Comparative study and analysis of bit error rate of CDMA, OFDM and UWB for different modulation techniques

Abstract

The work reported in the thesis includes the design, simulation and study of CDMA (Code Division Multiple Access), OFDM (Orthogonal Frequency Division Multiplexing), and UWB (Ultra Wide Band) for different modulation schemes. New modulation technique named as Advanced FBMC (Filter band Multi Carrier) is also designed and explored which is considered as promising candidate for fifth generation mobile communication system. The development of mobile technology started in the year 1860 when James Clerk Maxwell described a technology to propagate the electromagnetic waves in the space. Later, the face of mobile communication changed in the year 1899 when Guglielmo Marconi discovered the radio. The development of mobile communication led to further demands from subscribers like high-data-rate, capacity and better coverage. In order to fulfill the motto of communication system, CDMA became the first approach in the field of mobile communication system which increased the capacity and data-speed as per the demand of users. In CDMA, a large frequency band is used by the mobile base station. The input is taken as unique spreading codes which are used to spread the original information. At the receiver, modulated codes are despreaded by using an efficient co-relator. In CDMA, the transmitted signal bandwidth is more than that of original signal. The 3G CDMA uses frequency spectrum of 400 MHz, 800 MHz, 1700 MHz, 1900 MHZ and 2100 MHz, which is also compatible with other CDMA release. In the existing CDMA system, QPSK (Quadrature Phase Shift Keying) modulation is used for uplink and BPSK (Binary Phase Shift Keying) is used for downlink transmission. The data-speed of 3G is 14 Mbps which can be increased by using massive MIMO (Multiple In Multiple Out) and High order modulation scheme. However, CDMA has certain disadvantages like requirement of high power and ISI (Inter-Symbol-Interference) which make it unsuitable for next generation mobile communication, due to which it was not a choice for a 4G mobile communication.