MIMO CHANNEL CAPACITY OF FREE SPACE OPTICAL COMMUNICATION SYSTEM OF OOK AND M-PPM

multiple pulse position modulation performs better than the on-off keying on all ideal channels but its performance degrades on multipath channel. This is happen because of increase in complexity on multipath channel. With the increase in number of transmitter and receivers complexity of the system is increases so an effective modulation technique is need for multi input and multi output system so that communication can be done effectively. In this paper we study the channel capacity of on-off keying and multiple pulse position modulation for the multi input and multi output system in free space communication. In a single input and single output channel the pulse position modulation technique is much better because of low complexity in the system. But with the increase in number of transmitter make the system more complex for the pulse position modulation therefore in case of multi input and output on-off keying modulation scheme is preferred. As seen from the simulation results that the channel capacity of on-off keying is more than the pulse position modulation.