Due to the fact that encryption operations performed by any protocols increase the number of operations and also slow down the rate of data being sent or received over WiMAX network. Hence, Encryption may have negative effect on quality of services offered to the end users and the system capacity. The Performance enhancement over WiMAX network is needed by using optimized encryption algorithm, which reduces computations overheads. In this exertion, a proposed optimized encryption algorithm, which adopts AES algorithm as the encryption algorithm, is presented. In previous work
[1], a customized version of the “AES" block cipher was introduced to suit proprietary data encryption applications. In this paper, a higher security level for optimized AES is proposed by adding a dynamic permutation unit of input data in every round which allowing number of round reduction possibility, improves network performance and increases diffusion propriety for each round.