BER and SER Based Performance Analysis of BPSK and QPSK Modulation Schemes with OFDM in Rayleigh Fading Channel

BER is a key property of the digital communication system. Various types of modulation methods are used in the digital information transmission system. BER can be demarcated as the number of received bits of  a  data  stream  over  a  communication  channel  that  can  be  affected  due  to  noise,  interference  and  distortion or  bit synchronization errors. OFDM can be seen as either a modulation technique or a multiplexing technique. One of the main reasons to use OFDM is to increase the robustness against frequency selective fading or narrowband interference. In a single carrier system, a single fade or interferer can cause the entire link to fail, but in a multicarrier system, only a small percentage of the subcarriers will be affected.  The BPSK digital modulation technique for OFDM system over AWGN and Rayleigh fading channels.  From  comparison we  can  observe  that  the  OFDM- BPSK  modulation  has  no  any  specific advantage  over  a  conventional  BPSK  modulation  scheme  in  AWGN  channel  but  OFDM-BPSK  modulation  in  AWGN channel has great advantage over OFDM-BPSK modulation in Rayleigh fading channel.  The  performance  of  BER  of  BPSK  over AWGN  and  Rayleigh  channel  is  compared.  Simulation  of  BPSK  signals  is carried  with  both  AWGN  and  Rayleigh  channel. The work provides link level performance analysis of non-line of sight QPSK-OFDM data transmission over Rayleigh fading channels. Two scenarios have been considered in this thesis. Firstly, the performance of BPSK-OFDM and QPSK-OFDM over the AWGN and Rayleigh channel was obtained.

Keywords: OFDM,QPSK,BPSK,AWGN,RAYLEIGH CHANNEL