简介：High-speedmulti-useraccesswithhighspectralefficiencyisoneofthekeychallengesforband-limitedvisiblelightcommunication(VLC)systems.Inthispaper,weproposeanovelschemeforeffectivemultiple-accessVLCsystemsbasedonmulti-band,Nyquist-filteredpulseamplitudemodulation(PAM)-8modulation.Withinthisscenario,thespectralefficiencycanbeimprovedfrom1.5to2.73b/s/HzbyimplementinganappropriateNyquistfiltertosuppressspectralbandwidth.Weexperimentallydemonstrateamulti-bandVLCsystemat1.2Gb/safter1mindoorfreespacetransmission.Thesystemperformanceshavealsobeenthoroughlyinvestigatedfordifferentsub-bandnumbers,utilizingarectangularfilterinthefrequencydomainandaNyquistfilterbasedonsquarerootraisedcosine.TheresultsshowthattheNyquist-filteredPAM-8signalcanoutperformarectangularfilteredsignal.Themaximumimprovementofsystemcapacityisupto1.67timesfortheNyquist-filteredmulti-bandsystem.Theresultsclearlyshowtheadvantageandfeasibilityofmulti-bandNyquistPAMforhigh-speedmultiple-accessVLCsystems.