We propose an optimized Takagi-Sugeno Fuzzy Inference System based power control strategy for cognitive radio networks in both with and without path-loss propagation environments. The radio network consists of a primary user transmitter and receiver and a secondary user transmitter and receiver. The fuzzy inference system takes network parameters such as signal to noise ratio, interference channel gain ratio and relative distance ratio as antecedents and outputs a power scale factor as consequence to scale the transmit power of the secondary user such that it does not degrade the quality of service of the primary user. The OFDM transmission technique is applied towards SU transmitter in CRN, which enables SU to utilize the spectrum efficiently under various fading environments. Spectrum sharing networks in with and without path-loss propagation environments and OFDM transmission were tested for bit error rate (BER) performance after fading effects from m-Nakagami fading channel.