# Evaluation of 5G Positioning Based on Uplink SRS and Downlink PRS Under LOS and NLOS Environments
## 1 Introduction  
The rapid evolution of sensor, communication, and computing technologies has initiated a new era of connectivity and innovation, with 5G networks at the forefront of this transformation. With the development of Beyond 5G (B5G) and 6G networks, the demand for precise, high-accuracy positioning is increasing [1]. Location-based services have emerged as a cornerstone application of 5G systems, offering transformative potential across a wide range of industries. In the context of the retail sector, the advent of location data has precipitated a significant evolution in the shopping experience, thereby facilitating the provision of personalized services, targeted promotions, and the optimization of store layouts [2]. The evolution of 5G wireless communication [3] has expanded services and applications to meet the demands of an increasingly dynamic and interconnected society. Network-assisted positioning is a fundamental element of 5G and will retain its significance in 6G, particularly with regard to vehicle localization. Recent advancements in 4G LTE and 5 Gtechnologies have enabled the development of high-precision positioning services, prompting 3 GPP to prioritize localization for emerging industries [4]. Consequently, 3 GPP is advancing 5G and radio access technologies to meet more stringent accuracy requirements than earlier generations [5]. Nevertheless, attaining the key performance indicator (KPI) levels stipulated by 3 GPP for localization accuracy poses considerable challenges [6]. [PERSON] [7] presents a comprehensive overview of 5G positioning in the context of recent advancements and standardization efforts. The researcher begins with key performance indicators (KPIs) and subsequently undertakes an analysis of cellular positioning technologies from 1G to 4G, as well as advancements in 5G. Recent research [8] proposes positioning solutions for 5G and next-generation networks by using deep learning techniques and radio fingerprinting in 5G NR. Release 16 introduces significant advancements to the SRS specification. SRS positioning can be modified through the adjustment of the initial comb offset and cycle period. It has been determined that the SRS resource occupies a portion of the orthogonal frequency division multiplexing (OFDM) subcarriers. The adaptable nature of the 5G NR signal optimizes the design of the Positioning Reference Signal, making it more suitable for localization than its predecessor [9]. The PRS was originally standardized in 3 GPP Release 9 to support LTE positioning capabilities and form the basis of this approach. A substantial body of research has focused on exploring its implementation in LTE and 4G systems. The primary reference for NR positioning is 3 GPP TR 38.855. In Release 16, PRS was refined to achieve a positioning accuracy of less than 5 m in outdoor environments and less than 3 m in indoor environments. Release 17 introduced additional enhancements, thereby enabling centimeter-level accuracy to support high-precision applications. Release 18 expands localization support by incorporating sidelink-based positioning and ranging, improving performance in scenarios with insufficient coverage [10]. [PERSON] proposes a system for ultra-high-accuracy positioning in 5G New Radio (NR), enabled by new standardization features introduced in Release 18. The incorporation of carrier phase positioning, sidelink-based ranging, bandwidth aggregation techniques, and low-power solutions tailored for RedCap UE constitutes a key component of the proposed approach [11]. [PERSON] proposes a solution to the V2X sidelink tracking challenge. The proposed approach utilizes a Kalman filter to address the challenge, incorporating estimated error covariance lower bounds (EECLBs) to enhance tracking accuracy. A gating mechanism is also proposed to improve LOS detection and strengthen the robustness of the tracking framework [12]. A recent study proposes the CCM-SPS scheme to enhance resource allocation in sidelink-based joint communication and sensing systems.