Becue, Pieter

De Poorter, Eli

Gesquiere, J

Jooris, Bart

Liu, Wei

Lylon, C

Moerman, Ingrid

Sercu, Vincent

Vanhaverbeke, J

English

Ghent University Academic Bibliography

Demo: A Cognitive Solution for Commercial WirelessConferencing SystemWei Liu, Eli De PoorterPieter Becue, Bart Jooris, Vincent SercuIngrid MoermanUniversity Ghent - iMindsGaston Crommenlaan 8 Ghent, Belgium{lwei, eldpoort, pbecue, bjooris,vsercu,imoerman}@intec.ugent.beJeroen VanhaverbekeCarl Lylon, John GesquiereTelevicLeo Bekaertlaan 1Izegem, Belgium{J.Vanhaverbeke, C.Lylon,J.Gesquiere}@televic.comABSTRACTIn a modern conference room, various of video and audio de-vices are provided to ensure eﬃcient communications. Thisis commonly referred to as a conferencing system. Comparedto wired conferencing systems, wireless systems require lessdeployment eﬀort, but may become unreliable when the se-lected radio spectrum is highly occupied. This demo focuseson improving the quality of service of a commercial wirelessconferencing system using dynamic channel selection basedon real-time spectrum sensing. The proposed solution is ver-iﬁed in a large-scale wireless testbed, and the result showsthat the link of the conferencing system is indeed more ro-bust against interference when cognitive solution is applied.KeywordsWireless conferencing system; Cognitive Radio1. INTRODUCTIONIn a modern conference room, audio infrastructures (eg,micro phones and loudspeakers) are provided to ensure clearand eﬃcient communications. In addition, video devices andreal-time interpretation units are also widely used for remoteand international conferences. In general, the infrastruc-tures deployed in a conference room to facilitate communi-cation is called a conferencing system. Most existing con-ferencing systems rely on wired connections, which usuallyrequire heavy deployment eﬀorts. In addition, it is diﬃcultyto reorganize the layout of the conference room once thedeployment is ﬁnished.To overcome the limitations of wired conferencing system,Televic [1] proposes the Conﬁdea wireless conferencing sys-tem [2]. It contains two types of devices: the wireless cen-tralized access point (WCAP) and the wireless delegate unit,as shown in Figure 1. A conference room equipped with theConﬁdea system is shown in Figure 2. The WCAP and del-Permission to make digital or hard copies of part or all of this work for personal orclassroom use is granted without fee provided that copies are not made or distributedfor profit or commercial advantage, and that copies bear this notice and the full ci-tation on the first page. Copyrights for third-party components of this work must behonored. For all other uses, contact the owner/author(s). Copyright is held by theauthor/owner(s).MobiCom’14, September 7-11, 2014, Maui, Hawaii, USA.ACM 978-1-4503-2783-1/14/09.http://dx.doi.org/10.1145/2639108.2641751.Figure 1: The Confidea WCAP and delegate unitFigure 2: A conference room equipped with Con-fidea systemegate units operate in the unlicensed Industrial, Scientiﬁc,Medical (ISM) frequency band, which allows the conferenc-ing system to be used without extra licensing cost. However,the existing wireless technologies in the ISM bands (eg, Blue-tooth, Zibee, Wi-Fi) may cause severe interference to theconnection between the WCAP and the delegate units.To this end, Cognitive Radio (CR) techniques are usedto improve the connection quality. More speciﬁcally, theWCAP’s operating channel is updated in real-time accord-ing to the radio spectrum utilization. In this demo, thespectrum sensing is performed by a dedicated application to-gether with the Software-Deﬁned Radio (SDR) — USRP[3]. The complete solution is tested and veriﬁed in a large scalewireless testbed — w-iLab.t[4].The rest of the paper is organized as follows: Section 2brieﬂy introduces the implementation of the demo setup;Section 3 describes the demo scenario as well as the expectedresult; Finally Section 4 concludes this demo and points outthe direction for future work.3032. DEMO IMPLEMENTATIONThe w-iLab.t testbed is a generic and heterogeneous wire-less testbed. It is located at a utility room where no regularhuman activity is present. The majority of devices in thew-iLab.t testbed are embedded PCs equipped with Wi-Fi,Bluetooth interfaces and sensor devices. Each embedded PCare attached to a poll, and can be remotely conﬁgured viaa backbone Ethernet interface. For simplicity, an embeddedPC together with the attached wireless devices is referred toas a “node”. The overall testbed topology forms a grid.Two Conﬁdea delegate units and one WCAP are deployedin w-iLab.t testbed. The two delegate units are mounted ontwo adjacent nodes respectively. On one node, the audiooutput of the embedded PC is connected to the audio inputof the delegate unit via the audio jack cable, which formsthe “speaker” node. On the other node, the audio outputof the delegate is connected to the microphone input on theembedded PC via an audio jack cable, which can act as the“listener”. During testing, the audio signal is transferred viathe WCAP from the delegate at the“speaker”to the delegateat the “listener”. The “listener” node records the audio intoan “mp3” ﬁle, which can be used for audio quality analysis.The complete setup is illustrated in Figure 3.The WCAP updates its channel in real-time, based onthe spectrum information collected by a dedicated sensingapplication. This application uses the raw samples fromUSRP to perform Fast Fourier Transfer (FFT) based en-ergy detection. Parallelism and multi-threading are usedto increase the processing speed of the sensing application[5]. The sensing application together with USRP hardwareforms a USRP sensing engine. Each USRP sensing enginehas an instantaneous bandwidth of 20 MHz, we use sweepingin frequency domain and cooperation of multiple USRP’s tocover a wider frequency range. The sensing result is storedinto a database at run time, which can be queried by theWCAP periodically.3. DEMO SCENARIOThe demo consists of three stages. In all the stages, apiece of music is played at the “speaker” node and recordedat the “listener” node. At the same time, spectrum infor-mation is provided by USRP sensing engines and plotted inspectrogram in real-time.In the ﬁrst stage, the WCAP is conﬁgured to stay ona static channel and no background interference is intro-duced. The audience can hear that the recorded audio hasa similar quality with the original audio ﬁle. In the secondstage, the WCAP is still using a static channel, in addition,background interference is generated on the same channel.The audience can hear that the recorded audio quality hasdropped compared to the ﬁrst recording. In the third stage,the WCAP is conﬁgured to use dynamic channel conﬁgura-tion based on the spectrum information from USRP sensingengines. We can see on the spectrogram that the WCAPbecomes “aware” of the interferer, and is able to activelyavoid the interference. Audiences are encouraged to catchthe channel of the WCAP by conﬁguring the interferer inreal-time. The recorded audio in this stage may containshort interruptions, but the we observe that the overall audioquality is much better than the recording from the secondstage.Figure 3: Demo scenario4. CONCLUSIONSThis demo proves that dynamic channel selection can greatlyimprove the quality of service for the wireless conferencingsystem. In addition, it is shown that the custom-developedsensing application based on SDR can cooperate with com-mercial devices to achieve better performance. Finally, thisdemo also illustrates how to test a real-life application on aremote infrastructure in a convenient approach.5. ACKNOWLEDGMENTSThe research leading to this demo has received fundingfrom the European Union’s Seventh Framework ProgrammeFP7/2007-2013 under grant agreements n 258301 (CREWproject) and Belgium national project QoCON.6. REFERENCES[1] Televic Portal: http://www.televic.com/en/, lastaccessed in March 2014.[2] Conﬁdea wireless conferencing system:http://www.televic-conference.com/en/confidea-wireless-conference-system, last accessedin March 2014[3] Universal Software Radio Platform (USRP):https://www.ettus.com/product, last accessed inMarch 2014[4] S. Bouckaert et al. “Federating wired and wireless testfacilities through Emulab and OMF: the iLab.t usecase” in the proceedings of TridentCom 2012[5] Wei Liu, Daan Pareit, Eli De Poorter, Ingrid Modrman:“Advanced spectrum sensing with parallel processingbased on software-deﬁned radio” in EURASIP Journalon Wireless Communications and Networking, 2013304

Demo: a cognitive solution for commercial wireless conferencing system

https://biblio.ugent.be/publication/7171990/file/7172011.pdf

Demo: a cognitive solution for commercial wireless conferencing system

Abstract

Similar works

Full text

Available Versions

Ghent University Academic Bibliography