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Basic of 5G Networks: Review
Published in Ashish Bagwari, Geetam Singh Tomar, Jyotshana Bagwari, Advanced Wireless Sensing Techniques for 5G Networks, 2018
A.N. Ibrahim, M.F.L. Abdullah, M.S.M. Gismalla
QAM is widely used in mobile communications and is mainly used in LOS for microwave systems, coaxial cables, and satellite communications. QAM transmits the information data by modulating the amplitudes of two carrier waves, using straight amplitude modulation for the analog signal and Amplitude Shift Keying (ASK) for the digital signal. QAM requires linear amplifiers and coherent detection [59]. QAM has a moderate energy efficiency, excellent bandwidth, and complexity on the receiver side because it needs to track the frequency, phase, and amplitude of the carrier and also track the sampling time and symbol rate [59]. Some of common forms of QAM include 16QAM, 32QAM, 64QAM and 128QAM. In QAM, the signal in two carriers is shifted in phase by 90°, hence it will be modulated and the output consists of both phase and amplitude variations which may also be considered as a mixture of amplitude and phase modulations [3].
Modulation
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Techniques that modulate the amplitude of the carrier are full-carrier amplitude modulation (AM), reduced- or suppressed-carrier double-sideband (DSB) AM, single-sideband (SSB) suppressed-carrier modulation, vestigial-sideband (VSB) modulation, and on–off keying (OOK). Techniques that modulate the frequency or phase angle of the carrier include frequency modulation (FM), phase modulation (PM), frequency-shift keying (FSK), and phase-shift keying (PSK). Simultaneous variation of amplitude and phase are applied in quadrature AM (QAM). Each technique has its own particular uses. Full-carrier AM is used in radio broadcasting; VSB was formerly used in analog television broadcasting. DSB appears in instrumentation systems utilizing carrier amplifiers and modulating sensors, while SSB finds use in certain high-frequency radio communications. FM is used in broadcasting and point-to-point mobile communications. OOK is commonly used to transmit digital data in optical fiber links. FSK, PSK, and QAM are found in digital communications; analog QAM was formerly used to transmit chrominance (color) information in color television broadcasting. The emphasis of this particular chapter will be instrumentation systems; those interested principally in communications applications could begin by consulting Refs. [1–4].
Digital TV by Cable
Published in Lars-Ingemar Lundström, Understanding Digital Television, 2012
Digital cable TV in Europe is based on the same standard, digital video broadcasting, DVB, as is used for satellite broadcasting. The nucleus of DVB is the transport stream, including the data packets that contain the audio and video information. The main difference between digital cable TV and satellite distribution is the higher level of modulation. The most common kind of modulation is 64 QAM that is a combination of amplitude and phase modulation. There are even higher levels of standardized modulation, such as 128 and 256 QAM that can be used for cable TV. However, these higher modulation schemes would demand higher quality of the signals in the cable TV networks.
5G Mobile Wireless Access and Digital Channeling with RF Over Fiber for Long-Haul 64-QAM Communication
Published in IETE Journal of Research, 2023
Mazin Al Noor, Bal S. Virdee, Karim Ouazzane, Dion Mariyanayagam, Harry Benetatos, Svetla Hubenova
In [26] Ng et al. demonstrated the integration of a radio-over-fiber communication system composed of three modulation formats, i.e. quadrature phase-shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM), and 64-QAM, which are modulated onto orthogonal frequency division multiplexing (OFDM) signal. The bit rates for 16-QAM and 64-QAM achieved were 22 and 50 Mb/s, respectively. In [27] the authors report a network architecture where 5G multiple-input multiple-output (MIMO) radio-over fiber signals are transmitted over a standard PON. The architecture can be applied when using an OFDM-PON where efficient convergence of wired and wireless networks can be achieved. In addition, the single-sideband frequency translation technique is used to produce a high spectrally efficient approach involving two MIMO-RFoF. Radio-over-fiber technique of 10 GB/s giga-PON network architecture reported in [28] uses a single-mode fiber of length of 50 km to propagate the radio signals. Radio-over-fiber system architecture proposed in [29] employs three hybrid photonic millimeter-wave generation techniques in the WDM-PON network. Demonstrated in [30] is the convergence of a NOMA-CAP wireless waveform with a single carrier wired signal in a PON scenario using the radio-over-fiber (RoF) technology. Specifically, fifteen NOMA-CAP bands, with two NOMA power levels to double the capacity, transmit 15 Gb/s multiplexed with a digital 10 Gb/s four-level pulse amplitude modulation (PAM-4) signal for downlink application.
Performance Analysis of Radio Over Fiber System Employing Photonics Antenna and Different Modulation Schemes
Published in IETE Journal of Research, 2023
Table 6 gives the Q-factor and BER of different modulation schemes at a data rate of 2.5 Gbps over a fiber length of 50 km. From Table 6, it can be observed that 16-QAM modulation scheme best suits for the tranmission of data with better quality factor and least distortion. QAM stands for quadrature amplitude modulation which is again of different types like 8-QAM, 16-QAM, 32-QAM etc. The transition of 16-QAM to 32-QAM, 64-QAM and so forth results in the achievement of higher data rate but at the cost of noise margin [16,17]. Thus, 16-QAM is considered as better for the data transmission as it provides optimal data rate as well as noise margin. The constellation diagram of 16-QAM has been shown in Figure 14. This modulation scheme has been chosen for the rest of the analysis.
ASER of SISO system with rectangular QAM scheme over α-μ fading channels
Published in International Journal of Electronics Letters, 2022
To implement the high-speed mobile communication systems, quadrature amplitude modulation (QAM) technique can be used. QAM constellations are the basis of many high-speed mobile communication architectures: Wi-Fi (IEEE 802.11), WiMAX, cellular, digital video broadcasting (Suraweera et al., 2008). A large bandwidth is required for the multimedia transmission over wireless channels. The QAM is an efficient scheme, which can be used to meet the large bandwidth demand. Rectangular QAM (RQAM), square QAM (SQAM) and cross QAM (XQAM) are familiar QAM signal constellations that have numerous applications in communication systems. RQAM is a general modulation scheme which comprises SQAM, BPSK, QPSK, orthogonal binary frequency-shift keying and multilevel amplitude-shift keying (ASK) modulation schemes as particular cases (Proakis, 2001). The XQAM constellation has a cross shape by eliminating all the outer corner points from RQAM constellation to decrease the peak and average energy of the signal, and is found to be useful in the transmission for odd number of bits per symbol (Smith, 1975).