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QoE-aware Resource Provisioning and Adaptation inIMS-based IPTV Using OpenFlow

Thu Huong-Truong, Nguyen Huu Thanh, Nguyen Tai Hung

Hanoi University of Science and Technology (HUST)Hanoi, Vietnam

{huong.truongthu, thanh.nguyenhuu,hung.nguyentai}@hust.vn

Julius Mueller (1), Thomas Magedanz (2)

(1) Technical University Berlin(2) Fraunhofer FOKUS Institute

Berlin, Germany julius.mueller@tu-berlin.de,

Thomas.magedanz@fokus.frauenhofer.de

Abstract This article presents the architecture design andexperimental evaluation of a QoE-aware flexible-QoS-controlnext-generation IPTV network. The architecture extends the IMSservice control functionality by providing an efficientapplication-specific service control approach based on usersatisfaction on the connectivity. The validation NGN testbed usesOpenFlow network virtualization between individualcomponents.

KeywordsSDN, Openflow, IMS, QoE

I. I NTRODUCTIONIMS-based IPTV nowadays has stood out as a promising

architecture for the most-exciting new IP-based services. Bymaking use of the IP Multimedia Subsystem (IMS) [6] as thecontrol overlay for IPTV, the new architecture offers a widerange of new features compared to the conventional solutions.Furthermore, with the session and service control capabilities,IMS can be used as the layer to control users Quality-of-Service (QoS) and provision the corresponding resources onthe underlying network. However, until now there still existsome issues that are not completely solved in the existingIPTV architectures.

The fist issue is how to guarantee the quality of IPTV services in a more user-centric way than todays network-centric QoS mechanisms . Recent research has demonstratedthat guaranteeing QoS does not necessarily ensure userssatisfaction [1]. Therefore, the future multimedia servicesshould be delivered based on clients perceptual qualityrequirements, or Quality-of-Experience [1]. Unfortunately, theexisting IMS overlay infrastructure does not specify any QoE-aware mechanism within its service provisioning controlsystem.

The second issue is how to dynamically map QoE of IPTV sessions to network-centric QoS parameters and provision thecorresponding network resources efficiently, so that usersservice perception is satisfied while network resources areoptimized based on current network conditions. We previously

proposed a designed concept called the Generic-Adaptive- Resource Control (GARC) [3]. Incoming meta-dataapplication requirements (QoE) from the application layer aretranslated into network specific requests by the mediationlayer, then crossing over standardized interface towards theunderlying network. GARC applies different service controlmechanisms for each specific application and individual on

the connectivity to achieve smart usage of the networkresources.

The third issue is how it can impose the QoS policies aswell as other per-session network configurations on theunderlying network infrastructure in a dynamic way ; forinstance, routing, CODEC modification, adaptive bitrates,

bandwidth reservation, traffic prioritization etc. In the recentyears, the research and industrial communities have been

paying much attention on the Software Defined Networking (SDN) and OpenFlow [2]. OpenFlow allows separating thecontrol plane and data plane, thus offers a new flexibility toreconfigure, customize, and deploy different underlyingnetworking paradigms.

Motivating by the above issues, our main contributions fordesigning the innovative IPTV architecture are:

(1) Design a novel QoE-aware IPTV network architecture thatintegrates IMS overlay with the underlying Openflownetwork infrastructure that can adapt network resourcesand service characteristics based on users requirements.It allows users to rate their service satisfaction atubiquitous devices and enables service-aware networkingthrough user-demanded QoS requests.

(2) Build up a real testbed for development of new IPTVservices, network control mechanisms, and formeasurement and analysis.

II. R ELATED WORKS To the best of our knowledge, research [5] could be closest toour research. However, the cross-layer adaptation is only inthe bottom-up direction that reports the network condition tothe user terminal to adapt codec and bit rate. The architectureis not able to adapt application requirements to QoS settings inthe top-down direction. Moreover, the IP core network isassumed to be MPLS that cannot enable the SDN benefit.

III. THE ARCHITECTURAL DESIGN The whole concept is implemented in a testbed

infrastructure set up in our lab that helped us to prototype newmultimedia, rich-feature communication services using IMSframework; investigating the impact of network conditions upon users perception of the provided services; and checkingQoS control within Openflow real-time scenarios. The testbedconsists of three layers as illustrated in Figure 1 .

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Figure 1 QoE-aware next-generation IPTV architecture

Application layer : the IMS IPTV Client with the QoE

engine was prototyped based on the open source IMSCommunicator. The QoE engine learns its user in differentsprofiles (e.g talk show or action movie etc..). It then predictsthe users satisfaction level with the corresponding QoS

parameters at the same monitoring time, periodically duringthe course of an on-going session

The Application Server was developed for IPTV valueadded services based on Sailfin platform. The AS includesQoE/QoS module that collects Opinion Score from clientterminals including corresponding QoS parameters (e.g.Packet loss rate, delay, jitter) into the following table:

User Content Delay Jitter Bitrate PLR MOSalice Action 0 0 230006 0 4

bob talkshow 0 0 732177 0 5 bob Action 208 207 62977 0 2

Figure 2 Database of QoS settings and predicted MOS at the AS

A Video server was also developed based on DarwinStreaming Server.

The IMS core layer for signaling and session/servicecontrol [4] that delivers CSCF servers and a user profiledatabase (HSS).

The media layer for transportation of media traffic inunicast, multicast and broadcast. The core transportationnetwork is built with virtualized Openflow switches and itstechnology. The GARC component is also integrated to thecore network. Controller Switch Interface uses the specified

OpenFlow Protocol in version 1.1 [2], providing OpenFlowcontroller interfaces for performing Open Flow routing.Based on the collected database of each user with different

service categories, the GARC logic establishes a mappingfunction between QoE and QoS by using the linear regressionmethod: MoS = Br + Jt + Plr + (1)

Where:

Coeff , , , and are calculated particularly for each case.

Br : bit rate, Jt : jitter, Plr : packet loss rate

Based on the established mapping function with differentQoS profiles that translates user-centric QoE requirements tocorresponding network-centric QoS parameters, QoSmodification decisions can be: changing the networkconfiguration to get better transmission delay or packet lossrate within the transport network. The policy is then enforcedon the Openflow protocol.

IV. SUPPORTED I NTERFACES AND CALL -FLOWS This section outlines the detailed reference point

description and functionalities. The presented approach is backwards compatible with existing 3GPP network andPolicy-Control-and-Charging architectures, thereforestandardized interfaces are used for communication withexisting components.

A. InterfacesThe interfaces among the components in our architectureincluding GARC and the QoE AS are defined as follows:

OpenFlow controller (e.g.NoX): Interface between GARCany OpenFlow capable controller e.g. NOX [8] forexchanging OpenFlow specific messages (JSON via TCP)for transmitting network control and managementinformation, network monitoring data and statistics.

OF switch: For controlling flow-to-queue mapping overswitch specific DPCTL messages, which in turn enablesQoS differentiation between individual flows

P-CSCF of the IMS core: Diameter Gx for QoS provisioning in combination with the Diameter Gxxreference point for bearer-binding and event-reporting-functions.

HSS/HLR or user profile database: Diameter extended Spinterface for querying static or dynamic user profile

information. AS: Diameter extended Rx interface for signalingapplication layer QoS requirements from network-awareapplication towards GARC.

Interface OF controller OF switch : Controller SwitchInterface using the Open-Network-Foundation (ONF)specified OpenFlow Protocol in version 1.1 [7] providingstandard OpenFlow controller interfaces for performingOpenFlow conform routing.

Interface IMS client AS : SIP and XML. XML forexchanging collected data of QoE and corresponding QoSspectrum from the client to the AS.

B. Call-FlowsFigure 3 depicts a SIP based session setup and QoS

parameter negotiation between UE and IMS MRF resulting ina multimedia session. In the beginning, the UE initiates amultimedia session using a SIP INVITE indicating theterminal QoS parameter in terms of supported codecs, bit rate,etc. The QoS parameters are transported in the body of the SIPmessage as Session-Description-Protocol (SDP) including aset of supported QoS parameter for selection. The SIPINVITE signaled to the P-CSCF and is forwarded on to

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application server IMS MRF using S-CSCF for applicationserver selection.

Figure 3 QoE/QoS Control Call-Flow Model

The SIP MRF receives the SIP INVITE, pre-acknowledgesthe INVITE using a 183-session-progress response beforeanswering with the SIP 200 OK finally. The SIP 200 OKcontains the negotiated QoS parameter supported by the SIPMRF, which is forwarded to the UE through the IMS. Whilereaching the P-CSCF, the SDP parameter is transformed into3GPP Diameter access network specific Re-Auth-Requests(RAR). Each RAR is answered by an Re-Auth-Answer (RAA)indicating the successful or non-successful resource

reservation in the network. This procedure is standard conformto IETF Diamater Base Protocol [9]. The novelty in the

presented approach is the ability to apply these existing QoSreservation mechanisms in an OpenFlow virtual network.GARC receives the Diameter RAR, extracts traffic flowtemplates and QCI level and performs network resourcereservation in OpenFlow using the new defined OpenFlownorth-bound interface Rx#. A RAA is signaled back to the P-CSCF indicating the positive or negative resource reservationattempt. After the successful session was established over SIP,media data is transported between the UE and the SIP MRF

over RTP. MOS value is computed using user interaction andMOS prediction. A change in the QoE causes a re-INVITESIP signaling in behalf of the UE. The QoE module within theAS determines an enhanced QoS level. The new SDP isenforced within the network.

V. TESTBED R ESULTS We tested a scenario of four different users streamingmultimedia content over UDP. Figure 4 shows how 4 the-same-initial-QCI-level Service-Data-Flows (SDF) can be separatedinto 4 different QCI levels with particular QoS levels in theOpenFlow network having minimum guaranteed andmaximum bandwidth limitations. The modification happenedfrom sec 20 to sec 80 and reassigned from sec 80 to sec 140.

Figure 4 - Scenario Validation Measurements

Besides, Figure 5 describes how the GARC logic componentdefined separate QoE-QoS functions for each user with eachdifferent content category as generalized in equation (1).

User Content alice Action 0.003768 -0.00397 -0.430450 3.03429

bob talkshow 0.004324 -0.00283 -0.254657 2.78656 bob Action 0.003376 -0.00439 -0.714890 3.54069

Figure 5 QoE-QoS translation at the GARC Logic

VI. CONCLUSIONS

We proposed a novel IMS-based IPTV system that enablessmart cross-layer QoS control mechanism in the applicationand network layer, and the IPTV session adaptation based onQuality of Experience of users. The prototype succeeded inshowing that end-to-end QoS can be enhanced and TVsessions can be improved to satisfy each individual client

R EFERENCES [1] Markus Fiedler, et al, A Generic Quantitative Relationship between

Quality of Experience and Quality of Service, IEEE Network SpecialIssue on Improving QoE for Network Services, 2010. Vol.24, Isue.2.Page(s): 36 41

[2] OpenFlow Project and Protocol, http://www.openflow.org/[3] Julius Mueller, Thomas Magedanz, Towards a generic application

aware network resource control function for Next-Generation-Networksand beyond, ISCIT 2012, Page(s): 877 882, October 2012, Australia

[4] Open IMS Core Playground, see http://www.openimscore.org/[5] Koumaras, H. et al, A QoE-aware IMS infrastrusture for multimedia

services, ICUMT 2011, 5-7 October 2011, Budapest, Hungary[6] 3rd Generation Partnership Project; Technical Specification Group

Services and System Aspects; IP Multimedia Subsystem (IMS); Stage 2(Release 11), TS 23.228, V11.6.0 (2012-09)

[7] http://www.openflow.org/documents/openflow-spec-v1.0.0.pdf[8] N. Gude, et al, Nox: towards an operating system for networks,

SIGCOMM Comput. Com. Rev., vol. 38, no. 3, pp. 105110, Jul. 2008.[9] Diameter Base Protocol, RFC 6733, http://tools.ietf.org/html/rfc6733