QoS-Aware Active Queue Management for Multimedia Services over the Internet

Transcription

1 QoS-Aware Actve Queue Management for Multmeda Servces over the Internet I-Shyan Hwang, *Bor-Junn Hwang, Pen-Mng Chang, Cheng-Yu Wang Abstract Recently, the multmeda servces such as IPTV, vdeo conference emerges to be the man traffc source. When UDP coexsts wth TCP, t nduces not only congeston collapse but also unfarness problem. In ths paper, a new Actve Queue Management (AQM) algorthm, called Traffc Senstve Actve Queue Management (TSAQM), s proposed for provdng multmeda servces. The TSAQM comprse Dynamc Weght Allocate Scheme (DWAS) and Servce Guarantee Scheme (SGS), the purpose of DWAS s to allocate resource wth farness and hgh end-user utlty, and the purpose of SGS s to determne the satsfactory threshold (TH) and threshold regon (TR). Several objectves of ths proposed scheme nclude achevng hgh end-user utlty for vdeo servce, consderng the multcast as well as uncast propretes to meet nter-class farness and achevng the QoS requrement by adjustng the thresholds adaptvely based on traffc stuatons. Index Terms AQM, QoS-Aware, Multcast. I. INTRODUCTION In order to mprove the congeston collapse problem, the early TCP protocol has prompted the study of end-to-end congeston avodance and control algorthms [1]. Recently, several applcatons, such as IPTV and VoIP, usng User Datagram Protocol (UDP) wthout employng end-to-end flow and congeston control, are beng ncreasngly deployed over the Internet. When UDP coexsts wth TCP, t not only nduces congeston collapse problem but also unfarness problem that each flow cannot get the same treatment and causes the Internet unstable and lower lnk utlzaton. The congeston control methodologes can be categorzed as - the Prmal and the Dual [2]. The Prmal congeston control s that the source node dynamcally adjusts sendng rate or wndow szes dependng on the ndcaton nformaton fed back from the Internet. The Prmal methodology has two types, whch s classfed based on the way of reactng to congeston, adjustng the congeston wndow sze, called Wndow-Based; or the packet transmsson gap, called Rate-Based. The Rate-based s more sutable for delverng real-tme traffc due to t can provde more smooth transmsson rate and t has no need to wat an ACK message from recever [3]. The Prmal methodologes [4] use the flud Manuscrpt receved January 29, 21. I-Shyan Hwang s wth the Department of Computer Engneerng and Scence, Yuan-Ze Unversty, Chung-, Tawan, 323 (correspondng author to provde phone: ; fax: ; e-mal: shwang@saturn.yzu.edu.tw). Bor-Junn Hwang, s wth the Department of Computer and Communcaton Engneerng, Mng-Chuan Unversty, Tao-Yuan, Tawan, (e-mal: bjhuang@mal.mcu.edu.tw). Pen-Mng Chang s wth the Department of Computer Engneerng and Scence, Yuan-Ze Unversty, Chung-, Tawan, 323 (e-mal: s96641@mal.yzu.edu.tw). Cheng-Yu Wang s wth the Department of Computer Engneerng and Scence, Yuan-Ze Unversty, Chung-, Tawan, 323 (e-mal: cywang@wdma.cse.yzu.edu.tw). model to analyze the Internet traffc load or use probng-based methods ncludng probe gap model (PGM) and probe rate model (PRM) to estmate resdue bandwdth n the bottleneck [5]. In essence, those algorthms regardng the amount of packet loss and value of RTT s varaton mply as the network congeston occurs. However, the packets loss s not only due to congeston occurrence but also the envronment nterference,.e. fadng or nterference n wreless channel or hgh bandwdth delay envronment. Due to the lmtatons of Prme methodology, the Dual plays a more mportant actor to assst by provdng more accurate and quck feedback. The congest control algorthm for Dual s mplemented n routers gatherng traffc flow nformaton, such as flow numbers and traffc load, and sends mplctly or explctly feedback to sender or recever node for revsng sendng rate or makng actve queue management. The Dual methodology, Actve Queue Management (AQM), can be dvded nto two man categores ncludng closed-loop control and open-loop control dependng on whether the algorthm uses feedback nformaton or not. For closed-loop control, the most well-known proposals are RED, Adaptve-RED (ARED) [6] and BUE [7]. The RED s man dea s that usng two predefned thresholds, mnmum and maxmum thresholds, to separate the queue length nto the three congeston grades and adjusts the packet droppng rate accordng to dfferent stuatons. The ARED dynamcally adjust RED s thresholds based on the observed queue length and try to mantan the queung delay wthn a target range. BUE [7] uses packets loss and lnk-dle events as the crtcal factors to adjust packet droppng probablty nstead of the queue length. In the open-loop control, the major promsng proposals are RAP [8], XCP [9] and ts extended researches [1]. The man objectve of ths category s to acheve the ncomng data rate that s equal to the output lnk capacty of router, and each traffc flow s allocated the same bandwdth and also ensures the lower queue szes at the same tme. Ths category can elmnate the hgh bandwdth-delay product network effect on the TCP s throughput, whch s nversely proportonal to the RTT, to satsfy the TCP-frendly property [3]. However, the above congeston control algorthms only adopt homogeneous farness resource allocaton method. The works [11-13] allevate ths problem by modfyng AQM archtecture. In [11], the proposed algorthm rearranges the order of packets n the queue of router, dynamcally adjusts packet droppng rate and the target queung average sze based on the packet arrval tme, ncomng traffc s requrements and delay hnt. The work, n [12], uses three levels of RED to emulate the class-based archtecture that each level sets parameters accordng to dfferent traffc requrements and based on that to determne the ncomng packet s accepted or not. Research n [13], t provdes dfferent droppng rate adjustng algorthms for TCP and UDP wth TCP-Frendly property for

2 the dversty traffc characterstc. However, above surveyed algorthms cannot satsfy the delay and throughput requrements at the same tme snce t only adopt one-queue archtecture for all types of traffc. Recently, the multmeda streamng applcatons, such as IPTV and Vdeo conference, emerge to be the one of man traffc sources wth low tolerant of delay and jtter. Usually, the scalable layered codng (SVC) [14] technque s used to ncrease the end-user utlty under dversfed envronments. The SVC s an extenson of H.264/AVC whch uses layered structure scheme to generate multlayer wth one base layer and several enhancement layers. Therefore, a recever can subscrbe an approprate one scenaro based on the network status and requred transmsson qualty. In order to ensure the effcent use of network resources, ths knd of applcatons adapt the multcast technque to delver the contents. Besdes, the multcast servce over wreless envronment results n not only enhancng resource effcency but also reducng transmsson power consumpton due to the wreless multcast advantage [15] property. Accompanyng the wreless technque s mature enough to be the last mle soluton; the IPTV multcast servces under wre and wreless envronment such as the ntegraton EPON and WMAX [16] wll become a trend. However, all of the proposed actve queue management mechansms do not take account of the multcast servces, and the proposed algorthms wth an assumpton that the same weght for uncast and multcast connectons; however ths s unfar for the multcast connecton whch wll cause the poor system performance n the lght of the entre network average vdeo qualty. Several researches [17-19] utlze the vdeo codng technque to mprove throughput and end-user utlty when congeston occurs. In vew of the vdeo codng technque, the lterature [17], one of XCP extendng research, adds addton header feld to record how many resource has been assgned to each flow so that the sender can know whch layers should be delvered. In the lteratures [18-19], they support dfferent QoS by usng prorty droppng queue management and packet markng technque. In [2], the author adopts the SCED+ scheduler for guaranteeng delay requrement. In these researches [12,19-2], the proposed varous algorthms satsfy the QoS requrements by utlzng scheduler and markng technque; however, too complex and ncurrng addtonal process overhead to the router nduces the mpact on bottleneck obvously. In summary, current AQM algorthms have the followng problems: 1) Most of algorthms cannot acheve the delay and throughput requrements at the same tme. On the other hand, some AQM algorthms can satsfy each traffc type s requrement, but those algorthms are too complex and unsutable for hgh traffc load whch causes the heavy computng overhead. 2) Above mentoned algorthms barely consder the vdeo traffc characterstc that only adopt homogeneous farness bandwdth allocaton polcy. 3) They do not take account of multcast servce property, thus t leads to low bandwdth effcency and poor system average vdeo qualty. 4) Current AQM algorthms only utlze adjustng packet droppng rate to overcome the congeston problem; however, t should not only adjust packet droppng rate but also consder congeston level and the AQM wll be more effcent for reactng to varous traffc loads, 5) Most AQM algorthms do not have the adaptablty, and those algorthms have to be traned or adjust a set of parameters to meet the dverse traffc load and router lnk capacty. It s a challenge to overcome congeston problem to consder the vdeo codng technque, bandwdth effcency and dfferent traffc s QoS requrement for more outstandng performance. In ths paper, the Traffc Senstve Actve Queue Management (TSAQM) scheme s proposed to overcome those problems. Several objectves of ths proposed scheme are descrbed as follows: frst, a Dual methodology congeston control algorthm s proposed to meet the QoS requrement of dfferent servces by usng mult-queues mult-thresholds mechansm cooperatng wth weght-based scheduler algorthm; second, t acheves hgh end-user utlty for vdeo servce; thrd, t consders the multcast as well as uncast propretes to meet nter-class farness; fourth, t has the ablty to adaptvely adjust parameters of TSAQM accordng as tme-varyng traffc loads. The rest of paper s organzed as follows. Secton 2 presents the system archtecture. The system performance s analyzed and dscussed n secton 3. Fnally, the paper ends wth our conclusons n secton 4. II. SYSTEM ARCHITECTURE Fg. 1 System archtecture The system archtecture, as shown n Fg. 1, has four types of traffc ncludng UDP CBR (constant bt rate) traffc, UDP VBR (varable bt rate) uncast traffc (UVBR), UDP multcast traffc wth VBR (MVBR) and TCP traffc. The Traffc Senstve Actve Queue Management (TSAQM) wth Dynamc Weght Allocate Scheme (DWAS) and Servce Guarantee Scheme (SGS) s proposed for QoS-aware actve queue management. A. System Envronment Based on Fg. 1, the four-queues wth four-thresholds and weght-based scheduler are proposed; n addton, four ndvdual FIFO queues, Q={q 1, q 2, q 3, q 4 }, are set for dfferent traffc classes, T={t 1, t 2, t 3, t 4 }, respectvely, where the traffc class t 1 s the UDP traffc wth CBR (B CBR ), the traffc classes t 2 and t 3 are the multcast and the uncast UDP traffc wth VBR, and the traffc class t 4 s TCP traffc. For traffc types of VBR, each flow contans V vdeo layers and the bandwdth of each layer denotes as B={lb 1, lb 2, lb 3,, lb N }. The arrval rates and servce rates for dfferent traffc classes are λ={λ 1, λ 2, λ 3, λ 4 } and μ={μ 1, μ 2, μ 3, μ 4 }, and QoS requrement vector denotes as R={r 1, r 2, r 3, r 4 }, ncludng delay, packet droppng rate and throughput. Due to the performance of GRED-I s better than both RED and GRED [21,22], each queue apples GRED-I buffer management wth threshold TH and threshold regon TR for dfferent traffc classes n the proposed TSAQM scheme, where threshold TH and threshold regon TR denote the vector of each queue s threshold and threshold regon, respectvely. The purpose of threshold for dfferent traffc classes, TH={th 1, th 2, th 3, th 4 }, s estmated to determne the packet droppng rate, and the threshold regon for dfferent traffc classes, TR={tr 1, tr 2, tr 3,

3 tr 4 }, where the tr =(th -σ, th +σ ) wth threshold range σ for dfferent traffc classes, =1, 2, 3, 4, s cooperated wth TH to estmate sutable parameters for current traffc condton. Furthermore, n order to acheve effectve resource utlzaton, the dynamc weght-based scheduler s adopted wth weght for dfferent traffc classes, W={w 1, w 2, w 3, w 4 }, as a scheduler mechansm. B. Traffc Senstve Actve Queue Management (TSAQM) The TSAQM has two man tasks: one s to allocate resource wth farness and hgh end-user utlty n the Dynamc Weght Allocate Scheme (DWAS), and the other s to determne the satsfactory threshold (TH) and threshold regon (TR) n the Servce Guarantee Scheme (SGS).The DWAS s used to allocate bandwdth and adjust the weghts mechansm of W for dfferent traffc classes to acheve better resource utlzaton. Dfferental servce farness delmtaton, called Dffer-TCP-Frendly, s proposed to provde the mnmum requrement of each class frst and then dstrbute resdue bandwdth for TSAQM. Then, the thresholds (TH) and threshold regons (TR) are determned by a one-dmenson Markov-chan model n the SGS to adjust thresholds precsely to meet the QoS requrement of each traffc class. second phase s to use the DRBS (Dstrbute Resdue Bandwdth Scheme) to dstrbute the resdue bandwdth wth Dffer-TCP-Frendly to all traffc classes, except the CBR traffc. The DWAS dstrbutes bandwdth to traffcs T={t 1, t 2, t 3, t 4 } based on the traffc prorty and current actve connectons, N={n 1, n 2, n 3, n 4 }, for dfferent traffc classes. The traffc classes t 1, t 2, and t 3 have the property that the data rate s constant or starcase-lke bt rates, and traffc class, t 4, s throughput senstve wthout mnmum throughput requrement. However, n order to satsfy the Dffer-TCP-Frendly, the DWAS allocates bandwdth to traffc class, t 4, by the assumpton that the mnmum requrement of traffc class, t 4, s the maxmum throughput requrement of CBR and VBR. The basc bandwdth allocaton unt for VBR traffc s the bandwdth of each layer of SVC. Whle all layer s bandwdth are met or the resdue bandwdth s not enough for any class s requrement, the resource wll be dvded equally to all traffc classes, except CBR traffc, based on the proporton of current actve connecton(s). The detal procedure of DRBS algorthm s shown n the Fg. 3. D. Servce Guarantee Scheme (SGS) Fg. 4 SGS algorthm Fg. 2 DWAS algorthm Fg. 3 DRBS algorthm C. Dynamc Weght Allocate Scheme (DWAS) The DWAS has two phases: the frst phase s to satsfy the mnmum throughput requrement of each traffc class, and the Fg. 5 QV and MB functons The algorthm of SGS s shown Fg. 4. If the ncomng traffc class, t, s delay senstve traffc, t checks the trend flag, tf, s n decreasng trend (hgher than the upper bound) or ncreasng trend (less than lower bound of threshold regon). When the trend flag ndcates that the stuaton s n decreasng, then the threshold th, subtracts ε delay ; otherwse, adds ε delay, where ε delay s the adjustng TH unt; then, the SGS verfes the adjustment outcome usng the Qualty Verfcaton (QV) functon to verfy current threshold settng whether meets the requred QoS or not. The detals of QV functon s shown n Fg. 5. When the traffc class s throughput senstve, t uses the Modfy BUE IKE (MB) functon, shown n Fg. 5, to be

4 responsve to current traffc load by adjustng the packet droppng rate. Accordng to the QV functon, t compares the QoS requrements of th traffc class, r, to TP, DT and PD, respectvely, for verfyng current TH settng. In case of the requrements cannot be met, the SGS chooses the mnmum value as the TH settng value for guaranteeng delay requrement. Accordng to the MB functon, f the current queue sze s longer than TR or equal to, the th subtracts ε throughput ; otherwse, adds ε throughput whle there s no packet arrval n Freeze_tme, where ε throughput s the adjustng TH unt. Fnally, the varaton of connecton (CV) s used as a man crtcal factor based on varyng packet queue for each connecton to determne the threshold range (σ ). PN PN (1) CV = ( x k δ ) ( θ k ρ ) PN k = 1 PN k = 1 where δ and ρ are the average number of connecton and servce rate of traffc class, respectvely, χ k and θ k are the number of current actve connecton and arrval rate of k th record, respectvely, and PN s the hstory data quantty from prevous update to the present tme. The TSAQM montors the system condton, and based on the result of threshold regon nformaton determnes the proper moment to update the system parameters. Ths can avod unnecessary ntaton, snce there s no addtonal bandwdth for lower prorty traffc, and the ntal tmng s defned n Fg d λ (7) P = C P 1 k = μ = 1 = = + d j λ (8) P C j μ 1 = (9) TP ( P d λ ) DT PD = = = = = P P (1 d ) (( 1 P ) μ ) III. PERFORMANCE ANAYSIS Table 1 System Envronment Parameters Table 2 Parameters of traffc class Table 3 Vdeo nformaton (1) (11) Fg. 6 Intal tmng E. Dynamc Weght Allocate Scheme (DWAS) The one-dmenson Markov-chan model, shown n Fg. 7, s adopted to estmate the throughput (TP), delay tme (DT) and packet droppng rate (PD), whch s a M/M/1//th queung system under the Frst-In-Frst-Out (FIFO) servce dscplne. The traffc arrval follows a Posson process wth an average arrval rate λ and the servce tme s exponentally dstrbuted wth mean 1/μ and the total system capacty s wth one threshold. d Fg. 7 One-dmenson Markov-chan model 1, th (2) = th d max th th + 1 Refer to [23], the packet dropped behavor can be regarded as the trend to decrease arrval rate. A lnear droppng equaton, d, (obtaned from Eq. 2) s used to represent as packet dropped behavor and the maxmum droppng probabltes, d max, s 1. et P s the probablty of state,, and based on the Fg. 8, the balance equatons, Eq. 3, Eq. 4 and Eq. 5 can be obtaned. Based on M/M/1/ model and ttle s formula, the throughput, delay tme and packet droppng rate can be obtaned from Eq. 9, Eq. 1, and Eq. 11. d P = μ P1 ( d + μ ) P = ( d 1 λ ) P 1 + μ P λ (3) λ (4) P = ( d 1 λ ) P 1 P = 1 = μ (5) The probablty P and P can be expressed as follows: (6) Fg. 8 Smulaton topology In ths secton, the network smulator 2 (NS-2) s used to estmate the performance of TSAQM, and adopt the dumbbell topology as the smulaton topology, shown n Fg. 8, whch there are n sources, n destnatons, and two routers [6]. The bandwdth between source (or destnaton) and router s wth 1Mbps, and the bandwdth between routers s wth 1 Mbps. The buffer space at router s set to 1 packets as shown n Table 1. The traffc arrval rate follows the Posson process and the data rate of the CBR [24], the VBR vdeo source s the HARBOUR whch s generated by JSVM [25] and the TCP traffc s generated as the FTP Traffc Model [24] are shown n Table 2 and Table 3. Based on Fg. 8, the router R1 s chosen to evaluate system performance n terms of packet droppng rate, average delay tme and connecton throughput for two smulaton cases for dfferent CBR and MVBR traffc arrval rates, respectvely. A. TSAQM for dfferent CBR traffc arrval rates In the case, the arrval rate of CBR s vared from.6 to.14(flows/sec), and the others are fxed and set to be.65(flows/sec).fg. 9(a), 9(b) and 9(c) show the average packet droppng rate, delay tme and connecton throughput, respectvely, for dfferent CBR arrval rates. In Fg. 9(a), t shows that the packet droppng rate of the CBR, MVBR, and UVBR for dfferent CBR arrval rates. The average packet droppng rate of the CBR s always lower than the others and s mantaned at about.5. Ths shows that the proposed TSAQM can acheve the droppng gudelne of CBR

5 traffc. The packet droppng rate of MVBR s lower than UVBR due to the DRBS dstrbutng resdue bandwdth to MVBR through threshold adjustment. When the UVBR droppng rate s about 15%, t means that the DRBS does not allocate the bandwdth to the 5 th layer vdeo stream. In the case of the arrval rate of CBR s between.85(flows/sec) and.95(flows/sec), the UVBR droppng rates s about 23% whch means the DRBS does not allocate the bandwdth to the 4 th layer vdeo stream. The UVBR droppng rate s between 23% and 3%, n the case of the arrval rate of CBR s between.15(flows/sec) and.15(flows/sec), whch means the DRBS does not allocate the bandwdth to the 3 rd layer vdeo stream. Smlarly, n the case of the arrval rate of CBR s hgher than 1.(flows/sec), the 5 th layer vdeo stream wll be dropped for MVBR. dropped referrng to Fg. 1(a). There s the same phenomenon for the arrval rate of CBR s.1(flows/sec) case. B. TSAQM for dfferent MVBR traffc arrvals Fg. 1(a) Fg. 1(b) g. 9(a) F Fg. 9(b) Fg. 9(c) Fg. 9 (a) Packet droppng rate, (b) Delay tme of the CBR, MVBR and UVBR (c) Throughput of the CBR, MVBR, UVBR and TCP for dfferent CBR arrval rates. Fg. 9(b) shows the delay tme of the CBR, MVBR and UVBR for dfferent CBR arrval rates that the proposed TSAQM can acheve the latency gudelne of CBR and MVBR traffc. For the same reason, the delay tme of CBR s the lowest and UVBR s the hghest by the DRBS dstrbutng strategy. When the arrval rate of CBR s hgher than.1(flows/sec), the delay tme of UBVR s slghtly hgher than 15ms. Besdes, there are two reasons for the unstable delay tme. Frst, the frame varaton of the HARBOUR s more ntense that means the varaton of enterng queue rate s hgher than smooth one. Secondly, the proposed TSAQM uses the TR to avod the rentate snce burst traffc arrvng that wll result n the hgher TR value and cause the hgher delay than the TSAQM estmated especally for heavy load case. Fg. 9(c) shows the average connecton throughput of CBR, MVBR and UVBR, and total throughput of TCP for dfferent CBR arrval rates. Ths shows that the proposed TSAQM can acheve the requred transmsson rate for CBR, MVBR and UVBR. The mean throughput of CBR s about 64kbps for dfferent CBR arrval rates. Besdes, n the case of the arrval rate of CBR s.85(flows/sec), the throughput of TCP ncreases obvously due to the 4 th layer packets of UVBR are Fg. 1(c) Fg. 1 (a) Packet droppng rate, (b) Delay tme of the CBR, MVBR and UVBR (c) Throughput for dfferent MVBR arrval rates. In the case, the arrval rate of MVBR s vared from.6 to.14(flows/sec), and the others are fxed and set to be.65(flows/sec). Fg. 1(a), 1(b) and 1(c) show the average packet droppng rate, delay tme and connecton throughput, respectvely, for dfferent MVBR arrval rates for the proposed TSAQM and GRED-I. Comparng Fg. 1(a) wth Fg. 9(a), the packet droppng rate of CBR, MVBR and UVBR n Fg. 9(a) s hgher than that n Fg. 1(a) whch s due to the data rate of MVBR s hgher than CBR. Besdes, the packet droppng rate ncreases more rapdly than n Fg. 9(a) for the UVBR when the MVBR arrval rate s ncreased. However, the mpact on MVBR s slght for ncreasng MVBR arrval rate. Fg. 9(a) also sgnfes that n the cases of the arrval rate of MVBR at.85(flows/sec) and.1(flows/sec), the DRBS does not allocate the bandwdth to the 4 th and the 3 rd layer vdeo stream, respectvely, for MVBR. Fg. 1(b) shows the delay tme of the CBR, MVBR, and UVBR for dfferent MVBR arrval rates. Ths shows that the proposed TSAQM can acheve the latency gudelne of CBR and MVBR traffc through DRBS dstrbutes resdue bandwdth to them frst. Comparng Fg. 1(b) wth Fg. 1(b), t has unstable results n Fg. 1(b) n case of arrval rate between.8(flows/sec) and.1(flows/sec). The reason s the same as varyng CBR arrval rate case that s the mpact on frame varaton and the TR wll be obvous snce the MVBR traffc ncreasng. Due to the DWRR adopts packet based scheduler, the DWAS wll be mpacted snce the packet sze s varous greatly, and t s more obvous than n Case 1. Fg. 1(c) shows the average connecton throughput of CBR, MVBR and UVBR, and total throughput of TCP for dfferent MVBR arrval rates. Ths also shows that the proposed TSAQM can acheve the requred transmsson rate for CBR, MVBR and UVBR. The mean throughput of CBR s about 64

6 kbps for dfferent MVBR arrval rates. Accordng to Fg. 11(a), most of packets of the 5 th layer vdeo stream for UVBR are dropped when arrval rate s.7(flows/sec), therefore, TCP got more bandwdth. In the case of.75(flows/sec), due to a few of packets of the 4 th layer vdeo stream for UVBR and more packets of the 5 th layer vdeo stream for MVBR are dropped, the TCP got the hghest throughput. Snce the arrval rate s hgher than.85(flows/sec), more packets of MVBR and UVBR are dropped, the throughput of TCP s decreased due to ncreasng total UVBR as the UVBR arrval rate ncreases. Fg. 11(a) PSNR of Y Fg. 11 (b) PSNR of U Fg. 11 (c) PSNR of V Fg. 11 the PSNR of (a) Y, (b) U and (c) V for MVBR, UVBR and system for dfferent MVBR rates. C. Results of peak of SNR (PSNR) In order to estmate the vdeo qualty, the arrval rate of MVBR s vared from.6 to.14 (flows/sec), the others are fxed and set to be.65(flows/sec). Fg. 11(a), (b), and (c) show the peak of SNR (PSNR) of Y, U and V, respectvely, for MVBR, UVBR and system for dfferent MVBR rates. Accordng to Fg. 11(b) and (c), the varaton of PSNR for U and V s about 2.5dB (.e. between 36.5dB and 39dB). The decreased s more obvous for Y under ncreasng CBR arrval rate, and the varaton s about 6dB, referrng to Fg. 11. In addton, the values of MVBR are hgher than UVBR for all cases due to more packets of UVBR are dropped. IV. CONCUSION In ths paper, the Traffc Senstve Actve Queue Management (TSAQM) s proposed to overcome problems of current AQM algorthms. Based on smulaton results, several objectves of ths proposed scheme are acheved ncludng by usng mult-queues mult-thresholds mechansm cooperatng wth weght-based scheduler algorthm to meet the QoS requrement, hgh end-user utlty for vdeo servce, consders the multcast, and adaptvely adjust parameters of TSAQM accordng as tme-varyng traffc loads. 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