A Novel Underlay Cognitive Radio Based on Direct Sequence Complementary Coded CDMA

KIZILIRMAK, Refik Çağlar

In this study, we propose a spectrum sharing scheme where secondary-users (SUs) can co-exist at the same frequency band with the primary-users simultaneously. Both primary (PN) and secondary networks (SN) are considered as CDMA based networks with the same set of orthogonal complementary codes. An orthogonal complementary code set possesses both ideal auto-correlation function (ACF) of any code and ideal cross-correlation function for any two codes in the same set. In the proposed scheme, a delay is applied to the transmission of the SN which exploits ideal ACF properties of complementary code ...Daha fazlası

Makale 2014 SPRINGER 1 Görüntülenme

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Relay-assisted OFDM transmission for indoor visible light communication

KIZILIRMAK, Refik Çağlar | UYSAL, Murat

In this study, we investigate a relay-assisted visible light communication (VLC) system where an intermediate light source cooperates with the main light source. Specifically, we consider two light sources in an office space; one is the information source employed on the ceiling and the other one is a task light mounted on a desk. Our system builds upon DC biased optical orthogonal frequency division multiplexing (DCO-OFDM). The task light performs amplify-and-forward relaying to assist the communication and operates in half-duplex mode. We investigate the error rate performance of the propose ...Daha fazlası

Konferans Bildirisi 2014 IEEE Computer Society 7 Görüntülenme