delay equiements. The two algoithms can be potential candidates fo an all-ip based HipeLAN MAC potocol. Similaly, RSVP poved to pefom well with HipeLAN, by impoving significantly the pefomance of the whole system. ACKNOWLEDGMENT All the simulation models and the testbed wee implemented in the OPNET Simulation package. REFERENCES [] ETSI TS V.., BRAN; HIPERLAN Type ; Physical (PHY) laye, TS/ [] ETSI TS V.., BRAN; HIPERLAN Type ; Data Link Contol (DLC) Laye; Pat : Basic Data Tanspot Functions, TS/ [3] ETSI TS V.., BRAN; HIPERLAN Type ; Packet based Convegence Laye; Pat : Common Pat, TS/ [4] Sevane Bonjou et al, IP convegence laye fo HIPERLAN/, BRAIN London wokshop, Novembe 000. [5] Sudhi Dixit et al, Resouce Management and Quality of Sevice in Thid-Geneation Wieless netwoks, IEEE Communications Magazine, Febuay 00, vol. 39 No., pp [6] Dave Wisely et al, BRAIN-an achitectue fo a boadband adio access netwok of the next geneation, Wieless Communications & Mobile Computing, Jan-Ma 00, vol. No., pp [7] IETF, RFC, Specification of the Contolled- Load Netwok Element Sevice, Septembe 997. [8] IETF, RFC, Specification of Guaanteed Quality of Sevice, Septembe 997. [9] J. Woclawski, The Use of RSVP with IETF Integated Sevices. RFC0, Sept [0] IETF, RFC 474, Definition of the Diffeentiated Sevices Field (DS Field) in the IPv4 and IPv6 Heades, Decembe 998. [] S. Keshav, On the Efficient Implementation of Fai Queuing, Jounal of Intenetwoking Reseach and Expeience, Vol., No. 3, Septembe 99. [] Wakeman, I., Ghosh, A., Cowcoft, J., Jacobson, V., and Floyd, S., Implementing Real Time Packet Fowading Policies using Steams, Usenix 995 Technical Confeence, Januay 995, New Oleans, Louisiana, pp [3] E.N. Gilbet, Capacity of a Bust-Noise Channel, Bell Systems Technical Jounal, Vol.39, pp , 960. [4] A. Kadelka, A. Masella, Sevicing IP Quality of Sevice with HipeLAN/, in Poc. of the Euopean Wieless 000, pp. 7-, Desden, Gemany, Sept [5] William K. Wong et al, Scheduling fo Heteogeneous Taffic in Next Geneation Wieless Netwoks, in Poc. of the IEEE GLOBECOM 000, Dec [6] Mobile Wieless Intenet Foum (mwif), IP in the RAN as a Tanspot Option in 3 d Geneation Mobile Systems, Tech. Rep. MTR-006, Dec [7] C.N. Chuah, R. Katz, Netwok Povisioning & Resouce Management fo IP Telephony, Repot No. UCB/CSD-99-06, August 999. [8] ITU-T Recommendation G.4, Geneal Chaacteistics of Intenational Telephone Connections and Intenational Telephone cicuits: One Way Tansmission Time, Feb 996. [9] M. Kaam, F. Tobagi, On the Taffic and Sevice Classes in the Intenet, in Poc. of IEEE Globecom 000, San Fancisco, CA, US. [0] 3GPP TS 3.07 V3.5.0 (000-) 3d Geneation Patneship Poject; Technical Specification Goup Sevices and System Aspects; QoS Concept and Achitectue (Release 999).

7 Http Taffic/DiffSev Domain VoIP /IntS ev Domain R esevation Style: Shaed Explicit (R SVP E nabl ed) Thoughput (b/s) http (wf q) http (cbq) VoIP (wfq) VoIP (cbq) (a) Load (HipeLAN uses) (b) Load (HipeLAN uses) Http Taffic/IntSev Domain R esevation S tyle: S haed E xplicit (RSVP E nabl ed) Fig. 6. ETE Delay vs. Load fo VoIP fo (a) DiffSev and (b) IntSev domains Video Confeencing/DiffSev Domain Thoughput (b/s) (b) http (wfq) ht t p (cbq) Load (HipeLAN uses) VidConf (wfq) VidConf (cbq) 50 Fig. 5. Thoughput vs. Load of http taffic fo (a) DiffSev and (b) IntSev domains. (a) Load (HipeLAN uses) VoIP/DiffSev Domain Video Confeencing/IntSev Domain Resevation Style: Shaed Explicit (RSVP E nabl ed) VoIP(wf q) VoI P (cbq) VidConf (wfq) 5 VidConf (cbq) (a) Load (HipeLAN uses) (b) Load (HipeLAN uses) Fig. 7. ETE Delay vs. Load fo video confeencing fo (a) DiffSev and (b) IntSev domains.