Sanjib Sil

Simulation, design and analysis of a low power MIMO-OFDM system and its implementation on FPGA

In the world of modern communication systems, several newer techniques have come around to replace the conventional techniques of high speed data communication. As wireless communication protocols developed and user pressure started to increase, it became an absolute necessity to develop multi-user supporting techniques like Orthogonal Frequency Division Multiplexing (OFDM), Multi Carrier Code Division Multiple Access (MC-CDMA) for data security and reliability of data transmission. In this work, an effort has been made to simulate and design a low power consuming custom hardware for MIMO-OFDM system based on Field Programmable Gate Array (FPGA). Both the transmitters and the receivers were designed in the simulation environment targeting Xilinx Spartan 3E and Spartan 3A FPGA devices. The design was also implemented on the mentioned FPGA hardware and real experiments were carried out for the verification of the design. Our design proves that a very low power system can be designed using an FPGA device which can provide much higher data rate and very less power as compared to the conventional systems and it can also be reconfigured according to the requirement.

Realization of Vertical Handover - Applicable for 4G Communications

The objective of this paper is to present a realization of vertical Handover which is applicable for 4G communication networks. The authors have realized vertical handover in four levels. Four different experiments have been conducted in the laboratory corresponding to four levels from basic fundamental level to final complex levels of vertical handover. It is observed that acceptance; lock and track of particular spectrum and rejection of unwanted spectrum are achieved with this set up. It leads to vertical handover in 4G communications.

Modified switching DE algorithm to facilitate reduction of PAPR in OFDM systems

Abstract Partial Transmit Sequence (PTS) currently can be regarded as an extremely attractive and popular method which allows the achievement of very good Peak to Average Power Ratio (PAPR) reduction for signals that have undergone Orthogonal Frequency Division Multiplexing (OFDM), while also is being a technique which does not distort the signals being processed. In this method, a comprehensive search is conducted taking into account all possible combinations of phase-factors that can occur, leading to an increasing complexity of computation with respect to increasing in sub-blocks. The current paper outlines a novel low complexity sub-optimal PTS technique with its basis in an altered implementation of Differential Evolution (DE) algorithm shortly MBLX-DE which significantly diminishes the PAPR of OFDM signals. More specifically SWDE_Sucess_MBLX (Switched parameter Differential Evolution with success based mutation and modified blending crossover) algorithm (Ghosh et al., 2017) is modified in an efficient way and has been implemented for the PTS scheme. The proposed algorithm introduces modifications in three stages of SWDE_Sucess_MBLX like population central tendency based mutation scheme is incorporated along with the success based mutation, a random selection between two cross-over strategies with blending rate concept and threshold-based selection. A theoretical performance study with general formulas of the proposed scheme is presented and a comparative analysis is done with existing algorithms. Extensive simulation results demonstrate that our proposed method can substantially outperform against the currently best-known algorithms in the context of reduction of PAPR as well as performance in terms of complexity of the computations to be performed.

Reduction of Peak-to-Average Power Ratio of OFDM System Using Triangular Distribution Based Modified Companding Scheme

ABSTRACT Orthogonal frequency division multiplexing (OFDM) is an attractive multicarrier modulation technique, which is widely introduced in the present as well as future broadband wireless communication systems due to high data rate, high spectral efficiency, and robustness to the multipath fading channel. Despite its popularity, OFDM system suffers from the critical drawback of large peak-to-average power ratio (PAPR) of the transmitted signal, which may lead to undesired spectral re-growth, poor power efficiency, and overall performance degradation. In this paper, we propose an efficient non-linear companding transform (NCT) technique for reducing the PAPR of OFDM signals. Our proposed scheme coined as triangular distribution (TR) based companding offers an improved bit error rate (BER), better design flexibility, and more degrees of freedom while reducing PAPR effectively compared to the other existing companding schemes. The PAPR reduction performance of our proposed scheme for the different modulation approaches like QPSK, 4QAM, 16QAM, 32QAM, and 64QAM is also presented here. The theoretical analysis of the proposed scheme and comparative study with the existing algorithms are presented. Simulation results demonstrate that our proposed companding scheme can substantially outperform the existing NCT techniques in terms of PAPR reduction, BER performance, and bandwidth efficiency for each of the modulation approaches under different noisy channel conditions.

Bit error rate performance evaluation of different digital modulation and coding techniques with varying channels

This paper focuses mainly on Bit Error Rate (BER), Signal to Noise Ratio and different Rayleigh channels. We have designed four Rayleigh channels. This paper describes the comparative analysis of different digital modulation techniques like BPSK, QPSK, 8PSK, 16PSK and 16QAM for four Rayleigh channels which are designed. We also compare the convolution coding with different code rates i.e. 1/2, 1/3 and 2/3 code rate for various channels. Here we use MATLAB2009b software.

Frequency diversity improvement factor for rain fade mitigation technique for 50–90 GHz in tropical region

Microwave communication system in tropical region like South-East Asia, operating at higher frequency ranges, are attenuated due to the presence of particles in the atmosphere, like water vapor, water drops and the ice particles. The atmospheric gases and rain absorb and scatter the radio waves and consequently degrade the performance of the microwave link. Hence the rain fade must be taken in consideration for the Microwave link design to track the service of outage and quality. The aim of this is to develop and propose frequency diversity improvement factor prediction model for rain fade mitigation technique (FMT) from 50–90 GHz. Here the rain attenuation is predicted based on the ITU-R rain attenuation prediction model using measured rain rate in tropical region-South-East Asia. The predicted data are analyzed to develop and propose a prediction for the improvement factor. The proposed improvement factor model is investigated according to the fade margin where the frequency separation is set to 10 GHz.