On constant BER analysis for real time information transmission and adaptive modulation in WiMAX MISO system

Today's wireless communication system demands a sharing of multimedia information at higher data rate and constant connectivity for efficient multimedia information transmission. One of the possible solutions to fulfill theses requirements is adaptive modulation technique. As user in mobility moves towards base station or access point user's device receive more power so higher order modulation schemes are possible with good signal-to-noise ratio (SNR). At the same time there are changes in signal quality because of changing SNR due to movements. Due to that, also quality of services (QoS) is also affected. According to the changing SNR if modulation schemes are changing then it is possible to maintain constant bit error rate (BER). In this paper we have used the adaptive modulation concept in the Air Interface for Fixed broadband Wireless Access system which is a WiMAX IEEE 802.16 model with multiple antenna system and multicarrier modulation (OFDM). We have implemented and simulated the model with real time changing SNR (which indicates movement) simultaneously changing the modulation scheme according to SNR. In the results we observed the SNR vs. BER plots and real time information (image) on different modulation scheme which is used in the adaptive scheme with high and low SNR values. From the plot of the SNR vs. BER we found the constant BER which satisfies the objective.