Digital Modulations Archives - GaussianWaves

π/2 BPSK (pi/2 BPSK): 5G NR PHY modulation

Mathuranathan — Mon, 07 Feb 2022 03:36:47 +0000

The 5G New Radio (NR) supports quadrature phase shift keying (QPSK), 16- quadrature amplitude modulation (16-QAM), 64 QAM and 256 QAM modulation schemes for both uplink and downlink [1][2]. This is same as in LTE. Additionally, 5G NR supports π/2-BPSK in uplink (to be combined with OFDM with CP or DFT-s OFDM with CP)[1][2]. Utilization ... Read more

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Rician flat-fading channel – simulation

Mathuranathan — Sat, 15 Aug 2020 13:54:24 +0000

In wireless environments, transmitted signal may be subjected to multiple scatterings before arriving at the receiver. This gives rise to random fluctuations in the received signal and this phenomenon is called fading. The scattered version of the signal is designated as non line of sight (NLOS) component. If the number of NLOS components are sufficiently ... Read more

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BPSK bit error rate simulation in Python & Matlab

Mathuranathan — Thu, 23 Jul 2020 07:52:10 +0000

Key focus: Simulate bit error rate performance of Binary Phase Shift Keying (BPSK) modulation over AWGN channel using complex baseband equivalent model in Python & Matlab. Why complex baseband equivalent model The passband model and equivalent baseband model are fundamental models for simulating a communication system. In the passband model, also called as waveform simulation ... Read more

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Constellation diagram – investigate phase transitions

Mathuranathan — Sun, 28 Jun 2020 12:15:57 +0000

The phase transition properties of the different variants of QPSK schemes and MSK, are easily investigated using constellation diagram. Let’s demonstrate how to plot the signal space constellations, for the various modulations used in the transmitter. Typically, in practical applications, the baseband modulated waveforms are passed through a pulse shaping filter for combating the phenomenon ... Read more

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Maximum Ratio Combining (MRC) architecture simulation

Mathuranathan — Fri, 17 Jan 2020 06:13:44 +0000

In the previous post on Single Input Multiple Output (SIMO) models for receive diversity, various receiver diversity techniques were outlined. One of them is maximum ratio combining, the focus of the topic here. Channel model Assuming flat slow fading channel, the received signal model is given by where, is the channel impulse response, is the ... Read more

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Selection Combining – architecture simulation

Mathuranathan — Tue, 10 Dec 2019 09:50:23 +0000

In the previous post on Single Input Multiple Output (SIMO) models for receive diversity, various receiver diversity techniques were outlined. One of them is selection combining, the focus of the topic here. Channel model Assuming flat slow fading channel, the received signal model is given by where, is the channel impulse response, is the received ... Read more

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GMSK implementation and simulation – part 1

Mathuranathan — Thu, 10 Oct 2019 07:38:19 +0000

What’s the need for GMSK Minimum shift keying (MSK) is a special case of binary CPFSK with modulation index . It has features such as constant envelope, compact spectrum and good error rate performance. The fundamental problem with MSK is that the spectrum is not compact enough to satisfy the stringent requirements with respect to ... Read more

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Differentially encoded BPSK: coherent detection

Mathuranathan — Mon, 27 Nov 2017 08:04:03 +0000

In coherent detection, the receiver derives its demodulation frequency and phase references using a carrier synchronization loop. Such synchronization circuits may introduce phase ambiguity in the detected phase, which could lead to erroneous decisions in the demodulated bits. For example, Costas loop exhibits phase ambiguity of integral multiples of radians at the lock-in points. As ... Read more

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QAM Modulation using Karnaugh-map walks

Mathuranathan — Tue, 25 Nov 2014 07:58:05 +0000

This article focused on constructing constellation for rectangular QAM modulation using Karnaugh-map walks. Exploit inherent property of Karnaugh-maps to construct Gray coded QAM constellation points. M-ary Quadrature Amplitude Modulation (M-QAM) In MQAM modulations, the information bits are encoded as variations in the amplitude and the phase of the signal. The M-QAM modulator transmits a series ... Read more

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Symbol Timing Recovery for QPSK (digital modulations)

Mathuranathan — Mon, 18 Nov 2013 08:29:30 +0000

The goal of timing recovery is to estimate and correct the sampling instants and phase at the receiver, such that it allows the receiver to decode the transmitted symbols reliably. What is Symbol timing Recovery : When transmitting data across a communication system, three things are important: frequency of transmission, phase information and the symbol ... Read more

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