In this study, we propose a relative and clustering analysis correction (RCC) technique capable of improving the location accuracy of a smartphone global navigation satellite system (GNSS). The RCC technique improves the accuracy of the Android GNSS by eliminating common error components from pseudoscope measurements as well as noncommon errors through cluster analysis using Android GNSS signal attributes. Cluster analysis was applied to the RCC technique using the optimal clustering method among the hierarchical clustering, K-means clustering, and neural network clustering methods. As a result of verifying the RCC technique, the following results were obtained. The distance error of a zero-baseline experiment, which was performed to check the relative accuracy and precision between smartphone GNSSs, was 0.572 m for two sessions, which showed that the noise-causing error of the Android smartphone GNSS used in the experiment occurred similarly in each session. Positioning accuracy was much lower in a multipath environment than in an open environment due to the reflection and refraction of satellite signals by obstacles, such as buildings around the receiver and multipath generation due to low-elevation non-line-of-sight satellite signals. However, observations confirmed that applying the RCC technology to the Android smartphone GNSS with errors of more than 5 m in multipath environments can secure high location accuracy, even in multipath environments.Recent smartphones have been equipped with GNSS chipsets, and location information can be obtained through an application programming interface (API). (1)(2)(3) In May 2016, Google announced that it would provide GNSS raw data for smartphones and tablets that support the Android 7.0 (Android Nougat) operating system. Smartphones equipped with GNSS chipsets running Android 7.0 or later can calculate not only a user's location information (latitude, longitude, and elevation) but also the pseudodistance between the satellite and receiver as well as provide a direct signal timestamp that allows the user's location to be calculated. Notably, GNSS raw data are now available. (4)(5)(6) In particular, the first dual-frequency GNSS chipset was released in June 2018 in a smartphone equipped with a BCM47755 location hub, which increased the availability of satellite signals and improved positioning accuracy. The provision of such GNSS raw data enabled the design of an advanced positioning algorithm and improved accuracy in a usercentered location-based service (LBS). (7,8) Currently, programs and applications that can use GNSS raw data are being developed, and various studies related to the high positioning accuracy of smartphones are being conducted. For high-precision geodetic applications, precise point positioning (PPP) is well known to provide high positioning accuracy as evidenced in various research contributions. (6) The use of the dualfrequency ionosphere free linear combination has typically defined conventional GNSS PPP processing. (8) However, owing to satellite mod...