Wireless endoscopic capsules can transmit the picture of the inside of the digestive tract to the external receiver for the purpose of gastrointestinal diseases diagnose. The localization of the capsule is needed to correlate the picture of detected anomalies with the particular fragment of intestine. For this purpose, the analysis of wireless transmission parameters can be applied. Such methods are affected by the impact of the human body on the electromagnetic wave propagation that is specific to the anatomy of individual person. The article presents the algorithm of localization of endoscopic capsules with wireless transmitter based on the detection of phase difference of received signals. The proposed algorithm uses simplified human body models that can change their dielectric properties in each iteration to improve the location of the capsule endoscope. Such approach allows to reduce localization error by around 12 mm (15%) and can by used for patients of different physique without the need of the numerical models of individual body.
The 802.11ax standard final specification is expected in 2019, however first parameters are just released. The target of the new standard is four times improvement of the average throughput within the given area. This standard is dedicated for usage in dense environment such as stadiums, means of municipal communication, conference halls and others. The main target is to support many users at the same time with the single access point. The question arises if the new standard will have higher throughput then previous ones in the single user mode. The author calculated the maximal theoretical throughput of the 802.11ax standard and compared the results with the throughput of older 802.11 standards such as 802.11n and 802.11ac. The new he-wifi-network example included in the ns-3.27 release of the NS-3 simulator was used to simulate the throughput between the access point and the user terminal. The results indicate that in some conditions the 802.11ac standard has higher throughput than the new 802.11ax standard.
Wireless Sensor Networks (WSNs) have existed for many years and had assimilated many interesting innovations. Advances in electronics, radio transceivers, processes of IC manufacturing and development of algorithms for operation of such networks now enable creating energy-efficient devices that provide practical levels of performance and a sufficient number of features. Environmental monitoring is one of the areas in which WSNs can be successfully used. At the same time this is a field where devices must either bring their own power reservoir, such as a battery, or scavenge energy locally from some natural phenomena. Improving the efficiency of energy harvesting methods reduces complexity of WSN structures. This survey is based on practical examples from the real world and provides an overview of state-of-the-art methods and techniques that are used to create energyefficient WSNs with energy harvesting.
This work presents concepts of the use of algorithms inspired by the functions and properties of the nervous system in dense wireless networks. In particular, selected features of the brain consisting of a large number of nerve connections were analyzed, which is why they are a good model for a dense network. In addition, the action of a selected cells from the nervous system (such as neuron, microglia or astrocyte) as well as phenomena observed in it (e.g. neuroplasticity) are presented.
This article presents a consistent solution of Transmit Power Control in centralized (clustered) wireless network with and without jamming. Depending on the policy assumed, appropriate solutions are applied to minimize the power used in a system or to satisfy expected Quality of Service. Because of specific nature of the system there is no optimal solution which can be applied in practice. Correctness and effectiveness of four proposed Transmit Power Control algorithms was presented in the form of computer simulation results in which the system capacity, mean power used and the number of successful links were described.
The data aggregation process of wireless sensor networks faces serious security problems. In order to defend the internal attacks launched by captured nodes and ensure the reliability of data aggregation, a secure data aggregation mechanism based on constrained supervision is proposed for wireless sensor network, which uses the advanced LEACH clustering method to select cluster heads. Then the cluster heads supervise the behaviors of cluster members and evaluate the trust values of nodes according to the communication behavior, data quality and residual energy. Then the node with the highest trust value is selected as the supervisor node to audit the cluster head and reject nodes with low trust values. Results show that the proposed mechanism can effectively identify the unreliable nodes, guarantee the system security and prolong the network lifetime.
Cloud radio access network (C-RAN) has been proposed as a solution to reducing the huge cost of network upgrade while providing the spectral and energy efficiency needed for the new generation cellular networks. In order to reduce the interference that occur in C-RAN and maximize throughput, this paper proposes a sequentially distributed coalition formation (SDCF) game in which players, in this case the remote radio heads (RRHs), can sequentially join multiple coalitions to maximize their throughput. Contrary to overlapping coalition formation (OCF) game where players contribute fractions of their limited resources to different coalitions, the SDCF game offers better stability by allowing sequential coalition formation depending on the availability of resources and therefore providing a balance between efficient spectrum use and interference management. An algorithm for the proposed model is developed based on the merge-only method. The performance of the proposed algorithm in terms of stability, complexity and convergence to final coalition structure is also investigated. Simulation results show that the proposed SDCF game did not only maximize the throughput in the C-RAN, but it also shows better performances and larger capabilities to manage interference with increasing number of RRHs compared to existing methods.
A new configuration of rectifier suiting CMOS technology is presented. The rectifier consists of only two n-channel MOS transistors, two capacitors and two resistors; for this reason it is very favourable in manufacturing in CMOS technology. With these features the rectifier is easy to design and cheap in production. Despite its simplicity, the rectifier has relatively good characteristics, the voltage and power efficiency, and bandwidth greater than 89%, 87%, and 1 GHz, respectively. The performed simulations and measurements of a prototype circuit fully confirmed its correct operation and advantages.
A prototype of a DSP-based instrument for in-service transmitter power measurements is presented. The instrument implements a signal-selective algorithm for power measurements that is suitable for use in wireless environments, where possible uncontrolled interfering sources are present in the radio channel and are overlapped to the signal emitted by the transmitter under test, possibly in both time and frequency domain. The measurement method exploits the principles of cyclic spectral analysis, which are briefly recalled in the paper. Potentialities, as well as limitations of the prototype use are discussed, and the results of experiments with both modulated and unmodulated interfering sources are presented.
This paper presents a baseband model and an enhanced implementation of the wireless full duplex analog method introduced by [1].Unlike usual methods based on hardware and software self- interference cancelation, the proposed design relies on FSK modulation. The principle is when the transmitter of a local end is sending data by modulating the carrier with the appropriate frequency deviation, its own receiver is checking if the remote transmitter is using the opposite deviation. Instead of architectures often used by both non-coherent and coherent receivers that require one filter (matched filter for coherent detection) for each frequency deviation, our design uses one mixer and one single integrator-decimator filter. We test our design using Universal Software Radio Peripheral as radio frequency front end and computer that implements the signal processing methods under free and open source software. We validate our solution experimentally and we show that in-band full duplex is feasible and synthesizable for wireless communications.
The emerging potentials in the electronics field, which facilitate the creation of complex projects with innovative functionalities, while maintaining low costs, are becoming even more appreciated by designers and engineers. In this manuscript, a telemetry system was designed and realized for monitoring main parameters of a racing vehicle. A STM32 Nucleo board acquires data from sensors installed on vehicle and transmits them to a base station. Acquired data are both stored on a SD card and wirelessly transmitted, for ensuring robustness/reliability of operation. The carried out tests confirm the truthfulness and compatibility of acquired data related to the vehicle parameters.
The paper presents a circuit structure that can be used for powering an IoT (Internet of Things) sensor node and that can use energy just from its surroundings. The main advantage of the presented solution is its very low cost that allows mass applicability e.g. in the IoT smart grids and ubiquitous sensors. It is intended for energy sources that can provide enough voltage but that can provide only low currents such as piezoelectric transducers or small photovoltaic panels (PV) under indoor light conditions. The circuit is able to accumulate energy in a capacitor until a certain level and then to pass it to the load. The presented circuit exhibits similar functionality to a commercially available EH300 energy harvester (EH). The paper compares electrical properties of the presented circuit and the EH300 device, their form factors and costs. The EH circuit’s performance is tested together with an LTC3531 buck-boost DC/DC converter which can provide constant voltage for the following electronics. The paper provides guidelines for selecting an optimal capacity of the storage capacitor. The functionality of the solution presented is demonstrated in a sensor node that periodically transmits measured data to the base station using just the power from the PV panel or the piezoelectric generator. The presented harvester and powering circuit are compact part of the sensor node’s electronics but they can be also realized as an external powering module to be added to existing solutions.
In paper we present a case study of the radio dispatching communications for providing the voice service during mass events of the “Lednica 2000” Youth Meetings. The presentation is supported by over 20-year experience in organization of this event every year. We also describe a FM radio system deployed during this meeting for broadcasting the English translation.
The subject of the article is the design and practical implementation of the wireless mesh network. IQRF radio modules were used for the network design. The IQRF® technique has enabled the construction of a mesh network with the possibility of reconfiguration. The theoretical part contains a description of the IQRF® hardware solutions used. The practical scope includes the design part, where the configuration of the radio modules was carried out and the parameters of the radio network were set to allow its implementation in various topologies. Then, a wireless network consisting of 10 IQRF modules was launched in the P3 building of the Opole University of Technology. At this stage, configured radio modules were placed in selected rooms on all five floors of the building in order to carry out tests of the radio network constructed in this way. The tests included measuring the packet transmission delay time as well as the received signal strength. Research was carried out for several network topologies.
en
pl
