VLSI Based Adaptive Modulation and Adaptive OFDM

Abstract

In this paper, adaptive modulation technique is presented for Orthogonal Frequency Division Multiplexing (OFDM) based wireless communication system. The design of adaptive modulation is done through Very Large Scale Integration (VLSI) System design environment. In general, reducing the hardware complexity and increasing the speed of processors are the important requirements of VLSI System design environment. Quadrature Phase Shift Keying (QPSK) modulation and Quadrature Amplitude Modulation (QAM) are the important modulation techniques for wireless communication system. These two modulations have different types of advantages in terms of less area, high speed and lower power consumption. QAM modulation has high speed to modulate the digital input whereas QPSK modulation has low speed due to less angle coefficient. Similarly, QPSK modulation utilizes less hardware and lower power consumption than QAM modulation to design the modulation technique. In addition to adaptive modulation, adaptive decoder, adaptive frequency transformation techniques such as Fast Fourier Transformations (FFT) are incorporated in OFDM System to improve the performance of OFDM based communication System. Hence, proposed OFDM System technically referred as “Adaptive OFDM”.