Optimization of fairness index in wireless networks via NOMA technique is achieved in this thesis. The word NOMA refers to Non-Orthogonal Multiple Access. In the network that employs non orthogonal multiple access, the spectrum resources are allocated to all the users in the network utilizing the power domain. 5G networks use the NOMA technique to allocate the spectrum to the users. This technique is not in the earlier generations (1G – 4G). As part of thesis, various simulations are conducted in the downlink scenario for the networks using NOMA technique to optimize the fairness index. When the network applies NOMA technique to divide the spectrum among users, all the messages are sent as a single signal and each user decodes its message. Using the mathematical equations, the powers of transmission of each user are calculated to achieve the optimal fairness index. Comparison of the proposed algorithm with the existing algorithm is done as part of this thesis.