Abstract

 Adaptive modulation schemes for fading channels are usually required to fulfill certain long-term average BER targets. The analysis and design of variable-rate variable-power QAM schemes with average BER constraints are tackled for MIMO multiplexing. In closed-form policies are derived for continuous rate and power adaptation which are compared to the fully discrete policies In particular, if interference between Eigen channels is large, MultipleInput Multiple-Output multiplexing should utilize only one of its Eigen channels, in which case all multiplexing gain is los WiMAX is the upcoming wireless system. In this paper, performance of wimax physical layer is simulated using MATLAB and bit error rate (BER) performance is observed. The BER level is depend on the modulation type, SNR value and channel behavior. To transmit the faithful data over these systems the BER performance is further improved using forward error correction codes (FEC) is performed at different iterations in MATLAB. BER performance is evaluated for these codes under different modulation schemes like QAM-4 QAM-8 and QAM-16. We will use Orthogonal Frequency Division Multiplexing to achieve high data rate necessary for intensive application. The Space-Time Block Coding (STBC) with Multiple-Input Single-Output (MISO) and Multiple-Input Multiple-Output (MIMO) set-up for use in wireless channels.

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