In this paper, we introduce circle 16 quadrature amplitude modulation C 16QAM modulation format in matlab high spectral effectivity zero guard period ZGI coherent optical CO orthogonal frequency department multiplexing OFDM system. At transmitter, matlab programming C 16QAM has merits over matlab programming widespread square 16QAM in terms of transmission distance and tolerance to laser linewidth and fiber nonlinearities. ZGI CO OFDM permits to do away with matlab programming cyclic prefix CP, so it has matlab programming advantage of better spectral efficiency in comparison with matlab programming frequent CO OFDM system. At receiver, a good way to compensate chromatic dispersion CD and phase noise in matlab single channel ZGI CO OFDM system, we studied matlab programming overlapped frequency domain equalizer OFDE and two carrier phase restoration CPR algorithms. We simulate matlab programming above systems and matlab programming effects reveal that with matlab programming C 16QAM, matlab 28GBaud ZGI CO OFDM system can have matlab programming longer transmission distance, matlab programming higher tolerance to laser linewidth and fiber nonlinearities with contrast to matlab programming common square 16QAM. For orthogonal frequency department multiplexing OFDM based indoor seen light communication VLC techniques, partial non ideal transmission conditions akin to inadequate guard durations and matlab dispersive channel can bring about severe inter symbol crosstalk ISC. pptx Free down load as Powerpoint Presentation . The framework of this code was taken from Figure 4. Examples Illustrating Echo and Delay MATLAB software to find DFT and IDFT using matlab applications To view matlab programming program code of matlab MATLAB software, please click matlab programming name of that application from matlab programming list Chapter 6: Convolution. The operation of discrete time round convolution is described such that it plays this feature for finite length and periodic discrete time alerts. Using matlab programming approach of impulse decomposition, programs are described by matlab signal called matlab programming impulse reaction. Write matlab Program for matlab programming generation of basic signals similar to unit impulse, unit step, ramp, exponential, sinusoidal and cosine.