A diversity combining scheme is examined that utilizes a demodulator's hard decisions in conjunction with knowledge of each decision's reliability. A maximum-likelihood bit decision is made, based on these partial decisions from the demodulator and on measurements of the state of the fading channel. The technique is sub-optimal since hard decisions are processed, but it may find application in low cost receiver design. The technique is optimal in the sense that a minimum probability of bit error is achieved, given a set of partial decisions and knowledge of their reliability. Performance analysis for the case of non-coherent frequency shift keying on a slow Rayleigh fading channel with additive white Gaussian noise includes the derivation of a tight upper bound on the probability of bit error, and estimates of the asymptotic performance relative to standard diversity schemes such as majority-voting, selection diversity, square-law, and maximal ratio combining. These results are supported by simulation results for bit and packet error rates in an example system. With five independent bit repeats and a BER of 10⁻³, the receiver is about 3 dB more efficient than majority-voting, and about 1 dB more efficient than selection diversity. The gain in efficiency, relative to the standard partial decision combination schemes, increases with the number of repeats. The degradation in performance in a practical receiver implementation is addressed, and it is demonstrated that near ideal performance may be obtained with only a few reliability weights quantized to a small number of levels. Furthermore, this performance is maintained over a wide range of average signal to noise ratio without having to adapt the reliability weights. When the reliability estimate is corrupted by additive white Gaussian noise, it is demonstrated that simple low- pass filtering of the signal strength estimate is sufficient to obtain near ideal performance. The performance is degraded in the presence of cochannel interference, but for a moderate level of interference the performance is demonstrated to be superior to majority-voting or selection diversity. Other results include a method to estimate the optimal quantization thresholds, and a method to obtain the probability of error of selection diversity receivers employing signal to noise ratio measurement quantization. The selection diversity analysis is applicable to the more general case of Rician fading. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

by Hung Kwok Wah. / Summary in Chinese and English / Bibliography: leaves 43-46 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

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x, 120 leaves : diags., tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1978) from the Dept. of Electrical Engineering, University of Adelaide

116 leaves : diags., tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1978) from the Dept. of Electrical Engineering, University of Adelaide

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

The efficacy of providing water sources in desert ecosystems to enhance wildlife populations and their distribution continues to be debated among wildlife managers. Some argue wildlife water developments provide a direct benefit to numerous species, while others point to the potential that wildlife water developments alter competition or predation dynamics and disrupt native communities. Additionally, some have argued that the availability of water may become more important to wildlife in the face of vegetative changes associated with expansive fire and conversion of shrub or forest lands to grasslands which alters the thermal landscape available to animals. I evaluated the influence of free water and expansive fire on aspects of the ecology (habitat selection, space use and survival) of Gambel's quail (Callipepla gambelii) in the Mojave Desert of southwestern Washington County, Utah, USA. I attached radio-transmitters to a total of 206 quail (74 adult males, 67 adult females, and 65 juvenile males and females) and monitored them from 2010 – 2013. For chapter one of my thesis, I evaluated the response of marked quail to removal of access to water in a before-after controlled impact (BACI) design. I found little influence of water removal on survival as models with this effect received little to no support and overlap in confidence intervals occurred between treatment and reference groups. Likewise, the distance from the center of the summer home range to the nearest water source did not differ by year (F = 1.63; P = 0.19) or treatment (removal of water) (F = 0.89; P = 0.35) and pairwise comparisons of distances for the treatment by year interaction were not significant (P > 0.05 in all cases). For size of home range area, however, I found strong effects for year (F = 3.07; P = 0.03), treatment (F = 4.67; P = 0.03), and their interaction (F = 7.61; P = 0.01). Mean home range size for quail was 6.10 and 1.63 km2 for animals in the reference area during treatment years (2012 and 2013) compared to 5.07 and 8.99 km2 for quail in the treatment area during 2012 and 2013, respectively. Removal of water influenced size of summer home ranges, but not the location of the summer home range or survival rates. I hypothesize that removal of access to free water required quail in the treatment area to expand their space use patterns in 2013 in order to satisfy water demands via pre-formed water. For chapter two of my thesis, I evaluated habitat selection of Gambel's quail in relation to vegetation type, topographic features, water, and recent (4-7 years) expansive fire. Gambel's quail selected areas of decreased roughness which were closer to water and fire boundaries than random locations. I found that quail preferred moderate (< 10 degrees) hillsides and ravine bottoms. I found no evidence that quail avoided the burned areas within their home ranges and 80% of their telemetry points were <500 meters from a burn edge. The Beaver Dam slope topography strongly influenced habitat selection for Gambel's quail and they showed strong selection for water sources during summer months. These data also suggest that wildfires have had limited impact on habitat selection by this species, four to seven years later.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy