In this thesis it is investigated to what extent it is possible to accurately model path loss in indoor environments using a simple empirical approach. Two kinds of radio access antenna deployments are investigated: 1) standard dipole antennas and 2) leaky cables. For the case of standard dipole antenna deployment, a few well established empirical models are integrated in order to account for the main observed propagation mechanisms. One important propagation mechanism is wave guiding in corridors. It has been shown that a model designed for street microcells (“The recursive model”) combined with the power law model (combined model) well describes this wave guiding propagation. Some inaccuracies have, however, been observed when the direct pathway is dominating. In this master thesis it is therefore investigated if the model accuracy may be improved by integration of the Keenan-Motley and the Devasirvatham model (modified combined model) accounting for loss due to obstructions along the direct pathway. In this work, the primary models used for the case of leaky cable antenna deployments are the Keenan-Motley model (for short distances) and the modified combined model (for large distances). In order to improve and evaluate the modeling, propagation measurements have been carried out at the 2.44 GHz band in an indoor office environment. The measurement data, i.e., the calibrated frequency response of the channel, is obtained using the network analyzer measurement technique by sweeping the frequency over a range of 80 MHz around the center frequency. Hence, the path gain measured in dB-scale is obtained as the difference between the transmitted power and the received power. The combined model and the modified combined model are evaluated and parameterized based on the conducted measurements. The accuracy of the combined model is improved by the implemented modifications. In our case, the standard deviation error is reduced from 5-19 dB to 2-4 dB. Moreover, the measurements show that using leaky cables results in a better coverage in rooms alongside the corridor compared with using dipole antennas. Also the interference into adjacent cells is reduced using leaky cables compared with using dipole antennas.

Recently, there has been an enormous growth of interests in geolocation applications that demand an accurate estimation of the user’s location in indoor areas. The traditional geolocation system, GPS, which was designed for being used in outdoor environments, does not perform well in indoor areas, causing frequent inaccuracies in location estimation. Therefore the need for more accurate positioning systems and even positioning techniques is a motivation for researchers to turn their attention into indoor positioning systems. In this thesis we present a unique testbed for indoor geolocation system’s real-time performance evaluation. Then we present a real-time performance evaluation of a sample indoor positioning system. We make a comparison between the simulated results of the performance evaluation of the positioning engine and the real-time performance evaluation of the positioning system. Finally, we perform a sensitivity analysis for Ekahauâ„¢ indoor positioning engine. We show that the simulation with the introduced testbed yields the same results as one would obtain by evaluating the performance of the positioning system by means of massive measurement campaigns. Running the testbed for several measurement campaigns for different scenarios enabled us to compare the results and study the effect of selected parameters on the performance of the positioning system. We also perform primitive error analysis in terms of distance error to verify the validity of the result obtained with the testbed. We show that under the same configuration both real-time performance evaluation and simulated performance evaluation will yield same result with respect to position error. We also use error modeling to determine which error model is best matched to the observed indoor positioning error. Amongst all of the possibilities of choosing methods of positioning, we focused on the Received Signal Strength (RSS) based method along with fingerprinting. Briefly said, profiles previously gathered by measurement or simulation will decide on the location of mobile terminal if a new profile comes in. It is worth mentioning that previous work similar to this testbed has been done for outdoor areas according to Ekahau's white paper. Their work is mainly focused on outdoor environment, in which multipath does not exist. In this research effort we tried to analyze the effect of different parameters on sensitivity of indoor positioning systems who suffer from multipath. Different setups for simulating real-time radio channels have been studied in literature, but still not focused on indoor areas.

BACKGROUND:Humans can spend the majority of their time indoors, but little is known about the interactions between the human and built-environment microbiomes or the forces that drive microbial community assembly in the built environment. We sampled 16S rRNA genes from four different surface types throughout a university classroom to determine whether bacterial assemblages on each surface were best predicted by routine human interactions or by proximity to other surfaces within the classroom. We then analyzed our data with publicly-available datasets representing potential source environments.RESULTS:Bacterial assemblages from the four surface types, as well as individual taxa, were indicative of different source pools related to the type of human contact each surface routinely encounters. Spatial proximity to other surfaces in the classroom did not predict community composition.CONCLUSIONS:Our results indicate that human-associated microbial communities can be transferred to indoor surfaces following contact, and that such transmission is possible even when contact is indirect, but that proximity to other surfaces in the classroom does not influence community composition.

BACKGROUND: Dampness and mould exposure have been repeatedly associated with respiratory health. However, less is known about the specific agents provoking or arresting health effects in adult populations. We aimed to assess predictors of microbial agents in mattress dust throughout Europe and to investigate associations between microbial exposures, home characteristics and respiratory health. METHODS: Seven different fungal and bacterial parameters were assessed in mattress dust from 956 adult ECRHS II participants in addition to interview based home characteristics. Associations between microbial parameters and the asthma score and lung function were examined using mixed negative binomial regression and linear mixed models, respectively. RESULTS: Indoor dampness and pet keeping were significant predictors for higher microbial agent concentrations in mattress dust. Current mould and condensation in the bedroom were significantly associated with lung function decline and current mould at home was positively associated with the asthma score. Higher concentrations of muramic acid were associated with higher mean ratios of the asthma score (aMR 1.37, 95%CI 1.17-1.61). There was no evidence for any association between fungal and bacterial components and lung function. CONCLUSION: Indoor dampness was associated with microbial levels in mattress dust which in turn was positively associated with asthma symptoms.

This thesis reports the methods, the deployment strategies and the resulting system performance improvement of in-building environmental modification. With the increasing use of mobile computing devices such as PDAs, laptops, and the expansion of wireless local area networks (WLANs), there is growing interest in increasing productivity and efficiency through enhancing received signal power. This thesis proposes the deployment of waveguides consisting of frequency selective surfaces (FSSs) in indoor wireless environments and investigates their effect on radio wave propagation. The received power of the obstructed (OBS) path is attenuated significantly as compared with that of the line of sight (LOS) path, thereby requiring an additional link budget margin as well as increased battery power drain. In this thesis, the use of an innovative model is also presented to selectively enhance radio propagation in indoor areas under OBS conditions by reflecting the channel radio signals into areas of interest in order to avoid significant propagation loss. An FSS is a surface which exhibits reflection and/or transmission properties as a function of frequency. An FSS with a pass band frequency response was applied to an ordinary or modified wall as a wallpaper to transform the wall into a frequency selective (FS) wall (FS-WALL) or frequency selective modified wall (FS-MWALL). Measurements have shown that the innovative model prototype can enhance 2.4GHz (IEEE 802.11b/g/n) transmissions in addition to the unmodified wall, whereas other radio services, such as cellular telephony at 1.8GHz, have other routes to penetrate or escape. The FSS performance has been examined intensely by both equivalent circuit modelling, simulation, and practical measurements. Factors that influence FSS performance such as the FSS element dimensions, element conductivities, dielectric substrates adjacent to the FSS, and signal incident angles, were investigated. By keeping the elements small and densely packed, a largely angle-insensitive FSS was developed as a promising prototype for FSS wallpaper. Accordingly, the resultant can be modelled by cascading the effects of the FSS wallpaper and the ordinary wall (FSWALL) or modified wall (FS-MWALL). Good agreement between the modelled, simulated, and the measured results was observed. Finally, a small-scale indoor environment has been constructed and measured in a half-wave chamber and free space measurements in order to practically verify this approach and through the usage of the deterministic ray tracing technique. An initial investigation showing that the use of an innovative model can increase capacity in MIMO systems. This can be explained by the presence of strong multipath components which give rise to a low correlated Rayleigh Channel. This research work has linked the fields of antenna design, communication systems, and building architecture.

No description available.

No description available.

Background: Exposure to indoor air pollutants has been associated with poorer respiratory health in children. This study investigates the respiratory health of Malaysian schoolchildren in relation to indoor air pollution. Methods: This cross-sectional study was conducted among 2,164 schoolchildren aged 10-11 years in urban and semi-rural schools. Parents completed a questionnaire and concentrations of air pollutants were measured in schools. SHS exposure was assessed using salivary cotinine. Results: The WHO Air Quality Guideline for PM2.5 was exceeded for most of the semi-rural schools while almost all of the urban schools exceeded the annual exposure limit for NO2. The Geometric Mean salivary cotinine concentrations for non-smoking schoolchildren were 0.47 ng/ml. The 3 main predictors of nocturnal cough were the presence of a current smoker at home (OR 1.97; 95% CI: 1.31-2.96), the absence of exhaust system in the kitchen (OR 1.67; 95% CI: 1.03-2.68) and the use of air conditioning (OR 3.10; 95% CI: 1.37-5.71). Exposure to SHS of ≥4 hours per day (OR 2.53; 95% CI: 1.55-4.14) explained approximately 6.0% of the likelihood of reporting doctor-diagnosed asthma. For the measure of asthma severity, NO2 and log average family size were the 2 predictors of limited speech during wheeze; NO2 concentrations of >50 μg/m3 contributes an OR of 5.98 (95% CI: 1.02-34.9) and log average family size with an OR of 14.6 (95% CI: 1.70-126). Conclusion: This study has identified that many Malaysian schoolchildren experience exposure to air pollution indoors that exceeds WHO guidance limits for several pollutants. There was no clear relationship between traffic-generated air pollutants and children’s respiratory health but there was a strong relationship between the number of hours children were exposed to SHS and asthma. There is a need for increased enforcement of existing smoke-free legislation and policies to reduce children’s exposure to SHS.

In 2010 the housing stock was responsible for 30.5% of all energy consumed in the UK. The UK government has set a transition target to reduce the energy used from space heating in dwellings by 29% by 2020 as part of their drive to lower CO2 emissions and mitigate the risks of global climate change. Housing stock energy models have been developed as research tools to identify pathways to a low energy future. These tools use assumptions about how homes are heated that may reduce their effectiveness at making accurate energy predictions. This thesis describes the collection and analysis of temperature data from over 300 homes in Leicester to develop better understanding of how dwellings are heated. The temperature measurements were assessed for error and a final sample of 249 dwellings was established. Mean winter temperatures (December February) were found to be 18.5°C and 17.4°C for living rooms and bedrooms which are comparable with temperatures reported in previous studies. Statistically significant relationships were established between seven descriptors; three technical (house type, house age and wall type) and four social (household size, employment status, age of oldest occupants and tenure). Only 24% of the variation in mean winter temperature could be explained by these descriptors. Ten heating practice metrics were developed to give insight into how homes are heated; these included the duration of the heating period and the average temperature when heated. Statistically significant relationships were found between the heating practices and a number of technical and social household descriptors. It is concluded that the variation in heating practices which relates to social household descriptors will result in models being unable to make accurate predictions at the regional of city scale. Furthermore, this work has shown flaws in the idealised temperature profile as used in BREDEM. It is suggested that the findings of this work are considered in the development of future stock models.

ABSTRACT Indoor air pollution has been associated with acute lower respiratory infections amongst children less than five years old in developing countries. Very little is known about the potential role of behavioural change in reducing child indoor air pollution exposure. This thesis explores three questions: did people change their behaviours following exposure to an intervention that promoted the health benefits of behavioural change? Were changes in behaviour attributable to the intervention? What were the motivations and barriers to behavioural change? The evaluation included a quantitative and a qualitative study. The quantitative study utilised a quasiexperimental before-after design amongst an intervention village (n=98 households). Results were compared to a similar control village (n=121) that did not receive the intervention. Baseline data were collected during winter 2003 and follow-up data were collected during winter 2004 (12 months later). A qualitative evaluation, using two rounds of 4 focus group interviews each, was used to answer questions that emerged from the quantitative study. Indoor air quality - PM10, CO and CO (measured on the youngest child) - were measured over a 24 hour period in randomly selected households before and after the intervention in the intervention (n=36) and control (n=38) groups. After adjusting for confounding factors, there was no statistical association between having the received the intervention and the likelihood of burning outdoors at follow-up (OR=1.16; 95% CI 0.6-1.8). Indoor air quality data showed significant median reductions in PM10 (94-96%), CO (85-97%) and CO (child) (83- 95%) amongst households that burned outdoors compared to those that burned indoors. Results from the qualitative study suggest that motivations for outdoor burning included: health considerations, reaction to participating in the study, reduced drudgery and prestige. Barriers to outdoor burning included the need for space heating during winter, perceptions of low indoor air pollution risk and gender relations. This study highlights the potential for exposure reduction through behavioural change and is original for three reasons. It is the first behavioural intervention study designed to reduce indoor air pollution in a rural African setting. Secondly, it is the first intervention study in the indoor air pollution field to identify the factors that influenced behavioural change. Thirdly, it is one of the first studies to align debates about behavioural change in the field of indoor air pollution with those in the broader environmental health promotion literature.