Impact of Traffic Splitting on the Delay Performance of MPTCP

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1 Impact of Traffic Splitting on the Delay Performance of MPTCP Se-Yong Park, Changhee Joo, Yongeok Park, and Saewoong Bahk School of Electrical Engineering and INMC, Seoul National Univerity Ulan National Intitute of Science and Technology Samung Electronic Abtract MPTCP i a promiing tranport technique to boot oughput of wirele multi-homed device by upporting multiple concurrent tranmiion ough heterogeneou wirele interface. A the number of concurrent ubflow increae, MPTCP can achieve a linearly increaing oughput performance, but it i unclear how much improvement in the end-toend delay performance can be attained from additional ubflow. In thi paper, we develop an analytical framework to undertand the end-to-end delay performance of MPTCP that account for TCP dynamic and ubflow interaction. Interetingly, it turn out that the delay performance can be even degraded with additional ubflow. Conidering MPTCP in heterogeneou wirele network of Wi-Fi and LTE, we formulate a cot minimization problem ubject to the end-to-end delay contraint. Baed on the inight obtained from our model, we approximate the problem and develop a greedy cheme that plit traffic to minimize the cot while atifying the delay contraint. Through imulation, we demontrate that our propoed cheme outperform the conventional MPTCP, and ignificantly improve the delay performance while lowering the uer cot. Index Term MPTCP; end-to-end delay; cot minimization; bufferbloat I. INTRODUCTION MPTCP i the emerging technique to upport the concurrent tranmiion uing parallel TCP ubflow. Since the tate-ofthe-art mobile device already ha multiple wirele interface of Bluetooth, Wi-Fi, 3G, and LTE, we can expect the ue of MPTCP in heterogeneou wirele network to receive highreolution video treaming ervice in a robut and eamle way. However, the mot previou tudie in MPTCP have focued on bandwidth aggregation or TCP-friendline [1], [9], [10], and the delay characteritic of MPTCP are underexplored. Given the fact that many real-time application uch a Skype and Window Media Service provide their ervice ough TCP connection [2], [13], the end-to-end delay performance of TCP have attracted more attention in wirele environment [2], [3]. In [2], the end-to-end delay of TCP in treaming ervice i modeled by Markov proce. However, in their modeling, the network delay i fixed to contant, it make a large amount of error in wirele network. An analytical framework i provided in [3] to undertand the network queuing delay of liding-window tranmiion ytem(i.e TCP). A congetion window ize increae, the network queueing delay increae linearly to window ize, wherea the oughput i converged to network capacity. Beide the TCP congetion control, everal factor can impact on the end-to-end delay performance of TCP. The bufferbloat effect can deteriorate the delay performance [4]. In wirele acce point, the buffer ha been intalled to compenate wirele channel fluctuation. A a large amount of buffer i required due to cheap memory cot, TCP ometime ha an exceive window ize due to lack of lo and can uffer from lengthy packet delay. In [12], it ha been hown that the packet reordering delay from a packet lo or mimatch in round-trip time of ubflow can be ignificant under MPTCP, and that the delay performance of ubflow tend to align to the wort cae. In thi paper, we invetigate the end-to-end delay performance of MPTCP and deign a cot-efficient traffic-plit cheme that allocate tranmiion rate of each ubflow ubject to the end-to-end delay contraint. Our main contribution i a follow. We develop an analytical framework to undertand the end-to-end delay of MPTCP to capture the fundamental propertie that account for TCP dynamic and ubflow interaction. We divide the end-to-end delay into everal delay element and invetigate each delay element eparately. We formulate the cot minimization problem with the end-to-end delay contraint, and approximate it baed on our model to a impler form with two delay contraint. We develop a practical greedy heuritic cheme that plit traffic to MPTCP ubflow uch that the cot i minimized while the delay contraint are atified. We verify the performance of our propoed cheme in comparion with the conventional MPTCP. The ret of paper i organized a follow. Section II explain the ytem model of MPTCP, then we preent the analytical end-to-end delay modeling in Section III. Baed on thi modeling, we formulate the cot minimization problem within delay contraint and propoed traffic plitting cheme for thi problem in ection IV. In Section V, we verify the propoed cheme uing imulation.

2 Fig. 1. The end-to-end delay of MPTCP i modeled a the um of end buffer queueing delay, network delay, and reordering buffer delay. II. SYSTEM MODEL We conider an MPTCP connection with application that generate traffic at a contant-rate f, which i typical for live treaming ervice or real-time voice application. The traffic i tranmitted ough the et S of ubflow. At time t, each ubflow S ha congetion window of ize w (in byte), experience round-trip time delay RT T, and can tranmit at rate up to x cw = w /RT T. Let x denote the actual tranmiion rate of ubflow, and let x denote it vector. Alo, let c denote the bottleneck capacity of ubflow. Once the application generate a packet, it enter to a FIFO buffer named a the end buffer (ee Fig. 1), and wait for it tranmiion opportunity. When a ubflow can end an additional packet (e.g., by receiving an ACK), it fetche one packet from the head of the end buffer and tranmit it. If the tranmitted packet i lot in the network, it will be recovered by the retranmiion invoked by either ee duplicate ACK or timeout. Since the packet can be lot and may experience different network delay per ubflow, they may arrive at the receiver out of order. At the receiver, any out-ofordered packet are tored in the reordering buffer and wait until the miing packet arrive, o that the packet can be delivered to the application in order. From the above procedure, we identify ee different type of delay that compoe the end-to-end packet delay under MPTCP: delay in the ender buffer, delay in the network delay, and delay in the reordering buffer, a illutrated in Fig. 1. Queuing delay in the end buffer: When the application traffic rate f i greater than intantaneou tranmiion rate um of MPTCP (i.e., when f > S x ), the packet will be queued in the end buffer and experience queueing delay. Even if the application traffic rate i maller than the tranmiion rate um, the packet can experience a mall delay in the buffer, waiting for a tranmiion opportunity triggered by an incoming ACK. Network delay: Under lo-baed TCP congetion control (i.e., without uing explicit congetion notification (ECN) [11]), the ender will increae the tranmiion rate until a packet lo occur, and it i commonly oberved that the ender temporarily ha a larger congetion window than available bandwidth-delay product of the network. Exceive packet tranmiion reult in queueing at intermediate node and congetion, which can caue lengthy contention period in wirele connection. We approximate the extra delay in all the intermediate node a a cloed queueing ytem. Reordering buffer delay: The packet that arrive out of order at the receiver hould wait for the miing packet and experience additional latency before delivery. We model the end-to-end delay of MPTCP a the um of the ee delay, which depend on the application traffic rate, the tate of TCP (e.g., low tart, congetion avoidance, etc.) a well a the capacity of routing path. In the following, we eparately tackle each delay in teady tate and combine them together to undertand the end-to-end MPTCP behavior. III. ELEMENTS OF END-TO-END DELAY In thi ection, we develop an analytical framework to undertand the delay performance of MPTCP at the viewpoint of the end uer. We conider an MPTCP connection with contant-rate application and aume that each ubflow ha a ingle routing path. Baed on imple queueing model, we uccefully capture the delay inflation by exceive congetion window and the impact of the packet reordering induced by different round-trip time of ubflow. A. Queueing delay in the end buffer We aume that the end buffer queue evolve a an M/M/1 queueing ytem with arrival rate f and ervice rate S x. It i an approximation under the aumption that both the packet arrival from the application and the ACK arrival from the receiver follow a Poion proce. Let d end denote the packet delay in the end buffer. From M/M/1 queueing ytem, we have E[d end (x)] = 1 S x f, (1) where we implicitly aume that the traffic rate f i feaible, and TCP congetion control algorithm can upport up to x cw >= x for each ubflow in teady tate, atifying that S xcw >f. B. One-way delay in the network Sliding-window tranmiion ytem like TCP can be modeled a a cloed queueing ytem [3]. Suppoe that the network i aturated and there i alway data to end. Let RT T denote the round-trip time of the ubflow. It ha been known that given M -hop path, when the liding window ize i et to w, the expected round-trip time can be etimated a E[RT T ]=RT T min + w +(M 1), (2) c where RT T min denote the minimum round-trip time of ubflow for ignal propagation. Then we can re-write the tranmiion rate of ubflow with window ize w a x cw c (w )= E[RT T min ] = w c w +(M 1) + c RT T min. (3)

3 From (3), the tranmiion rate will be bounded by c a window ize w goe to the infinity, and average RTT will increae linearly. We verify (2) and (3) ough experiment in Wi-Fi and LTE network. Due to the lack of the pace, the reult of experiment i decribed in [ [14]]. Let d net denote the one-way network delay. Note that given x x cw, the wort-cae network delay of ubflow can be obtained when x = x cw. Auming the network delay i a half of RTT, we etimate the expected value of d net from (2) and (3) and a E[d net (x )] E[RT T /2] x=x cw = M 1+c RT T min (4). 2(c x ) C. Delay in the reordering buffer It ha been known that a large RTT can degrade the delay performance of conventional TCP [4], [5]. Under MPTCP, the ituation can be even wore ince the end-to-end packet delay tend to be aligned to the wort cae among all the ubflow due to waiting time in the reordering buffer [12]. Let u conider that an MPTCP connection with two ubflow, where the one-way network delay of each ubflow path i 50 m and 500 m repectively. Suppoe that one packet ha been tranmitted ough the high-delay ubflow, and oon after, another packet ha been tranmitted ough the lowdelay ubflow. After 50 m, the packet tranmitted ough the low-delay ubflow arrive at the receiver, but ha to wait in the reordering buffer until the packet tranmitted earlier arrive from the high-delay ubflow. Hence, a packet may wait for at mot the maximum difference in the network delay. We define E[d re ] a the expected maximum reordering delay caued by average delay difference between the ubflow, i.e., E[d re (x )] = max i S E[d net i (x i )] E[d net (x )]. (5) D. Lo recovery delay In addition to the above delay, there i another ignificant ource of delay: recovery from a packet lo. When a packet i lot in the network, it hould be retranmitted from the ource, and all the packet that tranmitted later and arrived at the receiver are held in the reordering buffer until the lot packet arrive. Let E[d lo ] denote the expected additional delay by the lo recovery, and let p lo denote the packet lo probability. We aume that the lo i recovered by Fat Retranmit, and it take additional RT T time. Note that Fat Retranmit i typically invoked for a packet lo unle the window ize i too mall. We etimate the additional delay E[d lo ] a E[d lo (X)] = S RT T p lo. (6) In general, predicting the packet lo probability of ubflow i difficult ince it depend on many factor like queueing capability in the path and packet burtine a well a the liding window ize. Several lo model have been developed for TCP connection (e.g., random lo model, correlated packet lo model, byte-baed network limitation model etc.) [2], [6]. A common feature i that the lo probability i an increaing function to window ize. Combing (4) and (6), we can obtain the expected value of lo recovery delay a E[d lo ]= M 1+c RT T min p lo (w ). (7) c x So far, we dicu each delay element of MPTCP, and now combine them to etimate it end-to-end delay. Let d e e denote the end-to-end delay of MPTCP, and let i denote the ubflow that experience the wort end-to-end delay. The expected end-to-end delay can be upper-bounded by the um of all the delay element of ubflow i, i.e., E[d e e (x)] E[d end + d net i = E[d end (x)]+max + d re i + d lo ] S E[dnet From (1), (4) and (7), we can obtain E[d e e (x)] 1 S x f +max S (x )] + E[d lo (x)]. (8) M 1+c RT T min 2(c x ) + M 1+c RT T min p lo (w ). c x (9) Note that the end buffer queueing delay i related to the um rate of ubflow and the bound on the other delay depend on the maximum network delay. Hence, given the total tranmiion rate um, it can be eaily hown that the endto-end delay bound can be minimized by allocating the tranmiion rate of individual ubflow uch that each experience an identical network delay. In the following, we formulate a cot optimization problem when each ubflow ha different cot for data tranmiion, and develop an efficient traffic plit cheme that atifie the end-to-end delay contraint. IV. COST-EFFICIENT TRAFFIC SPLITTING UNDER DELAY CONSTRAINTS Since MPTCP can achieve more oughput by initiating additional ubflow ough different network ytem, e.g., uing both LTE and Wi-Fi connection, it delay performance ha been attracting more attention. In particular, a real-time application like live video treaming or VoIP are becoming popular, the problem of long end-to-end delay become acute [4]. In thi ection, we conider cot-efficient traffic plitting problem of MPTCP in heterogeneou wirele acce network that conit of cellular network (3G/4G) and Wirele LAN (WLAN; IEEE b/g/n) ubject to the endto-end delay performance. The two network have different wirele characteritic. In general, cellular network provide reliable connectivity at low rate with low RTT, and WLAN have trength in capacity, battery ue, and cot. Given the end-to-end delay contraint, we firt formulate an optimization problem of traffic plit for the minimum

4 total network cot. We approximate the problem to obtain a practical low-complexity olution, by dividing the end-to-end delay contraint into two delay element contraint. A greedy olution to the latter problem ha been developed to minimize the cot while atifying the delay contraint. A. Problem Formulation We aume that the application generate traffic at rate f and require the end-to-end delay le than d req. Under MPTCP, the traffic can be unevenly plit to the ubflow that ue LTE network and to the ubflow that ue WLAN network. For each ubflow, we aociate it with a cot coefficient a, which denote the cot that the uer ha to pay to download data at unit rate. The total cot C(x(t)) can be written a a weighted um of ubflow cot, i.e., C(x(t)) := a x (t). Our objective i to minimize the total cot ubject to the delay requirement, i.e., minimize x 0 C(x(t)) ubject to E[d e e (10) (x(t))] d req. Note that (4) and the end-to-end delay contraint require a hidden feaibility contraint x <x cw for all. The problem i non-convex and it i hard to be olved directly due to the nonlinear relationhip between the delay element. We implify the problem in a couple of apect. Firt, we conider the ytem performance during an appropriate time period Δt uch that we can ue the expected value of the delay element. We take a hort interval for Δt (<< RTT) uch that we can keep tracking the ytem dyamic. Second, we divid the end-toend delay contraint into two main delay element: the end buffer queueing delay and the network delay. From (6) and (7), the reordering delay and the lo recovery delay can be repreented a a function of the two delay element. We now focu on the total cot within a time lot. Let k denote the k-th time lot, and let X k denote the tranmiion rate vector during the time lot. We aume that the application rate f k and the bottleneck capacity c (k) of ubflow are contant during a time lot. At each time k, we etimate f(k) and c (k), and allocate traffic x (k) for each ubflow to minimize the total cot ubject to the delay contraint. For the two delay element contraint, we introduce two ehold d end and d net, each of which contrain the expected end buffer queueing delay E[d end (x k )] and the network delay E[d net (x k )], repectively. Alo, let x (k) and x cw (k) denote the traffic allocation (from the end buffer) to ubflow and the maximum tranmiion rate of ubflow at time lot k, repectively. We now approximate (10) a follow. minimize xk 0 C(x k ) ubject to x k x cw k E[ E[ d net (x k )] d net end d (x k )] d end d net + d end d req. (11) The main difference between (10) and (11) include i) the dicrete time unit, ii) the eparation of the end-to-end delay contraint, and iii) the integration of the lo recovery delay and the network delay that account for the impact of tranmiion delay on lo probability. It i indeed a complicated proce to find the optimal delay ehold in (11). In general, a mall d net value lead to mall tranmiion rate, which can caue low capacity utilization. On the other hand, exceive d net may incur a number of packet loe, reulting in a large lo recovery delay. Baed on extenive imulation reult hown in Section V, we et d net to [100, 500] m and dend to 100 m. In the following, we develop a traffic plit cheme for good delay performance provided the two delay ehold. Finding the optimal ehold i out of the cope of the paper and remain a an open problem B. MPTCP with traffic plit control Given our formulation (11), we deign a traffic plitting cheme for MPTCP given the two delay ehold d end and d net. Overall, our cheme called a MPTCP with Traffic Split Control (MPTCP-TSC) work a follow. In each time lot, MPTCP-TSC doe, 1) Etimate f k and c,k : We aume that the value of f k and c,k doen t vary in one time lot. Therefore, fk and c,k i etimated from meaured value of f k 1 and c,k 1. f k+1 = f k = b k+1 b k Δt + S x,k, (12) where b k denote the amount of backlogged packet in end buffer. In the ame manner, we etimate the bottleneck link capacity from the tranmiion rate and the round-trip time change. Let RT T,k denote the RTT value of ubflow during the k-th time period. Rearranging (4), we can obtain the bottleneck link capacity c,k by meauring RT T,k after k- th time, i.e., c,k+1 = c,k = x,krt T,k +(M 1) RT T,k RT T min. (13) 2) Calculate available maximum tranmiion rate: From (4) and (13), the available maximum tranmiion rate x that atifie the network delay contraint and TCP congetion window x cw i obtained traightforwardly. However, when ubflow congetion control algorithm are coupled, a ubflow with large window may retrict the other ubflow window increae [1], [6]. We remedy thi initial bia by removing the bound x for the ubflow in the low tart phae. Specifically, if a ubflow i in the low tart phae, it tranmiion rate i contrained only by x x cw rapidly enlarge it congetion window.. Thi will help new ubflow to Further, we add a lower bound x min of the tranmiion rate to periodically meaure the RT T and c. Finally, the tranmiion rate x of ubflow i bounded by x min x { x cw if in low tart, min{x cw, x } otherwie. (14)

5 3) Greedy allocation of tranmiion rate: Baed on the bound (14), we determine the tranmiion rate from the end buffer to each ubflow in a greedy manner a follow. 1) For each ubflow, calculate the maximum tranmiion rate x from (4) and (13) with d net, i.e., x = c,k M 1+ c,k RT T min 2d net. (15) 2) Define total reidual tranmiion rate T, and initialize it to the minimum total tranmiion rate to atify the end buffer delay that can be calculated from (1) and (12) with d end, i.e., T = f k + 1. (16) d end 3) Among the ubflow whoe tranmiion rate i not determined, find the ubflow with the mallet cot efficient a and et it tranmiion rate a { min{t,x cw x,k =,k } if in low tart, min{x,t,x cw,k } otherwie. (17) Reet x,k = x min if x,k <x min. 4) Update T T x,k. Repeat 3) if T>0, and et the tranmiion rate of the ret ubflow to 0 otherwie. Our greedy heuritic allocate the traffic to the ubflow with the mallet cot firt, under the delay contraint. In the following we evaluate our traffic plitting cheme and compare it with the conventional MPTCP. V. PERFORMANCE EVALUATION We evaluate MPTCP-TSC uing n-3 imulator [7] and compare it with the conventional MPTCP. We conider heterogeneou wirele network where the receiver ha two air interface of Wi-Fi and LTE. By etablihing an MPTCP connection to the receiver, we et the erver to maintain two ubflow: one ough each wirele interface. We conider an Video application with H.264 AVC that ha a VBR traffic with f [0, 6] Mbp [8]. For Wi-Fi connection, we et the cot coefficient to a wifi =1per Mbp and the link capacity c wifi to 3 Mbp on average (and up to 5 Mbp), which i retrained for imulation purpoe 1. For LTE connection, we et a lte =10per Mbp and the link capacity c lte to [10, 20] Mbp. A. Delay performance We meaure the cumulative ditribution of one way end-toend packet delay under the conventional MPTCP and our propoed MPTCP-TSC. For MPTCP, we conider the both cae with uncoupled and coupled congetion control. MPTCP with uncoupled congetion control maintain their ubflow independently a if parallel TCP connection, while MPTCP with coupled congetion control determine each ubflow 1 If c wifi > f, the olution become trivial and all the traffic will go ough the Wi-Fi network. Fig. 2. Cumulative ditribution of one way end-to-end delay. Fig. 3. Cumulative ditribution of RTT in WiFi network. window a pecified in Section IV-B2. In thi imulation, we et the end buffer delay contraint(d end ) to 100m. Fig. 2 how that under MPTCP with uncoupled congetion control, even though the um of wirele capacity i much higher than traffic rate, only 24% of tranmitted packet arrive within the required delay and the 95-percentile delay i about 2.02 econd. Becaue of low packet lo rate, each ubflow ha almot the ame tranmiion rate regardle of their capacity. For MPTCP with coupled congetion control, the delay performance i further degraded due to the biaed ubflow uage. Only 18% of tranmitted packet atify the required delay, and the 95-percentile delay i about 1.96 eccond. Poor delay performance of MPTCP can everely impair the quality of real-time application. In contrat, our propoed traffic plitting cheme with different network delay contraint of d net = {100, 200, 500} m uccefully maintain the endto-end delay and efficiently ditribute the traffic according to each ubflow bottleneck capacity. Under the ame circumtance, we meaure the cumulative ditribution of RTT of the Wi-Fi connection. Fig. 3 illutrate that more than 40% of packet experience additional network queueing delay under the conventional MPTCP, indicating that too many packet are injected to the Wi-Fi ubflow. Under our MPTCP-TSC, more than 80% of packet have RTT le than 2d net. Some packet have experienced additional delay due to meaurement error and unexpected ytem dynamic. Unlike the Wi-Fi ubflow, the packet in the LTE ubflow

6 Fig. 4. Average network cot and ratio of tranmiion rate to capacity. Fig. 5. Max intantaneou ratio of tranmiion rate to capacity. alway experience the minimum RTT (40 m) for all cae, ince it capacity i ufficiently larger than the application rate. B. Cot-efficient traffic plit We conider the total uer cot and the the link utilization meaured a the ratio of tranmiion rate to bottleneck capacity (x /c ). It ha been oberved in Fig. 2 that under MPTCP-TSC, a tighter delay contraint lead to better delay performance. Fig. 4 how the impact of the tight delay contraint d net on the network cot, and how the trade-off between the delay performance of the cot: a decreaing d net, MPTCP-TSC route more traffic ough the LTE conenction, which increae the total uer cot. MPTCP-TSC with d net = 100} m ha even higher cot than the conventional MPTCP at the expene of low end-to-end delay. The reult implie that finding an appropriate ehold i an intereting problem, which i beyond the cope of the paper. Fig. 5 demontrate the maximum intantaneou utility of both Wi-Fi and LTE connection. For the conventional MPTCP, the intantaneou utility peak in 1.39 and 1.56 for the Wi-Fi connection, repecitvely. Thi implie that under the conventional MPTCP, packet can be over-injected beyond the capacity and experience ignificant queueing delay. In contrat, our MPTCP-TSC maintain the intantaneou utility and uccefully avoid unneceary queueing delay. VI. CONCLUSION In thi paper, we develop an analytical framework to analyze the end-to-end delay performance of MPTCP. We divide the end-to-end delay into four different delay element and provide in-depth undertanding on each element. Baed on the model, we formulate an optimization problem for cot minimization under the end-to-end delay contraint, when each ubflow ha a different cot for data tranmiion. We approximate the problem with two delay element of the end buffer delay and the network delay, and develop a novel traffic plit control for MPTCP to minimize the uer cot while atifying the delay contraint. Baed on the anlaytical model of delay performance of MPTCP, our propoed cheme MPTCP-TSC clarifie the trade-off relationhip between the cot efficiency and the delay performance. We evaluate the propoed cheme ough imluation. The reult how tht MPTCP-TSC outperform the conventional MPTCP, and uccefully plit the traffic while minimizing the uer cot and atifying the endto-end delay contraint. For future work, we aim to extend our reult to develop more precie and efficient algorithm that are provably efficient. ACKNOWLEDGMENT Thi work wa upported by the Samung Electronic DMC reearch center. REFERENCES [1] Damon Wichik, Cotin Raiciu, Adam Greenhalgh, Mark Handley, Deign, implementation and evaluation of congetion control for multipath TCP, in Proc. of ACM NSDI, no. 5, Jun [2] Eli Broh, Salman Abdul Baet, Vihal Mira, Dan Rubentein,Henning Schulzrinne, The Delay-Friendline of TCP for Real-Time Traffic, IEEE/ACM Tranaction on Networking, vol. 18, no. 5, Jan [3] M. Schwartz, Telecommunication network : protocol, modeling and analyi, Prentice Hall, Jan [4] H. Jiang, Yaogong Wang, Kyunghan Lee, Injong Rhee, Tackling bufferbloat in 3G/4G network, in Proc. of IEEE IMC, Nov [5] Yung-Chih Chen, Yeon-up Lim, Richard J. Gibben, Erich M. Nahum, Ramin Khalili, Don Towley A Meaurement-baed Study of MultiPath TCP Performance over Wirele Network, in Proc. of ACM IMC, Nov [6] J Padhye, V Firoiu, D Towley, J Kuroe, Modeling TCP oughput: a imple model and it empirical validation, ACM SIGCOMM Computer Communication Review, Oct. 1998, pp [7] MPTCP implementation for NS-3. [online] Available : [8] H.264/SVC Video Trace Library. [online] Available : [9] Yu Cao, Mingwei Xu, Xiaoming Fu, Delay-baed congetion control for multipath TCP, in Proc. of IEEE ICNP, Nov [10] Ramin Khalili, Nicola Gat, Mirolav Popovic, Utkarh Upadhyay, Jean-Yve Le Boudec, MPTCP i not Pareto-optimal: performance iue and a poible olution, in Proc. of ACM CoNext, Dec [11] K Ramakrihnan, S Floyd, D Black, The Addition of Explicit Congetion Notification (ECN) to IP, IETF RFC 2481, Sep [12] A. Ford, C. Raiciu, M. Handley, S. Barre, J. Iyengar, Architectural Guideline for Multipath TCP Development, IETF RFC 6182, Mar [13] Xinggong Zhang, Yang Xu, Hao Hu, Yong Liu, Zongming Guo, Yao Wang, Profiling Skype Video Call: Rate Control and Video Quality, in Proc of IEEE INFOCOM, Mar [14] Se-Yong Park, Changhee Joo, Yongeok Park, and Saewoong Bahk Comparion of queueing delay and BDP in current wirele network technical report, Feb [online] Available : py/tr-queiueing.pdf