classifiedsloha.blogg.se

• WIRELESS SIGNAL STRENGTH MEASUREMENT OFFLINE

Compared with the location technology based on location fingerprint, this method does not need to consume a lot of manpower and material resources to construct the location fingerprint database in offline stage.ĭue to the fact that Wi-Fi signals are easily interfered by the environment or human factors when propagating indoors, multi-path effects such as reflection, diffraction, scattering and refraction are generated, which easily affects the accuracy of ranging . No special hardware is needed at the receiving terminal, and the location can be located directly using the existing widely deployed wireless local area network (WLAN) infrastructure. Compared with the existing technologies, such as time of arrival , time difference of arrival , angle of arrival  and channel state information , RSSI-based location methods are based on wireless network interface card (NIC) . Received signal strength indication (RSSI)-based location methods are based on the rule of signal strength changing with the propagation distance to achieve location, which has the characteristics of simple detection mechanism, low development cost and easy realisation, and is the mainstream method of indoor positioning. . Therefore, the use of Wi-Fi to locate indoor targets is the best choice, with good prospects for development. However, the existing GPS satellite positioning can only be more accurate in the outdoor environment. For example, critically ill patients track monitoring, shopping cart positioning, travel route navigation, real-time location queries and so on. At the same time, the positioning service market is developing rapidly, and the demand for positioning services is also increasing rapidly. The experimental results show that: (i) the RSSI value measured is the strongest when the antenna of the receiver is vertically oriented to the antenna of the transmitter, while the weakest when the antenna is vertically back-facing and the difference between the strongest signal and the weakest signal is 20–25% at the same test point (ii) the wider the measurement range of NIC, the more conducive to data collection (iii) the distribution of RSSI signals generated by an access point at a fixed position is inconsistent with time (iv) when the height of receiving antenna is 0.5 m different from each other, the path loss index of ranging model produces a deviation of about 10%.ĭue to the advantages of wide coverage, fast transmission speed and low transmission power, Wi-Fi can be said to be ubiquitous in life. This paper quantitatively analyzes the characteristics of the 2.4 GHz RSSI collected in indoor scenes from the following four aspects: antenna orientation of the receiver, type of wireless network interface card (NIC) of the receiver, time period of the data measurement and height difference between the transmitting and receiving antenna. The indoor positioning method based on received signal strength indication (RSSI) ranging is a lack of systematic quantitative research on the factors affecting the characteristics of indoor RSSI, which affect the accuracy of positioning.

IET Electrical Systems in Transportation.