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Survey: RTCP Feedback In A Large Streaming Sessions

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					                                                             (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                            Vol. 8, No. 8, November 2010

       SURVEY: RTCP FEEDBACK IN A LARGE STREAMING
                       SESSIONS

     Adel Nadhem Naeem1, Ali Abdulqader Bin Salem2 Mohammed Faiz Aboalmaaly3 and Sureswaran Ramadass4
                                                  National Advanced IPv6 Centre
                                                    Universiti Sains Malaysia
                                                        Pinang, Malaysia


Abstract—RTCP has limitation with scalability for large                  The SR provides more statistics summarizing data transmission
streaming sessions; because of the limitation of the bandwidth           from the sender, e.g. timestamps, count of RTP data packets,
space that given to RTCP reports. Many researchers studied and           and number of payload octet’s transmitted [4].
still studying how to solve this limitation, and most of the
researchers come out with tree structure as a solution but in a             •    RRs are used mainly in sender-based adaptive
different ways.                                                                  applications (The packet loss parameter in the RRs has
                                                                                 been used as an indicator of congestion in the
   Keywords- RTCP/RTP; Scalability; Large Streaming Sessions                     network).
                                                                            •    The SR is useful in lip-synchronization (inter-media
                        I.   INTRODUCTION                                        synchronization) and in calculating transmission bit
    Communication is everywhere in our life and as a part of it                  rates.
is multimedia communication like, VoIP, multimedia
                                                                             What does scalability mean when it uses with RTCP term,
conferencing, teleconferencing, video surveillance, satellite
                                                                         increase the number of hosts in one session then increase the
communication, etc. Multimedia communication is mainly
                                                                         number of RTCP report, which means RTCP scalability. RTCP
using Real time protocol (RTP) that works together with Real
                                                                         is kind of reports' protocol that sends/receive reports from/to
time control protocol (RTCP) to do transfer data that depend on
                                                                         hosts in one session. These reports limited to bandwidth size,
real time like video or audio over networks. RTCP is used to
                                                                         RTCP given 5% from the whole session bandwidth size. RTCP
monitor RTP-Packets and reports feedback [1]. The main
                                                                         has two types of the report: Sender report and Receiver report.
function of RTCP is to transmit periodically the sender and
                                                                         Sender report uses 75% of RTCP bandwidth size while
receiver reports to all members in RTP/RTCP. These reports
                                                                         Receiver report uses 25%. The limitation of bandwidth size of
allow a host to know if a problem exists or not and if the
                                                                         RTCP makes it control the interval of sending receiving
problem is local or global [2]. RTCP like other protocols and
                                                                         reports, increasing the number of hosts caused to increase the
techniques facing a lot of problems, one of the important
                                                                         interval of sending receiving time and that makes the reports
problems is RTCP scalability. [3] Increasing the number of
                                                                         useless [6].
hosts in RTP/RTCP sessions caused some problems under the
name of the scalability problems; the problems can be the
feedback delay, storage problem, flood of initial/bye RTCP                         III.   CHALLENGES OF RTCP SCALABILITY
reports, etc.                                                                Many researchers studied and wrote about RTCP problems,
                                                                         and the most important problems are about the scalability of
                  II.    SCALABILITY OF RTCP                             RTCP and reports’ feedback in a large streaming session. The
                                                                         scalability in RTCP faces many problems when it comes to a
    RTP is a real time transmission protocol of audio and video,
                                                                         group of thousands of users. Some of these problems are
which provide several functions that help the transmission of
                                                                         addressed in [2 ... 11]. The first serious study done by El-
audio and video such as [4]. Identification of payload data type,
                                                                         Merakby, with three main researches 1998 “A Scalability
give a Sequence numbering to detect packet loss and to order
                                                                         Scheme for the Real-time Control Protocol”, 2000 “Design and
packets, Time stamping so that data is played out at the right
                                                                         Performance of a Scalable Real Time Control Protocol:
speeds [5]. RTCP is the attached protocol to RTP, and its
                                                                         Simulations and Evaluations”, and 2005 “Scalability
working by sending/receiving reports, and it has several kinds
                                                                         improvement of the real time control protocol” where she
of reports the main reports in RTCP are the sender report (SR)
                                                                         studied RTCP problems with scalability and suggested a
and receiver report (RR). Both include performance statistics
                                                                         solution by divide the large session group to small session
on the total number of packets lost since the beginning of
                                                                         groups [4, 8, 9].
transmission, the fraction of packet loss in the interval between
sending this feedback report and sending the previous one, the
highest sequence number received, jitter, and other delay
measurements to calculate the round-trip feedback delay time.




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                                                                                                    ISSN 1947-5500
                                                                (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                               Vol. 8, No. 8, November 2010
A. Feedback delay challenge                                                    The following are the advantages of using the scheme in
    One of the important challenges is the feedback delay and               large RTCP groups [4, 8, 9]:
caused by increasing the group size, because of the limitation                •    Resolving the storage scalability problem: Members do
of the bandwidth size the RTCP reporting interval increased                        not need to store the state of the distinct member in the
which decreases the significance and value of the feedback, and                    group because they are in a different small group size.
then the feedback reports either send rarely or not at all [3, 4, 8,
9].                                                                           •    Timely reporting of feedback reports: Feedback reports
                                                                                   become more useful because the number of members
B. Storage challenge                                                               became less.
    The group size could be known if every member stores a                    •    Effective use of the bandwidth: the formation of local
count of distinct for every member it heard during the session                     regions where RRs are not multicast but are sent with
using the unique Synchronization Source identifier (SSRC)                          limited scope and not global scope decrease the number
found in the RTP header [3, 4, 8, 9].                                              of RRs.

C. Multicasting RRs to the whole group (bandwidth effect)                     •    Decrease in the number of redundant reports: the total
                                                                                   number of redundant RRs, which used to be multicast,
    Every member in the session group will multicast RRs                           is decreased, because the measurements in RRs are
(Receiver Report) to all other which are not senders and that                      aggregated into AGRs summarizing the quality of the
causes a load at every member processing and Congestion will                       received data.
happen because of members increase then RR increase also[4,
8, 9, 10].                                                                      In the other side, another researcher was interesting in the
                                                                            same area, Julian from University of Cambridge. He published
D. Initial/bye flood challenge                                              an article with title “An Extensible RTCP Control Framework
                                                                            for Large Multimedia Distributions” in 2003. Julian thought
    If many members join/leave the session at the same time, a              that is two serious challenges with RTCP and they are: the
flood of join/Bye packets will happen and congestion in the                 growing of using unidirectional and asymmetric broadcast
network may occur, especially at members who have low                       architectures, and the second challenge: per-receiver RTCP
bandwidth links [3, 4, 5, 8, 9].                                            reporting frequency diminishes prohibitively due to the
    El-Merakby tried to explain that the normal case for RTCP               bandwidth-sharing algorithm [2].
feedback reports are multicast mainly for receivers to calculate
the group size and thus compute their RTCP reporting interval,              A. The growing deployment of unidirectional and
and the suggested solution is saying that the members do not                    asymmetric broadcast architectures challenge
need to compute the whole size of the multicast group and RRs                   In RTP/RTCP, the data and control share a many-to-many
are not multicast, and to divide the big session to many groups.            communication channel, such as that provided by IP multicast
The proposed structure is called S-RTCP, and shown in Fig 1,                [11]. The unidirectional and asymmetric broadcast
explains how members organize dynamically in a multi-level                  architectures have problems with these issues; instead the
hierarchy of local regions.                                                 channel allows not only the bidirectional flow of
                                                                            communication from sources to receivers and vice-versa, but
                                                                            also direct receiver-to-receiver communication over a single
                                                                            channel [2, 11].

                                                                            B. Per-receiver RTCP reporting frequency diminishes
                                                                                prohibitively due to the bandwidth-sharing algorithm
                                                                                RTCP is keeping the frequency of reports inversely
                                                                            proportional to the number of members. And because of that
                                                                            RTCP institutes a bandwidth-sharing algorithm that divides the
                                                                            resources of the control channel among members’ group. The
                                                                            standard bandwidth-sharing algorithm used by RTCP expects
                                                                            that as groups grow in size, the frequency of individual
             Figure 1. Structure of El-Merakby scheme [9].                  feedback reports will decrease [2]. This problem is the same
                                                                            challenge that introduced by El-Merakby, 1998 with a
    Each region has an aggregator (AG). Each member sends                   challenge title Feedback delay challenge [4].
the RR feedback to its AG which gathers and aggregates
statistics from these reports which is passed to a manager or to                To solve these challenges, two new schemes are devised
another AG level. Additional statistics are computing by the                that are complementary to the existing RTCP feedback
manager to evaluate the transmission quality and to estimate                algorithm and influence the unique characteristics of
the regions which suffer from congestion. Time-to-Live (TTL)                summaries to efficiently scale the feedback of the unicast
field in the IP header is used by the scheme to build the multi-            backchannel for large groups. The two schemes that influence
level hierarchy with locally scoped regions [4, 8, 9].                      summarization to scale the backchannel: biasing and
                                                                            hierarchical aggregation [2].



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                                                                                                       ISSN 1947-5500
                                                                 (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                Vol. 8, No. 8, November 2010
     •     The technique of biasing provides preferential treatment              The MS-RTCP managers join the control multicast group,
           to the feedback of one or more groups of receivers.               while the MS-RTCP children join the data multicast group.
                                                                             Each group of children constructs a region which is controlled
     •     The technique of hierarchical aggregation supports the            by a manager. Each child should know its region before sharing
           existence of multiple summarization nodes throughout a            the RTP session. The Load Balancing Manager (LBM)
           collection topology, which distributes the load and               accomplishes this target by testing the real position of each
           bandwidth usage of summarization, and in turn lends               child and the real number of children per region. The scheme
           much-needed support to heterogeneous topologies as                structure is shown in Fig. 2.
           well as to frequency-driven applications.
    In 2005, another researcher was interesting in scalability of
RTCP, but instead of studying the main RTCP protocol. He
decided to study S-RTCP (Scalable Real Time Protocol) that
invented by El-Marakby [4, 8,9], Elramly published two papers
“Scalability Solutions For Multimedia Real-Time Control
Protocol (PDPTA'06)” 2005, and “Analysis, Design, and
Performance Evaluation of MS-RTCP: More Scalable Scheme
for the Real-Time Control Protocol” 2005. Elramly introduced
a new protocol MS-RTCP (More Scalable Real Time Control
Protocol). MS-RTCP scheme is based on a hierarchical
structure, distributed management, and EL-Marakby scheme.
The idea of El-Marakby scheme is depending on a tree-based
hierarchy of report summarizers. The tree leafs (nodes) in the
session send RRs to some node that acting as AG (aggregator),
collects and summarizes these reports. The summaries result
then passed up to the next highest level in the tree, until finally
they reach the sender or some other appropriate feedback point.
The summarization scheme is most useful when the nodes at
one level of a sub-tree see similar network performance. El-
Marakby uses network hop counts to a summarizer, measured
through Time To Live (TTL), to group hosts together in the
tree. She also proposed a dynamic scheme for building the tree
[4, 8, 9, 12, 13]. The most important introduced problems by
Elramly to El-marakby scheme (S-RTCP):
1.       Fault tolerance is not guaranteed: When any AG is                               Figure 2. General view of Elramly schem [13].
         crashed or has left the RTP session, all the children in its
         region search for other AG. This will affect the
                                                                             The suggested solution and the proposed protocol MS-RTCP:
         convergence time during this interval, and will make an
                                                                             1. Fault tolerance guarantee: any control component in the
         old child to a new one.
                                                                                 MS-RTCP has a spare one. If one or more scheme
2.       Load balancing is not guaranteed: The load balancing
                                                                                 components fail, can replace the failed one with its spare
         depends on the maximum number of children with which
                                                                                 one by the decision from the GM (or FTM) until the failed
         the AGs deals. This is not sufficient, because if we
                                                                                 one is fixed and the normal situation is re-established.
         suppose that the maximum number of each AG is 100
                                                                             2. Load balancing guarantee: the decision for receiving a
         children, we may find AG has 90 children and another has
                                                                                 new child in the RTP session depends on the real number
         10 children.
                                                                                 of children per scheme manager. Consequently, if any
3.       The structure of the model depends on the central
                                                                                 new child joins a session, it is told with the best manager
         processing unit (manager). Hence, if the manager is
                                                                                 taking in consideration the manager load (real children
         crashed there is no other unit that can take place. The
                                                                                 number) and the new child position.
         model in this case will become unstable (failed in worst
                                                                             3. The basic idea of the MS-RTCP is based on the
         case).
                                                                                 management distribution. So, the central management
4.       Overkill the small groups, which the IP telephone is
                                                                                 processing is eliminated, as the scheme has one manager
         mainly dealing with. This is due to the condition of low
                                                                                 for each management process.
         children number per AG that was put after the model
                                                                             4. The maximum number of children per manager reaches
         evaluation [8].
                                                                                 the upper limit at which the RTP session is working safely
5.       Election of LAN Aggregator (LAG) is not sufficient.
                                                                                 (some hundreds or more). Hence, if a small group joins
         Source Description (SDES) items [1] about any multicast
                                                                                 the RTP session, the MS-RTCP will be transformed to the
         group member will take a long time to access it.
                                                                                 simple RTCP view with one manager and it’s spare. The
                                                                                 other MS-RTCP managers will be found, but with
                                                                                 minimal overhead (neglected values).



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                                                                                                          ISSN 1947-5500
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5.   The LAN Manager (LAN-M) has its pre-determined spare               Dan Komosny, and Vit Novotny come out with:
     component. So, in this scheme, no need to elect another            1. Solve round trip delay by suggestion tree structure.
     LAN-M when the basic one fails.                                    2. The problem of the RTCP feedback tree establishment
6.   The GM can access any data about any MS-RTCP entity                    was solved.
     by requesting the SDESM (or by CDM in case of any                  3. The method for finding the nearest summarization node in
     problem happened for the SDES-M).                                      the IP network structure was designed.
                                                                        4. To manage the tree the new protocol (TTP) was designed
    In Brno University of Technology, Czech Republic, 2007,                 and specified.
new researchers work with scalability of RTCP. Dan Komosny,
and Vit Novotny, started to study scalability of RTCP and its               Shaahin Shahbazi comes with two papers about RTCP
challenges. They published three papers together, “Tree                 scalability, “A new design for improvement of scalable-RTCP”
Structure for Source-Specific Multicast with Feedback                   2009, and “Error Resistant Real-Time Transport Control
Aggregation” 2007, “Optimization of Large-Scale RTCP                    Protocol” 2009. As Elramly 2005, he preferred to deal with El-
Feedback Reporting in Fixed and Mobile Networks” 2007, and              Marakby protocol (Scalable Real Time Control protocol)
“Large-Scale RTCP Feedback Optimization” 2008. The                      SRTCP. Shahbazi explained about the challenges associated
researchers find that RTCP in a large session causes delays in          with S-RTCP, and proposed different approaches to solve
sending feedback data from each receiver, and to solve this             the challenges [18, 19, 4, 8 ,9].
problem they proposed a hierarchical structure and new
protocol called Tree Transmission Protocol (TTP). Their work            A. The S-RTCP challenges
more to be extended to Julian 2003[2], where they solve some               •      Congestion: If the number of AGs becomes very big
of the hierarchical structure that proposed by Julian 2003. The                   of AG-0, congestion may occur at the links connected
Fig. 3 is shown the tree structure [14, 15, 16, 17].                              to AG-0.
                                                                           •      Overload: because of the same reason overload may
                                                                                  happen.
                                                                           •      Lack of error-tolerance: S-RTCP design is quite
                                                                                  vulnerable to any sort of malfunctions within AG-0.

                                                                        B. Proposed Design for Stability Improvement
                                                                           problems are caused due to the singularity of AG-0 in
                                                                        S-RTCP’s design and also the fact that no precautions
                                                                        have been taken into account in case AG-0 fails [18]. See Fig.
                                                                        5.
                                                                            •       The number of AG-0 nodes: fix the amount of AG-0s
                                                                                    at two.
                                                                            •       Mirrored tasks versus split tasks: all AG-0s receive
Figure 3. Tree topology of the RTCP feedback network [17].                          the same information.
                                                                            •       Existence of pre-assigned AG-0: new design will
    To solve the problem of hierarchical structure organization                     allow two or more AG-0s to operate within the
new protocol has been proposed TTP (Tree Transmission                               session, in order to provide stability.
Protocol), this protocol is quite a flexible and robust protocol
use to organizing the hierarchical tree overlays. It can be used
for any hierarchically organized protocols. It can work for
simple hierarchical tree overlays as well as for large-scale
overlays with many hierarchical levels. The fig 4 shows TTP
position [15, 16].




                                                                               Figure 5. The architecture of the modified version of S-RTCP [18]

Figure 4. Position of TTP to related protocols [16].
                                                                            Shahbazi was designed a new proposed scheme ER-RTCP
                                                                        (Error Resistant Real-Time Transport Control Protocol).
                                                                        Modifications included designing the multi-manager scheme,



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                                                                                                          ISSN 1947-5500
                                                                   (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                  Vol. 8, No. 8, November 2010
improving parent-seeking procedures, reducing distribution of                        IV.    COMPARISON BETWEEN RESEARCHERS’ WORK
request packets, reforming the design to be independent of                         The comparison can be show in Table 1.
TTL, adding methods to check on sanity of manager nodes.
This study considered packet loss ratio of below 2% as
desirable [18, 19]. See Fig. 6.                                                                            V.      SUMMARY
                                                                                  RTCP protocol has some problems and many researchers
                                                                              studied to solve it specially the scalability issue, the main
                                                                              problem was with the limitation of bandwidth space that given
                                                                              to RTCP reports, which all the researcher come with tree
                                                                              structure as a solution for it but in different ways.




             Figure 6. The architecture of ER-RTCP [19]



                                             TABLE I.      COMPARISON BETWEEN RESEARCHERS’ WORK

                                                                                                                                 New
                                Period of
               Researcher                                              Problems that solved                                   suggested
                                 studies
                                                                                                                               protocol
                                              1-   The research studied RTCP.
                                              2-   Feedback delay.
                               1998, 2000,    3-   Increasing storage state.
               El-Marakby                                                                                                      S-RTCP
                               2003, 2005     4-   Multicasting RRs congestion.
                                              5-   Flood (Initial/Bye).
                                              6-   Come out with tree structure.
                                              1-   The research studied RTCP.
                 Julian                       2-   Unidirectional and asymmetric broadcast architectures problem.
                                   2003                                                                                            -
               Chesterfield                   3-   Bandwidth-sharing algorithm.
                                              4-   Come out with tree structure.
                                              1-   The research studied S-RTCP.
                                              2-   Fault tolerance is not guaranteed.
                                              3-   Load balancing is not guaranteed.
                                              4-   The structure of the model depends on the central processing unit.
                El-Ramly           2005                                                                                       MS-RTCP
                                              5-   Overkill the small groups.
                                              6-   Election of LAN Aggregator (LAG) is not sufficient.
                                              7-   Source Description (SDES) items.
                                              8-   Come out with tree structure.
                                              1-   The research studied RTCP.
                                              2-   Round trip delay.
              Dan Komosny,
                                2007, 2008    3-   The RTCP feedback tree establishment.                                         TTP
              & Vit Novotny
                                              4-   Finding the nearest summarization node in the IP network structure.
                                              5-   Come out with tree structure.
                                              1-   The research studied S-RTCP.
                                              2-   Congestion.
                 Shaahin           2009       3-   Overload.                                                                  ER-RTCP
                                              4-   Lack of error-tolerance.
                                              5-   Come out with tree structure.




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                                                                                                                ISSN 1947-5500
                                                                        (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                       Vol. 8, No. 8, November 2010
                                                                                    [18] S. Shahbazi, K. Jumari, and M. Ismail, "A new design for improvement
                          ACKNOWLEDGMENT                                                 of scalable-RTCP," 2009, pp. 594-598.
                                                                                    [19] S. Shahbazi, K. Jumari, and M. Ismail, "Error Resistant Real-Time
   I would like to thank National Advanced IPv6 Center                                   Transport Control Protocol," Am. J. Engg. & Applied Sci, vol. 2, pp.
(NAv6), Universiti Sains Malaysia for their support that                                 620-627, 2009.
enabled me to complete this work.
                                                                                                              AUTHORS PROFILE
                               REFERENCES
[1]    H. Schulzrinne, S. Casner, R. Frederick, and V. Jacobson, "RTP - A                               Adel Nadhem Naeem: He completed his bachelor
       Transport Protocol for Real-time Applications," RFC 3550 (STD 64),                               degree in computer science in 2004 from Shat Al-Arab
       July 2003.                                                                                       University College, worked as IT in Iraqna
                                                                                                        Telecommunications Company from October 2004 until
[2]    J. Chesterfield, E. M. Schooler “An extensible RTCP control framework                            June 2007, started his master's degree in July 2007 in
       for large multimedia distributions”, 2003.                                                       computer science school, USM , and completed it in
[3]    J. Rosenberg, H. Schulzrinne, Timer reconsideration for enhanced RTP                             August 2008, now he is a PhD candidate in National
       scalability, Proceedings of IEEE Infocom’98, San Francisco, CA, 1998,             Advance IPv6, USM. He is one of the researchers that help to develop
       pp. 233–241.                                                                      and improve the communications and networking field, working in
[4]    R. El-Marakby, D. Hutchison, A scalability scheme for the real-time               multimedia conferencing area.
       control protocol, Proceedings of IFIP TC-6 Eighth International
       Conference on High Performance Networking (HPN’98), Vienna, 1998,                                 Ali Abdulqader Bin Salem: received B.S (computer
       pp.153–168.                                                                                       science) degree from Al-Ahgaff University, Yemen in
[5]    J. Rosenberg, H. Schulzrinne, Timer reconsideration for enhanced RTP                              2006 and M.S (computer science) from University
       scalability, Proceedings of IEEE Infocom’98, San Francisco, CA, 1998,                             Science Malaysia (USM), Malaysia in 2009. Currently,
       pp. 233–241.                                                                                      he is a PhD student at National Advance IPv6 Center
[6]    T. Friedman, R. Caceres, A. Clark "RTCP Reporting Extensions", RFC                                (NAv6), (USM). His current research interests include
       3611, 2003.                                                                                       wireless LAN, multimedia QoS, and video
[7]    J. Rosenberg, H. Schulzrinne, New Results in RTP Scalability, IETE,               transmission over wireless, distributed system, P2P, and client-server
       1997, Internet draft: draft-ietf-avt-byerecon-00.ps                               architecture.
[8]    R. El-Marakby, Design and performance of a scalable real time control
       protocol: simulations and evaluations, Proceedings of the Fifth IEEE                               Mohammed Faiz Aboalmaaly : A PhD candidate, He
       Symposium on Computers and Communications (ISCC’2000), Antibes-                                    received his bachelor degree in software engineering
       Juan Les Pins, France, 2000, pp.119–124.                                                           from Mansour University College (IRAQ) and a
[9]    Randa El-Marakby, David Hutchison: Scalability improvement of the                                  master’s degree in computer science from Univeriti
       real-time control protocol, Computer Communications 28 (2005) 136–                                 Sains Malaysia (Malaysia). His PhD. research is
       149.                                                                                               mainly focused on Overlay Networks. He is interested
                                                                                         in several areas of research such as Multimedia Conferencing, Mobile
[10]   B. Aboba, Alternatives of enhancing RTP scalability, IETF, 1996,                  Ad-hoc Network (MANET) and Parallel Computing.
       Internet draft: draftaboba-rtpscale-02.txt.
[11]   S. Deering. Host extensions for IP multicasting. Request for Comments
       1054, Internet Engineering Task Force, Aug. 1989                                                    Professor Dr. SureswaranRamadass: is a Professor
                                                                                                           and the Director of the National Advanced IPv6 Centre
[12]   O. Essa, N. El-Ramly, and H. Harb, "SCALABILITY SOLUTIONS                                           of Excellence (NAV6) at UniversitiSains Malaysia.
       FOR MULTIMEDIA REAL-TIME CONTROL PROTOCOL
       (PDPTA'06), 2005.                                                                                   Dr. Sureswaran obtained his BsEE/CE (Magna Cum
                                                                                                           Laude) and Masters in Electrical and Computer
[13]   N. Elramly, A. Habib, O. Essa, and H. Harb, "Analysis, Design, and                                  Engineering from the University of Miami in 1987 and
       Performance Evaluation of MS-RTCP: More Scalable Scheme for the                                     1990 respectively. He obtained his PhD from
       Real-Time Control Protocol," Journal of Universal Computer Science,               UniversitiSains Malaysia (USM) in 2000 while serving as a full time
       vol. 11, pp. 874-897, 2005.                                                       faculty in the School of Computer Sciences.
[14]   V. Novotný, D. Komosný, “Optimization of Large-Scale RTCP                         Dr. Sureswaran's recent achievements include being awarded the
       Feedback Reporting in Fixed and Mobile Networks”. Proceedings of                  AnugerahTokoh Negara (National Academic Leader) for Innovation and
       international scientific conference ICWMC2007(the third International             Commercialization in 2008 by the Minister of Science and Technology.
       Conference on Wireless and Mobile Communications), March 2007, pp.                He was also awarded the Malaysian Innovation Award by the Prime
       1 – 6, ISBN: 0-7695-2796-5, Guadeloupe, 2007                                      Minister in 2007. Dr. Sureswaran is also the founder and headed the
[15]   D. Komosny and V. Novotny, "Tree structure for source-specific                    team that successfully took Mlabs Systems Berhad, a high technology
       multicast with feedback aggregation," 2007, pp. 0-7695.                           video conferencing company to a successful listing on the Malaysian
[16]   R. Burget, D. Komosny, and M. Simek, "Transmitting Hierarchical                   Stock Exchange in 2005. Mlabs is the first, and so far, only university
       Aggregation Information Using RTCP Protocol," IJCSNS, vol. 7, pp.                 based company to be listed in Malaysia.
       11-44, 2007.
[17]   V. Novotn and D. Komosn, "Large-scale RTCP feedback optimization,"
       Journal of Networks, vol. 3, p. 1, 2008.




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