Mehmet Yavuz

Learn More
Femtocells are low-power cellular base stations that operate in licensed spectrum. They are typically deployed indoors to improve coverage and provide excellent user experience, including high data rates. Cellular operators benefit from reduced infrastructure and operational expenses for capacity upgrades and coverage improvements. Femtocells also bring(More)
Positron emission tomography (PET) measurements are usually precorrected for accidental coincidence events by real-time subtraction of the delayed-window coincidences. Randoms subtraction compensates on average for accidental coincidences but destroys the Poisson statistics. We propose and analyze two new approximations to the exact log-likelihood of the(More)
In PET, usually the data are precorrected for accidental coincidence (AC) events by real-time subtraction of the delayed window coincidences. Randoms subtraction compensates in mean for AC events but destroys the Poisson statistics. Furthermore, for transmission tomography the weighted least-squares (WLS) method leads to systematic biases, especially at low(More)
Femtocells are low power cellular base stations typically deployed indoors in residential and enterprise environments as well as hotspots in order to improve voice and high rate data coverage and provide excellent user experience. The cellular operator benefits from reduced infrastructure deployment costs for capacity upgrades and coverage improvements.(More)
Most PET scans are compensated for accidental coincidence (AC) events by real-time subtraction of delayed-window coincidences. Real time subtraction of delayed coincidences compensates for the average of AC events, but also destroys the Poisson statistics. Moreover, negative values result during the real-time subtraction which would cause conventional(More)
Femtocells are low-power cellular base stations that are typically deployed indoors in residential, enterprise or hotspots settings. Femtocell deployments provide excellent user experience through better coverage for voice and very high data throughputs. In this paper, we focus on 3G UMTS femtocells and analyze the impact of femtocells on idlemode mobility(More)
This paper analyzes and compares image reconstruction methods based on practical approximations to the exact log likelihood of randoms precorrected positron emission tomography (PET) measurements. The methods apply to both emission and transmission tomography, however, in this paper the authors focus on transmission tomography. The results of experimental(More)
In this article we analyze performance of VoIP services over 1xEVDO-Revision A (DO-Rev A) networks and show that high-quality VoIP with unconstrained mobility and high capacity can be achieved. Together with quality of service (QoS) requirements, we emphasize practical issues such as mobility, degradation of feedback-channel quality, and packet overheads.(More)