Indian Journal of Science and Technology

Abstract

Orthogonal Frequency-Division Multiplexing (OFDM) is a robust multi carrier modulation system most commonly used in many wireless communication standards. The overall OFDM system performance is stable over signal distortions caused by multipath fading channels but synchronization problems caused significant quality degradation at receiver side. In recent years many papers have been published to mitigate this synchronization problem still the overall system performance is getting worsened due error caused by fixed point model. In this paper we analyzed the limitations of the fixed point computations in timing and frequency offset estimation and its performance in terms of error rate. Here we carry out both analytical approach and statistical results obtained through extensive numerical simulations and the bit length of floating point IEEE 754 standard single precision formats is optimized with the required degree for an accurate offset estimation to reduce OFDM design complexity. Also, a unique floating point precision model for error less FFT computations for all mapping levels used in OFDM system. The proposed scaled floating point precision model is compared over full precision model and its efficiency against fixed point model in OFDM synchronization process is proved through MATLAB simulations. Finally through FPGA hardware synthesis the complexity reduction of proposed scaled precision model is proved in basic arithmetic models such as adder and multiplier against single precision format. Here we proved the resource utilization rate is reduced by half as compared to standard full precision models without compromising any quality degradations. The computational error free nature of proposed scaled precision model in both timing and frequency offset estimation process and its overall OFDM system performance in terms of BER rate is proved.

Keywords: Customization, Fast Fourier Transform, Floating Point Aithmetic, OFDM, Synchronization