GAME THEORETIC APPROACH TO RADIO RESOURCE MANAGEMENT ON THE REVERSE LINK FOR MULTI-RATE CDMA WIRELESS DATA NETWORKS

This work deals with efficient power and rate assignment to mobile stations (MSs) involved in bursty data transmission in cellular CDMA networks. Power control in the current CDMA standards is based on a fixed target signal quality called signal to interference ratio (SIR). The target SIR represents a predefined frame error rate (FER). This approach is inefficient for data-MSs because a fixed target SIR can limit the MS's throughput. Power control should thus provide dynamic target SIRs instead of a fixed target SIR. In the research literature, the power control problem has been modeled using game theory. A limitation of the current literature is that in order to implement the algorithms, each MS needs to know information such as path gains and transmission rates of all other MSs. Fast rate control schemes in the evolving cellular data systems such as cdma2000-1x-EV assign transmission rates to MSs using a probabilistic approach. The limitation here is that the radio resources can be either under or over-utilized. Further, all MSs are not assigned the same rates. In the schemes proposed in the literature, only few MSs, which have the best channel conditions, obtain all radio resources. In this dissertation, we address the power control issue by moving the computation of the Nash equilibrium from each MS to the base station (BS). We also propose equal radio resource allocation for all MSs under the constraint that only the maximum allowable radio resources are used in a cell. This dissertation addresses the problem of how to efficiently assign power and rate to MSs based on dynamic target SIRs for bursty transmissions. The proposed schemes in this work maximize the throughput of each data-MS while still providing equal allocation of radio resources to all MSs and achieving full radio resource utilization in each cell. The proposed schemes result in power and rate control algorithms that however require some assistance from the BS. The performance evaluation and comparisons with cdma2000-1x-Evolution Data Only (1x-EV-DO) show that the proposed schemes can provide better effective rates (rates after error) than the existing schemes

Performance of hard handoff in 1xev-do rev. a systems

1x Evolution-Data Optimized Revision A (1xEV-DO Rev. A) is a cellular communications standard that introduces key enhancements to the high data rate packet switched 1xEV-DO Release 0 standard. The enhancements are driven by the increasing demand on some applications that are delay sensitive and require symmetric data rates on the uplink and the downlink. Some examples of such applications being video telephony and voice over internet protocol (VoIP). The handoff operation is critical for delay sensitive applications because the mobile station (MS) is not supposed to lose service for long periods of time. Therefore seamless server selection is used in Rev. A systems. This research analyzes the performance of this handoff technique. A theoretical approach is presented to calculate the slot error probability (SEP). The approach enables evaluating the effects of filtering, hysteresis as well as the system introduced delay to handoff execution. Unlike previous works, the model presented in this thesis considers multiple base stations (BS) and accounts for correlation of shadow fading affecting different signal powers received from different BSs. The theoretical results are then verified over ranges of parameters of practical interest using simulations, which are also used to evaluate the packet error rate (PER) and the number of handoffs per second. Results show that the SEP gives a good indication about the PER. Results also show that when considering practical handoff delays, moderately large filter constants are more efficient than smaller ones

An emission and discard priority scheme for optical burst switched networks

Word processed copy.Includes bibliographical references (leaves 76-79).Optical burst switching (OBS) is a promising technology designed to meet the growing demands for internet handwidth and better Quality of Service (QoS). This technology provides all optical and high speed switching to overcome the bottleneck of electronic routers in the core network. In this thesis, I describe several critical issues that affect OBS networks. I highlight the need to resolve contention efficiently and cost-effectively to improve QoS in OBS networks

Performance of hard handoff in 1xev-do rev. a systems

1x Evolution-Data Optimized Revision A (1xEV-DO Rev. A) is a cellular communications standard that introduces key enhancements to the high data rate packet switched 1xEV-DO Release 0 standard. The enhancements are driven by the increasing demand on some applications that are delay sensitive and require symmetric data rates on the uplink and the downlink. Some examples of such applications being video telephony and voice over internet protocol (VoIP). The handoff operation is critical for delay sensitive applications because the mobile station (MS) is not supposed to lose service for long periods of time. Therefore seamless server selection is used in Rev. A systems. This research analyzes the performance of this handoff technique. A theoretical approach is presented to calculate the slot error probability (SEP). The approach enables evaluating the effects of filtering, hysteresis as well as the system introduced delay to handoff execution. Unlike previous works, the model presented in this thesis considers multiple base stations (BS) and accounts for correlation of shadow fading affecting different signal powers received from different BSs. The theoretical results are then verified over ranges of parameters of practical interest using simulations, which are also used to evaluate the packet error rate (PER) and the number of handoffs per second. Results show that the SEP gives a good indication about the PER. Results also show that when considering practical handoff delays, moderately large filter constants are more efficient than smaller ones

Rate Assignment in Wireless Networks: Stability Analysis and Controller Design

In this thesis, the problem of resource allocation in IS-856 is studied. The problem is first formulated in an interference model framework on reverse channel (uplink). A simple controller is then designed for the system and the closed-loop stability is analyzed using the Lyapunov technique. The possible oscillation in the network output caused by the limit cycles associated with the nonlinear elements in the control loop is analyzed in the framework of describing functions. A dynamic control strategy is developed subsequently for efficient rate assignment in the network. This is carried out in two steps: in the first step, the controller is designed for a simple case when the number of users in the network is fixed and known, and all users are full-buffered. The asymptotic stability property of the proposed controller is verified. Then, the designed controller is further developed for a dynamic network, where the number of active users is subject to change but is known to the users by means of the communication link between the base station and users. In this step, the activation/deactivation of users at different time instants is formulated as a switched system, and sufficient conditions on the speed of activation and deactivation of users are obtained in the control theoretic framework to achieve stability and the desired performance. In the next step, the obtained controller is adjusted properly for the case when the information about the number of active users is not communicated to the users (in order to allocate more bandwidth for data transmission). A controller is also designed to guarantee network stability and performance in the presence of time-delay in the feedback loop. Finally, the long-term fairness in rate allocation is studied. Simulation results are also provided throughout the thesis to elucidate the effectiveness of the proposed approach

Designing Flexible, Energy Efficient and Secure Wireless Solutions for the Internet of Things

The Internet of Things (IoT) is an emerging concept where ubiquitous physical objects (things) consisting of sensor, transceiver, processing hardware and software are interconnected via the Internet. The information collected by individual IoT nodes is shared among other often heterogeneous devices and over the Internet. This dissertation presents flexible, energy efficient and secure wireless solutions in the IoT application domain. System design and architecture designs are discussed envisioning a near-future world where wireless communication among heterogeneous IoT devices are seamlessly enabled. Firstly, an energy-autonomous wireless communication system for ultra-small, ultra-low power IoT platforms is presented. To achieve orders of magnitude energy efficiency improvement, a comprehensive system-level framework that jointly optimizes various system parameters is developed. A new synchronization protocol and modulation schemes are specified for energy-scarce ultra-small IoT nodes. The dynamic link adaptation is proposed to guarantee the ultra-small node to always operate in the most energy efficiency mode, given an operating scenario. The outcome is a truly energy-optimized wireless communication system to enable various new applications such as implanted smart-dust devices. Secondly, a configurable Software Defined Radio (SDR) baseband processor is designed and shown to be an efficient platform on which to execute several IoT wireless standards. It is a custom SIMD execution model coupled with a scalar unit and several architectural optimizations: streaming registers, variable bitwidth, dedicated ALUs, and an optimized reduction network. Voltage scaling and clock gating are employed to further reduce the power, with a more than a 100% time margin reserved for reliable operation in the near-threshold region. Two upper bound systems are evaluated. A comprehensive power/area estimation indicates that the overhead of realizing SDR flexibility is insignificant. The benefit of baseband SDR is quantified and evaluated. To further augment the benefits of a flexible baseband solution and to address the security issue of IoT connectivity, a light-weight Galois Field (GF) processor is proposed. This processor enables both energy-efficient block coding and symmetric/asymmetric cryptography kernel processing for a wide range of GF sizes (2^m, m = 2, 3, ..., 233) and arbitrary irreducible polynomials. Program directed connections among primitive GF arithmetic units enable dynamically configured parallelism to efficiently perform either four-way SIMD GF operations, including multiplicative inverse, or a long bit-width GF product in a single cycle. This demonstrates the feasibility of a unified architecture to enable error correction coding flexibility and secure wireless communication in the low power IoT domain.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/137164/1/yajchen_1.pd

The molecular ontogeny of follicular lymphoma

Background: Advanced-stage follicular lymphoma (FL) is considered incurable, with patients typically suffering from a chronic relapsing clinical course. Relapsed FL is thought to originate from common progenitor cells (CPCs) through divergent evolution. CPCs typically contain the hallmark BCL2/IGH translocation, in addition to other recurrent mutations. Targeting CPC-defining, early acquired (i.e., truncal) mutations offers the chance to eradicate/cure the disease. Aim: To define and functionally characterize early acquired mutations in FL. Results: We hypothesized that CPC-defining mutations can be acquired before the FL-hallmark BCL2/IGH translocation in hematopoietic stem and progenitor cells (HSPCs). To directly define the molecular ontogeny of FL, we used highly sensitive mutation detection of purified BCL2/IGH-negative (BCL2/IGH-) HSPCs from leukapheresis samples of 3 patients in clinical remission. However, using complementary approaches, we did not identify CPC-defining mutations in BCL2/IGH- progenitor cells. Vice versa, we identified B cells harboring the FL-specific BCL2/IGH translocation but without CPC-defining mutations in one informative case. We next used indirect approaches to identify truncal mutations for functional characterization. Using cancer cell fraction corrected (CCF)-variant allele frequency (VAF) from FL patients, we identified STAT6 (based on a previous study) and IKZF3 (based on our own data) as truncal events by high clonality. Previous work from our group (Boesl et al.) provided the first insights into the biology of STAT6 mutations, however, the mechanisms remained incompletely understood. In my thesis, I significantly contributed to this work by showing that STAT6 mutations drive a self-reinforcing microcircuit. Specifically, I showed that in the presence of interleukin-4 (IL-4) (i) STAT6D419G mutations are gain-of-function (by serial replating pre-B cell colony-forming-units (CFU) assays), that (ii) STAT6D419G (but not STAT6WT) binds to the PARP14 promoter and activates gene expression of PARP14 (which is a component of the STAT6 enhanceosome), and that (iii) increased nuclear accumulation of phosphorylated STAT6D419G drives increased expression of known STAT6 target genes, including FCER2, CCL17, CCL22, as well as PARP14 itself. Finally, using our own available DNA sequencing data, we identified IKZF3 mutations as truncal events by high clonality. Of note, mutations cluster in distinct hotspots, mostly L162R and S215R. To model early and later mutation acquisition, I utilized Cre-Lox recombination restricted IKZF3 expression in lineage negative (lin-) HSPCs from Emu-BCL2/Vav-Cre mice (IKZF3 expression before B-lineage commitment) vs. Emu-BCL2/Mb1-Cre mice (IKZF3 expression in B-lineage committed cells). My results indicate that IKZF3S215R mutations are primarily gain-of-function (i.e. provide a serial replating phenotype) when expressed in HSPCs. In contrast, IKZF3L162R mutations provide a serial replating phenotype when expressed in pre-B cells. Phenotypic analysis of IKZF3L162R mouse pre-B CFUs identified them to be in a highly proliferative differentiation state (B220+ CD24++ CD43+), characterized by ongoing pre-BCR signaling and increased SYK expression. In primary human FL-like B cells, we confirmed this phenotype, with IKZF3L162R cells showing increased SYK expression and an increased proliferative rate. RNA sequencing analysis of IKZF3L162R FL-like B cells vs. IKZF3WT identified B cell proliferation and activation to be enriched. Discussion and conclusion: The absence of mutations in HSPCs suggests that in human FL, the BCL2/IGH translocation can precede the acquisition of CPC-defining mutations. We also identified BCL2/IGH+ cells in a patient in ongoing clinical remission but without CPC-defining mutations. The absence of CPC-defining mutations suggests that these cells are not contributing to relapse. In the second part of my thesis, I studied early acquired STAT6 mutations. My results significantly contributed to further characterizing the STAT6 mutation phenotype. We propose that the STAT6D419G gain-of-function phenotype is strictly dependent on IL-4. STAT6D419G but not STAT6WT aberrantly increases PARP14 levels in lymphoma cells. Increased PARP14 levels then contribute to increased assembly/stabilization of the STAT6 enhanceosome complex, resulting in increased STAT6-dependent gene expression and thereby amplifying an IL-4 driven self-reinforcing microcircuit. Therefore, PARP14 represents an attractive therapeutic target in STAT6MUT FL. Lastly, I identified IKZF3 with mutation-specific phenotypes when expressed in HSPCs vs. B cells. My results indicate that IKZF3L162R induces proliferative expansion of pre-B cells and FL-like mature B cells, characterized by increased BCR signaling and SYK expression. Further functional experiments are required to better define the precise mechanism

Propuesta de arquitectura y circuitos para la mejora del rango dinámico de sistemas de visión en un chip diseñados en tecnologías CMOS profundamente submicrométrica

El trabajo presentado en esta tesis trata de proponer nuevas técnicas para la expansión del rango dinámico en sensores electrónicos de imagen. En este caso, hemos dirigido nuestros estudios hacia la posibilidad de proveer dicha funcionalidad en un solo chip. Esto es, sin necesitar ningún soporte externo de hardware o software, formando un tipo de sistema denominado Sistema de Visión en un Chip (VSoC). El rango dinámico de los sensores electrónicos de imagen se define como el cociente entre la máxima y la mínima iluminación medible. Para mejorar este factor surgen dos opciones. La primera, reducir la mínima luz medible mediante la disminución del ruido en el sensor de imagen. La segunda, incrementar la máxima luz medible mediante la extensión del límite de saturación del sensor. Cronológicamente, nuestra primera opción para mejorar el rango dinámico se basó en reducir el ruido. Varias opciones se pueden tomar para mejorar la figura de mérito de ruido del sistema: reducir el ruido usando una tecnología CIS o usar circuitos dedicados, tales como calibración o auto cero. Sin embargo, el uso de técnicas de circuitos implica limitaciones, las cuales sólo pueden ser resueltas mediante el uso de tecnologías no estándar que están especialmente diseñadas para este propósito. La tecnología CIS utilizada está dirigida a la mejora de la calidad y las posibilidades del proceso de fotosensado, tales como sensibilidad, ruido, permitir imagen a color, etcétera. Para estudiar las características de la tecnología en más detalle, se diseñó un chip de test, lo cual permite extraer las mejores opciones para futuros píxeles. No obstante, a pesar de un satisfactorio comportamiento general, las medidas referentes al rango dinámico indicaron que la mejora de este mediante sólo tecnología CIS es muy limitada. Es decir, la mejora de la corriente oscura del sensor no es suficiente para nuestro propósito. Para una mayor mejora del rango dinámico se deben incluir circuitos dentro del píxel. No obstante, las tecnologías CIS usualmente no permiten nada más que transistores NMOS al lado del fotosensor, lo cual implica una seria restricción en el circuito a usar. Como resultado, el diseño de un sensor de imagen con mejora del rango dinámico en tecnologías CIS fue desestimado en favor del uso de una tecnología estándar, la cual da más flexibilidad al diseño del píxel. En tecnologías estándar, es posible introducir una alta funcionalidad usando circuitos dentro del píxel, lo cual permite técnicas avanzadas para extender el límite de saturación de los sensores de imagen. Para este objetivo surgen dos opciones: adquisición lineal o compresiva. Si se realiza una adquisición lineal, se generarán una gran cantidad de datos por cada píxel. Como ejemplo, si el rango dinámico de la escena es de 120dB al menos se necesitarían 20-bits/píxel, log2(10120/20)=19.93, para la representación binaria de este rango dinámico. Esto necesitaría de amplios recursos para procesar esta gran cantidad de datos, y un gran ancho de banda para moverlos al circuito de procesamiento. Para evitar estos problemas, los sensores de imagen de alto rango dinámico usualmente optan por utilizar una adquisición compresiva de la luz. Por lo tanto, esto implica dos tareas a realizar: la captura y la compresión de la imagen. La captura de la imagen se realiza a nivel de píxel, en el dispositivo fotosensor, mientras que la compresión de la imagen puede ser realizada a nivel de píxel, de sistema, o mediante postprocesado externo. Usando el postprocesado, existe un campo de investigación que estudia la compresión de escenas de alto rango dinámico mientras se mantienen los detalles, produciendo un resultado apropiado para la percepción humana en monitores convencionales de bajo rango dinámico. Esto se denomina Mapeo de Tonos (Tone Mapping) y usualmente emplea solo 8-bits/píxel para las representaciones de imágenes, ya que éste es el estándar para las imágenes de bajo rango dinámico. Los píxeles de adquisición compresiva, por su parte, realizan una compresión que no es dependiente de la escena de alto rango dinámico a capturar, lo cual implica una baja compresión o pérdida de detalles y contraste. Para evitar estas desventajas, en este trabajo, se presenta un píxel de adquisición compresiva que aplica una técnica de mapeo de tonos que permite la captura de imágenes ya comprimidas de una forma optimizada para mantener los detalles y el contraste, produciendo una cantidad muy reducida de datos. Las técnicas de mapeo de tonos ejecutan normalmente postprocesamiento mediante software en un ordenador sobre imágenes capturadas sin compresión, las cuales contienen una gran cantidad de datos. Estas técnicas han pertenecido tradicionalmente al campo de los gráficos por ordenador debido a la gran cantidad de esfuerzo computacional que requieren. Sin embargo, hemos desarrollado un nuevo algoritmo de mapeo de tonos especialmente adaptado para aprovechar los circuitos dentro del píxel y que requiere un reducido esfuerzo de computación fuera de la matriz de píxeles, lo cual permite el desarrollo de un sistema de visión en un solo chip. El nuevo algoritmo de mapeo de tonos, el cual es un concepto matemático que puede ser simulado mediante software, se ha implementado también en un chip. Sin embargo, para esta implementación hardware en un chip son necesarias algunas adaptaciones y técnicas avanzadas de diseño, que constituyen en sí mismas otra de las contribuciones de este trabajo. Más aún, debido a la nueva funcionalidad, se han desarrollado modificaciones de los típicos métodos a usar para la caracterización y captura de imágenes