Dynamic Node Join Algorithm with Rate-Distortion for P2P Live Multipath Networks

Transcription

1 Dynamc Node Jon Algorthm wth Rate-Dstorton for P2P Lve Multpath Networs Shyh-Chang Lu 1,Tsung-Hung Chen 1, Tsang-Hung Wu 1, Peter P.S. Wang 2 1 Dept. of Informaton Eng, 2 Dept. of Computer Scence and Informaton Eng 1 I-Shou Unversty, 2 Natonal Central Unversty 1 Koushung, 2 Taoyuan Tawan lusc@su.edu.tw, jhchenysl@yahoo.com.tw, peterw8865@hotmal.com, pdespd@gmal.com Abstract: - The delvery of multmeda that effcently maxmzes ts qualty n changng networ condtons s one of the most challengng tass n the desgn of lve streamng systems. Ths study attempts to mprove current P2P (peer-to-peer) lve streamng systems by allowng users to enjoy hgh-qualty servce under the lmtatons of networ resources. The proposed mprovement method nvolves summng up and analyzng the consderaton factors and restrcton factors nvolvng lve stream qualty durng system operatons. The proposed R-D (Rate-Dstorton) optmzed dynamc nodes jon algorthm s based on multpath streamng concept and recever-drven approach. Ths dstrbuted algorthm enables the system to evaluate the current networ statu n order to optmze the end-to-end dstorton of P2P networs. Results of ths study demonstrate the effectveness of the proposed approach. Key-Words: - P2P lve streamng, Rate-Dstorton, multpath streamng, recever-drven, end-to-end dstorton 1 Introducton The use of lve streamng systems s growng dramatcally, especally for sharng real-tme multmeda programs. The structures of multmeda streamng systems are classfed as CDN (Content Delver Networ) systems and P2P lve streamng systems. A CDN system has a clent-server archtecture (e.g., Aama, Lmelght Networs) [1][2]. One advantage of CDN systems are that users can effcently obtan hgh-qualty streamng servce from adjacent proxy servers. Ther drawbacs are hgh server costs and bandwdth rental fees for ICP (Internet Content Provder). P2P lve streamng systems ntegrate the dspersed resource dstrbute system loadng and have low ICP operaton cost. Achevng hgh streamng qualty n end-to-end streamng transmsson and broadcastng poses a major challenge for systems wth varous equpment and bandwdth [3]. The followng ssues need to be addressed : (1) Related Scalablty Analyss: the selecton of the best nodes for future end-to-end connectons by a networ probe or recever-drven approach[4][5]; (2) Related R-D Optmzaton Method: how optmzed R-D algorthm mprove pacet schedulng or flow transmsson qualty[6][7]; (3) Related Meshed- Multpath approach: ncreasng the qualty of system servce through Meshed-Multpath archtectures [3][8]. Whle meda schedulng processes and system archtectures have been extensvely studed, the lmtatons of P2P lve meda transmsson n enhancng streamng qualty have seldom been addressed [9][10]. However, users of P2P lve streamng systems usually do not use them for very long perods. Snce the stream paths change frequently, the mang too many adjustments to optmze the transmssons for clents affects the vewng stablty for users. Therefore, ths paper presents a novel approach that s optmzed for P2P lve transmsson, based on prevous approache that acheves vewng stablty. The rest of ths paper s organzed as follows. Secton 2 summarzes the ssues nfluencng meda streamng qualty, and explans the mproved method n these ssues. Secton 3 then dscusses recever-drven approach wth rate-dstorton theory, and apples t to the relevant proposed approach. Secton 4 descrbes the smulaton test performed wth dfferent algorthms to measure the effcency of the proposed algorthm. Conclusons are fnally drawn n Secton 5. ISSN: Issue 6, Volume 6, June 2009

2 2 Improvement for Lve Stream Qualty of P2P Networ Wthout loss of generalty, ths chapter dscusses the ssues nfluencng the qualty of P2P lve streamng. An approprate networ structure and operatonal process are then presented to acheve our research objectve. 2.1 Qualty Issues of P2P Lve Stream Networ Indvduals access the Internet frequently. In partcular, P2P lve streamng systems are ncreasngly popular due to advances n computer equpment, applcaton functons and operatng envronments[11][12]. Streamng servces have a hgh bandwdth requrement, as well as requre both serve and play streamed content smultaneously. Ths operaton pattern not only maes a heavy load on the networ nterface, but also ncreases the utlzaton of CPU and Memory, mang ts operaton unrelable. Varous studes have ndcated that the stream flow qualty of the clents networs s affected by endto-end dstorton (ncludng the end-to-end streamng rate and dstorton rate)[13][14], Addtonally, lmtatons n computer resources and bandwdth nfluence the networ capablty of a node when the user clent transmts meda streamng to others (reference Table 1)[15]. We can thus nfer that the followng factors nfluence the stream qualty of the P2P lve streamng system: Table 1 Optmal degree out number of a P2P clent under dfferent bandwdths Downln Bandwdth Upln Bandwdth Degree out 512 bps 256 bps 0 3 Mbps 384 bps Mbps 896 bps 3 20 Mbps 2 Mbps 6 20 Mbps 5 Mbps 17 The test streamng rate n the experments s 220 bps [Issue 1: Maxmum Connectons Capacty] The number of upln (degreeout) and downln (degreen) connectons n a node should be restrcted accordng to computer performance and the networ envronment. [Issue 2: End-to-end Delay Lmtaton] To ensure that the P2P lve stream networ s operatng n real tme, the end-to-end delay must be no larger than a reasonable lmt value (δ). [Issue 3: End-to-end Dstorton Effect] Although the stream qualty of the P2P lve stream networ s affected by the end-to-end dstorton, the value of the end-to-end dstorton contans the end-to-end streamng rate and the dstorton rate. Based on these three factor the lve stream qualty of P2P networ s assessed accordng to the end-to-end delay, streamng rate and dstorton rate. 2.2 P2P Networ Structure The frst ssue [Issue 1] s a fundamental restrcton. Therefore, based on the other two ssue ths study chooses an approprate networ structure and handlng mechansm, then develops an algorthm to mprove the lve streamng qualty of P2P networ. The networ structure n ths wor s based on Mesh-Overlay, and has the followng characterstcs. Frst, every front-end may have parent nodes and chld nodes (as found n other Mesh-Overlay P2P systems such as CoopNet and Splt Stream) [16][17][18]. Second, any networ nner-node can ndependently obtan the requred resources from adjacent nodes va a pull method [19]. Ths approach mproves transmsson performance, snce the Mesh-Overlay structure suffcently maes good use of the upln bandwdth of each node. However, ths approach s unsutable for the lve streamng servce, because the characterstcs of the Mesh- Overlay structure are loosely controllng and nconsstent undrectonal transferrng [20]. To elmnate overcome ths shortcomng, two mechansms are added, namely multpath streamng concept and a recever-drven approach. Frst, the multpath streamng concept s added to the Mesh- Overlay structure so that each node can mantan the consstent stream flow drecton [21]. The resultng networ s called a P2P multpath networ. In recever-drven networng, the recever node controls the download schedule durng meda transmsson based on the estmaton of the current networ status. One control method s the "Parent selecton" [20]; Therefore, parent selecton s addressed n order to mprove the end-to-end delay, the streamng rate and dstorton rate of lve streamng n the P2P multpath networ. 2.3 Operaton Scenaro and Processes Wthout loss of generalty, the operaton scenaro of the proposed system has three aspects (Fg.1). Frst, the ssues relatng to the P2P multpath networ structure are consdered. Second, the proposed system adopts RTP streamng strateges wth nether feedbac nor pacet retransmsson. Thrd, snce the streamng rate does not affect the dstorton rate, the proposed approach does not consder the nfluence of channel codng such as FEC (forward error correcton) protecton [22]. ISSN: Issue 6, Volume 6, June 2009

3 Ths wor focuses on two types of afflated nodes: Node A as the new node. Node B as the node loses ts parents and loos for new parents. Under such condton Note A selects the sutable parents to establsh connectons usng optmzed dstorton method, through the recever-drven approach when t adds tself to a networ. The process flow and related algorthm of an apprasal process are descrbed below (Table 2). RTP Stream RTP Stream Fg.1 Operaton Scenaro of P2P Multpath Networ The algorthm can be broen down nto four parts. Frst, f Node A wshes to jon the system, t transmts the request appont parent to the server, and obtans Canddate_lst_1 from the server. After that, to begn wth through Algorthm_1 flterng out those canddate node Node A obtans the end-toend delay nformaton of all canddate nodes from Canddate_lst_1 through ICMP. Based on the prncple of [Issue 2], Node A elmnates the nodes wth RTT>δ, and generates Canddate_lst_2. Second, Node A tests each connecton on Canddate_lst_2 one by one usng Algorthm_2 (from the server passng through the canddate nodes to Node A), then gets ASR (the average streamng rate) and ADR (average dstorton rate) whch are generated durng streamng transmsson between all canddate nodes and Node_A n a perod of tmes. Thrd, Algorthm_3 s responsble for streamng test n a unt perod tme and provdes nformaton needed by Algorthm_2. It computes RTP dstorton rate wth followng nformaton: the accumulatve RTP pacet lost from canddate node, and extended hghest sequence number of the current RTP pacet. Fnally, Algorthm_Opt proceeds the most mportant wor-selects the best parent nodes. Durng the selectng proces Node A transmts these end-to-end streamng and dstorton rates to Algorthm_Opt to calculate the most approprate canddate node and establshes the networ connectons. The followng secton descrbes the mathematcal model and detals of the proposed method. Unle Node A, Node B must transmt ts degree to ts orgnal grandfather node after beng dsconnected from ts parent. Node B selects other canddate nodes accordng to the above procedure once the degree out values of all grandfather nodes have been dstrbuted. Snce ths process nvolves mult-stage dstrbuted handlng, t can be appled to large scale networ and therefore s consstent wth the man am of ths study. Table2. Parent Selecton Algorthm Algorthm_1 Input Canddate_lst_1 1.For each canddate_nodes n Canddate_lst_1 [1] Node_A gets the RTT value from canddate nodes through ICMP protocol. 2.End for 3.Flter n [1] the canddate nodes wth RTT value> δ away, and the remanng nodes wll output as Canddate_lst_2 4.Output(Canddate_lst_2) Algorthm_2 Input Canddate_lst_2 1. Use all avalable downln connecton of Node_A, proceed: 2.For each canddate_nodes n Canddate_lst_2 [1] Call Algorthm-3 to calculate ASR and ADR of connecton provded by these nodes [2]Save the nformaton whch Algorthm-3 sends bac nto canddate_lst_3 [3] If the dstorton rate of ths connecton s the lowest on Node_A, eep ths connecton, otherwse Node_A stops acceptng that stream flow connecton 1. 3.End for 4.Output(Canddate_lst_3) 1 :f avalable downln connecton of Node_A s only one, drectly test next canddate node. Algorthm_3 Input canddate node 1. Requre that canddate_node sends the stream comng from the server to Node_A, establsh connecton 2. Record the followng nformaton from RR pacet 1 : A.cumulatve_number_of_pacet lost(cpl) : accumulatve RTP pacet lost from canddate node. B.extended_hghest_sequence_number_receved (EHS)(32bt) : low 16 bts record the maxmal sequence number of the current RTP pacet, and Hgh 16 bts are sequence cycles. 3. Compute RTP dstorton rate (DR): DR= ( RR2[ CPL] RR1[ CPL]) ( RR [ EHS] RR [ EHS]) 2 1 ISSN: Issue 6, Volume 6, June 2009

4 base on two consecutve RR pacets (RR 1 and RR 2 ) and the travelng tme from RR 1 to RR Compute statstcs for average streamng rate (SR). 5. Output (SR, DR). 1: RR(Receve Report) s conveyed n exstng RTCP pacets. Algorthm_Opt 1 Input Canddate_lst_3 1.For =1 to m 2 [1] Get th path nformaton form server,(nclude N, P, p, mn(b ) n P ) [2] Compute the streamng btrate r and dstorton rate p of th path 3. 2 End for. 3.Intal J m (π)=[j(π 1 ),J(π 2 ),.., J(π m )], π 1 =[P 1 ], π 2 =[P 1, P 2 ],..,π m =[P 1,..,P m ], arrange the networ paths s ascendng order of ther p 4.For = 1 to m do [1] If [Frst Termnated Condton] s hold then brea; [2] Compute D(π ),R(π ) [3] If [Second Termnated Condton] s hold then brea; [4] Compute J(π ) 5.End for 6.Comput J*(π)= arg mn π J m (π) 7.Output the optmzed parent node set:j*(π) 1 : the tme complexty of Algorthm_Opt s O(N) 2 : m equal to the number of Canddate_lst_3 3 : th path s the dsjont path from server to Node_A through canddate node N 3 Optmzed Parents Selecton wth R-D Algorthm An optmzed parent selecton algorthm s descrbed to ensure that Node A selects the most approprate canddate nodes (such that stream paths have mnmal end-to-end dstorton scenaros based on a recever-drven P2P multpath networ. The related mathematcal model and method of the algorthm s descrbed below. Step 1: Identfy the method of quantzng end-to-end dstorton, n terms of [Issue 3]. Step 2: Establsh the basc flow model for P2P multpath networng n order to analyze the relevant flow constrants. Step 3: Acheve the multpath streamng characterstcs based on the stream features (streamng rate and dstorton rate) and the analyss results n Step 2. Step 4: Ln the nformaton provded by Step 3 wth the quantzaton process of Step 1, and buld the optmzed parent selecton algorthm. 3.1 Dstorton Model and Related Constrants Frst, the end-to-end dstorton of stream flow n the system s measured usng ths well-nown formula [23]: J=J R +J D.. (1). Here, J denotes the end-to-end dstorton, and comprses the expected rate J R and expected dstorton J D. The J R depends on the average streamng rate R (also called encodng rate), and J D s drven by p(rtt > τ) (where RTT s roundtrp tme, and p(rtt > τ) denotes the average dstorton rate that a pacet transmtted at sender tme T s s not receved at recever by T s +τ, whether lost or smply delayed, and τ < δ). A smple P2P multpath networ M(N,L) s used to explan the requred relevant parameter (see Fg. 2). N denotes a peer node, and N N. L s the networ ln between two adjacent nodes N and N j, and L L. p represents the dstorton rate of the stream flow F passng through L, and p [0,1). b (o ) ndcates the upln bandwdth of N ; b () s the downln bandwdth of N. P,j denotes the stream path from N to N j (such as P 1,5 ). Fnally, r,j represents the streamng rate of P,j. The relevant constrants n the P2P multpath networ are descrbed below. [Constrant 1: End-to-End Flow Constrants] The streamng rate r,j of drect connecton between two adjacent nodes N and N j s not greater then the mnmum value between the upln bandwdth of N and the downln bandwdth of N j, such that r, j mn( b ( o), b j( ) ). [Constrant 2: Downln Flow Constrants] If node N has many flow resources wth stream paths between N and the resource then the sum of the streamng rate passng through all the paths s no larger than the downln bandwdth of the node N, such that P M r b. j,, j j, ( ) [Constrant 3: Upln Flow Constrants] If a node N has many flow recevers wth stream path then the sum of the streamng rate passng through all the paths s no greater than the upln bandwdth of N, such that P M r b., j, j, j ( o) [Constrant 4: Flow Conservaton Constrants] If flow F passes through node N, then the streamng ISSN: Issue 6, Volume 6, June 2009

5 rate r ( o ) r ( ) of F nto N s equal to the streamng rate of F leavng N : b 1 ( O ) b 2 ( O ) ( ) = r ( o, and ) = r ) b 3 ( I ) b 3 ( O ) r F ( r F ( o). b 4 ( I ) b 5 ( I ) Fg.2 Dagram of a Basc P2P Multpath Networ 3.2 Optmzed Method and Related Lemmas The system adopts the parameters of end-to-end dstorton n P2P multpath networ derved n the thrd step for canddate selecton [13][14]. Thu f the system can calculate the J R and J D of stream flows from the server that pass through canddate nodes to Note A, then t can evaluate the total endto-end dstorton J through formula(1). Every the Scenaro of Fg. 1 can be transformed nto the P2P multpath networ dagram of Fg. 3, the notaton of Fg. 3 s explaned as follows. Fg.3 Operaton Scenaro of a P2P Multpath Networ 1. N s denotes the server, and A denotes Node A. 2. The degree table on the rght hand sde of Fg. 3, based on [Constrant 3], shows the restrctons of the upln and the downln numbers of all user nodes. 3. The b of L between adjacent nodes N and N j replaces mn( b ( o), b j( ) ). Defne P as the stream path from N s to N, and defne p as the dstorton rate of P. Defne r as the streamng rate of P (note that f more than one dsjont stream path s found from N s to N, these dsjont paths are ndcated as P (), by analogy wth p () and r () ) 4. All stream paths on the P2P multpath networ are mared. Ln L 1 s shared by paths P S,4(1) and P S,5(1), and L 2 s shared by P S,4(2) and P S,5(2), These shared lns on dfferent paths are called bottlenec lns. The canddate nodes (N 3, N 4, N 5 ) for Node A are also mared, and the possble lns are gven by { La, Lb, Lc} (These lns are adopted to estmate the end-to-end dstorton J ). The quantzaton procedures for the end-to-end dstorton are followed to obtan all r and p, and thus obtan the followng deducton based on the multpath characterstc and the above constrants. [Lemma 1: Server Flow Budget] The total streamng bandwdths of drect-ln from N s to adjacent nodes N s no larger than the upln bandwdths of N s such that b s( o) r. [Proof] Snce the server s regarded as a specfc node wth no downln bandwdth, ICP can estmate the upln bandwdth of N s n the networ center by [Constrant 3]. Ths bandwdth s no less than the streamng rate obtaned by clents lned drectly to servers. [Lemma 2: Server-to-end Flow Rate] In a P2P Multpath networ, each streamng rate of the dsjont path from N s to N s no greater than the mnmal networ bandwdth of all lns n the path, such that: r s mn { b }., L P [Proof] Accordng to [Constrant 1] and [Constrant 4], any flow F passes through adjacent nodes N and N j wth r, j = r ( ) = r j ( o ) mn( b ( o), b j( ) ). Snce P s conssts of the lns connectng contnuous adjacent nodes from N s to N, the mnmal b of all lns can be obtaned by multple comparson. The streamng rate r s computed from ths mnmal b. [Lemma 3: Server-to-End Dstorton Rate] The dstorton rate p of path P n a P2P multpath networ s wrtten as. p s = 1 (1 p ), L P s, [Proof] The dstorton rate n the prevous operaton scenaro s not affected by the streamng rate, and s derved ndependently for each ln. Therefore, p of each L s not nfluenced by other lns. Hence, get the total dstorton rate p s calculated by dervng the value (1- p ) of each ln sesson. The computaton formula of r and p can be confrmed by applyng [Lemma 2] and [Lemma 3] [22][24][25]. The Langrangan formulaton and polcy π s adopted to quantze (1), as: J m (π)=( J(π 1 ), J(π 2 ),, J(π m )).. (2), and J(π )=λ 1 [R(π )] η + D(π ). (3) p j r j Amog R(π ) = r s, j, D(π )= λ 2 (4) r j = 1 j= 1 j ISSN: Issue 6, Volume 6, June 2009

6 In ths wor, polcy π conssts of a set of vectors {π 1,.., π m } as π 1 ={P 1 },,π m ={P 1,.., P m }, and m s the number of all nodes n canddate_lst_2. π s the paths set from N s to Node A through the canddate nodes. Thu λ 1 and λ 2 are postve Langrangan multplers and η [ 1,0]. The system generates the dstorton metrc J m (π) based on two factor namely the restrctons mposed by the operaton scenaro, and the most sutable polcy π *. The system generates the dstorton metrc J m (π) by runnng Algorthm_Opt to calculate nodes n Canddate_lst_2 (accordng to formula(2)). The close-to-optmal dstorton J * s thus obtaned from the mnmum argument of J m (π): J * =arg mn J ( π ) = arg mn (J(π 1 ),, J(π m ))..(5) π m π Formulae (3) and (4) reveal that the orderng approach of polcy π nfluences the result of formula (5). Therefore, experments were performed to fnd an orderng method of polcy π * that yelds J *. Experment A: A node was connected to two parent nodes (denoted as N 3, N 1 and N 2 of Fg 2), where N 1 and N 2 separately transmt stream flows F 1 and F 2 to N 3, p 1 and p 2 are fxed and p 1 < p 2. Based on [Constrant 2], b3 = 1M and r 1,3 + r2,3 = b3 were set so that r2,3 = b3 r 1,3. The value of r 1,3 was rased gradually from 0 bps to 1 Mbps to observe the dstorton MSE (mean-square-error) of N 3. Fgure 4 shows the expermental results. The transmsson dstorton gradually decreased as r 1,3 ncreased (and r 2,3 decreased), and was lowest when r1,3 = b3, r2, 3 = 0. Thu f a node has more than one source node then t has mnmal dstorton when all of ts downln bandwdths are assgned to the recever node wth the lowest dstorton rate. Fg. 4 Experment for Measurng End-to-End Dstorton Experment B: A node was connected to two chld nodes (see N 3, N 4 and N 5 of Fgure. 2; N 4 and N 5 are chld nodes of N 3 ); N 3 transmtted stream flows F 3 and F 4 to N 4 and N 5 ; p 3 and p 4 were fxed, and p 3 < p 4. Accordng to [Constrant 3], b4 = 1M and b 4 = r3,4 + r3,5 were set such that r 3, 5 = b4 r3,4. The expermental results produced the same concluson as those of experment A. Thu f a node has more than one recevng node then ts dstorton s optmal when t assgns ts upln bandwdths to the recever node wth the lowest dstorton rate. The path arrangement order for polcy π can be determned from these expermental results as ascendng order for the dstorton rate of all paths. Stll, three ssues need to be solved to obtan the optmal J * n the proposed algorthm. 1. Gven that the sequence of P n polcy π s n ascendng order of the dstorton rate, then the streamng rates of P formng soluton J * need to be determned. 2. The streamng rate of the bottlenec ln to all paths P allocated by the system needs to be consdered. 3. The termnaton condtons of the algorthm must be dentfed. The frst ssue s deduced n terms of the nfluence of J ( π ) on the varance of r. Thu formula (4) s transformed nto (3). The partal dfferental form of J ( π ) s then taen, resultng n the followng Formula (6): J (π ) 1 r, (,, ) j s j ps p η s j = λ1η ( r, ) r s λ.(6) ( r, ) s Accordng to ths formula, J ( π ) decreases when the value of formula (6) s negatve, whle J ( π ) s ncreased when the value of the formula (6) s postve. Addtonally, the parametrc propertes of formulae (3) and (4) demonstrate that formula (6) s always negatve f =1. Thu dsregardng the streamng rate r s (0, mn { b }) based on [Lemma, 1 L Ps,1 2], the path P 1 wth the mnmal dstorton rate s always part of J * (whch s why Algorthm_2[3] must eep a stream path wth the mnmal dstorton rate). To obtan the value of the streamng rate for other paths that may form part of J *, formula (6) = 0 * s set n order to obtan the extreme r of r : * λ2 1+ η r = [ ( p p j ) r j j ] r j j (7) λ1η Accordng to formula (7), streamng rate r = 0 for P ( 2 m ). The dstorton of J ( π ) ncreases * * when r < rs,, and decreases when rs, > rs,. Therefore, a possble component of J * s 1 ISSN: Issue 6, Volume 6, June 2009

7 * r s = mn { b } when r s < mn { b }. Consequently,, L P, L Ps, for all J ( π ) ( 2 m), the soluton of J * may nclude r = 0 and r = mn { b }. s, L P Fgure 2 llustrates the second problem. A bottlenec ln can be defned as a ln where the end nodes of the path have more than one resource node or recevng node. Hence, based on [Constrant 2], [Constrant 3] and [Constrant 4], the paths sharng the same bottlenec ln are separated nto fully ndependent paths. The bandwdth of the bottlenec ln s allocated to these dsjont path accordng to the concluson of the frst problem. Therefore, the dstrbuted prncple can be nferred as follows: [Lemma 4: Bottlenec-ln Bandwdth Sharng] In a P2P multpath networ, f one bottlenec ln s shared by many stream path then t allocates ts bandwdth n a greedy way, begnnng wth the path P wth the lowest dstorton rate, and sets the streamng rate accordng to mn { b (the last one L P s, P j, the allocated streamng rate may be less than mn { b } ). L Ps, j The termnaton condton of the algorthm s now consdered. Frst, accordng to [Issue 1] and [Lemma 4], Node A can choose from numbers n=mn(m,degree n (1)) n canddate_lst_3, ndcatng the Frst Termnaton Condton (Judgment reference for Algorthm_Opt 4[1]). The dstorton resultng from N afflatng wth a new end-to-end stream path may rse f r <, accordng to * rs, formula (4) and answers from the frst and second problems. In summary, not all canddate nodes necessarly be chosen, and the frst termnaton condton s as follows (combnng Eqs. (5) and (6)): J m ( π ) 0, r 1= mn { b }, r = mn { b } rs, L Ps, 1 L Ps, J m ( π ) 0, r 1= mn { b }, rs, = 0 rs, L Ps, 1 Therefore, the second termnated condton s as follows (Judgment reference for Algorthm_Opt 4[3]): λ1η η (Condton-2A): D( π ) [ R( π )] + p s,, λ2 = mn { b }, r = mn { } r s, 1 L P 1 } L P λ1η η (Condton-2B): D( π ) [ R ( π )] + p s,, λ2 r, 1= mn { b }, r, = 0 s L P 1 s b Thu n a P2P lve stream networ, the calculaton of the end-to-end dstorton for J m (π) termnates the computaton when ether the Frst Termnaton Condton or the Second Termnaton Condton occurs. In summary, Algorthm_Opt based on the lemmas n ths chapter s shown after suspendng the calculaton of the end-to-end dstorton. The optmzed soluton set J * s derved by computng the optmal answer of J m (π). 4 Smulaton Results Ths chapter descrbes the smulaton results obtaned wth the descrbed operaton scenaro and algorthms. The P2P stream networ was constructed on NS2 and MyEvalvd (relevant parameters n Table 3) [26][27]. The networ comprsed 20 nodes (wth the frst node labeled N s ). Node nformaton was recorded n a matrx M as M(degree n (N ), degree out (N ), p,j, b,j ) contanng the degree n, degree out of N, and b,j, p,j of the drect-ln value wth N j. The followng three networ scenaros were smulated. Scenaro-1) Wred networ pattern: lns between nodes have hgh bandwdth and low dstorton rate. Scenaro-2) Wreless networ pattern: lns between nodes have low bandwdth and hgh dstorton rate. Scenaro-3) Hybrd networ pattern: a hybrd of above two pattern where N s s connected to a wred networ, and clents can access streams va a wred or wreless ln. Table 3: Parameters for Smulaton Scenaros p -max p -mn b -max b -mn Smulaton M bps 1 Mbps Smulaton bps 128 pbs Smulaton M bps 128 pbs degree n/out =[1,4], δ=200mτ=100mθ=[2.00,4.00]sec η=-0.87,λ 1 =1.8x10 5,λ 2 =1624, The dstorton smulatons were performed accordng to these three patterns (total 18 smulaton networs). Wth the b,j, p,j values of each of the twenty nodes n M assgned from parameter s range n Table 3 accordng to the followng algorthms. The values of N of matrx M gradually afflate system n tme nterval θ (wth α as the path parameter, and S=mn(3,degree n (N ))). 1.A DR : a sngle-path selecton algorthm wth dstorton rate gven by α [1-Π (1-p )]. ISSN: Issue 6, Volume 6, June 2009

8 2.A DR3 : an S-path selecton algorthm wth dstorton rate measured as α [1-Π (1-p )], usng the maxmum avalable value of S. 3.A GP : a sngle-best-path selecton algorthm wth good-put value gven by α b p. 4.A GP3 : an S-path selecton algorthm wth good-put value measured as α b p. 5.A MP : a maxmum-paths algorthm, usng the maxmum avalable degree n number of N. In the NS2 networ smulaton scenaro, the networ maxmum transmsson unt (MTU) was set to 1000 bytes worth of vdeo data. The foreman_cf sequence was joned wth tself to form 2700-frame vdeo stream encoded at 30 frames per second. Each GOP (Group of Pctures) conssted of 9 frames (pctures). Each newly afflated node passes through the paths chosen by those sx algorthm and gans the pacets from N s followng an FCFS schedulng. The three networ scenaros were each smulated 100 tmes. The PSNR (Pea Sgnal-to- Nose Rato) between the orgnal and decoded sequences was calculated, and the average total endto-end dstorton was then computed. Fgures 5, 6 and 7 present the expermental results. The proposed algorthm had the hghest average effcency among the sx algorthms tested. The expermental results are summarzed as follows: 1. In the Scenaro-1 smulaton, calculated dstorton of A MF was closest to A OPT. Clearly, a new node n an envronment wth a lower dstorton rate and hgher streamng rate can obtan a better stream qualty by usng more alternatve paths to transmt stream flow thus reducng the end-to-end dstorton. 2. In the Scenaro-2 smulaton, the dstorton calculaton result of A DR compared to others s closer to A OPT, n contrast to Scenaro-1. A new node n an envronment wth a hgher dstorton rate and lower streamng rate t cannot decrease the dstorton effect by usng many transmsson paths. In ths case, the closest to optmal streamng qualty s obtaned by streamng meda only through the path wth the lowest dstorton rate. 3. The smulaton Scenaro-3, whch combnes propertes of both Scenaro-1 and Scenaro-2, confrmed the smulaton results of both those scenaros. Algorthm A DR acheved less total dstorton than A GP algorthm n choosng canddate nodes. To compare smulaton results wth actual executon, experments were performed wth A OPT, A MF and A DR (smulaton 1, Node A pattern). Fgure 8 shows the expermental result. The result sequences of the smulated and actual dstorton for each algorthm were smlar. Next, 18 smulaton networs were constructed by sx algorthms randomly removes 5 nodes excludng N s. The chld nodes were requred to loo for other parent and generate connected paths under each of the sx algorthms. Each smulaton was performed 50 tme and the average dstorton value was obtaned. Fgures 9, 10 and 11 llustrate the expermental results. The results of these smulatons were smlar to those of the orgnal smulatons. These smulaton results demonstrate that the user node can reduce overall networ dstorton by selectng paths wth hgh streamng rates and low dstorton rates for meda transmsson under varous P2P multpath networ scenaros AO P T ADR 1 ADR 3 AG P 1 AG P 3 AMF Fg.5 Dstorton Comparson for Scenaro-1 (Type: NodeA) AO P T ADR 1 ADR3 AG P 1 AG P 3 AMF Fg.6 Dstorton Comparson for Scenaro-2 (Type: NodeA) AO P T ADR 1 ADR3 AG P 1 AG P 3 AMF Fg.7 Dstorton Comparson for Scenaro-3(Type: NodeA) ISSN: Issue 6, Volume 6, June 2009

9 Smulaton Experment AOPT ADR1 AMF wor proposes a recever-drven dynamc node jon algorthm for a P2P multpath networ. Smulaton results ndcate that the proposed algorthm performs better than others under varous networ crcumstances. The proposed dstrbuted structure and algorthm can decrease the computatonal loadng of servers and mprove the overall streamng qualty. Fg8. Dstorton Comparson for Smulaton wth Experment AO P T ADR1 ADR3 AG P 1 AG P 3 AMF Fg.9 Dstorton Comparson for Scenaro-1 (Type: Node B) AO P T ADR1 ADR3 AG P 1 AG P 3 AMF Fg.10 Dstorton Comparson for Scenaro-2 (Type: Node B) PSNR(DB) AO P T ADR1 ADR3 AG P 1 AG P 3 AMF Fg.11 Dstorton Comparson for Scenaro-3 (Type: Node B) 5 Concluson Owng to the shared stream flows between front end P2P lve streamng s affected by bandwdth lmtaton and the clent computer envronment. In addton to summarzng stream qualty-related ssues and analyzng n depth the end-to-end dstorton constrants n the operaton scenaro, ths References: [1] Aama, [2] Lmelght Networ rs.com. [3] Hucheng Ch, Qan Zhang, Juncheng Ja and Xuemn (Sherman) Shen, "Effcent Search and Schedulng n P2P-based Meda-on-Demand Streamng Servce," IEEE Journal on Selected Areas n Communcaton Vol. 25, No. 1, Jan [4] We Cheng, We Tsang Oo,"Recever-Drven Vew-Dependent Streamng of Progressve Mesh,"n proceedng of NOSSDAV 2008, Braunschweg, Germany, [5] Jn-feng Zhang, Rong-gang Wang, Jan-we Nu, Yuan Dong, Ha-la Wang,"Rate-dstorton optmzed btstream swtchng for peer-to-peer lve streamng," Journal of Zhejang Unversty Scence, Vol. 9, pp , [6] Prashant Ramanathan, Mar Kalman, Bernd Grod, "Rate-Dstorton Optmzed Interactve Lght Feld Streamng," IEEE Transactons on Multmeda 9(4): pp , [7] Dan Jurca, Pascal Frossard,"Dstrbuted Meda Rate Allocaton n Multpath Networ" Image Communcaton, Vol. 23, pp , Nov [8] Feng Wang,Yongqang Xong,Jangchuan Lu,"mTreebone: A Hybrd Tree/Mesh Overlay for Applcaton-Layer Lve Vdeo Multcast," Internatonal Conference on Dstrbuted Computng System ICDCS 07, pp ,, Burnaby,Canada, [9] Bo Lu,Yansheng Lu,Y Cu,Yuan Xue,"A measurement study on AS-aware P2P streamng stratege" ChnaCom2008, pp ,aug [10] Xaojun He, Yong Lu, Keth W. Ros"Inferrng Networ-Wde Qualty n P2P Lve Streamng System" IEEE Journal on Selected Areas n Communcaton" 25(9): pp , 2007 [11] PPLve, [12] PPStream, ISSN: Issue 6, Volume 6, June 2009

10 [13] E. Setton, J. Noh and B. Grod, "Rate- Dstorton Optmzed Vdeo Peer-to-Peer Multcast Streamng", n ACM P2PMMS, [14] P. Mundur, R. Smon, and A. Sood, "End-toend Analyss of Dstrbuted Vdeo-on-Demand System" IEEE Transactons on Multmeda, Volume 6, Number 1, Feb [15] J. Noh, S. Deshpande, "A Method for P2P Streamng System Jon Latency Reducton Usng Preferred Peer Lst," Proc. IEEE 5th Consumer Communcatons and Networng Conference (CCNC 2008), USA, Jan [16] Nazann Maghare, Reza Rejae, "Understandng Mesh-based Peer-to-Peer Streamng," Proceedngs of the Internatonal Worshop on Networ and Operatng Systems Support for Dgtal Audo and Vdeo, pp , Newport, Rhode Island, May [17] Nazann Maghare, Reza Rejae, Yang Guo,"Mesh or Multple-Tree: A Comparatve Study of Lve P2P Streamng Approache" Proceedngs of IEEE INFOCOM, pp , Alasa, USA, May [18] Damano Carra, Renato Lo Cgno, Ernst W. Bersac: Graph Based Analyss of Mesh Overlay Streamng Systems. IEEE Journal on Selected Areas n Communcatons 25(9): pp , [19] Xaojun He, Yong Lu and Keth Ros"IPTV over P2P Stream networs: the Mesh-pull Approach", IEEE Communcatons Magazne, Feb [20] N Maghare, R Rejae, "PRIME: Peer-to-Peer Recever-drIven MEsh-Based Streamng," 26th IEEE Internatonal Conference on Computer Communcaton pp , [21] Irfan Sherff, Elzabeth M. Beldng-Royer, "Multpath Selecton n Mult-rado Mesh Networ " Broadband Communcaton Networs and System pp.1-11, [22] L. Golubch, J. Lu, T. Tung, A. Chow, and W. Lee, Mult-path contnuous meda streamng: What are the benefts? ACM Journal of Performance Evaluaton, vol. 49, no. 1-4, pp , Sept [23] P. A. Chou and Z. Mao, "Rate-dstorton optmzed sender-drven streamng over besteffort networ" IEEE Worshop on Multmeda Sgnal Processng, pp , France, Oct [24] A. C. Begen, Y. Altunbasa, O. Ergun, and M. H. Ammar, "Multpath selecton for multple descrpton vdeo streamng over overlay networ" Sgnal Processng: Image Communcaton, vol. 20, pp , [25] Jacob Chaare Sangeun Han, Bernd Grod, "Layered codng vs. multple descrptons for vdeo streamng over multple path Multmeda System,10(4), pp , 2005 [26] J. Klaue, B. Rathe, and A. Wolsz, "EvalVd - A Framewor for Vdeo Transmsson and Qualty Evaluaton", In Proc. of the 13th Internatonal Conference on Modellng Technques and Tools for Computer Performance Evaluaton, pp , Urbana, Illno USA, Sept [27] ISSN: Issue 6, Volume 6, June 2009