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Download In November 1993, student Jennifer Koon was kidnapped and killed in New York state in the United States. Before her death, the 18-year-old college sophomore and daughter of a New York state assemblyman managed to call 911, but police could not determine her position from the cellphone signal. Three years later, the public safety network Location-based Services was established, allowing authorities to locate users through radio signals. Now, in China, nearly two decades later, such services are not far away. "LBS is nothing new. The reason we could not develop an LBS in China until now is that the Internet on mobiles only became popular in the past few years," said Shi Chuang, a professor at Wuhan University and director of the National Engineering Research Center for Satellite Positioning System. "With LBS, we can integrate information on people ... and things, so that we can dig out business value," he said. As a result, life can be made more convenient, such as through live monitoring of traffic congestion or monitoring dangerous and poisonous goods. However, nothing can be accomplished without a highly accurate positioning system. Paul Zandbergen, an associate professor at the University of New Mexico's geography department, did an accuracy survey on positioning systems on the 3G iPhone in 2009. Results showed Wi-Fi locations using this phone had an average error of 74 meters for 58 observations, failing to meet the published accuracy specifications, while cellular positioning using this phone had a median error of 600 meters for 64 observations. | 
