A Comparison of CP-OFDM, PCC-OFDM and UFMC for 5G Uplink Communications

Polynomial-cancellation-coded orthogonal frequency division multiplexing (PCC-OFDM) is a form of OFDM that has waveforms which are very well localized in both the time and frequency domains and so it is ideally suited for use in the 5G network. This paper analyzes the performance of PCC-OFDM in the uplink of a multiuser system using orthogonal frequency division multiple access (OFDMA) and compares it with conventional cyclic prefix OFDM (CP-OFDM), and universal filtered multicarrier (UFMC). PCC-OFDM is shown to be much less sensitive than either CP-OFDM or UFMC to time and frequency offsets. For a given constellation size, PCC-OFDM in additive white Gaussian noise (AWGN) requires 3dB lower signal-to-noise ratio (SNR) for a given bit-error-rate, and the SNR advantage of PCC-OFDM increases rapidly when there are timing and/or frequency offsets. For PCC-OFDM no frequency guard band is required between different OFDMA users. PCC-OFDM is completely compatible with CP-OFDM and adds negligible complexity and latency, as it uses a simple mapping of data onto pairs of subcarriers at the transmitter, and a simple weighting-and-adding of pairs of subcarriers at the receiver. The weighting and adding step, which has been omitted in some of the literature, is shown to contribute substantially to the SNR advantage of PCC-OFDM. A disadvantage of PCC-OFDM (without overlapping) is the potential reduction in spectral efficiency because subcarriers are modulated in pairs, but this reduction is more than regained because no guard band or cyclic prefix is required and because, for a given channel, larger constellations can be used

Synthesis, spectral characterization, anti-bacterial, cytotoxic evaluation and docking studies of new urea and thiourea derivatives

Isoniazid is one of the main API’s used in the combination treatment of tuberculosis recommended by the WHO. Urea and its derivatives are an important class of heterocyclic compounds that possess a wide range of therapeutic and pharmacological properties, while thiourea is an organosulphur compound in that it resembles urea except that the atom oxygen has been replaced by a Sulphur atom, but the properties of urea and thiourea are significantly different. The current work concerns the synthesis of a new class of urea and thiourea derivatives of isoniazid with various isocyanates and isothiocyanates in the presence of trimethylamine. The IR and NMR spectral data were performed for the urea and thiourea derivatives of the compounds [(3c & 3f) & (3d & 3e)], respectively. Molecular docking studies of the compounds (3a-h) revealed the binding mode involved in the active site of DNA gyrase. The synthesized urea and thiourea derivatives of isoniazid with various isocyanates and isothiocyanates were tested for their antibacterial activity against gram-positive and gram-negative bacteria using the “disc diffusion method”. Of all compounds tested, the urea derivatives (3a &3d), the thiourea derivatives (3e & 3g) showed more potent activity than the other compounds. The MTT assay revealed concentration dependent cytotoxic effects over a concentration range 25-200 µg/mL

Space-Frequency Equalization in Broadband Single Carrier Systems

Broadband wireless access systems can be used to deliver a variety of high data rate applications and services. Many of the channels being considered for such applications exhibit multipath propagation coupled with large delay spreads. Cur- rently, orthogonal frequency division multiplexing is employed in these channels to compensate the effect of dispersion. Single carrier (SC) modulation in conjunc- tion with frequency-domain equalization (FDE) at the receiver has been shown to be a practical alternate solution as it has lower peak to average power ratio and is less sensitive to frequency offsets and phase noise compared to OFDM. The effect of multipath propagation increases with increasing data rate for SC systems. This leads to larger inter-symbol-interference (ISI) spans. In addition the achievable ca- pacity of SC-broadband systems depends on their ability to accommodate multiple signal transmissions in the same frequency band, which results in co-channel inter- ference (CCI) when detecting the desired data stream. The effects of CCI and ISI are more pronounced at high data rates. The objective of this research is to investi- gate and a develop low-complexity frequency domain receiver architectures capable of suppressing both CCI and ISI and employing practical channel estimation. In this thesis, a linear and a non-linear receiver architecture are developed in the frequency domain for use in highly dispersive channels employing multiple input multiple output (MIMO) antennas. The linear receiver consists of parallel branches each corresponding to a transmit data stream and implements linear equalization and demodulation. Frequency domain joint CCI mitigation and ISI equalization is implemented based on estimated channel parameters and is called space-frequency Broadband wireless access systems can be used to deliver a variety of high data rate applications and services. Many of the channels being considered for such applications exhibit multipath propagation coupled with large delay spreads. Cur- rently, orthogonal frequency division multiplexing is employed in these channels to compensate the effect of dispersion. Single carrier (SC) modulation in conjunc- tion with frequency-domain equalization (FDE) at the receiver has been shown to be a practical alternate solution as it has lower peak to average power ratio and is less sensitive to frequency offsets and phase noise compared to OFDM. The effect of multipath propagation increases with increasing data rate for SC systems. This leads to larger inter-symbol-interference (ISI) spans. In addition the achievable ca- pacity of SC-broadband systems depends on their ability to accommodate multiple signal transmissions in the same frequency band, which results in co-channel inter- ference (CCI) when detecting the desired data stream. The effects of CCI and ISI are more pronounced at high data rates. The objective of this research is to investi- gate and a develop low-complexity frequency domain receiver architectures capable of suppressing both CCI and ISI and employing practical channel estimation. In this thesis, a linear and a non-linear receiver architecture are developed in the frequency domain for use in highly dispersive channels employing multiple input multiple output (MIMO) antennas. The linear receiver consists of parallel branches each corresponding to a transmit data stream and implements linear equalization and demodulation. Frequency domain joint CCI mitigation and ISI equalization is implemented based on estimated channel parameters and is called space-frequenc

Synthesis, spectral characterization, antibacterial, cytotoxic evaluation and docking studies of new urea and thiourea derivatives

767-776Isoniazid is one of the main API’s used in the combination treatment of tuberculosis recommended by the WHO. Urea and its derivatives are an important class of heterocyclic compounds that possess a wide range of therapeutic and pharmacological properties, while thiourea is an organosulphur compound in that it resembles urea except that the atom oxygen has been replaced by a Sulphur atom, but the properties of urea and thiourea are significantly different. The current work concerns the synthesis of a new class of urea and thiourea derivatives of isoniazid with various isocyanates and isothiocyanates in the presence of trimethylamine. The IR and NMR spectral data were performed for the urea and thiourea derivatives of the compounds [(3c & 3f) & (3d & 3e)], respectively. Molecular docking studies of the compounds (3a-h) revealed the binding mode involved in the active site of DNA gyrase. The synthesized urea and thiourea derivatives of isoniazid with various isocyanates and isothiocyanates were tested for their antibacterial activity against gram-positive and gram-negative bacteria using the “disc diffusion method”. Of all compounds tested, the urea derivatives (3a &3d), the thiourea derivatives (3e & 3g) showed more potent activity than the other compounds. The MTT assay revealed concentration dependent cytotoxic effects over a concentration range 25-200 μg/mL