Wireless Sensor Network (WSN) localization is a critical area with growing research interest due to the increasing applications of WSNs. This paper provides an overview of measurement techniques and one-hop localization algorithms used in WSNs. It discusses multihop connectivity-based and distance-based localization algorithms, and presents open research problems in distance-based localization. Key terms include wireless sensor networks, localization, AOA, RSS, and TDOA. WSNs consist of small, low-cost, low-power sensors that communicate in short distances. These sensors can be deployed in large numbers to monitor and control environments, including homes, cities, and the environment. However, most sensors do not know their locations, so localization algorithms are needed to estimate their positions using known anchor nodes (with known coordinates) and inter-sensor measurements such as distance and bearing. Measurement techniques in WSN localization include AOA, distance-related measurements, and RSS profiling. AOA measurements determine the direction of a signal, while distance-related measurements include time-of-arrival (TOA), time-difference-of-arrival (TDOA), and received signal strength (RSS). RSS profiling involves creating a map of signal strength behavior in the coverage area. One-hop localization techniques use measurements from a few anchors to estimate the location of a non-anchor node. AOA-based techniques use bearing lines from multiple receivers to determine a location. TDOA-based techniques use the difference in arrival times of signals at multiple receivers to estimate a location. Distance-based techniques use distance measurements from anchors to estimate a location. Multihop localization techniques use connectivity and distance-based methods to estimate the location of non-anchor nodes. Open research problems in distance-based localization include improving accuracy and handling errors in measurements. The paper discusses various techniques for WSN localization, including AOA, TDOA, and RSS-based methods, and highlights the challenges and opportunities in this field. It also provides a summary of the key findings and open research problems in distance-based localization.Wireless Sensor Network (WSN) localization is a critical area with growing research interest due to the increasing applications of WSNs. This paper provides an overview of measurement techniques and one-hop localization algorithms used in WSNs. It discusses multihop connectivity-based and distance-based localization algorithms, and presents open research problems in distance-based localization. Key terms include wireless sensor networks, localization, AOA, RSS, and TDOA. WSNs consist of small, low-cost, low-power sensors that communicate in short distances. These sensors can be deployed in large numbers to monitor and control environments, including homes, cities, and the environment. However, most sensors do not know their locations, so localization algorithms are needed to estimate their positions using known anchor nodes (with known coordinates) and inter-sensor measurements such as distance and bearing. Measurement techniques in WSN localization include AOA, distance-related measurements, and RSS profiling. AOA measurements determine the direction of a signal, while distance-related measurements include time-of-arrival (TOA), time-difference-of-arrival (TDOA), and received signal strength (RSS). RSS profiling involves creating a map of signal strength behavior in the coverage area. One-hop localization techniques use measurements from a few anchors to estimate the location of a non-anchor node. AOA-based techniques use bearing lines from multiple receivers to determine a location. TDOA-based techniques use the difference in arrival times of signals at multiple receivers to estimate a location. Distance-based techniques use distance measurements from anchors to estimate a location. Multihop localization techniques use connectivity and distance-based methods to estimate the location of non-anchor nodes. Open research problems in distance-based localization include improving accuracy and handling errors in measurements. The paper discusses various techniques for WSN localization, including AOA, TDOA, and RSS-based methods, and highlights the challenges and opportunities in this field. It also provides a summary of the key findings and open research problems in distance-based localization.