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Afifi, Mohammed Ahmed Melegy MohammedTCP FTAT (Fast Transmit Adaptive Transmission): A New End-To- End Congestion Control Algorithm
Master of Science in Electrical Engineering, Cleveland State University, 2014, Washkewicz College of Engineering
Congestion Control in TCP is the algorithm that controls allocation of network resources for a number of competing users sharing a network. The nature of computer networks, which can be described from the TCP protocol perspective as unknown resources for unknown traffic of users, means that the functionality of the congestion control algorithm in TCP requires explicit feedback from the network on which it operates. Unfortunately this is not the way it works with TCP, as one of the fundamental principles of the TCP protocol is to be end-to-end, in order to be able to operate on any network, which can consist of hundreds of routers and hundreds of links with varying bandwidth and capacities. This fact requires the Congestion Control algorithm to be adaptive by nature, to adapt to the network environment under any given circumstances and to obtain the required feedback implicitly through observation and measurements. In this thesis we propose a new TCP end-to-end congestion control algorithm that provides performance improvements over existing TCP congestion control algorithms in computer networks in general, and an even greater improvement in wireless and/or high bandwidth- delay product networks.

Committee:

Nigamanth Sridhar, PhD (Committee Chair); Chansu Yu, PhD (Committee Member); Pong Chu, PhD (Committee Member)

Subjects:

Computer Engineering; Computer Science; Electrical Engineering

Keywords:

TCP; Congestion Control; Computer Networks; TCP NewReno; TCP Westwood; TCP Cubic; Linux TCP; ns-3; DCE Cradle; Direct Code Execution Cradle - ns-3; high bandwidth delay product networks; random loss radio signal; Adaptive Transmission

Majerus, Steve JWireless, Implantable Microsystem for Chronic Bladder Pressure Monitoring
Doctor of Philosophy, Case Western Reserve University, 2014, EECS - Electrical Engineering
This work describes the design and testing of a wireless implantable bladder pressure sensor suitable for chronic implantation in humans. The sensor was designed to fulfill the unmet need for a chronic bladder pressure sensing device in urological fields such as urodynamics for diagnosis and neuromodulation for bladder control. Neuromodulation would particularly benefit from a wireless bladder pressure sensor providing real-time pressure feedback to an implanted stimulator, resulting in greater bladder capacity while using less power. The pressure sensing system consists of an implantable microsystem, an external RF receiver, and a wireless battery charger. The implant is small enough to be cystoscopically implanted within the bladder wall, where it is securely held and shielded from the urine stream, protecting both the device and the patient. The implantable microsystem consists of a custom application-specific integrated circuit (ASIC), pressure transducer, rechargeable battery, and wireless telemetry and recharging antennas. Because the battery capacity is extremely limited, the ASIC was designed using an ultra-low-power methodology in which power is dynamically allocated to instrumentation and telemetry circuits by a power management unit. A low-power regulator and clock oscillator set the minimum current draw at 7.5 µA and instrumentation circuitry is operated at low duty cycles to transmit 100-Hz pressure samples while consuming 74 µA. An adaptive transmission activity detector determines the minimum telemetry rate to limit broadcast of unimportant samples. Measured results indicated that the power management circuits produced an average system current of 16 µA while reducing the number of transmitted samples by more than 95% with typical bladder pressure signals. The wireless telemetry range of the system was measured to be 35 cm with a bit-error-rate of 10-3, and the battery was wirelessly recharged at distances up to 20 cm. A novel biocompatible packaging method consisting of a silicone-nylon mesh membrane and a compliant silicone gel was developed to protect the sensor from water ingress while only reducing the sensor sensitivity by 5%. Dynamic offset removal circuitry extended the system dynamic range to 2,900 cm H2O but limited the sensor AC accuracy to 3.7 cm H2O over a frequency range of 0.002 – 50 Hz. The DC accuracy of the sensor was measured to be approximately 2.6 cm H2O (0.9% full-scale). Functionality of wired prototypes was confirmed in feline and canine animal models, and wireless prototypes were implanted in a female calf large-animal model. Measured in vivo pressure recordings of bladder contractions correlated well with reference catheters (r =0.893–0.994).

Committee:

Steven Garverick (Advisor); Swarup Bhunia (Committee Co-Chair); Margot Damaser (Committee Member); Pedram Mohseni (Committee Member); Christian Zorman (Committee Member)

Subjects:

Biomedical Engineering; Electrical Engineering

Keywords:

Implantable electronics; bladder pressure sensor; low-power; integrated circuit; wireless; chronic implantation; bladder implant; pressure sensor; power management; adaptive transmission rate; wireless battery recharge