Thank you Dhiman and Tanveer for requesting such wonderful research work and finally being uploaded by Tanveer.
Both the papers are good and quite appreciable and important in terms of knowledge and information.
One is ieee papers of JOURNAL OF LIGHTWAVE TECHNOLOGY,
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6334404&newsearch=true&queryText=Constant%20Envelop%20Minimum-Shift%20Keying%20OFDM%20Coherent%20Optical%20Communication%20System