The development of an advanced cellular terminal and wideband application in a mobile network is becoming robust due to its vast capacity, low latency, and high scalability. Edge computing is exceptionally suitable for reducing time delays and improving the nature of network service quality. By Combining rain computing with the wireless access network (WAN) and exploiting edge computing, rain WAN (R-WAN) is expected to be a promising model for advanced wireless networks such as 5G and 6G wireless network architectures. Power domain orthogonal multiple access (PD-OMA) has the possibility of recognize various subscribers whose data are multiplexed by various power factors into the corresponding orthogonal resource and the progressive interference cancellation (PIC) is being used for the detection data at the rain access wireless hub locations. This paper emphasis on the static power allocation of wireless sub channel in PD-OMA and the extension to R-WAN. A six-subscriber multiplexing model is developed on the transmitting side of a PD-OMA multiuser framework model, and a comparable PIC receptor is designed. In addition, a group of static power change elements is characterized by subscriber channel conditions, and an improved fractional send power assignment (E-FSPA) calculation is proposed for PD-OMA and computed to the various subscriber models. The experimental results indicate that EFSPA performs in a way better than the past SPA and FSPA. More specifically, it is possible to find more than one wireless channel power distribution technique performing better than MIMO under similar R-WAN conditions via E-FSPA.