In the present paper we give a classification of the position and the number of inertial measurement units (IMU) used to detect human activities and position tracking based on literature review. It presents a separate view of IMU position and IMU numbers placed on the human body. In total 60 relevant studies were found which focused on human activity recognition (HAR) and tracking with dead-reckoning. The focus lies on the number, the sample frequencies and the positioning of IMUs. To the best of our knowledge, this is the first work which looks particularly at the number and position of IMUs. The result shows that a comparison between the different studies fails, because the description of the positions is not precise enough and not uniform.

The focus of this study in progress is based on a non-GPS navigation technique which can be used in an environment without any infrastructure. Our proposed system combines a Wireless Body Area Network (WBAN) consisting of different sensors with Complex Event Processing (CEP). For the identification of complex events for independent navigation three use cases are provided.

This work focuses on practical research in the field of Bluetooth 5.0 and the maximum number of Bluetooth sensors nodes in a wireless body area network (WBAN) for human activity recognition (HAR). As network topology M:1 multi-pairing is used. For the best of our knowledge no direct related work in this field can be found. We investigated how many Bluetooth connections can be simultaneously connected with different smartphones (iOS) with real sensor data and in which time intervals the data can still be processed and stored. Our results show that a maximum of 14 Bluetooth devices can be connected under practical conditions. A stable transmission with 48 bytes per package are found with most reliability in an minimal interval of 40 ms per node.

This work focuses on the analysis of Bluetooth Sensor Networks and the maximum number of Bluetooth sensors nodes for real-time human activity recognition (HAR). M:1 multipairing is used as network topology. The tests use notify for the Bluetooth data transmission. We investigated the quality of service (QoS) for the maximum number of Bluetooth connections with real-time sensor data based on inertial measurement units (IMU). We show how many Bluetooth sensor nodes can be simultaneously connected using different commercial off-theshelf hardware and OS. On top of that we point out how the package loss behaves depending on the set time interval and used hardware. Our results show that a maximum number of 13 Bluetooth sensor nodes can be connected using an external Bluetooth dongle with the Linux OS. Connecting more than 10 Bluetooth sensor nodes at a frequency of 0.025 s tested in the Thinkpad P53 in combination with the DeLock Bluetooth dongle being most useful. This combination allowed a maximum number of simultaneous connections by having only a package loss of about 1.2%.