From providing only voice communications, wireless networks aim to provide a wide range of services in which soft real-time, high priority critical data, and best effort connections seamlessly integrate. Some of these applications and services have firm resource requirements in order to function properly (e.g. videoconferences), others are flexible enough to adapt to whatever is available (e.g. FTP). Providing differentiation and resource assurance is often referred to as providing quality of service (QoS). In this thesis we study how novel resource allocation algorithms can improve the offered QoS of dynamic, unpredictable, and resource constrained distributed systems, such as a wireless network, during periods of overload. We propose and evaluate several bandwidth allocation schemes in the context of cellular, hybrid and pure ad hoc networks. Acceptable quality levels for a connection are specified using resource-utility functions, and our allocation aims to maximise accumulated systemwide utility. To keep allocation optimal in this changing environment, we need to periodically reallocate resources. The novelty of our approach is that we have augmented the utility function model by identifying and classifying the way reallocations affect the utility of different application classes. We modify the initial utility functions at runtime, such that connections become comparable regardless of their flexibility to reallocations or age-related importance. Another contribution is a combined utility/price-based bandwidth allocation and routing scheme for ad hoc networks. First we cast the problem of utility maximisation in a linear programming form. Then we propose a novel distributed allocation algorithm, where every flow bids for resources on the end-to-end path depending on the resource ``shadow price'', and the flow's ``utility efficiency''. Our periodic (re)allocation algorithms represent an iterative process that both adapts to changes in the network, and recalculates and improves the estimation of resource shadow prices. Finally, problems connected to allocation optimisation, such as modelling non-critical resources as costs, or using feedback to adapt to uncertainties in resource usage and availability, are addressed.

The number of wireless communication applications increase steadily, leading to the competition for currently allocated frequency bands. Pressure on authorities around the world to permit communications in higher and wider frequency ranges to achieve higher wireless capacity than those existed in the past has resulted in several new specifications. The federal communication commission (FCC) in USA has unleashed the band 3.1-10.6 GHz for ultra-wideband radio (UWB) communications. The release has triggered a worldwide interest for UWB. Other regulatory instances throughout the world have issued use of UWB techniques as well. Capacity issues in form of data rate and latency have always been a bottleneck for broadened wireless-communication usages. New communication systems like UWB require larger bandwidth than what is normally utilized with traditional antenna techniques. The interest for compact consumer electronics is growing in the meantime, creating a demand on efficient and low profile antennas which can be integrated on a printed circuit board. In this thesis, some methods to extend the bandwidth and other antenna parameters associated with wideband usages are studied. Furthermore, methods on how to enhance the performance when one antenna-element is not enough are studied as well. The principle of antenna parallelism is demonstrated using both microstrip patch antennas and inverted-F antennas. Several techniques to combine the antennas in parallel have been evaluated. Firstly, a solution using power-splitters to form sub-arrays that covers one 500-MHz multi-band orthogonal frequency division multiplexing (OFDM) UWB is shown in Paper I. It is then proposed that the sub-bands are selected with a switching network. A more convenient method is to use the later developed frequency multiplexing technique as described in Paper V and VIII. Using the frequency multiplexing technique, selective connection of any number of antennas to a common junction is possible. The characteristic impedance is chosen freely, typically using a 50-Ω feed-line. Secondly, in Paper VIII a frequency-triplexed inverted-F antenna system is investigated to cover the Mode 1 multi-band UWB bandwidth 3.1-4.8 GHz. The antenna system is composed of three inverted-F antennas and a frequency triplexer including three 5th order bandpass filters. In Paper VI a printed circuit board integrated-triplexer for multi-band UWB radio is presented. The triplexer utilizes a microstrip network and three combined broadside- and edge-coupled filters. The triplexer is fully integrated in a four metal-layer printed circuit board with the minimum requirement on process tolerances. Furthermore, the system is built completely with distributed microstrips, i.e., no discrete components. Using the proposed solution an equal performance between the sub-bands is obtained. Finally suitable monopoles and dipoles are discussed and evaluated for UWB. In Paper X circular monopole and dipole antennas for UWB utilizing the flex-rigid concept are proposed. The flex-rigid concept combines flexible polyimide materials with the regular printed circuit board material. The antennas are placed entirely on the flexible part while the antenna ground plane and the dipole antenna balun are placed in the rigid part.

Tjänster för strömmad media stiger kraftigt i popularitet, samtidigt som utbudet av denna typ av tjänster ökar. Internet protocol television (IPTV) med standardupplösning levereras redan till många hem, och högupplöst IPTV kommer att bli vanligt inom en relativt snar framtid. Mer avancerade tjänster, som tredimensionell TV och TV med fritt valbara vyer, står sedan på tur. Strömmad video är av naturen väldigt bandbreddskrävande, och denna utveckling kommer därför att sätta den befintliga nätverksinfrastrukturen på prov. Multicast är mer bandbreddseffektivt än unicast för scenarion där många mottagare samtidigt är intresserade av samma data, vilket är fallet med populärt direktsänt material. Anledningen är att mottagarna av multicast-sessioner delar på resurserna via ett gemensamt transmissionsträd, där ingen data sänds mer än en gång över någon gren. Användningen av multicast kan därför generera stora besparingar av bandbredd. Internetleverantörerna har dock inga riktigt starka skäl för att stödja multicast, vilket medfört att spridningen varit långsam. Vi föreslår att multicast-sessioner tilldelas mer bandbredd när det uppstår trafikstockningar i näten. Fördelningen baseras på antalet mottagare och datatakten som de erhåller, eftersom det är det som avgör graden av resursdelning. Vi anser att det är rättvist att ta hänsyn till detta, och kallar därför den föreslagna bandbreddsfördelningen multicast-favorable max-min fair. Vidare så presenteras två bandbreddstilldelningspolicyer som använder sig av olika mängd återkoppling för att uppnå fördelningar som ligger förhållandevis nära den föreslagna. Vi föreslår även två mekanismer för kostnadsallokering, vilka bygger på antagandet att kostnaden för dataöverföring ska täckas av mottagarna. De föreslagna mekanismerna fördelar kostnaderna mellan mottagarna baserat på deras andel av resursutnyttjandet, vilket generellt är fördelaktigt för multicast-mottagare. De två mekanismerna för kostnadsallokering skiljer sig åt genom att den ena eftersträvar optimalt rättvis fördelning av kostnaderna, medan den andra kan ge rabatt till vissa mottagare. Rabatten möjliggör större grupper med mottagare, vilket även kan reducera kostnaderna för icke rabatterade mottagare. Förslagen gör multicast mer attraktivt för användarna av strömmad media. Om förslagen implementerades i nätverk med multicast-stöd så skulle övriga Internetleverantörer bli tvungna att stödja multicast för att vara konkurrenskraftiga. / Media-streaming services are rapidly gaining in popularity, and new ones are knocking on the door. Standard-definition Internet protocol television (IPTV) has already entered many living rooms, and high-definition IPTV will become common property in the not too distant future. Then even more advanced and resource-demanding services, such as three-dimensional and free-view TV, are next in line. Video streaming is by nature extremely bandwidth intensive, and this development will put the existing network infrastructure to the test. In scenarios where many receivers are simultaneously interested in the same data, which is the case with popular live content, multicast transmission is more bandwidth efficient than unicast. The reason is that the receivers of a multicast session share the resources through a common transmission tree where data are only transmitted once along any branch. The use of multicast transmission can therefore yield huge bandwidth savings. There are however no really strong incentives for the Internet service providers (ISPs) to support multicast transmission, and the deployment has consequently been slow. We propose that more bandwidth is allocated to multicast flows in the case of network congestion. The ratio is based upon the number of receivers and the bitrate that they are able to obtain, since this is what determines the degree of resource sharing. We believe that it is fair to take this into account, and accordingly call the proposed allocation multicast-favorable max-min fair. Further, we present two bandwidth-allocation policies that utilize different amount of feedback to perform allocations that are reasonable close to be multicast-favorable max-min fair. We also propose two cost-allocation mechanisms that build upon the assumption that the cost for data transmission should be covered by the receivers. The mechanisms charge the receivers based on their share of the resources usage, which in general is favorable to multicast receivers. The two cost-allocation mechanisms differ in that one strives for optimum fair cost allocations, whereas the other might give discounts to some receivers. The discounts facilitate larger groups of receivers, which can provide cheaper services for the non-discounted receivers as well. The proposals make multicast transmission more attractive to the users of media-streaming services. If the proposals were implemented in multicast-enabled networks, the rest of the ISPs would be forced to support multicast, to stay competitive.

Phase Locked Loops(PLLs) are an integral part of almost every electronic system. Systems involving low frequency clocks often require PLLs with low bandwidth. The area occupied by the large loop filter capacitor and resistor in a low bandwidth PLL design makes the realization of traditional charge-pump PLL architecture impractical on a single die, mandating external components on the board. In order to maintain low loop bandwidth the designer is often forced to choose very low values of charge pump current which can lead to reliability issues. In this work, a semi-digital architecture for very low bandwidth monolithic PLLs is proposed. This architecture eliminates large components in traditional charge-pump PLL, thus allowing the realization of on-chip low bandwidth PLLs. A 2x2mm PLL is realized in 180nm CMOS with 75mHz bandwidth consuming 400μW power from 1.8V supply. The prototype PLL locks to an input clock of 1Hz and generates 20kHz output clock with a measured peak-to-peak jitter of 100ns. / Graduation date: 2013

Tradicionalment, les tècniques d'accés múltiple en sistemes de comunicacions multi-usuari han estat desenvolupades o bé orientades a la connexió o bé orientades al tràfic. En el primer cas, l'objectiu és establir tants canals ortogonals com sigui possible per tal d'assignar-los als usuaris. Aquesta idea va motivar el disseny de les estratègies més conegudes, com són FDMA, TDMA i CDMA. Per altra banda, però, els mètodes d'accés aleatori que s'iniciaren amb el conegut ALOHA pretenen compartir estadísticament un mateix medi de comunicació aprofitant la necessitat de transmetre la informació a ràfegues que s'origina en les xarxes de dades. Així, molts dels actuals sistemes es poden encabir dins d'aquest esquema si a més a més, tenim en compte combinacions d'aquestes. No obstant, sistemes moderns com el DVB-RCS en l'entorn de comunicacions digitals per satèl·lit o el WiMAX en l'accés terrestre de banda ampla implementen mecanismes de petició i assignació de recursos, els quals requereixen una gestió dinàmica d'aquests en el sistema (és el que s'anomena distribució dinàmica de l'amplada de banda en un sentit ampli).L'anterior concepte inclou múltiples variables, configuracions i protocols tant de capa física com de capa d'enllaç. En aquesta tesi s'exploren en primer lloc les bases matemàtiques que permeten coordinar les diferents capes de la divisió OSI dels sistemes i els distints nodes dins la xarxa. Ens referim a les tècniques de descomposició focalitzades en problemes d'optimització convexa, els quals han aportat, durant els últims anys, solucions elegants a molts problemes dins dels camps del processament del senyal i les comunicacions. Revisarem els esquemes coneguts i proposarem una nova metodologia. Acte seguit, es comparen les diferents possibilitats de descomposició, cadascuna de les quals implica diferents maneres d'establir la senyalització. A la pràctica, són aquestes diverses opcions de descomposició les que infereixen les diferents interaccions entre capes o els protocols de control entre elements de la xarxa. Els resultats en quant a nombre d'iteracions requerides per a convergir a la solució òptima són favorables al nou mètode proposat, la qual cosa obra noves línies d'investigació.Finalment, es contribueix també amb dos exemples d'aplicació, en DVB-RCS i en WiMAX. Formulem el problema de gestió de recursos resultant de l'accés múltiple dissenyat per cadascun dels sistemes com un problema de maximització d'utilitat de xarxa (conegut com a NUM en la bibliografia) i el solucionarem aplicant les tècniques anteriors. L'objectiu serà garantir l'equitativitat entre els usuaris i preservar, al mateix temps, la seva qualitat de servei. Per aconseguir-ho, cal seleccionar funcions d'utilitat adequades que permetin balancejar l'assignació de recursos cap als serveis més prioritaris. Mostrarem que en els escenaris considerats, l'ús del mètode proposat comporta guanys significatius ja que requereix menys iteracions en el procés (i per tant, menys senyalització) o bé menys temps de càlcul en un enfoc centralitzat (que es tradueix en la possibilitat d'incloure més usuaris). També es mostren els avantatges de considerar interaccions entre capes, ja que es poden ajustar els paràmetres de capa física per tal d'afavorir els tràfics més prioritaris o bé extreure els requeriments de servei de valors típicament disponibles en capes superiors.En general, la implementació eficient de tècniques de gestió dinàmica de recursos treballant en l'accés múltiple dels sistemes pot aportar guanys significatius però implica establir una bona coordinació entre capes i elements de xarxa. L'eina matemàtica que ho possibilita són les tècniques de descomposició. Cada nou escenari i sistema introdueix un nou repte d'optimització i la capacitat que tinguem de coordinar totes les variables del sistema cap al punt òptim en determinarà el rendiment global. / Traditionally, multiple access schemes in multi-user communications systems have been designed either connection-oriented or traffic-oriented. In the first ones, the goal was to provide as many orthogonal channels as possible, each one serving a different connection. That is the motivation of the so-called FDMA, TDMA and CDMA solutions. On the other hand, random access techniques, which started with the so-called ALOHA protocol, aim to statistically multiplex a shared communication medium by means of exploiting the random and bursty nature of transmission needs in data networks. Most of the multiple access solutions can be interpreted according to that classification or as a combination of those approaches. Notwithstanding, modern systems, such as the digital satellite communications standard DVB-RCS or the broadband wireless access WiMAX, have implemented a multiple access technique where users request for transmission opportunities and receive grants from the network, therefore requiring dynamic bandwidth allocation techniques. The concept of dynamic bandwidth allocation is wide and involves a number of physical and link layer variables, configurations and protocols. In this Ph.D. dissertation we first explore the mathematical foundation that is required to coordinate the distinct layers of the OSI protocol stack and the distinct nodes within the network. We talk about decomposition techniques focused on the resolution of convex programs, which have elegantly solved many problems in the signal processing and communications fields during the last years. Known schemes are reviewed and a novel decomposition methodology is proposed. Thereafter, we compare the four resulting strategies, each one having its own particular signalling needs, which results in distinct cross-layer interactions or signalling protocols at implementation level. The results in terms of iterations required to converge are favourable to the proposed method, thus opening a new line of research.Finally, we contribute with two practical application examples in the DVB-RCS and WiMAX systems. First, we formulate the dynamic bandwidth allocation problem that is derived from the multiple access schemes of both systems. Thereafter, the resulting Network Utility Maximization (NUM) based problem is solved by means of the previous decomposition mechanisms. The goal is to guarantee fairness among the users at the same time that Quality of Service (QoS) is preserved. In order to achieve that, we choose adequate utility functions that allow to balance the allocation towards the most priority traffic flows under a common fairness framework. We show that in the scenarios considered, the novel proposed coupled-decomposition method reports significant gains since it reduces significantly the iterations required (less iterations implies less signalling) or it reduces the time needed to obtain the optimal allocation when it is centrally computed (more users can be managed). We further show the advantages of cross-layer interactions with the physical and upper layers, which allow to benefit from more favourable adjustments of the transmission parameters and to consider the QoS requirements at upper layers. In general, an efficient implementation of dynamic bandwidth allocation techniques in Demand Assignment Multiple Access (DAMA) schemes may report significant performance gains but it requires proper coordination among system layers and network nodes, which is attained thanks to decomposition techniques. Each new scenario and system adds another optimization challenge and, as far as we are able to coordinate all the variables in the system towards that optimal point, the highest will be the revenue.

The main scope of this thesis is to implement a new architecture of a high bandwidth phase-locked loop (PLL) with a large operating frequency range from 100~MHz to 1~GHz in a 150~$nm$ CMOS process. As PLL is the time-discrete system, the new architecture is mathematically modelled in the z-domain. The charge pump provides a proportionally damped signal, which is unlikely as a resistive or capacitive damping used in the conventional charge pump. The new damping results in a less update jitter and less peaking to achieve the lock frequency and fast locking time of the PLL. The new semi-digital PLL architecture uses $N$ storage cells. The $N$ storage cells is used to store the oscillator tuning information digitally and also enables analogue tuning of the voltage controlled oscillator (VCO). The storage cells outputs are also used for the process voltage temperature compensation. The phase-frequency detector (PFD) and VCO are implemented like a conventional PLL. The bandwidth achieved is 1/4th of the PFD update frequency for all over the operating range from 100~MHz to 1~GHz. The simulation results are also verified with the mathematical modelling. The new architecture also consumes less power and area compared to the conventional PLL.

This report has been written at SAAB Bofors Dynamics (SBD) AB in Gothenburg at the department of optronic systems. In military observation operations, a target to hit is chosen by illumination of a laser designator. From the targetpoint laser radiation is reflected on a detector that helps identify the target. The detector is a semiconductor PIN-type that has been investigated in a laboratory environment together with a specially designed laser source. The detector is a photodiode and using purchased components, circuits for both the photodiode and the laserdiode has been designed and fabricated. The bandwidth of the op-amp should be about 30 MHz, in the experiments a bandwidth of 42 MHz was used. Initially the feedback network, which consists of a 5.6 pF capacitor in parallel with a 1-kohm resistor determined the bandwidth. To avoid the op-amp saturate under strong illuminated laser radiation the feedback network will use a 56-pF capacitor and a 100-ohm resistor respectively. The laser should be pulsed with 10-20 ns width, 10 Hz repetition frequency, about 800 nm wavelength and a maximum output power of 80 mW. To avoid electrical reflection signals at measurement equipment connections, the laser circuit includes a resistor of about 50 ohm, that together with the resistance in the laserdiode forms the right termination that eliminate the reflection signals. The wire-wound type of resistor shall be avoided in this application and instead a surface mounted type was beneficial with much lower inductance. The detector showed a linear behaviour up to 40-mW optical power. Further investigation was hindered by the breakdown of the laserdiodes. The function generator limits the tests to achieve 80 mW in light power. In different experiments the responsivity of the photodiode is different from the nominal value, however it would have required more time to investigate the causes.

In this thesis, we propose a new bandwidth-enhancement method of using a parasitic open slot to achieve a wide lower band for the internal laptop computer antenna with a small size to cover the GSM850/900 operation and a wide upper band to cover the GSM1800/1900/UMTS operation as well. The occupied antenna volume is only 48 ¡Ñ 10 ¡Ñ 3.5 mm^3 above the top edge of the display ground. For practical application, we analyze the effects of the antenna position, nearby metal plate, shielding metal plate, keyboard ground, FR4 substrate, and the size of display ground on the performance of the WWAN antenna. In addition, effects of the user¡¦s whole-body on the proposed antenna are also analyzed. Owing to the user¡¦s whole-body being mainly lossy materials, a decrease in the antenna¡¦s radiation efficiency is observed when the user¡¦s whole-body is in close proximity to the WWAN laptop computer antenna.

Along with rapid development of information technology, all kinds of algorithms have been presented, to achieve significant progress in image tracking. Most methods tend to identify features of moving objects, and filter out background components which do not meet these features. This thesis uses a spatio-temporal planar-resonant filter to accomplish moving object tracking tasks. Under the condition without prior knowledge about features of moving objects, choosing appropriate filter¡¦s parameters is able to enhance the object with a certain moving speed and reduce intensity of objects with different velocities. Nevertheless, this filter cannot solve the problem background filtering. Therefore, a homomorphic filtering with fast optical flow estimation is implemented to identify and separate the background and moving components in dynamic images. This thesis also considers different 3-D bandwidth parameters. To develop a systematic approach to design filter¡¦s parameters for actual implementations.

Though erasure codes are widely adopted in high fault tolerance storage systems, there exists a serious small-write problem. Many algorithms are proposed to improve small-write performance in RAID systems, without considering the network bandwidth usage. However, the network bandwidth is expensive in cloud systems. In this thesis, we proposed an ECL-based (E-MBR codes, Caching and Logging-based) technique to improve the small-write performance without using extra network bandwidth. In addition, the ECL-based technique also reduces the delayed parity update and data recovery latency compared with the competing algorithm.