1,079 research outputs found
Indoor wireless communications and applications
Chapter 3 addresses challenges in radio link and system design in indoor scenarios. Given the fact that most human activities take place in indoor environments, the need for supporting ubiquitous indoor data connectivity and location/tracking service becomes even more important than in the previous decades. Specific technical challenges addressed in this section are(i), modelling complex indoor radio channels for effective antenna deployment, (ii), potential of millimeter-wave (mm-wave) radios for supporting higher data rates, and (iii), feasible indoor localisation and tracking techniques, which are summarised in three dedicated sections of this chapter
An indoor variance-based localization technique utilizing the UWB estimation of geometrical propagation parameters
A novel localization framework is presented based on ultra-wideband (UWB) channel sounding, employing a triangulation method using the geometrical properties of propagation paths, such as time delay of arrival, angle of departure, angle of arrival, and their estimated variances. In order to extract these parameters from the UWB sounding data, an extension to the high-resolution RiMAX algorithm was developed, facilitating the analysis of these frequency-dependent multipath parameters. This framework was then tested by performing indoor measurements with a vector network analyzer and virtual antenna arrays. The estimated means and variances of these geometrical parameters were utilized to generate multiple sample sets of input values for our localization framework. Next to that, we consider the existence of multiple possible target locations, which were subsequently clustered using a Kim-Parks algorithm, resulting in a more robust estimation of each target node. Measurements reveal that our newly proposed technique achieves an average accuracy of 0.26, 0.28, and 0.90 m in line-of-sight (LoS), obstructed-LoS, and non-LoS scenarios, respectively, and this with only one single beacon node. Moreover, utilizing the estimated variances of the multipath parameters proved to enhance the location estimation significantly compared to only utilizing their estimated mean values
Improvement of strength and water absorption of Interlocking Compressed Earth Bricks (ICEB) with addition of Ureolytic Bacteria (UB)
Interlocking Compressed Earth Brick (ICEB) are cement stabilized soil bricks that allow for dry stacked construction. This characteristic resulted to faster the process of building walls and requires less skilled labour as the bricks are laid dry and lock into place. However there is plenty room for improving the interlocking bricks by increase its durability. Many studies have been conducted in order to improve the durability of bricks by using environmentally method. One of the methods is by introducing bacteria into bricks. Bacteria in brick induced calcite precipitation (calcite crystals) to cover the voids continuously. Ureolytic Bacteria (UB) was used in this study as a partial replacement of limestone water with percentage of 1%, 3% and 5%. Enrichment process was done in soil condition to ensure the survivability of UB in ICEB environment. This paper evaluates the effect of UB in improving the strength and water absorption properties of ICEB and microstructure analysis. The results show that addition of 5% UB in ICEB indicated positive results in improving the ICEB properties by 15.25% in strength, 14.72% in initial water absorption and 14.68% reduction in water absorption. Precipitation of calcium carbonate (CaCo3) in form of calcite can be distinguish clearly in microstructure analysis
Statistical millimeter wave channel modelling for 5G and beyond
Millimetre wave (mmWave) wireless communication is one of the most promising technologies for the fifth generation (5G) wireless communication networks and beyond. The very broad bandwidth and directional propagation are the two features of mmWave channels. In order to develop the channel models properly reflecting the characteristics of mmWave channels, the in-depth studies of mmWave channels addressing those two features are required. In this thesis, three mmWave channel models and one beam alignment scheme are proposed related to those two features.
First, for studying the very broad bandwidth feature of mmWave channels, we introduce an averaged power delay profile (APDP) method to estimate the frequency stationarity regions (FSRs) of channels. The frequency non-stationary (FnS) properties of channels are found in the data analysis. A FnS model is proposed to model the FnS channels in both the sub-6 GHz and mmWave frequency bands and cluster evolution in the frequency domain is utilised in the implementation of FnS model.
Second, for studying the directional propagation feature of mmWave channels, we develop an angular APDP (A-APDP) method to study the planar angular stationarity regions (ASRs) of directional channels (DCs). Three typical directional channel impulse responses (D-CIRs) are found in the data analysis and light-of-sight (LOS), non-LOS (NLOS), and outage classes are used to classify those DCs. A modified Saleh-Valenzuela (SV) model is proposed to model the DCs. The angular domain cluster evolution is utilised to ensure the consistency of DCs.
Third, we further extend the A-APDP method to study the spherical-ASRs of DCs. We model the directional mmWave channels by three-state Markov chain that consists of LOS, NLOS, and outage states and we use stationary model, non-stationary model, and “null” to describe the channels in each Markov state according to the estimated ASRs. Then, we propose to use joint channel models to simulate the instantaneous directional mmWave channels based on the limiting distribution of Markov chain.
Finally, the directional propagated mmWave channels when the Tx and Rx in motion is addressed. A double Gaussian beams (DGBs) scheme for mobile-to-mobile (M2M) mmWave communications is proposed. The connection ratios of directional mmWave channels in each Markov state are studied
Radio channel characterisation and system-level modelling for ultra wideband body-centric wireless communications
PhDThe next generation of wireless communication is evolving towards user-centric networks,
where constant and reliable connectivity and services are essential. Bodycentric
wireless network (BCWN) is the most exciting and emerging 4G technology
for short (1-5 m) and very short (below 1 m) range communication systems. It has
got numerous applications including healthcare, entertainment, surveillance, emergency,
sports and military. The major difference between the BCWN and conventional
wireless systems is the radio channel over which the communication takes place. The
human body is a hostile medium from the radio propagation perspective and it is
therefore important to understand and characterise the effect of the human body on
the antenna elements, the radio propagation channel parameters and hence the system
performance. In addition, fading is another concern that affects the reliability and
quality of the wireless link, which needs to be taken into account for a low cost and
reliable wireless communication system for body-centric networks.
The complex nature of the BCWN requires operating wireless devices to provide
low power requirements, less complexity, low cost and compactness in size. Apart
from these characteristics, scalable data rates and robust performance in most fading
conditions and jamming environment, even at low signal to noise ratio (SNR) is
needed. Ultra-wideband (UWB) technology is one of the most promising candidate for
BCWN as it tends to fulfill most of these requirements. The thesis focuses on the characterisation
of ultra wideband body-centric radio propagation channel using single
and multiple antenna techniques. Apart from channel characterisation, system level
modelling of potential UWB radio transceivers for body-centric wireless network is
also proposed. Channel models with respect to large scale and delay analysis are derived
from measured parameters. Results and analyses highlight the consequences
of static and dynamic environments in addition to the antenna positions on the performance
of body-centric wireless communication channels. Extensive measurement
i
campaigns are performed to analyse the significance of antenna diversity to combat
the channel fading in body-centric wireless networks. Various diversity combining
techniques are considered in this process. Measurement data are also used to predict
the performance of potential UWB systems in the body-centric wireless networks.
The study supports the significance of single and multiple antenna channel characterisation
and modelling in producing suitable wireless systems for ultra low power
body-centric wireless networks.University of Engineering and Technology Lahore Pakista
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