Görünür Işık Haberleşmesi için Çift Dördün Uzaysal Yoğunluk Modülasyonu

Bu çalışmada, çift dördün uzaysal modülasyon (ÇDUM) adı verilen izgesel verimi yüksek yeni bir uzaysal modülasyon tekniği çoklugiriş çoklu-çıkış (ÇGÇÇ) görünür ışık haberleşmesi (GIH) sistemleri için önerilmiştir. Sayısal modülasyon planı olarak, eş evreli (I) ve dördün (Q) sinyallerin yoğunluk modülasyonlu direk sezim (YM/DS) sistemlerde kullanımına olanak sağlayan, alt-taşıyıcılı yoğunluk modülasyonu (AYM) kullanılmıştır. Radyo frekans (RF) haberleşmesinde dördün uzamsal modülasyon (DUM) I/Q sinyallerini her biri diğerinden bağımsız olarak seçilmiş antenlerden iletir. Dahası I/Q sinyalleri arasındaki diklik sinüzoidal sinyallerin yarım periyodunda da korunmaktadır. ÇDUM bu iki özelliği kullanarak uzamsal modülasyonun (UM) dört katı biti uzaysal boyutta iletir. AYM, aç-kapa anahtarlamaya (AKA) kıyasla iki kat bant genişliği kullanırken, ÇDUM üç kat kullanır. Bu çalışmada ÇDUM performansı AYM-UM ve darbe genlik modülasyonlu uzamsal modülasyon (DGM-UM) ile karşılaştırılmış ve daha iyi bir performans sergilediği gösterilmiştir. Ek olarak, verici taraftaki LED sayısı arttıkça ÇDUM performansı artmaktadır.

Double Quadrature Spatial Intensity Modulation for Visible Light Communications

n this paper, a new spectrally efficient space modulation technique, which is called double quadrature spatial intensity modulation(DQSIM), is proposed for multiple-input multiple-output (MIMO) visible light communication (VLC) systems. Sub-carrier intensitymodulation (SCM), which ensures the use of in-phase/quadrature (I/Q) signals in intensity modulation direct detection (IM/DD)systems, is used as a digital modulation scheme. In RF, quadrature spatial modulation (QSM) transmits the I/Q signals through singleor multiple antennas selected independently from each other. Furthermore, the orthogonality between I and Q components is providedfor the half period of sinusoids. DQSIM utilizes these two features and transmits four fold more bits than spatial modulation (SM) viaspatial constellation. SCM uses two-fold bandwidth compared to on-off keying (OOK), while DQSIM uses three fold. DQSIMoutperforms benchmark modulation schemes, which are SCM-SM and pulse amplitude modulation spatial modulation (PAM-SM), atthe bit error rate (BER) value of $10^{-4}$. Furthermore DQSIM performance has increased with the increasing number of LEDs.

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