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1 IEEE. Personal use of ths materal s permtted. Permsson from IEEE must be obtaned for all other uses, n any current or future meda, ncludng reprntng/republshng ths materal for advertsng or promotonal purposes, creatng new collectve works, for resale or redstrbuton to servers or lsts, or reuse of any copyrghted component of ths work n other works.

2 FamTV: An Archtecture for Presence-Aware Personalzed Televson Patrca Aras Cabarcos, Member, IEEE, Rosa Sánchez Guerrero, Member, IEEE, Florna Almenárez Mendoza, Member, IEEE, Danel Díaz-Sánchez, Member, IEEE, and Andrés Marín López, Member, IEEE Abstract Snce the advent of the dgtal era, the tradtonal TV scenaro has rapdly evolved towards an ecosystem comprsed of a myrad of servces, applcatons, channels, and contents. As a drect consequence, the amount of avalable nformaton and confguraton optons targeted at today s end consumers have become unmanageable. Thus, personalzaton and usablty emerge as ndspensable elements to mprove our content-overloaded dgtal homes. Wth these requrements n mnd, we present a way to combne content adaptaton paradgms together wth presence detecton n order to allow a seamless and personalzed entertanment experence when watchng TV 1. Index Terms Dgtal TV, content personalzaton, dentty management, presence detecton. I. INTRODUCTION Convergence has nfluenced consumer electronc devces, especally those capable of dsplayng TV, and content dstrbuton, leadng to a revoluton n the televson market. In fact, the combnaton of tradtonal broadcastng TV servces and vdeo streamng, ether over Telco networks or the Internet, sets up the trend. Emergng standards such as HbbTV [1] promote the utlzaton of hybrd set-top boxes for the recepton of broadcast and broadband dgtal TV and multmeda applcatons wth a sngle user nterface. Nowadays, consumers have avalable a wde range of advanced nteractve servces va ther televson set, such as Vdeo on Demand (VoD) and catchup TV, as well as nternet applcatons, ncludng vdeo telephony, gamng or shoppng. It s reasonable to thnk that ths mmense growng content avalablty should mprove the TV entertanment experence by ts own, but the lack of personalzaton servces hnders the experence, sgnalng the need of personalzaton as the Internet growth sgnaled the need for searchng engnes n the last decade. 1 Ths work has been partally supported by the Communty of Madrd (CAM), Span under the contract number S2009/TIC Patrca Aras Cabarcos s wth the Telematc Eng. Department, Carlos III Unversty, 28911, Leganés, Madrd, SPAIN (e-mal: arasp@t.uc3m.es). Rosa Sánchez Guerrero wth the Telematc Eng. Department, Carlos III Unversty, 28911, Leganés, Madrd, SPAIN (e-mal: rmsguerr@t.uc3m.es). Florna Almenárez Mendoza wth the Telematc Eng. Department, Carlos III Unversty, 28911, Leganés, Madrd, SPAIN (e-mal: florna@t.uc3m.es). Danel Díaz-Sánchez s wth the Telematc Eng. Department, Carlos III Unversty, 28911, Leganés, Madrd, SPAIN (e-mal: dds@t.uc3m.es). Andrés Marín López s wth the Telematc Eng. Department, Carlos III Unversty, 28911, Leganés, Madrd, SPAIN (e-mal: amarn@t.uc3m.es). Personalzaton and usablty emerge as key features to prevent vewers from feelng overwhelmed by complex management tasks allowng them to squeeze ther TVs gettng the most from them. Accordng to these premses, and pursung to enhance the vewng experence, we ntroduce n ths artcle a presenceaware personalzed TV system. Our contrbuton s twofold, t provdes presence awareness, detectng and dentfyng whch users are present at each moment, and personalzaton, so t has the ablty to show the most approprate content dependng on the users currently vewng the TV. Related works n the feld usually base the personalzaton on content-flterng based accordng to recommendaton technques and semantc rules as n [2]. The combnaton of personalzaton technques wth presence awareness to automatcally generate content s an nnovatve aspect of our soluton. Moreover, we address new challenges such as prvacy-based flterng and group preference modelng besdes ndvdual preferences. We envsage future TV systems to be smart enough to determne what a user (or group of users) wants to watch. Therefore, presence detecton and ndvdual dentfcaton are essental features for provdng talored servces. Presence awareness can be acheved by means wthout requrng hgh nvestments from user sde. For nstance, user personal devces, as moble phones, can nteract wth the personalzed TV servce n a seamless way to communcate user presence, whch s a pvotal concept as envsaged by Weser n hs defnton of ubqutous computng [3]. Wth the aforementoned goals n mnd, we propose FamTV: a prototype archtecture for presence-aware personalzaton amed on enhancng the TV experence through famly-orented applcatons. The rest of ths paper s structured as follows: Secton II provdes a bref background on hybrd TV systems and personalzaton, dentfyng the challenges to be faced. Secton III provdes a global overvew of the proposed archtecture. Then, Sectons IV, V and VI, descrbes the dfferent layers of FamTV. Secton VII descrbes the prototype mplementaton. Related work s sketched out n Secton VIII. Fnally, Secton IX summarzes the presented work and some future lnes. II. BACKGROUND The objectve of ths secton s to gve an overvew of the hybrd TV systems and TV content personalzaton. 2

3 A. Hybrd TV: man concepts and standardzaton The concept of hybrd televson, depcted n Fg. 1, refers to the combnaton of tradtonal broadcast servces together wth external nternet contents obtaned va a broadband connecton. The convergence of these two content sources broadens the possbltes to offer vsually-attractve and hghly enjoyable content on a TV screen. The sole requrement for and dsplayng those contents s a hybrd TV or set-top box. Bascally, applcatons on hybrd devces can be classfed nto broadcast-related applcatons, whch are assocated wth broadcast televson, rado or data channel, and applcatons wth no relaton to any broadcast servce, also called broadcast-ndependent applcatons. Hence, the servces delvered through hybrd TV nclude VoD, nteractve advertsng, votng, games, socal networkng and also program-related servces, such as Electronc Program Gudes (EPGs). An example of applcaton that merges both worlds s the superposton of wdgets of well known socal web servces (e.g. facebook, twtter) over a broadcasted program to show nformaton related wth the content. Fg. 1. Hybrd TV system overvew extracted from the HbbTV specfcaton [1]. The fgure shows contents receved from tradtonal broadcast operators can be coalesced wth, for nstance, Internet applcatons. Despte the concept of hybrd TV s anythng but new, the attenton has recently ncreased. Ths nterest s motvated by two fundamental reasons: nternet access s almost ubqutous wth hgher bandwdths due to new last-mlle access technologes, and the rchness of current web 2.0 servces, whch make content mergng feasble, as well as appealng. The most recent standardzaton actvty has been conducted by the HbbTV European ntatve. The goal of HbbTV s the defnton of an open standardzed HTML-based system that allows effcent content development by leveragng exstng onlne servces, ndependently of specfc manufacturers or platform operators. The HbbTV specfcaton [1] reles on three exstng standards: CE-HTML [4], whch profles the applcaton language (CSS, XHTML, JavaScrpt); the Open IPTV Forum s browser profle [5], that provdes nterfaces to the DVB world; and the DVB s Applcaton Sgnalng specfcaton [6], whch descrbes transport over broadcast and HTTP. The goal of HbbTV specfcaton s the defnton of a specfc profle of avalable technologes, rather than a defnng a new one. As the reader may nfer, hybrd TV brngs a great potental to nteractvty that could not be acheved wth nowadays regular TV. However, the coexstence of many content provders results on a overload that hampers TV usage turnng smple tasks, as selectng contents to watch, nto confusng and dffcult. For ths reason, personalzaton s requred snce offers a customzed experence to the TV consumer. B. Personalzaton of TV contents As we have mentoned before, the exploson n the amount of avalable TV channels and other contents over hybrd televson platforms (broadcast or nternet protocols) turns searchng and locatng nterestng content out a cumbersome task for the user. In ths context, personalzaton research s concerned wth the adaptaton of content (e.g. moves, news, advertsements) n order to show elements and servces that are relevant to the vewer and ft her preferences. Flterng systems desgned for ths purpose are usually classfed nto two categores accordng to the underlyng recommendaton mechansm [7] they use: content-based and collaboratve flterng. Content-based flters contents accordng to the user hstory records. Thus, these systems recommend tems that are smlar to the ones she preferred n the past. Collaboratve flterng systems recommend tems that people wth smlar tastes and preferences lked n the past. Other approaches combnng both technques, as [8] and [9], have been also proposed. But hybrd TV poses new specfc challenges n personalzaton research. For example, web elements that so far were typcally vewed on PCs, can now be placed n the TV screen whle broadcast content s beng dsplayed. However, there are substantal dfferences between PC and TV envronments. Specfcally, we can assert that unlke the computers, TVs are socal, and people watch t together. In fact, most of the tme there are more than one vewer n front of TV. Ths partcular condton rases prvacy problems: e.g. a user may want some tems to be presented only when she s alone n front of the TV but not when the whole famly s present. Furthermore, group modelng technques are desred to offer suted, relevant tems for the famly members watchng TV at a gven moment. We am to capture these new constrants and apply them to content presentaton. Thus, we propose personalzaton framework for hybrd TVs that combnes content-based flterng wth securty and prvacy management. Moreover, the contextual nformaton can be enrched wth presence data n order to allow user/group detecton, provdng dynamc adaptaton n a seamless and natural manner. 3

4 III. PRESENCE-AWARE TV OVERVIEW AND ARCHITECTURE FamTV s a framework that can be used to buld presenceaware personalzed applcatons. In order to show the benefts of FamTV, n ths secton, we descrbe some potental use cases that can be for applcatons usng FamTV framework. A. Use cases Swtchng a TV set on, selectng a channel wth the remote and adjust the volume s one of the task any user performs regularly. FamTV provdes the means to buld an applcaton that shows personalzed content mmedately after the user swtches the TV on. Contents, ncludng several channels n small wndows, wdgets or preferred news can be automatcally dsplayed accordng to the preferences and habts of the person who s currently n the room. FamTV provdes also predcton-based servces that can be useful n several crcumstances. For example, f the vewer s away when her favorte TV show starts, the applcaton wll detect t and start recordng the show. The content wll be ready when the user presence s detected. Our framework supports exportng profles between devces. That could make the dfference when a user that has been watchng TV for a long tme n a devce, so hs profle s very rch and the applcatons behaves as he lkes, s movng for long perod of tme. FamTV enables a user to move hs profle between dfferent devces n order to mantan a smooth personal experence even when changng hs usual locaton. FamTV protects user prvacy. When a vewer s watchng TV, her senstve wdgets, such as socal network comments, are automatcally hdden when the presence of another user s detected. B. Archtecture The archtecture of FamTV s comprsed of a seres of nterconnected software blocks that dstrbute all the functonalty n a modular fashon. Fg. 2 presents components n a layered model. The Interface Layer at the top of the archtecture s the part handlng user applcaton nterfaces, so the closer to the user. The nterface layer s composed by the Personal Content Adapter (PCA) and the Presence Manager Servce (PMS). On the one hand, the Presence Manager Servce provdes endponts to detect whch users are n the room. Currently, we have only mplemented a Bluetooth servce snce ths technology s wdely deployed and present n almost every moble phone today. However, other wreless-based detecton technques could be supported (e.g. Rado Frequency Identfcaton, RFID). We enumerate and dscuss dfferent detecton technques n Secton IV. On the other hand, the Personal Content Adapter offers a user-frendly web nterface for confguraton. As far as confguraton concerns, the confguraton dashboard contans the followng tasks: addng famly members, regsterng devces for detecton and adjustng user preferences and securty polces. These tasks can be accessed on TV by means of the natve browser of the hybrd devce, or they can be updated va the Internet. All the logc functonaltes requred by the applcatons n the upper layer are performed by modules n the Logc Layer. Such operatons nclude profle creaton and mantenance, user devce and user dentty mappng, managng of prvacy and securty features, etc. To dve deeply nto the detals of these modules, we provde an ndvdual explanaton of each one n the followng sectons. Fnally, the Data Layer accommodates the nformaton requred for the applcatons to operate, that s: user credentals (e.g.: username/passwords), securty polces and user/group profles and hstory logs. FamTV manages all these data locally so t s mpossble for provders to track the user behavor, thus mprovng prvacy. Fg. 2. Archtecture for presence-aware personalzed TV IV. INTERFACE LAYER FamTV offers an nterface layer consstng of two modules: the Personal Content Adapter (PCA) and the Presence Manager Servce (PMS). The PCA provdes a user-frendly web nterface for confguraton and ncludes a man portal to dsplay FamTV applcatons and to regster devces for detecton. Regardng the PMS, t adds an nterface to our connected Set Top Box n order to perform presence detecton. A. Personal Content Adapter The Personal Content Adapter module s n charge of adaptng the content accordng to the current vewer(s). Note that ths content adaptaton procedure mples adjustng user preferences and securty polces. Adaptablty can be acheved through ether explct or mplct profle based technques. In the frst case, the system receves nformaton about user s preferences. However, these methods cannot adapt the content dynamcally snce changes are not detected unless explctly provded by the user. 4

5 In regard to the mplct profle based technques, the system can deduce users preferences by analyzng ther vewng hstory. Our proposal combnes both technques n order to analyze the ntal ndvdual or group profle and merge t wth the nferred preferences obtaned from the vewng hstory. On the other hand, the PCA s also responsble for collectng, processng and dsplayng TV shows, personal wdgets, etc, to TV vewers. To carry out these tasks, the Personal Content Adapter module works as follows: Frstly, the PCA collects nformaton from the broadcast or broadband flows. Then, t apples a content flter and a prvacy and securty flter that have been composed by the Profle Handler. The techncal detals about the composton of the flters can be found below n Secton V. Eventually, wth the ntroducton of web technologes and Java code, we acheve automatc web content adaptaton. The PCA shows the contents that ft the best to the user or group of users that are present n the room. Also, ths module automatcally hdes any elements consdered prvate when another user comes nto the room. B. Presence Manager Servce The Presence Manager Servce (PMS) provdes a web nterface for regsterng users that belong to the famly. In addton, the PMS offers a detecton nterface and notfes Presence Detector events wth the am to mantan the presence context at each moment. Currently, there are multple detecton technques that allow us to know whch users are n front of the televson. We wll focus on the followng methods: Bluetooth, RFID and Natural Interacton. In ths secton, we brefly descrbe them and dscuss ther advantages and drawbacks to be used n the proposed archtecture. Bluetooth s a wreless protocol for exchangng data over short dstances from fxed and moble devces. Locatonaware systems based on Bluetooth technology are low-cost and low-power technology solutons. However, a dsadvantage of applyng Bluetooth for presence detecton n our archtecture s that user presence s detected n a range of 10m (Bluetooth class 2) and the ntended accuracy s around 2 or 3 m. RFID (Rado Frequency Identfcaton) s a technology that uses rado communcaton to exchange data between a reader and an electronc tag attached to an object, for the purpose of dentfcaton and trackng. The basc method of locaton usng RFID tags s ndcaton of proxmty. The prmary advantage of an RFID postonng system s that RFIDs are lght, small and very cheap. The man dsadvantage s the relatvely short effect range, typcally 1 2m. Natural nteracton (NI) refers to a concept where humandevce nteracton s based on human senses, mostly focused on hearng and vson. Thus, facal and voce recognton technques can be used for automatc dentfcaton of users. Frameworks such as OpenNI [10] provde applcaton programmng nterfaces (APIs) that allow the development of NI applcatons by enablng communcaton both wth hardware sensors and mddleware components. The man advantage for dentfcaton s that users are not requred to carry a personal devce. There are several knds of benefts n the RFID technology when compared, for nstance, wth Bluetooth: RFIDs do not need to go through all the steps requred when parng Bluetooth devces; RFID technology does not have the knd of securty or power consumpton problems that Bluetooth suffers from [11]. On the other hand, nnovatve frameworks for Natural Interacton, such as OpenNI, have some attractve features to perform presence detecton and dentfcaton wth hgh precson. Our prototype mplementaton uses Bluetooth detecton snce t was the best soluton for a proof of concept, takng nto account the easness of development and ts wde adopton. Hence, we assume that FamTV users have a moble phone wth Bluetooth connectvty. Obvously, our approach s not flawless. For nstance, t may happen that the presence of a user s not detected because her devce s not connected at the moment or that a user n a contguous room s detected as f she was n front of the TV because she s nsde the detecton range. In the future, we am to complete an enhanced mplementaton wth other detecton mechansm that fts better nto the seamless phlosophy of the archtecture (.e. NI), elmnatng the need to carry a personal devce. Sensors, lke mcrophones and cameras, are good canddates snce 1) they mprove the freedom of the user, and 2) ther presence n ncreasngly avalable n many home entertanment systems lke the Knect for Xbox 360 and others. V. LOGIC LAYER The core of FamTV s bult up of the followng logc components: A. Presence Detector The Presence Detector (PD) currently conssts of Bluetooth server and clent applcatons for the set-top box (STB) and the moble phone respectvely. Note that the frst tme that a user regsters n the FamTV system, she has to assocate her profle wth the devce that wll be used for detecton (devce parng). The PD s n charge of collectng the Bluetooth MAC addresses (or other hardware dentfer) of the devces near the TV at every moment. In addton, the PD s connected to the Profle Handler (PH) to perform profle management. Therefore, detecton s automatc and f the number of famly members vares, the PD notfes ths event to the PH whch readapts the content dynamcally. The dea s that the TV should be able to automatcally recognze a vewer when she approaches the system. Smlarly, when the user leaves, the PD should be able to detect ths event and to automatcally reconfgure ts appearance. 5

6 IEEE Transactons on Consumer Electroncs, Vol. 57, No. 1, February 2011 B. Profle Handler The Profle Handler (PH) bulds an Assocaton Table (AT), so that each Bluetooth MAC address s assgned a user dentfer (User ID). When the PH receves a notfcaton from the PD, t looks up n the AT to retreve the correspondng user profle and asks the Securty Manager to obtan an applcable securty polcy. Moreover, our proposal also consders the case of detectng the presence of multple users. So, we ntroduce a double flterng mechansm based on a set of algorthms for ndvdual and group personalzaton. Hence, the PH s able to construct flters n order for the Personal Content Adapter to analyze the multtude of avalable channels, programs and web tems and select the most relevant ones. The complete methodology s explaned below n more detal. The goal of the system s to flter the avalable tems and show only those that are more relevant to the user(s), takng also nto account securty and prvacy. The tem space s composed of every content or applcaton that can be dsplayed by a hybrd TV (programs, wdgets, etc). The user space contans a fnte number of elements: the famly members. And each element of the user space s defned by a profle that ncludes varous user characterstcs, such as age, favorte channels, genre preferences, etc. We dvde ths profle nformaton nto two subsets: data related to securty and prvacy confguraton; and data for content personalzaton. The frst subset of data s sent to the Securty Manager and translated nto a securty polcy. On the other hand, all the nformaton that s relevant for personalzaton s represented based on Vector Space Model technques [12]. Thus, when a user regsters her profle, an ntal Personalzaton Vector (PV) s created wth the form: w w w, PV w {0,5} (1) 1 2 n Where each component w represents the degree of preference that the user assgns to attrbute. Values of w range from 0 to 5. And the set of attrbutes (or corpus) s composed of a number of ordered keywords that can be used to categorze tems, ether these tems are programs or web applcatons. For example, a PV wth values [5 4] for the set of attrbutes (sport, terror) means that the user lkes sportrelated tems wth the maxmum degree of preference, and that she lkes terror-related tems wth a degree of preference equal to 4. So, the system wll put sport programs n the frst place when showng recommendatons for ths user. The ntal PV s constructed based on the explct data provded by the user at regstraton tme. But FamTV s also fed wth mplct nformaton nferred from the vewer hstory. So, we defne an updatng functon to adjust the preference weghts n the ntal PV as the vewer uses the system: w w, UF (2) prevous Where α,β < 1 and (α+β)=1. By varyng these two parameters we can assgn more mportance to the behavor hstory (.e. tems preferred by the user n the past) or to the new nformaton, respectvely. The Updatng Factor for attrbute (UF ) represents the proporton of tme a user spends n watchng contents that are related to attrbute, and ths factor s expressed as: T UF MDP (3) T total Note that the proporton of tme n UF s multpled by the MDP or Maxmum Degree of Preference (.e. 5) n order to express the result n the scale from 0 to 5 that we defned for the preference metrc. Thus, consderng UV as the Updatng Vector that contans all the UFs for the set of attrbutes n the system, Personalzaton Vectors are updated by calculatng: PV PV, UV (4) prevous We take the prevous equatons as the bass to acheve personalzaton n the FamTV system. In order to show personalzed content, all the avalable tems are also represented by an Item Vector (IV) whose terms are bnary: component wll be 1 f the tem can be categorzed by attrbute, and 0 otherwse. Thus, an ordered set of preferred tems s obtaned by weghng each Item Vector wth the Personalzaton Vector: the hgher s the addton of the weghed terms n the Item Vector, the more relevant s ths tem for the user. In the prevous example, a sport program would have an IV wth components [1 0], whereas a terror flm would be represented by [0 1]. Thus, after weghng both vectors wth PV = [5 4], the sport program wll be recommended frst. Fnally, after a set of personalzed tems s obtaned by applyng the descrbed algorthm, a new flter s used to dscard those contents that must not be shown accordng to the applcable securty polces. A securty polcy s defned by a set of rules wth the form "f condton then acton", but t wll be explaned n more detal n Secton VI. The case of group personalzaton s smlar to the sngleuser case. Group profles are not requred to be created manually. Instead, the nformaton s dynamcally acqured by the system. A group profle s automatcally created whenever a new group of regstered vewers appears n front of the TV. Components n the ntal GPV (Group Personalzaton Vector) are flled by mergng ndvdual PVs: degrees of preference are set to the mnmum values n the PVs of the users that wll form the group. Next, group personalzaton s acheved by applyng the same algorthms descrbed for a sngle user, but usng the GPV for the operatons nstead of usng an ndvdual PV. Furthermore, the securty flter for a group s based on the most conservatve ndvdual polcy. 6

7 To summarze, Fg. 3 depcts the double flterng process that s employed to dsplay the fnal contents, as well as the nformaton requred by the system. The mprovement over the tradtonal nformaton retreval approaches n TV scenaros comes from the use of detaled profles that contan nformaton about users tastes, preferences, and needs. The most sgnfcant nnovaton les n the technque for group personalzaton, whch provdes automatc learnng usng mplct nformaton extracted from group behavor over tme. Moreover, the system s enhanced by applyng securty and prvacy flters, ssues that have not been yet consdered n related work. Fg. 3. Flterng procedure to show personalzed contents n FamTV. C. Securty Manager The Securty Manager (SM) module s n charge of dealng wth securty and prvacy features. It nteracts wth the Profle Handler n order to determne the most approprate securty confguraton for the current user or group of users. Ths block has three fundamental functons, namely: 1) Polcy enforcement Securty polces are created and managed by ths module to ensure that an adequate securty context s actve. For nstance, parental control rules can be establshed to prevent chldren from watchng napproprate contents when ther parents are away. Apart from lmtng access to ageapproprate content, rules may be defned to set other usage constrants such as, for example, placng tme lmts. 2) Credental management User credentals are stored by ths module to provde addtonal functonalty n the applcaton. For example, when a specfc user s watchng TV, her personal wdgets could be automatcally presented wthout askng for authentcaton snce the SM performs ths task on behalf of the vewer. 3) Sesson management In order to create and mantan a vald securty context at each moment, the SM also manages sessons that can dynamcally change and readapt dependng on the present users. VI. DATA STORAGE LAYER The Data Storage Layer accommodates the nformaton requred for the system to operate, that s: user/group profles, user credentals, securty polces and hstory logs. Users of FamTV must regster ther profle va a web nterface before they start usng the system. A user s asked to enter dfferent knds of nformaton. Frst, the user provdes personal data (age, name) and prvacy preferences, whch wll be used n the securty flter. Next, the user selects her preferences regardng contents. For ths purpose a lst wth the man categores n the DVB standard [13] s presented. Every tem n the lst must be ranked by the user wth a degree of preference between 0 and 5. Examples of these categores are: comedy, romance, documentary, varety show, water sport, talk show, news, entertanment, cookng, etc. If a specfc category s not ranked, a default value of 2.5 s assgned and the preference wll be later derved from the vewer hstory. As explaned before, group profles are automatcally created by the system. Users must also regster a Bluetooth devce for presence detecton so that the system can buld an assocaton between profles and devces and provde automatc adaptaton. In order to adapt the contents of FamTV to preferences and habts of famly members, a hstory log that records ndvdual and group behavor s mantaned. More specfcally, the hstory log contans nformaton about whch programs and contents have been consumed by every user or group as well as the ntal and fnal tmes. Ths nformaton s the source for the calculaton of the Updatng Vectors descrbed n the prevous secton. Regardng securty, every user can store her credentals (e.g. username/passwords, dgtal certfcates) that are requred by external applcatons that can be accessed from the TV: personal wdgets, payment servces, etc. Thus, the system wll act on behalf of the user and perform authentcaton n the dfferent applcatons provdng an easy and seamless navgaton experence. Fnally, securty polces are defned by a confgurable set of rules that evaluate condtons based on profle attrbutes n order to deny or grant permssons for a subject to access partcular tems. Condtons are whether boolean expressons that consder attrbutes, such as the user age; or rules based on other context varables, such as tme. An example of a tmebased rule s the followng: "John may access TV content from 4pm untl 7pm". 7

8 It must be noted that all the descrbed data are stored locally n the system, n order to preserve user prvacy. VII. PROTOTYPE IMPLEMENTATION Our hybrd TV demonstrator s a proof of concept for a PC envronment usng open source technologes accordng to the test scenaro depcted n Fg. 4. wth prvacy and securty ssues. Our system allows the establshment of prvacy rules and provdes securty management functons. In addton, the combnaton of content flterng technques wth presence detecton to automatcally adapt contents s an nnovatve aspect. We am to address the man lmtatons regardng TV personalzaton by defnng a user-centrc archtecture that takes nto account group-modelng technques, snce watchng televson s most a group experence rather than a snglevewer actvty [18]. Fg. 4. Test scenaro. For the broadcast part we are usng OpenCaster [15], an open source MPEG2 transport stream data generator and packet manpulator, n order to create the broadcast streams. Moreover, ths framework allows us to enrch the result wth servce nformaton as well as wth other DVB servces. Regardng the FamTV logc, the web nterface for the Personal Content Adapter to regster user profles has been completed. We have also tested the Bluetooth connectvty functon n the Presence Detector, as well as the nteracton of ths module wth the Profle Handler. Furthermore, an adaptaton servce s beng developed to offer personalzed EPGs based on XMLTV [14] feeds that vary accordng to whch users are detected. For ths purpose, the algorthms descrbed n Secton V have been developed n Java. We are mprovng the Personal Content Adapter, workng to ntegrate the nformaton n the generated broadcast streams wth the web EPG to offer a really hybrd experence and apply personalzaton flters to both knd of contents. VIII. RELATED WORK As far as the related work s concerned we found several research ntatves n the feld. The man approaches to personalzaton are: collaboratve flterng and content flterng. In ths context, typcal research drectons n TV personalzaton are related to development of more accurate, effectve and effcent algorthms wth partcular focus on hybrd solutons that combne the basc user modelng and the predcton methods [16][17]. Furthermore, other related works n the feld are focused on semantc rules and ontologes [2]. However, current approaches are based on ndvdualzed modelng of the vewng experence for each user but do not consder the case of group modelng. Furthermore, none of these works deals IX. CONCLUSIONS AND FUTURE WORK Presence-aware personalzed system combnes the benefts of content-flterng and presence detecton technologes to acheve seamless personalzaton. Wth the ntroducton of the Presence Manager Servce and the Personal Content Adapter, we have desgned a user-centrc archtecture that allows the set-top box to know who s watchng TV n order to act accordngly. Furthermore, securty and prvacy are also consdered. The addton of these features s of specal mportance: on the one hand, automatc management of user credentals eases the task of authentcaton wth the new applcatons that can be accessed by hybrd TVs; on the other hand, prvacy rules can be establshed, whch s essental havng nto account that TVs are usually located n a common place at home and most of the tme there are more than one vewer. Usablty s paramount n a system lke FamTV, and we expect to obtan measures on user acceptance through testng usng our proof of concept mplementaton and evaluaton wth real users. As future work, we want to enhance the presence detecton module by addng other mechansms apart from Bluetooth and allow natural nteracton wth the users. Moreover, t would be nterestng to test other predcton algorthms [19] to construct more ntellgent servces. Further research s needed to defne a delegaton model and polces allowng the transfer of tokens and permssons between dfferent users, for example, for payment servces. REFERENCES [1] European Telecommuncaton Standards Insttute, "Hybrd Broadcast Broadband TV", ETSI TS V1.1.1, June [2] S.Alam, Z.Iqbal, J.Noll and M.R.Chowdhury, "Semantc Personalzaton Framework for Connected Set-Top Box Envronment", Advances n Human-orented and Personalzed Mechansms, Technologes, and Servces, [3] M. Weser, "The Computer for the 21st Century", Scentfc Amercan, September [4] Consumer Electroncs Assocaton, "A Web-based Protocol and Framework for Remote User Interface on UPnP Networks and the Internet (Web4CE)", CEA-2014-B, June [5] Open IPTV Forum, Release 1 specfcaton, volume 2 (V1.1): Meda Formats", Tech. Report, January, [6] European Telecommuncaton Standards Insttute, "Dgtal Vdeo Broadcastng (DVB); Sgnallng and carrage of nteractve applcatons and servces n Hybrd Broadcast/Broadband envronments", ETSI TS (V1.1.1), January, [7] G. Adomavcus and A. Tuzhln, "Toward the Next Generaton of Recommender Systems: A Survey of the State-of-the-Art and Possble Extensons", IEEE Transactons on Knowledge and Data Engneerng, pp , June,

9 [8] P. Cotter and B. Smyth, "A Personalzed Televson Lstng Servce",. Communcatons of ACM, vol. 43 (8), [9] A. Martnez, J. Aras, A. Vlas, J. Garca Duque and M. Lopez Nores, "What's on TV tonght? An effcent and effectve personalzed recommender system of TV programs", IEEE Transactons on Consumer Electroncs, vol.55, no.1, pp , February [10] The OpenNI organzaton, "OpenNI User Gude", December Avalable at [11] H. Seppä and J. Vesa, "Wreless Functonal Envronment: The Future of Wreless Servce Delvery", Hong Kong Moblty Roundtable, [12] D. L. Lee, H. Chuang and K. E. Seamons, "Document rankng and the vector-space model", IEEE Software, 14(2), pp , [13] European Telecommuncaton Standards Insttute, "Dgtal Vdeo Broadcastng (DVB); Specfcaton for Servce Informaton (SI) n DVB systems", ETSI EN V1.9.1, March [14] The XMLTV Project, [15] A. Berger, L. Pallara and R. Schatz, "An opensource framework for DVB-* transmsson", Proceedngs of the 16th ACM nternatonal conference on Multmeda (MM 08), Vancouver, Canada, October [16] K. Choranopoulos. "Personalzed and moble dgtal TV applcatons", Multmeda Tools and Applcatons, volume 36, no. 1-2, pp. 1-10, Sprnger Netherlands, January [17] B. Bezerra, F. Carvalho, G. Ramalho and J. Zucker. "Speedng up Recommendaton Systems", Proceedngs of the AH2002 Workshop on personalsaton n future TV, Malaga, Span, [18] J. Masthoff, "Group modelng: selectng a sequence of televson of tems to sut vewers", User Modelng and User-Adapted Interacton, vol. 14, no.1, pp.37-85, [19] A. Rodrguez-Carron, C. Garca-Rubo and C. Campo, "Performance Evaluaton of LZ-Based Locaton Predcton Algorthms n Cellular Networks", Communcatons Letters IEEE, 14(8), , BIOGRAPHIES Aras Cabarcos, Patrca receved her Telecom. Eng. degree from Unv. Carlos III of Madrd n 2008 and she obtaned the MSc degree n Telematcs n Currently, she s pursung a PhD at the Department of Telematcs Engneerng n the Unv. Carlos III of Madrd, workng wthn the Pervasve Computng research group. Her research focuses on the problem of dentty management n open and dynamc envronments, wth specal attenton to rsk analyss and the underlyng trust models. Sánchez Guerrero, Rosa receved a Telecom. Eng. degree from Unv. Carlos III de Madrd n In September 2010 she started her MsC studes n the Unv. Carlos III of Madrd. Currently, she combnes her studes wth a poston as researcher at the Department of Telematcs Eng. n the Unv. Carlos III of Madrd, workng wthn the Pervasve Computng research group. Her research topcs nclude the problem of dentty management, securty and prvacy n healthcare. Almenárez Mendoza, Florna (M 07) receved the Computer Engneer degree from the Unversty Autónoma of Bucaramanga (Columba) n 1999, and her Ph.D. degree from the Unversty Carlos III of Madrd (Span) n She currently works as an assocate professor and researcher n the Unversty Carlos III of Madrd. Her research nterests nclude dstrbuted trust management models for dynamc envronments, securty archtectures n pervasve devces, and securty for ad hoc networks. Díaz-Sánchez, Danel (M 07) receved a Telecom. Eng. degree from Unv. Carlos III de Madrd n He graduated as Master Telematc Engneerng (2004) and obtaned hs PhD (2008) from Unv. Carlos III of Madrd. He works as researcher and teacher at Unversdad Carlos III. Hs research topc s dstrbuted authentcaton, authorzaton and content protecton actvtes. Marín López, Andrés (M 07) receved a Telecom. Eng. degree and PhD from the Techncal Unv. of Madrd n 1992 and 1996 respectvely. He lectures n Computer Networks and Ubqutous Computng n the Unv. Carlos III de Madrd, as an assocate professor. Hs research nterests nclude ubqutous computng: lmted devces, trust, securty servces, and securty n NGN. 9