Signal Processing for Communication Systems
Mathuranathan Key focus: 5G NR resource block : a block of 14 OFDM symbols (1 slot across time domain) with the corresponding 12 subcarriers for those symbols 5G NR protocol stack In the 5G New Radio (NR), the protocol architecture can be separated into two categories: user plane protocol stack and control plane protocol stack. The … Read more
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
Key focus: Array pattern multiplication: total radiation pattern of N identical antennas is product of single-antenna radiation vector and array factor. Antenna arrays Ferdinand Braun invented the Phased Array Antenna in 1905. He shared a Nobel Prize in physics in recognition of their contributions to the development of wireless telegraphy. An antenna array is a … Read more
Key focus: Far-field region is dominated by radiating terms of antenna fields, hence, knowing the far field retarded potentials is of interest. Introduction The fundamental premise of understanding antenna radiation is to understand how a radiation source influences the propagation of travelling electromagnetic waves. Propagation of travelling waves is best described by electric and magnetic … Read more
Antennas are radiation sources of finite physical dimension. To a distant observer, the radiation waves from the antenna source appears more like a spherical wave and the antenna appears to be a point source regardless of its true shape. The terms far-field and near-field are associated with such observations/antenna measurement. The terms imply that there … Read more
Key focus: Understand retarded potentials – the basic building block for understanding antenna array patterns. Retarded potentials are potentials at an observation point when the quantities at the source are non-static (varies in both space and time) The static case : potentials The fundamental premise of understanding antenna radiation is to understand how a radiation … Read more
Key focus: Briefly look at the building blocks of antenna array theory starting from the fundamental Maxwell’s equations in electromagnetism. Maxwell’s equations Maxwell’s equations are a collection of equations that describe the behavior of electromagnetic fields. The equations relate the electric fields () and magnetic fields () to their respective sources – charge density () … Read more
Key focus: Briefly look at linear antennas and various dipole antennas and plot the normalized power gain pattern in polar plot and three dimensional plot. Linear antennas Linear antennas are electrically thin antennas whose conductor diameter is very small compared to the wavelength of the radiation λ. Viewed in a spherical coordinate system (Figure 1), … Read more
Key focus: Bayes’ theorem is a method for revising the prior probability for specific event, taking into account the evidence available about the event. Introduction In statistics, the process of drawing conclusions from data subject to random variations – is called “statistical inference”. Usually, in any random experiment, the observations are recorded and conclusions have … Read more
Line code is the signaling scheme used to represent data on a communication line. There are several possible mapping schemes available for this purpose. Lets understand and demonstrate line code and PSD (power spectral density) in Matlab & Python. Line codes – requirements When transmitting binary data over long distances encoding the binary data using … Read more