Cellular telephones--Design

With the increasing number of cellular phone service subscribers, the
telecommunications service providers have placed immense emphasis on improving
audio quality and ensure fewer dropped calls. Handoff behavior of all handsets is an
important factor in quality of service of a mobile phone service. This thesis focuses
on the analysis of large volumes of diagnostic data collected from mobile phones in
the real world and the identification of aberrant behavior of a mobile handset under
test by means of drive test data visualization. Our target was to identify poor mobility
decisions that are made by the handsets in calls. Premature, delayed or exceedingly
sensitive decisions are considered poor mobility decisions. The goal was to compare a
set of behaviors from a baseline unit (one accepted to generally operate well). We
were able to identify a particular call that was exhibiting a different path (talking to a
different cell than expected or taking longer to move to a new cell). We designed a
chi-square statistical test to evaluate the performance of specific mobile handset
models. We also developed a mobility tool that evaluated the handset's performance
by means of mapping the handoffs on the Google Maps. The mapping of the handoffs
by means of the Google Maps were very powerful in identifying the above mentioned
mobility patterns.

The ever increasing demand for capacity in wireless cellular networks is
resolved by decreasing the size of the cells. The smaller cells created inside large
cells are called microcells and they cover smaller and dense areas. As a result of this,
the mobile device ends up changing the base stations or performing handover at a
much higher rate. To maintain the reliability and quality of the call, it is obligatory to
ascertain that the handover is performed at a proper location. If the handover is
delayed or the mobile handset drags its base station, it is more probable that either the
call will drop or the quality of the call will be compromised. The last thing a mobile
handset user would want is to experience any of these two consequences. In this
thesis we study the methods to analyze the performance ofhandover by the mobile
handsets in the drive setup under test. This thesis presents a model for analyzing the
performance ofhandoffbased on the measurements ofthe received signal strength
indicator and the color code recorded by the mobile handset in the drive test field
path. The model from the simulations is seen to yield results that agree with other
research about the performance of mobile handsets.

Debonding failure of cored marine composite materials is investigated. A new test method that subjects the bond line between the core and the face sheets to a shear stress singularity is presented and studied analytically by laminated beam shear deformation theory, numerically by the finite element method, and experimentally with specimens of glass/polyester face sheets on balsa wood or PVC core sandwich beams.