T.Jaya1, V. Rajendran 2
1Assistant Professor, Department of Electronics and Communication Engineering, Vels University, Chennai.India
2Professor and Head, Department of Electronics and Communication Engineering, Vels University, Chennai.India
Communication has become one of the important aspects of life in present day technology. With the rapid growth in technology, the need for larger, faster and error free data has become the order of the day. In this regard the communication system faces some problems that are time varying channel characteristics and spectrum bandwidth is a mainly expensive thing in that service. However the channel state information changes always which results in reduced stability of link throughout the transmission. The occurrence of fast multipath fading and intrusion from other customers, the Signal to Noise ratio is keep on varying in time on wireless transmission medium. The system performance is degraded due to above metrics. The proposed method is dynamically changing the modulation method that is Adaptive Modulation for Multi Carrier Code Division Multiple Access (AM based MC-CDMA) in WIMAX (Wide Band Interoperability for Micro wave Access) systems which is a hopeful method to enhance throughput of the system with stable transmission technique on time varying transmission mediums. Here the different modulation techniques are introduced that are BPSK, QPSK and M-ary PSK mapping schemes useful to a proposed MC-CDMA scheme in Rayleigh medium or channel surroundings. It measure up with the Bit Error Rate metric of different code rates in the MC-CDMA method and further select the most excellent modulation technique and code rate to get improved Bit Error Rate performance metric. Also it improves the spectral efficiency up to 6 bps and throughput is 120 bps in the system.
Index terms: Multiple Carrier Code division multiple access (MC-CDMA), Adaptive Modulation, Multipath fading, Wide Band Interoperability for Micro wave Access (WIMAX), Spectral efficiency, Bit Error Rate(BER)