Khalid Khalil Mohammed
Ninevah University

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Performance improvement of fractional N-PLL synthesizers for digital communication applications Nour Zaid Naktal; A. Z. Yonis; Khalid Khalil Mohammed
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 6: December 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i6.21929

Abstract

Loop filter with two order was designed to improve the performance of the fractional N-phase locked loop (PLL) circuit (reference spurs noise and switching time), decreasing these two factors give good characteristic to fractional N-PLL circuit, the second order and third order loop filters are widely used in frequency synthesizer because they give good stability tolerance and for their simple architecture. They are designed at bandwidth B=125 KHz and its multipoles, at two values of the phase margin (pm)= 35°, 57°. MATLAB program was used to find the lock time, the component values for each element in the loop filter, also the filter impedance T(s), the bode plot of frequency response for close loop (CL) and open loop gain (OL). It is found by comparing the result of the frequency response for the 2nd order loop filter and 3rd order loop filter, that increasing the order of the filter will reduce the spurs noise that destroy the received signal at receiving side.
Investigation of pattern division multiple access technique in wireless communication networks Aws Zuheer Yonis; Khalid Khalil Mohammed
Indonesian Journal of Electrical Engineering and Computer Science Vol 26, No 1: April 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v26.i1.pp296-303

Abstract

Recently, pattern division multiple access (PDMA) is a non-orthogonal multiple access system that is now being developed in next-generation telecoms to address the requirement for mass connectivity. The core premise of non-orthogonal multiple access is to simultaneously serve multiple users with varying power levels across the same spectrum resources such as time, frequency, code, as well as space with minimal inter-user interference. A simulation analysis of significant technology enhancements focusing on PDMA aims to describe the benefits of the two plans now being examined by the third-generation partnership project for 5G technologies, namely filtered orthogonal frequency division multiplexing (F-OFDM) and windowed orthogonal frequency division multiplexing (W-OFDM), and to compare them to alternative modulation processes such as 16, 32, and 128 modulations. The research results explained the PDMA is less bit error rate used in multiple access technologies compare with W-OFDM and F-OFDM.