Mobile user tracking system with ZigBee

The Global Positioning System (GPS) is unable to provide precise localization services indoors, which has led to wireless sensor network (WSN) localization technology becoming a hot research issue in the field of indoor location. At present, the ranging technology of wireless sensor networks based on received signal strength has been extensively used in indoor positioning. However, wireless signals have serious multipath effects in indoor environments. In order to reduce the adverse influence of multipath effects on distance estimation between nodes, a multi-channel ranging localization algorithm based on signal diversity is herein proposed. In real indoor environments, the parameters used for multi-channel localization algorithms are generally unknown or time-varying. In order to increase the positioning accuracy of the multi-channel location algorithm in a multipath environment, we propose an optimal multi-channel trilateration positioning algorithm (OMCT) by establishing a novel multi-objective evolutionary model. The presented algorithm utilizes a three-edge constraint to prevent the traditional multi-channel localization algorithm falling into local optima. The results of a large number of practical experiments and numerical simulations show that no matter how the channel number and multipath number change, the positioning error of our presented algorithm is always smaller compared with that of the state-of-the-art algorithm.

https://www.mdpi.com/1424-8220/20/6/1798/pdf

An Optimal Multi-Channel Trilateration Localization Algorithm by Radio-Multipath Multi-Objective Evolution in RSS-Ranging-Based Wireless Sensor Networks.

The study of the coexistence capabilities of networks based on the IEEE 802.11 and IEEE 802.15.4 standards has long been of interest to researchers owing to the individual success of these two technologies in various applications of Internet of Things (IoT). Operating in the same Industrial-Scientific-Medical (ISM) band, their coexistence does not always yield satisfactory results. The performance of a network based on IEEE 802.15.4 standard has been shown to be significantly lowered in the presence of a strong IEEE 802.11 based network (Wireless LAN) to the extent that communication based on the IEEE 802.15.4 standard can be rendered impossible in certain scenarios. This work is an effort towards analyzing interference caused by the three non-overlapping channels 1, 6 and 11 of IEEE 802.11b/g/n on the usable 2.4GHz spectrum of IEEE 802.15.4 standard. Recommendations of plausible scenarios for successful coexistence of these two networking technologies have been made. Assessment of the performance of an IEEE 802.15.4 standard based network through the Packet Delivery Ratio (PDR) on various channels of operation has yielded valuable insights. The experiments carried out in real-world environment stand as a datapoint in predicting and understanding the interference behavior in real-life applications.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1187&context=creativecomponents

Assessing Coexistence of IEEE 802.15.4 Networks and IEEE 802.11b/g/n Networks - A Study of Interference Effects

ZigBee is a popular short-range wireless communication protocol and has been widely adopted by wireless sensor networks, which runs on the same 2.4G band with WiFi. When wireless sensor networks with WiFi nodes run on overlapped bands, their signals could generate interferences with each other, and then wireless sensor networks could detect WiFi signal in this situation. In this paper, we propose an effective way to detect WiFi signal in wireless sensor networks and build signal attenuation model of WiFi signal to locate WiFi nodes. In our experiments, we set up wireless sensor network of 49 nodes to evaluate our methods. The evaluation shows that our WiFi signal detection and localization methods work and achieve relative high accuracy.

Yibin Lin

Papers

Cross-platform Interference: Locating wifi devices with ZigBee sensor networks