## 1 Introduction  
Advertising has always been an indispensable element in the business world. Since the internet began to flourish in 2000, online advertising has always been closely related to our lives. Since 2010, mobile advertising has gradually replaced online advertising and has entered the mainstream in the advertising industry. However, what has not changed, whether it is online or mobile advertising, is the fact that it is tough to obtain audiences' location. Therefore, in the past 20 years, digital advertising has not been able to deliver advertising effectively based on the audiences' location. All advertising systems have always cared about the audiences' location since if the audiences' position can be obtained, the audiences' identity can be more effectively distinguished. In the early days of non-mobile advertising, the advertising system was often only able to judge the audiences' location based on the audiences' connection IP. This was indeed a suitable method in the early days since the IP locations of cities, schools, or institutions are fixed. Once you know the IP, you can know the audiences' location and then consider their identity. However, the problem with this approach is that it is limited to places where the IP is known. If an audience is in a place where the IP cannot be determined, it is impossible to know its location. For audiences with the same IP address, it is also impossible to distinguish between audiences. Or, if the same audience appears or moves in different places, it is impossible to track and analyze the path of their movement, too. Since the beginning of the era of the popularization of mobile devices, the dilemmas have gradually improved. Each advertising system has used a variety of methods to detect the location of the audience. With the aid of geographic information on mobile devices, the advertising system has finally been able to get rid of the geographic location analysis limited by IP. It can further accurately locate and analyze the audience. There are three main methods of geographic location analysis through mobile devices. The first is to use the mobile phone's GPS for positioning, the second is to use the mobile phone's WIFI for positioning, and the third is to use the mobile phone's Bluetooth for positioning. However, these positioning methods are not without defects. When GPS is used for positioning, the mobile device will consume a lot of power. If an APP keeps the GPS positioning function on, the mobile device may soon run out of energy. If the user encounters such a situation, they will often remove the APP directly. Thus, most APPs will not always turn on the GPS function. Another possible solution is to use WiFi for positioning. Since a mobile phone can collect nearby WiFi signal sources, if you further analyze the WiFi signals in the current area you can infer a user's current location. The advantage of this is that there is no need to keep the GPS positioning function always on, there will be no problem of excessive power consumption, and the app will be less likely to be removed due to customer dislike. However, this approach is not without other costs. If you want to use WiFi for positioning, you must regularly collect WiFi signals for each specific location. For the advertising system, this is also a cost, but the advantage is that it is no need to worry about power consumption issues such as collecting user location through GPS. Compared with the positioning method using GPS, although the operating cost is higher, and its feasibility is greatly improved once it is passed on to advertisers. Looking at it from another aspect, the task of regularly updating WiFi signals has become a very troublesome and costly problem. Finally, let's look at the problem of using Bluetooth for positioning. The Bluetooth function on early mobile phones is often not turned on. In recent years, thanks to the rise of various wireless connection devices and the popularization of IoT (such as wearable bracelets, wireless earphones, etc.