## 2 Related Work
In [27], it is proven that RIS-aided mmWave NOMA in the downlink scenario outperforms mmWave NOMA without RIS. A downlink IRS-aided system over fading channels is considered in which two users are served by different multiple access techniques, namely, NOMA, time division multiple access (TDMA) and frequency division multiple access (FDMA) system in [28]. A success convex approximation method is framed for the joint optimization of phase shift and resource allocation in solving average sum rate maximization. It is observed that the focus is mainly on the sum rate maximization and error performance of an RIS-assisted downlink NOMA system with and without the assistance of intelligent RIS. RIS is an excellent option for improving the performance of vehicle-to-everything (V2X) applications. In [29], it is proven that RIS improves QoS demands for vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2I) communications, assuming slowly varying channels. However, the nature of V2X channels is rapidly changing. Recently, the concept of blind-RIS was introduced in [30]. It has been proven that blind-RIS systems have the advantage of improving SNR by \(N\) times at the user end. In blind-RIS, low-cost and passive reflector elements are used for transmission without RF processing. This is more suitable for the uplink process. The following research gaps have been identified from the related work:  
* The majority of the research assumes intelligent RIS, where the BS-RIS and RIS-users' channels are known in advance at the RIS. Each RIS element in these models is supposed to pre- and post-cancel the phase distortions brought on by the related channels. The channels are rapidly varying in applications such as V2X. It is quite difficult to gather precise channel information for every user, especially when there are many users and reflecting elements;
* The majority of classic works presuppose the deployment of RIS between the transmitter and receiver. The received signal at the RIS may be quite weak when it is far from the transmitter. RIS may not therefore provide the anticipated benefits. The majority of studies examined the sum capacity and outage probability for RIS when configured as an SR. These models might not be realistic in all scenarios;Further, it is also noted that outage analysis and optimal power allocation for near user and far user of the uplink NOMA system with RIS have not been addressed. In this paper, the concept of blind-RIS is used for the uplink process, especially in the NOMA system. Motivated by these observations, the technical contributions of this paper are listed below:  
* Two different system models are proposed for the blind-RIS-assisted uplink NOMA system: 1. RIS is modeled as a smart reflector (SR) for the near and far users of the uplink NOMA system and it is termed as blind-RIS-SR-NOMA. 2. RIS is modeled as an access point (AP) for the near and far users of the uplink NOMA system and it is termed as blind-RIS-AP-NOMA. * The optimization problem is formulated to allocate optimal powers at both near and far users to maximize the sum rate of the proposed uplink NOMA systems. Closed-form expressions for optimal power allocation are also obtained by solving the optimization problem;
* Extensive Monte-Carlo simulations are performed to corroborate the closed-form expressions that have been derived. The analytical and simulation curves are nearly identical, indicating that the obtained expressions are accurate.