Shahid Manzoor

This work proposes a time domain signal-to-noise ratio (SNR) estimator for a single input-single output (SISO) orthogonal frequency division multiplexing (OFDM) system using a pre-fast Fourier transform (pre-FFT) SNR estimator. The pre-FFT SNR estimator requires no additional overhead since it reuses the preamble for synchronization in the OFDM system. In this work, a preamble structure proposed by Morelli and Mengali to overcome carrier frequency offset (CFO) due to Doppler effects is utilized. The proposed pre-FFT SNR estimator has been employed to estimate SNR for the SISO-OFDM system, and its performance has been evaluated against the corresponding frequency domain SNR estimator, also known as a post-FFT SNR estimator. The normalized mean square error (NMSE) of the pre-FFT SNR estimator has also been evaluated against the normalized Cramer-Rao bound (NCRB). The simulation results show that for the additive white Gaussian noise (AWGN) and Stanford University Interim-5 (SUI-5) channels, the pre-FFT SNR estimator exhibits 0.41 dB and 0.66 dB difference between the estimated SNR and the actual SNR, respectively. The NMSE of the pre-FFT SNR estimator outperforms the benchmarker post-FFT SNR estimator, which is close to the NCRB. The proposed pre-FFT SNR estimator achieved bit error rate (BER) improvements of about 1 dB and 2 dB for AWGN and SUI-5 channels, respectively, over the post-FFT SNR estimator at BER= 10−4. Moreover, there is an approximately 50% reduction in complexity between the proposed pre-FFT SNR estimator and the benchmarker post-FFT SNR estimator

This paper presents an adaptive modulation in a single-input-single-output (SISO)-OFDM-based cooperative system that employs a Constant Amplitude Zero Autocorrelation (CAZAC) preamble-based SNR estimator. A novel CAZAC preamble-based SNR estimator that does not incur a throughput penalty is derived by exploiting a modified CAZAC preamble structure for the OFDM system. The proposed CAZAC SNR estimator is used to estimate the channel quality by finding the instantaneous SNR of the received cooperative data, which is sent to the transmitter via feedback channel. The modulation scheme is then changed according to the estimated SNR. The performance of the CAZAC preamble-based SNR estimator exhibits less than 0.02 dB and less than 0.2 dB bias when communicating over AWGN and SUI-5 channels, respectively. The proposed adaptive modulation scheme with the CAZAC SNR estimator significantly improved the channel throughput in comparison with the corresponding benchmarker scheme dispensing with adaptive modulation that invokes M -PSK and M -QAM. More explicitly, the proposed adaptive modulation system with the CAZAC SNR estimator that invokes M -PSK exhibits significant improvement by about 5 dB at BER=10 ^-3 in comparison to its corresponding benchmarker scheme dispensing with adaptive modulation when communicating over the SUI-5 channel. On the other hand, the relay-aided cooperative transmission exhibited an approximately 6 dB SNR gain in terms of channel throughput in comparison to the corresponding non-cooperative benchmarker scheme, and benefited from spatial diversity.

Typically, interleaver is used to recover information signal from outage where errors in burst form is transformed into single errors. The best interleaver should have the optimal properties of spread and dispersion. Therefore, this paper reports a method to design highly dispersive and systematic interleaver. The interleaver is designed using an incremental approach, which uses a Chaotic Logistic Map (CLM) to generate interleaver positions and utilizes the counter-based difference distribution table (DDT) that has been used in cryptanalysis, in order to achieve highly random and disperse interleaver positions by avoiding bad positions that produce repetitive pairs in the output. The proposed interleaver is implemented in single input single out (SISO) and cooperative Orthogonal frequency division multiplexing (OFDM) system. The performance of the proposed interleaver is evaluated in terms of spread, dispersion, bit error rate (BER) as a function of the burst error length and BER versus channel signal-to-noise-ratio (SNR). The performance of the proposed interleaver is compared with chaotic interleaver, block interleaver and with Matlab® random interlaever. The results show that the proposed interleaver outperforms all the interleavers considered in the simulations and there is 1 dB to 3.5 dB improvement in different scenarios of length of burst errors in terms of BER for proposed SISO OFDM systems. More specifically, the employment of the proposed interleaver in the cooperative OFDM system gives improvement of about 2.75 dB to 3.5 dB at BER = 10 ⁻² , as compared to the non cooperative OFDM systems when having the burst error length of 5 bits, 10 bits and 15 bits.

The three core means to increasing system capacity, considering the heterogeneity of the Next Generation Mobile Network (NGMN) are: - bandwidth, spectrum efficiency, and cell densification. For the latter one, small cells are envisioned to provide higher throughput by distributing vast numbers of them under macro cell coverage, creating a way to offload traffic and reduce transmitter-receiver distance. However, it immediately poses a problem of routing traffic from small cells to backbone network (backhauling). Here, advances in Massive Multiple Input Multiple Output (MIMO) antenna systems could bridge the gap in wireless backhaul, which is considered the most viable option for dense-urban small cell deployments. In this paper, we propose a 5GNR-compatible Heterogeneous Network (HetNet) architecture, where backhaul for millimeter wave small cells is provided by Massive MIMO enabled macro cell using FDD duplex in sub-6GHz band. Such an uncommon design would have the following advantages: (1) Non-mmWave backhaul links need not to be Line-Of-Sight, (2) Inter-cell interference between mmWave small cells is negligible, (3) The required Channel State Information(CSI) feedback rate for backhaul links is much smaller, if compared to the prospected 5G NR Base Station (gNB) to User Equipment (UE) fast fading links due to high level mobility; making MMIMO FDD deployment feasible in overcoming the issue of CSI feedback overhead, which is the major contribution of the proposed architecture.

This paper proposes a study of a PID Controller design for a Magnetic levitation system. The system is composed of an electromagnet (coil), an infrared sensor used to measure the levitated object’s position and a controller. The PID continuously adjusts its output based on the information provided by the sensor, thus modifying the electromagnetic field intensity influencing on the ball’s position. The paper presents the basic theory revolving around the maglev system and PID controlling and then presents simulation results of the system step response.

A solar inverter converts the variable direct current (DC) output of a photovoltaic (PV) panel into alternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical networks. It is a critical balance of system (BOS) component in a photovoltaic system, allowing the use of ordinary AC-powered equipment. Solar power inverters have special functions adapted for photovoltaic arrays and maximum power point tracking systems. While running the appliances in day time, the device will charge the battery because the solar energy only can be used during the day time, while during night the battery will support to run the appliances until next morning. Consumer can check Voltage and Current on device via the Liquid Crystal Display. Once consumer compare the Off grid system from main power source, consumer will understand the power usage and also differentiate the cost. At the end of this project, inverter also provides 240V single phase same as power delivered by the grid, but the cost will be totally different. In this paper stand-alone off grid solar inverter is designed in MATLAB & Proteous and then fabricated to test the simulations. The P& O algorithm is used for maximum power point tracking. The results are tested via MATLAB and validated by developing the hardware.

In this paper, we present a novel signal to noise ratio (SNR) estimation technique using Constant Amplitude Zero Autocorrelation (CAZAC) time synchronization preamble in cooperative communication system. More specifically, a SNR estimation technique is proposed based on CAZAC preamble which was originally designed for time synchronization in orthogonal frequency division multiplexing (OFDM) system. Therefore, there is no extra load or throughput penalty on the system as the preamble used is already present in the system for time synchronization in OFDM systems and can be adapted for SNR estimation. In this work, we consider single-input-single-output (SISO)-OFDM cooperative with decode-and-forward (DAF) single relay and non-cooperative communication systems, when communicating over multipath channel in MATLAB ^® . At the receiver of the destination node in the SISO-OFDM cooperative system, the proposed SNR estimator exhibits around 0.5dB improvement over SNR estimation based on Schmidl's preamble technique. Whilst, the proposed SISO-OFDM cooperative system that invokes the proposed SNR estimator exhibits 2 dB improvements in comparison with non-cooperative system, when communicating over multipath channel. However, for transmission over AWGN channel the SISO-OFDM cooperative system that employs the proposed SNR estimator exhibits about 1 dB improvement over the non-cooperative system.