Performance evaluation on the basis of Bit error rate for different   order of Modulation and different length of Subchannels in ofdm system
  Today, we have required to accommodate a large number of users under a single base station. This can be possible only if we have some flexibility over the spectrum. Previously we have lots of multiplexing methods to accommodate large number of signals in time and frequency domain. But now we have required to accommodate a large number of users in the same bandwidth, without any fading over the received signal. So, orthogonality can be maintained over the frequency response. This technology is now more popular in the mobile communication domain, called Orthogonal Frequency Division Multiplexing (OFDM). Actually user data can be converted into the parallel form and then they are modulated using digital modulation techniques. Finally, they have followed by OFDM Modulator and cyclic prefix can be inserted into the OFDM symbols. Here, I have worked on the measurement of Bit error rate for different modulation techniques in OFDM technology. It has been considered that subchannel size is not constant. According to that I have concluded the overall idea regarding the performance under OFDM technology. 
Sutanu Ghosh
cs.IT math.IT