In recent years there has been an increasing need for miniature, low-cost, commercially accessible, and user-friendly sensor solutions for wireless body area networks (WBAN), which has led to the adoption of new physical communication interfaces providing distinctive advantages over traditional wireless technologies. Ultra-wideband (UWB) and intrabody communication (IBC) have been the subject of intensive research in recent years due to their promising characteristics as means for short-range, low-power, and low-data-rate wireless interfaces for interconnection of various sensors and devices placed on, inside, or in the close vicinity of the human body. The need for safe and standardized solutions has resulted in the development of two relevant standards, IEEE 802.15.4 (for UWB) and IEEE 802.15.6 (for UWB and IBC), respectively. This paper presents an in-depth overview of recent studies and advances in the field of application of UWB and IBC technologies for wireless body sensor communication systems.

The robust measuring system for the continuous monitoring of the ship motor shaft average torque, power, and rotational speed was developed and tested. The system was designed for permanent installation in ships under realistic working conditions. The strain gage sensor is employed to measure the torque, whereas the shaft rotational speed is measured by the inductive proximity switch. The strain gage signal conditioning circuit design was highly simplified by using a high-resolution SigmaDelta A/D converter (ADC). Such an approach minimizes the overall number of analog components and the input measuring chain errors. A contactless power transmission subsystem was developed based on the specifically designed rotary transformer operating at low frequency. Strain measurement results are transmitted over the near-field low-frequency capacitive link by using a specifically designed communication protocol based on the digital modulation principle. The receiver microprocessor-based unit processes the measured data and transmits the results to the monitoring human-machine interface over some commonly used industrial analog and digital communication protocols. The principal advantages of the novel measuring system design over some state-of-the-art commercial solutions are simplicity, higher accuracy, stability, reliability, simplified calibration procedure, and contactless signal transmission and processing completely in a digital form, which, hence, reduces the most common shortcomings of similar analog-based systems.

The concept of weakly hard real-time systems can be used to model real-time systems that may tolerate occasional deadline misses in a bounded and predictable manner. This model applies to many practical applications and is particularly interesting in the context of real-time control systems. In practice, applying hard real-time constraints may be too rigid since a certain amount of deadline misses is acceptable in some applications. In order to maintain system stability, limitations on the amount and distribution of violated deadlines need to be imposed. These limitations can be formally expressed as weakly hard real-time constraints. Current research in the field of weakly hard real-time task scheduling is focused on designing scheduling algorithms that guarantee the fulfillment of constraints, while aiming to maximize the total number of timely completed task instances. This paper provides an extensive literature review of the work related to the weakly hard real-time system model and its link to the field of control systems design. The weakly hard real-time system model and the corresponding scheduling problem are described. Furthermore, an overview of system models derived from the generalized weakly hard real-time system model is provided, with an emphasis on models that apply to real-time control systems. The state-of-the-art algorithms for scheduling tasks with weakly hard real-time constraints are described and compared. Finally, an overview of controller design methods that rely on the weakly hard real-time model is given.

In this paper we point to some errors in recent paper by Asyaban et al. in which they devise an exact schedulability test. These errors are critical for the correct operation of the algorithm and they should be corrected.

This paper presents a data-fusion algorithm for respiration rate (RR) extraction by employing the ultra-wideband (UWB) transversal propagation measurement method. In the experimental scenario the UWB transmitter and receiver units were placed on the front and back sides of the thoracic wall. The measurement principle is based on the fact that periodic movements of lung affect the communication channel properties that can be measured. We measured the energy attenuation variations on the receiver side caused by tissue movements from which we extracted the information about the respiration rate. For testing purpose, a custom developed UWB platform suitable for on-body placement was used, with an integrated inertial motion unit (IMU) sensor. UWB and IMU signals were combined by means of a data fusion algorithm. Data fusion algorithms based on Extended Kalman filtering (EKF) and Naïve Bayes inference show better estimation performance than an estimation from individual signal sources. The obtained error rate of RR estimation by means of the proposed data fusion method is lower than 0.2 respiration per minute (rpm) in comparison to the reference respiration system. Our results show that the proposed method of UWB and IMU sensor fusion is a promising candidate for reliable RR monitoring by compact wearable units under relatively non-stationary body movement conditions.

Harmonic periods have been of great importance in the design of real-time applications due to their high schedulability, predictability, and ease of analysis. Therefore, period assignment is an important part of the design process of many real-time systems. This includes various applications such as radar dwell tasks, robotics, and industrial control applications, where tasks are specified using period ranges and worst-case execution times. In this paper, we study the issue of assigning a fixed number of harmonic periods from period ranges to maximize utilization in real-time systems. In the existing period assignment approaches, the number of different harmonic period values in the solution was not addressed. In this work, we show that, in real-time systems in which the number of available task periods is restricted, such a constraint is crucial for efficient system design. We formally define the problem in the context of existing harmonic period assignment research. We show that this problem is at least weakly NP-hard and devise an optimal algorithm and suboptimal heuristics. Based on an extensive evaluation on synthetically generated task sets, we conclude that our approach is efficient and applicable in a variety of real-world scenarios.