Quality of service optimization of multimedia traffic in mobile networks

Mobile communication systems have continued to evolve beyond the currently deployed Third Generation (3G) systems with the main goal of providing higher capacity. Systems beyond 3G are expected to cater for a wide variety of services such as speech, data, image transmission, video, as well as multimedia services consisting of a combination of these. With the air interface being the bottleneck in mobile networks, recent enhancing technologies such as the High Speed Downlink Packet Access (HSDPA), incorporate major changes to the radio access segment of 3G Universal Mobile Telecommunications System (UMTS). HSDPA introduces new features such as fast link adaptation mechanisms, fast packet scheduling, and physical layer retransmissions in the base stations, necessitating buffering of data at the air interface which presents a bottleneck to end-to-end communication. Hence, in order to provide end-to-end Quality of Service (QoS) guarantees to multimedia services in wireless networks such as HSDPA, efficient buffer management schemes are required at the air interface. The main objective of this thesis is to propose and evaluate solutions that will address the QoS optimization of multimedia traffic at the radio link interface of HSDPA systems. In the thesis, a novel queuing system known as the Time-Space Priority (TSP) scheme is proposed for multimedia traffic QoS control. TSP provides customized preferential treatment to the constituent flows in the multimedia traffic to suit their diverse QoS requirements. With TSP queuing, the real-time component of the multimedia traffic, being delay sensitive and loss tolerant, is given transmission priority; while the non-real-time component, being loss sensitive and delay tolerant, enjoys space priority. Hence, based on the TSP queuing paradigm, new buffer managementalgorithms are designed for joint QoS control of the diverse components in a multimedia session of the same HSDPA user. In the thesis, a TSP based buffer management algorithm known as the Enhanced Time Space Priority (E-TSP) is proposed for HSDPA. E-TSP incorporates flow control mechanisms to mitigate congestion in the air interface buffer of a user with multimedia session comprising real-time and non-real-time flows. Thus, E-TSP is designed to provide efficient network and radio resource utilization to improve end-to-end multimedia traffic performance. In order to allow real-time optimization of the QoS control between the real-time and non-real-time flows of the HSDPA multimedia session, another TSP based buffer management algorithm known as the Dynamic Time Space Priority (D-TSP) is proposed. D-TSP incorporates dynamic priority switching between the real-time and non-real-time flows. D-TSP is designed to allow optimum QoS trade-off between the flows whilst still guaranteeing the stringent real-time component’s QoS requirements. The thesis presents results of extensive performance studies undertaken via analytical modelling and dynamic network-level HSDPA simulations demonstrating the effectiveness of the proposed TSP queuing system and the TSP based buffer management schemes

Exploiting programmable architectures for WiFi/ZigBee inter-technology cooperation

The increasing complexity of wireless standards has shown that protocols cannot be designed once for all possible deployments, especially when unpredictable and mutating interference situations are present due to the coexistence of heterogeneous technologies. As such, flexibility and (re)programmability of wireless devices is crucial in the emerging scenarios of technology proliferation and unpredictable interference conditions. In this paper, we focus on the possibility to improve coexistence performance of WiFi and ZigBee networks by exploiting novel programmable architectures of wireless devices able to support run-time modifications of medium access operations. Differently from software-defined radio (SDR) platforms, in which every function is programmed from scratch, our programmable architectures are based on a clear decoupling between elementary commands (hard-coded into the devices) and programmable protocol logic (injected into the devices) according to which the commands execution is scheduled. Our contribution is two-fold: first, we designed and implemented a cross-technology time division multiple access (TDMA) scheme devised to provide a global synchronization signal and allocate alternating channel intervals to WiFi and ZigBee programmable nodes; second, we used the OMF control framework to define an interference detection and adaptation strategy that in principle could work in independent and autonomous networks. Experimental results prove the benefits of the envisioned solution

Optimization and Performance Analysis of High Speed Mobile Access Networks

The end-to-end performance evaluation of high speed broadband mobile access networks is the main focus of this work. Novel transport network adaptive flow control and enhanced congestion control algorithms are proposed, implemented, tested and validated using a comprehensive High speed packet Access (HSPA) system simulator. The simulation analysis confirms that the aforementioned algorithms are able to provide reliable and guaranteed services for both network operators and end users cost-effectively. Further, two novel analytical models one for congestion control and the other for the combined flow control and congestion control which are based on Markov chains are designed and developed to perform the aforementioned analysis efficiently compared to time consuming detailed system simulations. In addition, the effects of the Long Term Evolution (LTE) transport network (S1and X2 interfaces) on the end user performance are investigated and analysed by introducing a novel comprehensive MAC scheduling scheme and a novel transport service differentiation model

Overview of UMTS network evolution through radio and transmission feature validation

This project is based on several UMTS network feature validation with the aim to provide an end-to-end in-depth knowledge overview gained in parallel in the areas of radio network mobility processes (cell camping and inter-system handover), Quality of Service improvement for HSPA data users and transport network evolution towards the All-IP era.Hardware and software validation is a key step in the relationship between the mobile network operator and the vendor. Through this verification process, while executing that functionality or testing a specific hardware, the difference between the actual result and expected result can be better understood and, in turn, this in-depth knowledge acquisition is translated into a tailored usage of the product in the operator’s live network. As a result, validation helps in building a better product as per the customer’s requirement and helps satisfying their needs, which positively impacts in the future evolution of the vendor product roadmap implementation process for a specific customer. This project is based on several Universal Mobile Telecommunication Services (UMTS) network feature validation with the aim to provide an end-to-end in-depth knowledge overview gained in parallel in the areas of radio network mobility processes (cell camping and inter-system handover), Quality of Service improvement for High Speed Downlink Packet Access (HSPA) data users and transport network evolution towards the All-IP era.Las campañas de validación hardware y software son un paso clave en las relaciones comerciales establecidas entre un operador de telecomunicaciones y su proveedor de equipos de red. Durante los procesos de certificación, mientras se ejecuta una funcionalidad software o se valida un determinado hardware, se obtiene un conocimiento profundo de la diferencia entre el resultado obtenido y el esperado, repercutiendo directamente en un uso a medida de dicha funcionalidad o hardware en la propia red del cliente. Como consecuencia de lo anterior, podemos aseverar que los procesos de validación permiten en gran medida al proveedor adaptarse mejor a los requerimientos del cliente, ayudando a satisfacer realmente sus necesidades. Esto implica directamente un impacto positivo en la futura evolución del portfolio que el fabricante ofrece a un determinado cliente. Este proyecto está basado en la validación de diferentes funcionalidades de red UMTS, cuyo objetivo es proporcionar un conocimiento global de distintos aspectos que conforman el funcionamiento de una red de telecomunicaciones 3G, como son los procesos de movilidad de acceso radio (acampado de red y handover inter-sistema), las mejoras en la calidad de servicio para usuarios de datos HSPA y la convergencia de la red de transporte hacia la era IP.Els processos de validació hardware i software són un punt clau en les relacions comercials establertes entre un operador de telecomunicaciones i el proveïdor d'equipament de la xarxa. En el transcurs dels processos de certificació, a la mateixa vegada que s'executa una funcionalitat software o es valida un determinat hardware, s'obtenen grans coneixements respecte la diferència entre el resultat obtingut i l'esperat, que són d'aplicació directa a l'hora d'establir un ús adpatat a la xarxa del client. En conseqüència, podem asseverar que les campanyes de validació permeten en gran mesura al proveïdor adaptar-se millor als requeriments del client, ajudant a satisfer realment les seves necessitats. Això implica directament un impacte positiu en la futura evol.lució del portfoli que el fabricant ofereix a un determinat client. Aquest projecte es basa en la presentació d'un procès de validació de diferents funcionalitats relacionades amb la xarxa UMTS, amb l'objectiu de proporcionar un coneixement global de la varietat d'aspectes que conformen el funcionament d'una xarxa de telecomunicacions 3G, com són els processos de mobilitat en accès radio (acampat de l'usuari i handover inter-sistema), millores en la qualitat de servei per a usuaris de dades HSPA i la convergència de la xarxa de transport cap a l'era IP

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

TD-SCDMA Relay Networks

PhDWhen this research was started, TD-SCDMA (Time Division Synchronous Code Division Multiple Access) was still in the research/ development phase, but now, at the time of writing this thesis, it is in commercial use in 10 large cities in China including Beijing and Shang Hai. In all of these cities HSDPA is enabled. The roll-out of the commercial deployment is progressing fast with installations in another 28 cities being underway now. However, during the pre-commercial TD-SCDM trail in China, which started from year 2006, some interference problems have been noticed especially in the network planning and initialization phases. Interference is always an issue in any network and the goal of the work reported in this thesis is to improve network coverage and capacity in the presence of interference. Based on an analysis of TD-SCDMA issues and how network interference arises, this thesis proposes two enhancements to the network in addition to the standard N-frequency technique. These are (i) the introduction of the concentric circle cell concept and (ii) the addition of a relay network that makes use of other users at the cell boundary. This overall approach not only optimizes the resilience to interference but increases the network coverage without adding more Node Bs. Based on the cell planning parameters from the research, TD-SCDMA HSDPA services in dense urban area and non-HSDPA services in rural areas were simulated to investigate the network performance impact after introducing the relay network into a TD-SCDMA network. The results for HSDPA applications show significant improvement in the TDSCDMA relay network both for network capacity and network interference aspects compared to standard TD-SCDMA networks. The results for non- HSDPA service show that although the network capacity has not changed after adding in the relay network (due to the code limitation in TD-SCDMA), the TD-SCDMA relay network has better interference performance and greater coverage

QoS management in UMTS terrestrial radio access FDD networks

This work investigates the role and importance of some of the key aspects of QoS planning, provisioning, monitoring and optimisation (QoS Management) for UMTS Terrestrial Radio Access (UTRA) FDD networks within the framework of the 3rd Generation Partnership Project (3GPP). Firstly, the differences between Quality of end user Experience (QoE) and Quality of Service (QoS) are explained. This is followed by a review of 3GPP requirements for QoS concept and architecture. Then all models and the main assumptions in this dissertation are presented. Based on these, original QoS mechanisms in the radio access network domain, means and methods for QoS provisioning, planning, monitoring and "optimisation" are discussed. Simulation results showed substantial spectral efficiency gains provided by service (or user) differentiation in UTRAN by means of priorities and differentiated parameter settings. When appropriately configured, the proposed QoS mechanisms can greatly reduce the need for bandwidth. Performance results proved also the proposed virtual time simulator to be an appropriate tool for service driven WCDMA radio interface dimensioning and detailed radio network planning. It is also shown that measuring QoS performance by a proper classification of counters (and or gauges), based on a particular subset of radio access bearer attributes, is a promising technique for assessing performances of service applications through WCDMA networks. With this new method there is no need to trace upper layer protocols at different interfaces or dumping data in mobile terminals. The proposed metrics allow operators to measure the bandwidth required for robust statistical reliability, to assess and exploit statistical sharing of resources, to configure QoS functions effectively, and to monitor QoE. The application of the proposed technique is not limited to the WCDMA Radio Network Subsystem (RNS), yet it can be deployed in any radio access and packet core network supporting mapping of performance indicators onto a particular subset of QoS attributes. Finally, in order to maximise the performance of the available services in UTRAN, at a given QoE, simulation results showed clear needs for the network administrator to adapt the parameter settings to diverse input application traffic conditions and the proposed genetic approach to be an appropriate solution space search algorithm for this purpose.reviewe

Carrier aggregation in lte-advanced

Advancement in mobile communication technology has led to an increase in data usage due to smart electronic gadgets. Despite of increased spectrum efficiency the required data rates (1 Gbps) for 4G LTE Advanced system cannot be attained. To attain these very high data rates it is required to increase the transmission bandwidths (up to 100 MHz) over those that can be supported by a single carrier or channel. The technique being proposed is named as carrier aggregation (CA) to aggregate two or more component carriers (CCs). These channels or carriers may be contiguous components of the spectrum, or they may be in different bands resulting in Intra-band contiguous CA, Intra-band non-contiguous CA and Inter-band CA. Carrier aggregation is supported by both formats of LTE, namely the FDD and TDD variants. This guarantees that both FDD LTE and TDD LTE are capable of meeting the high data throughput requirements placed upon them. With carrier aggregation, it is likely to schedule a user equipment (UE) on multiple component carriers simultaneously i.e. multiple spectrum bands are exploited by the same user in order to fulfil the large bandwidth requirement of the service and attain enhanced performance. The first release of 3GPP LTE facilitated extensive support for deployment in spectrum allocations of several characteristics, with transmission bandwidths extending from 1.4MHz up to 20MHz in both paired and unpaired bands. One of the most significant features to drift from LTE system to LTE-A system is Carrier aggregation. Furthermore an LTE Advanced user is backward compatible with LTE. Carrier aggregation is a multi-carrier technique, where vacant SCC (Secondary Component Carrier) is combined with the PCC (Primary Component Carrier) that is allocated to the user equipment. Five component carriers each of 20 MHz are combined to increase bandwidth to 100 MHz for high data rates

Mobility: a double-edged sword for HSPA networks

This paper presents an empirical study on the performance of mobile High Speed Packet Access (HSPA, a 3.5G cellular standard) networks in Hong Kong via extensive field tests. Our study, from the viewpoint of end users, covers virtually all possible mobile scenarios in urban areas, including subways, trains, off-shore ferries and city buses. We have confirmed that mobility has largely negative impacts on the performance of HSPA networks, as fast-changing wireless environment causes serious service deterioration or even interruption. Meanwhile our field experiment results have shown unexpected new findings and thereby exposed new features of the mobile HSPA networks, which contradict commonly held views. We surprisingly find out that mobility can improve fairness of bandwidth sharing among users and traffic flows. Also the triggering and final results of handoffs in mobile HSPA networks are unpredictable and often inappropriate, thus calling for fast reacting fallover mechanisms. We have conducted in-depth research to furnish detailed analysis and explanations to what we have observed. We conclude that mobility is a double-edged sword for HSPA networks. To the best of our knowledge, this is the first public report on a large scale empirical study on the performance of commercial mobile HSPA networks