The individual subcarriers experience flat fading only and this can be compensated using a trivial frequency domain single-tap equalizer. A sufficiently high value of N makes the individual bandwidth (W/N) of subcarriers narrower than the coherence bandwidth of the channel. In OFDM the high rate data stream (bandwidth W) is decomposed into N lower rate data streams and then they are transmitted simultaneously over a large number of subcarriers. This is achieved by using a long symbol period which minimizes the ISI. OFDM has grown dramatically in the field of wireless communication because of its robustness against multipath delay spread. Orthogonal frequency division multiplexing (OFDM) is a multiplexing technique used in above standards. WLAN and WiMAX are emerging standards for wireless broadband communication system.
It support simultaneous voice, data and multimedia services to a large group of subscribers without the need for digital subscriber line (DSL) or cable modem. It provides enhancement in multimedia data services and quality of service (QoS). Broadband wireless access (BWA) systems have evolved as the solution for the persistent demand of these multimedia services. The global demand for multimedia data services has grown at a remarkable pace which has led to the expansion of system capacity in terms of the number of subscribers supported, higher data rate and ubiquitous coverage with high mobility. INTRODUCTION The world is passionately accepting the new wireless communication methods and services. Keywords: OFDM FEC FPGA WLAN WiMAX VHDL 1. The simulation results and circuit parameters are also presented. Moreover using this modified address generator an efficient multimode WiMAX Interleaver has been implemented using VHDL. The proposed work presents that a modification in the FSM of address generator for WiMAX Interleaver provides a considerable improvement in terms of logic cells and slice flip flops used. The complete Interleaver has been divided into two sub modules address generator and interleaved memory. Interleaver plays a vital role in improving the performance of FEC codes in terms of Bit Error Rate over wireless channel. Standards mentioned above can be implemented efficiently in FPGA.
OFDM is multiplexing technique used in above standards as it reduces inter symbol interference and multipath fading over wireless channel. Abstract-Wireless communication is one of the most vibrant research areas in the communication field today. VHDL Implementation of Efficient Multimode Block Interleaver for WiMAX Deepak Bhardwaj 1, S P Singh 2, V K Pandey 3 1, 2 3 Electronics & Communication Engineering Department of Electronics & Communication Engg, Noida Institute of Engineering and Technology, Greater Noida, U P, India.
International Journal of Electronics and Computer Science Engineering Available Online at 302
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