As IEEE802.11 (wireless local area network standards) technologies have become gradually mature, WiFi (Wireless Fidelity), as a technology of wireless Internet access, has been used by more and more users, and has covered a wider area. Thus, an Access Point (AP) becomes an important way for the public to connect to a network. With the development of mobile equipment, nowadays, mobile communication equipment can also act as a mobile access point, that is, a mobile accessing hotspot technology, in which mobile network resources of the mobile equipment are shared over WiFi, to enable other mobile equipment to access the mobile access point over a WiFi network.
However, each access point is configured with an access password for authentication. All kinds of equipment that need to access the access point must input the password to complete the authentication. It is difficult for a user to acquire access passwords of too many access points, not to mention remembering them. As a result, it is difficult for a user to access WiFi conveniently anytime and anywhere.
A position information of a target has played an important role in various scenarios, for example, vehicle navigation, staff positioning under coal mine, construction site management, and so on. GPS (Global Positioning System), as a satellite navigation positioning technology being most widely used globally, has been widely applied in various fields. However, its signals are extremely easily interfered and blocked by barriers, which results in poor positioning effects in the environment such as intense metropolitan areas, tunnels, indoor areas, and even results in positioning failure.
WiFi mainly relies on received signal strength (RSS) information contained in a beacon signal periodically sent by an access point or a base station to implement positioning and mobile computation. The WiFi-based positioning has the following advantages: it is feasible to work in different scenarios such as an indoor scenario, an outdoor scenario, and so on, offering a possibility for implementing positioning anywhere; it merely relies on the existing WiFi networks, for which no change is needed, therefore the usage cost is lower; and it can be used even in the case that barriers exist, since WiFi signals are less affected by non-line-of-sight factors.
An overwhelming majority of WiFi-based positioning systems are implemented based on RSS, the method of which are mainly classified into two types: a triangle algorithm and a position fingerprint identification algorithm. In the triangle algorithm, a target position is estimated by using the information of distance from a target to be measured and at least three reference points, which is converted to a distance from the target to be measured to each corresponding access point in practice based on a propagation fading model of wireless signals. In contrast, in the position fingerprint identification algorithm, a target position is acquired by comparing signal feature fingerprint information requested by positioning. Since the received signal strength is easily affected by an antenna height, a linear direction, and an environment, the WiFi positioning based on the triangle algorithm fails to achieve an ideal performance. On the contrary, the wireless positioning based on the position fingerprint identification does not need to figure out a position of the access point and an accurate signal channel model, which thus has a higher superiority compared with that based on triangle algorithm, regardless of specific implementation and positioning performance.
The Chinese Patent Application No. 201110131432.2 has provided a WiFi-based layered positioning system. The positioning system firstly determines a floor where a user of a mobile terminal stays based on a strength of wireless signals of a plurality of access points acquired and floors where the access points are located, and then acquires a final location information of the user of the mobile terminal by means of a fingerprint identification method. Meanwhile, reference points in the fingerprint identification method can be added and corrected continuously by means of participation of the users, thereby achieving the object that a plurality of terminal users can share the system. The system not only satisfies the demands that the users of the mobile terminals can acquire a positioning information of the exact floors where the users themselves stay, but also can make a judgment for the condition that a plurality of floors share the same access point, that is, identification stability is higher.
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