Auto-tuning of RRM parameters in UMTS networks. Feasibility study.

Due to the intrinsic characteristics of WCDMA and the great number of services offered by UMTS, its radio channel is much more dynamic compared with GERAN systems. The traffic fluctuations and users mobility can cause the impairment of the network performance and of the quality of service (QoS) in certain cells. In the worst case a significant degradation of the QoS may be observed and as a result the operator defined targets are not met. Nowadays UMTS operators have fixed, and usually uniform, settings for their network parameters. This static configuration is not able to adapt automatically to the changes that occur in the network. A fixed parameter setting then gives a non optimal solution for the network optimization process and thus the utilization of the radio interface is not maximized. The goal of the automated tuning is to adjust dynamically these parameters in a continuous way without human intervention, which is only required in definition of the reference QoS. The current PFC aims at validating the feasibility of automated optimization of certain UMTS RRM parameters. The main tasks to be developed by the students are: - Simulator developement (Matlab programmed). A basic static Montecarlo simulator is available as a reference. - Study of UMTS handover algorithm and study of potential parameters to be automatically tuned. - Proposal of algorithm to tune the previously selected parameters, and evaluation of achieved gains. - Study of UMTS CAC algorithm and study of potential parameters to be automatically tuned. Development of first and basic ideas to propose tuning algorithm.The present PFC is located inside the framework of the UMTS networks, and more specifically in the development of new Radio Resource Management (RRM) algorithms capable to maximize the capacity and the performance of the network. In this sense a powerful simulation tool capable to analyze in depth the behavior of the UMTS network under different simulation scenarios has been developed. It has been focused in the study of the main algorithms that manage the allocation of radio resources in UMTS networks: Power Control (PC), Admission Control (AC) and Soft/Softer Handover (SHO). The problem observed in classical SHO strategies is the rigidity of the mechanism, which cannot adapt to variations in the traffic patterns. The improvements on SHO procedures are based on dynamic automated tuning of SHO parameters. A three blocks based functional architecture is described to adapt parameters to service mix dynamics and overcome capacity problems. Several tests have been done over different traffic situations in order to demonstrate the feasibility of the Auto-Tuning System (ATS). The results obtained show a considerable increment in the network capacity. In this sense ATS is considered as an effective pre-congestion-control strategy. Referring now to AC strategies, it is necessary to underline that three new AC algorithms have been implemented: Dynamic AC, Complete Partitioning AC (CP-AC) and Complete Sharing AC (CS-AC) strategies have been developed with the same goal, enhance the capacity of the network. Dynamic AC was proposed to provide flexibility to the current AC algorithm. This strategy is based on the ATS philosophy where a dynamic AC threshold is fixed to the optimum threshold in real time according to the current service mix. On the other hand, CS-AC and CP-AC are complex strategies based on static algorithms where fixed thresholds or load margins were applied in order to note their advantages and drawbacks depending on the users distribution, uniform or mostly close to the cell edge. As a result of this project a scientific publication inside the context of COST european projects has been carried out. In special, is about the COST 2100 ”Pervasive Mobile & Ambient Wireless Communications” and the title of the publication is ”Automatic Tuning of Soft Handover Parameters in UMTS Networks”. The paper was presented in the meeting number 3, held in Duisburg (Germany) between 10th and 12th of September 2007

Ground plane booster antenna technology for wireless handheld devices

This thesis is framed in the field of mobile communications and more particularly in handset antennas. The wireless industry is constantly growing, which entails challenging handset antenna specifications. Handset antennas not only have to be multi-band for satisfying the great number of communication services, but also sufficiently small as for fitting in the reduced space imposed by the handset platforms. The appearance of the MIMO (Multiple Input Multiple Output) technology, further exacerbates these challenges. In order to satisfy these requirements, this thesis proposes the use of the ground plane, inherently present in any handset platform, as the main radiator. Electrically small nonresonant elements, called along this thesis as ground plane boosters, are used to transfer energy to this ground plane. The solution removes the need of including a dedicated antenna featured by considerable dimensions, thus releasing space to integrate other antennas, as well as, other handset components, services and functionalities.Postprint (published version

Ground plane booster antenna technology for wireless handheld devices

This thesis is framed in the field of mobile communications and more particularly in handset antennas. The wireless industry is constantly growing, which entails challenging handset antenna specifications. Handset antennas not only have to be multi-band for satisfying the great number of communication services, but also sufficiently small as for fitting in the reduced space imposed by the handset platforms. The appearance of the MIMO (Multiple Input Multiple Output) technology, further exacerbates these challenges. In order to satisfy these requirements, this thesis proposes the use of the ground plane, inherently present in any handset platform, as the main radiator. Electrically small nonresonant elements, called along this thesis as ground plane boosters, are used to transfer energy to this ground plane. The solution removes the need of including a dedicated antenna featured by considerable dimensions, thus releasing space to integrate other antennas, as well as, other handset components, services and functionalities

The Hilbert monopole revisited

A comparison between the resonant performance of the third iteration Hilbert monopole and a spiral shaped one of the same size and resonant frequency is presented. Quality factor, bandwidth, efficiency and radiation patterns are investigated. Although the Hilbert monopole total wire length is longer, it shows nearly the same radiation efficiency yet a lower quality factor. Hence the higher compression efficiency of the spiral shaped monopole does not provide any advantage in the antenna electromagnetic performance. Differences in radiation pattern are also observed. It is demonstrated that antenna resonance performance depends on its geometry, and not only on its size or wire length.Peer ReviewedPostprint (published version

Analysis of the specific absorption rate in handset antennas with slotted ground planes

The study of the interaction between human head and handset antennas should be taken into account since all the mobile phones have to guarantee a biological compatibility. This research analyzes several antennas with different slotted ground planes in terms of free space and also in terms of human head interaction. The main objective is to compare the measured bandwidth and efficiency in free space and the impact on measured SAR (Specific Absorption Rate) of such antennas as a function of the slot configuration and the antenna/slot location. Results show that slots may be useful to increase bandwidth and efficiency while keeping a similar SAR compared to the non-slotted ground plane. Changing the antenna and the slot location is a good way to achieve a significant SAR reduction.Peer ReviewedPostprint (published version

Conformación del diagrama de radiación de un monopolo en L

The typical radiation pattern of an L-monopole antenna can be easily modified by changing the geometrical characteristics of the structure. To shape a specific radiation pattern through a basic structure becomes an interesting freedom degree in order to better adapt the behaviour of the antenna to the design specifications. Thus, to solve the question,an accurate analysis following the radiated field basic equations has been carried out. The theoretical study is validated through a simulation and experimental process. The results depict three main regions, delimited by geometrical boundaries, where the Lshaped wire antenna present three specific radiation pattern types, a monopole-type, a half isotropic type or even, a patchtype radiation pattern. Consequently, the method described herein demonstrates that simple modifications applied to the geometry of a basic structure, allow obtaining radiation properties associated to more complex structures.Peer ReviewedPostprint (published version

Análisis del comportamiento de antenas móviles multibanda en presencia del cuerpo humano

The great majority of wireless devices are used close to the human head. These changes the antenna performance compared to free space situation. The human head absorbs an amount of power from the antenna radiation. In this sense, it is important not only to increase the robustness of the antenna performance, but also to reduce the amount of power absorbed by the human head. A coupled monopole and a PIFA antenna are evaluated in terms of antenna performance in presence of the human head. The most significant parameters (SAR, efficiency and return losses) are obtained at two different positions of the antenna as a function of the frequency band, to finally evaluate the impact of the human head to the antenna performance, and the effect of the antenna on it. Despite both antennas have a similar efficiency value at Free Space, monopole antenna has more sensitivity to the interaction with the human head.Peer ReviewedPostprint (published version

Diseño de una antena multibanda con ranuras en el plano de masa: una técnica para facilitar la integración de la línea de alimentación

The integration of transmission lines is a difficult task due to the presence of slots. In order to facilitate the integration of the feeding transmission line which connects the antenna with the RF-module, this research proposes a ground plane modification using central slots. Numerical simulation using MoM is used to understand the effect of the slots on the ground plane and several prototypes have been built to validate the present technique. Through this technique is possible to obtain a multiband antenna while keeping the same antenna geometry, small volume and simplifying the PCB (Printed Circuit Board) design.Peer ReviewedPostprint (published version

Auto-tuning of RRM parameters in UMTS networks. Feasibility study.

Due to the intrinsic characteristics of WCDMA and the great number of services offered by UMTS, its radio channel is much more dynamic compared with GERAN systems. The traffic fluctuations and users mobility can cause the impairment of the network performance and of the quality of service (QoS) in certain cells. In the worst case a significant degradation of the QoS may be observed and as a result the operator defined targets are not met. Nowadays UMTS operators have fixed, and usually uniform, settings for their network parameters. This static configuration is not able to adapt automatically to the changes that occur in the network. A fixed parameter setting then gives a non optimal solution for the network optimization process and thus the utilization of the radio interface is not maximized. The goal of the automated tuning is to adjust dynamically these parameters in a continuous way without human intervention, which is only required in definition of the reference QoS. The current PFC aims at validating the feasibility of automated optimization of certain UMTS RRM parameters. The main tasks to be developed by the students are: - Simulator developement (Matlab programmed). A basic static Montecarlo simulator is available as a reference. - Study of UMTS handover algorithm and study of potential parameters to be automatically tuned. - Proposal of algorithm to tune the previously selected parameters, and evaluation of achieved gains. - Study of UMTS CAC algorithm and study of potential parameters to be automatically tuned. Development of first and basic ideas to propose tuning algorithm.The present PFC is located inside the framework of the UMTS networks, and more specifically in the development of new Radio Resource Management (RRM) algorithms capable to maximize the capacity and the performance of the network. In this sense a powerful simulation tool capable to analyze in depth the behavior of the UMTS network under different simulation scenarios has been developed. It has been focused in the study of the main algorithms that manage the allocation of radio resources in UMTS networks: Power Control (PC), Admission Control (AC) and Soft/Softer Handover (SHO). The problem observed in classical SHO strategies is the rigidity of the mechanism, which cannot adapt to variations in the traffic patterns. The improvements on SHO procedures are based on dynamic automated tuning of SHO parameters. A three blocks based functional architecture is described to adapt parameters to service mix dynamics and overcome capacity problems. Several tests have been done over different traffic situations in order to demonstrate the feasibility of the Auto-Tuning System (ATS). The results obtained show a considerable increment in the network capacity. In this sense ATS is considered as an effective pre-congestion-control strategy. Referring now to AC strategies, it is necessary to underline that three new AC algorithms have been implemented: Dynamic AC, Complete Partitioning AC (CP-AC) and Complete Sharing AC (CS-AC) strategies have been developed with the same goal, enhance the capacity of the network. Dynamic AC was proposed to provide flexibility to the current AC algorithm. This strategy is based on the ATS philosophy where a dynamic AC threshold is fixed to the optimum threshold in real time according to the current service mix. On the other hand, CS-AC and CP-AC are complex strategies based on static algorithms where fixed thresholds or load margins were applied in order to note their advantages and drawbacks depending on the users distribution, uniform or mostly close to the cell edge. As a result of this project a scientific publication inside the context of COST european projects has been carried out. In special, is about the COST 2100 ”Pervasive Mobile & Ambient Wireless Communications” and the title of the publication is ”Automatic Tuning of Soft Handover Parameters in UMTS Networks”. The paper was presented in the meeting number 3, held in Duisburg (Germany) between 10th and 12th of September 2007

Antenes, setembre 2012

Material docent de la Universitat Oberta de Catalunya.Material docente de la "Universitat Oberta de Catalunya".Learning material of the "Universitat Oberta de Catalunya"