Study of WiMAX Physical Layer under Adaptive modulation Technique using Simulink

IEEE 802.16e WIMAX (Worldwide interoperable Microwave Access) is the upcoming wireless system which can offer high speed voice, video and data service up to the customer end..It offers both LOS&N-LOS wireless communication. By using WIMAX Technology we can overcome the limitation of short coverage area, lack of security and low data rate. The aim of this paper is the performance evaluation of an WIMAX system under different combinations of digital modulation and different communication channels AWGN and fading channels. And the WIMAX system incorporates ReedSolomon (RS) encoder with Convolutional encoder with 1⁄2 and 2⁄3 rated codes in FEC channel coding. Orthogonal frequency division multiple accesses use adaptive modulation technique such as(BPSK,QPSK,16QAM,64-QAM) on the physical layer of WIMAX and it uses the concept of cyclic prefix that adds additional bits at the transmitter end. The signal is transmitted through the channel and it is received at the receiver end. Then the receiver removes these additional bits in order to minimize the inter symbol interference, to improve the bit error rate and to reduce the power spectrum. The simulation results of estimated Bit Error Rate (BER) displays that the implementation of interleaved RS code (255,239,8) with 2/3 rated Convolutional code under BPSK modulation technique is highly effective to combat in the WIMAX communication system. Keyword: OFDM, Block Coding, Convolution coding, Additive White Gaussian Noise, Fading Channel, orthogonal frequency division multiplexing (OFDM); Line-of-Sight (LoS); Physical (PHY) layer.