We experimentally demonstrated a robust dual-wavelength digital radio-over-fiber (DRoF) link by quasi-2-bit delta-sigma modulated 256- quadrature amplitude modulation orthogonal frequency-division multiplexing (QAM OFDM) data. By optically constructing the 2-bit data with optical group delay compensation technique, proposed system combined advantages from either conventional or 1-bit system. Du...

ABSTRAKRadio Over Fiber (ROF) adalah sistem komunikasi yang digunakan untuk mentransmisikan sinyal radio frequency (RF) melalui serat optik. Kapasitas dan mobilitas jaringan akses dapat ditingkatkan dengan memanfaatkan ROF. Modulasi optik dilakukan teknik modulasi langsung maupun eksternal. Dalam jurnal ini perbandingan kinerja dari kedua tersebut. Input RF termodulasi 4-QAM, 16-QAM, 64-QAM fre...

This letter adopts higher-order modulation scheme than 16QAM to our previously proposed semi-blind uplink interference suppression for multicell multiuser massive MIMO systems. Our approach is attained by the decision feedback channel estimation (DFCE) and sample matrix inversion (SMI) spatial adaptive filtering. However, its efficiency depended on inter-cell (ICI), in particular QAM. We propos...

In this paper, introduced below are the concepts of digital modulation used in many communication systems today. Techniques described include quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) and how these techniques can be used to increase the capacity and speed of a wireless network. These modulation techniques are the basis of communications for systems like cabl...

Orthogonal Frequency Division Multiplexing (OFDM) is a special form of multicarrier modulation scheme, which divides the entire frequency selective fading channel into many orthogonal narrow band flat fading sub channels. Orthogonal Frequency Division Multiplexing (OFDM) is considered to be a promising technique against the multipath fading channel for wireless communications [1]. However, OFDM...

Sequences with good correlation properties have been widely adopted in modern communications, radar and sonar applications. In this paper, we present our new findings on some constructions of single H-ary Golay sequence and 4-QAM Golay complementary sequence with a large zero autocorrelation zone, where H ≥ 2 is an arbitrary even integer and q ≥ 2 is an arbitrary integer. Those new results on G...

This paper presents performance comparison of various modulation techniques in Rayleigh fading channel. In the comparison, the space time coding has been used. The performance comparison are made on the basis of bit error rate(BER) and symbol error rate(SER) performance matrices over Rayleigh fading channel with BPSK,QPSK,8PSK and QAM modulation technique. The comparison results shows that in R...

In this paper we propose a new form of adaptive modulation which has the ability of using the higher order modulation schemes such as 256-QAM and 128-QAM at low SNR values in order to enhance the data rate without degrading the SER performance especially at low SNR values. This new form of adaptive modulation is combined together with the power control and the PAPR clipping and filtering techni...

This investigation demonstrates the generation of OFDM-RoF signal using frequency doubling technique for the first time, to the author's best knowledge. The 4-Gb/s OFDM signal using 16-QAM format modulated on each subcarrier at a center frequency of 19GHz is experimentally demonstrated. Benchmarked against the OOK format, the 16-QAM OFDM format has the higher spectral efficiency with a sensitiv...

This paper presents an instrument for the automatic classification of the common impairments on Quadrature Amplitude Modulation (QAM) signals. The instrument is intended to help telecommunication service providers to guarantee Quality of Service (QoS) to their customers. Starting from an already developed method based on the processing of the constellation diagram image, the paper presents both...