Soft handover issues in radio resource management for 3G WCDMA networks

PhDMobile terminals allow users to access services while on the move. This unique feature has driven the rapid growth in the mobile network industry, changing it from a new technology into a massive industry within less than two decades. Handover is the essential functionality for dealing with the mobility of the mobile users. Compared with the conventional hard handover employed in the GSM mobile networks, the soft handover used in IS-95 and being proposed for 3G has better performance on both link and system level. Previous work on soft handover has led to several algorithms being proposed and extensive research has been conducted on the performance analysis and parameters optimisation of these algorithms. Most of the previous analysis focused on the uplink direction. However, in future mobile networks, the downlink is more likely to be the bottleneck of the system capacity because of the asymmetric nature of new services, such as Internet traffic. In this thesis, an in-depth study of the soft handover effects on the downlink direction of WCDMA networks is carried out, leading to a new method of optimising soft handover for maximising the downlink capacity and a new power control approach

Issues on packet transmissioin strategies in a TDD-TD/CDMA scenario

This paper presents a packet transmission scheme that deals with the problems of a TDD CDMA scenario with different levels of frame structure asymmetry in adjacent base stations by distributing the users in the slots depending on their Time Advance. A multiple access protocol and a scheduling algorithm are also proposed to provide a certain degree of Quality of Service.Peer ReviewedPostprint (published version

Self-organising comprehensive handover strategy for multi-tier LTE-advanced heterogeneous networks

Long term evolution (LTE)-advanced was introduced as real fourth generation (4G) with its new features and additional functions, satisfying the growing demands of quality and network coverage for the network operators' subscribers. The term muti-tier has also been recently used with respect to the heterogeneity of the network by applying the various subnetwork cooperative systems and functionalities with self-organising capabilities. Using indoor short-range low-power cellular base stations, for example, femtocells, in cooperation with existing long-range macrocells are considered as the key technical challenge of this multi-tier configuration. Furthermore, shortage of network spectrum is a major concern for network operators which forces them to spend additional attentions to overcome the degradation in performance and quality of services in 4G HetNets. This study investigates handover between the different layers of a heterogeneous LTE-advanced system, as a critical attribute to plan the best way of interactive coordination within the network for the proposed HetNet. The proposed comprehensive handover algorithm takes multiple factors in both handover sensing and decision stages, based on signal power reception, resource availability and handover optimisation, as well as prioritisation among macro and femto stations, to obtain maximum signal quality while avoiding unnecessary handovers

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

Power control for WCDMA

This project tries to introduce itself in the physical implementations that make possible the denominated third generation mobile technology. As well as to know the technology kind that makes possible, for example, a video-call in real time. During this project, the different phases passed from the election of WCDMA like the access method for UMTS will appear. Its coexistence with previous network GSM will be analyzed, where the compatibility between systems has been one of the most important aspects in the development of WCDMA, the involved standardization organisms in the process, as well as the different protocols that make the mobile communications within a network UTRAN possible. Special emphasis during the study of the great contribution that has offered WCDMA with respect to the control of power of the existing signals will be made. The future lines that are considered in the present, and other comment that already are in their last phase of development in the field of the mobile technology. UMTS through WCDMA can be summarized like a revolution of the air interface accompanied by a revolution in the network of their architecture

An emulator framework for a new radio resource management for QoS guaranteed services in W-CDMA

In the context of third-generation (3G) systems a mix of services with different requirements are expected. Consequently, packet scheduling mechanisms for quality of service (QoS) guarantees will play a key role. This paper proposes a new scheduling strategy that makes consistent the target quality in the radio link with the priority level assigned to each user. The performance of such a strategy is assessed by system level simulations and, in order to gain more insight into the difficulties of this optimization problem, it is compared to other alternatives. This work is part of the Wineglass project, within the Fifth Framework Program of the European Commission (IST), where a real time demonstrator including the radio resource management tasks is being developed. Thus, an implementation approach of the proposed scheduling is also described. The implementation is based on lookup tables and this approach is validated by simulation.Peer Reviewe

Interference analysis of and dynamic channel assignment algorithms in TD–CDMA/TDD systems

The radio frequency spectrum for commercial wireless communications has become an expensive commodity. Consequently, radio access techniques are required which enable the efficient exploitation of these resources. This, however, is a difficult task due to an increasing diversity of wireless services. Hence, in order to achieve acceptable spectrum efficiency a flexible air– interface is required. It has been demonstrated that code division multiple access (CDMA) provides flexibility by enabling efficient multi user access in a cellular environment. In addition, time division duplex (TDD) as compared to frequency division duplex (FDD) represents an appropriate method to cater for the asymmetric use of a duplex channel. However, the TDD technique is subject to additional interference mechanisms in particular if neighbouring cells require different rates of asymmetry. If TDD is combined with an interference limited multiple access technique such as CDMA, the additional interference mechanism represents an important issue. This issue poses the question of whether a CDMA/TDD air–interface can be used in a cellular environment. The problems are eased if a hybrid TDMA (time division multiple access) / CDMA interface (TD–CDMA) is used. The reason for this is that the TDMA component adds another degree of freedom which can be utilised to avoid interference. This, however, requires special channel assignment techniques. This thesis analyses cellular CDMA/TDD systems used in indoor environments. A key parameter investigated is the interference in such systems. In the interference analysis a special focus is placed on adjacent channel interference since the jamming entity and victim entity can be in close proximity. The interference analysis shows that co–location of BS’s using adjacent channels is not feasible for an adjacent channel protection factor that is less than 40 dB and frame synchronisation errors of more than 10%. Furthermore, it is demonstrated that ideal frame synchronisation does not necessarily yield the highest capacity. As a consequence, a new technique termed ’TS–opposing’ is introduced. This method is intended to enable a cellular TD–CDMA/TDD system to apply cell independent channel asymmetry. For this purpose, a centralised DCA is developed. It is found that this algorithm indeed enables neighbouring cells to adopt different rates of asymmetry without a significant capacity loss. Moreover, a decentralised DCA algorithm based on the TS–opposing principle is developed. In this context, a novel TS assignment concept is proposed which reduces the complexity associated with the TS–opposing technique. In addition, the TS assignment plan allows for full spatial coverage. It is shown that the capacity of a TD–CDMA/TDD interface can be greater than the capacity of an equivalent FDD interface. The performance of the decentralised DCA algorithm is limited by the interference in the uplink. Therefore, additional methods which assist in reducing the interference in the uplink are envisaged to further improve the performance of the decentralised DCA algorithm. The exploitation of the TS–opposing technique in two different ways demonstrates that this method can be used to improve the performance of a TD–CDMA/TDD system significantly

The new enhancement of UMTS: HSDPA and HSUPA

During the last two decades, the world of the mobile communications grew a lot, as a consequence of the increasing necessity of people to communicate. Now, the mobile communications still need to improve for satisfies the user demands. The new enhancement of UMTS in concrete HSDPA and HSUPA is one of these improvements that the society needs. HSDPA and HSUPA which together are called HSPA, give to the users higher data rates in downlink and uplink. The higher data rates permit to the operators give more different types of services and at the same time with better quality. As a result, people can do several new applications with their mobile terminals like applications that before a computer and internet connection were required, now it is possible to do directly with the mobile terminal. This thesis consists in study these new technologies denominated HSDPA and HSUPA and thus know better the last tendencies in the mobile communications. Also it has a roughly idea about the future tendencies

Terminal LTE flexível

Mstrado em Engenharia Eletrónica e TelecomunicaçõesAs redes móveis estão em constante evolução. A geração atual (4G) de redes celulares de banda larga e representada pelo standard Long Term Evolution (LTE), definido pela 3rd Generation Partnership Project (3GPP). Existe uma elevada procura/uso da rede LTE, com um aumento exponencial do número de dispositivos móveis a requerer uma ligação à Internet de alto débito. Isto pode conduzir à sobrelotação do espetro, levando a que o sinal tenha que ser reforçado e a cobertura melhorada em locais específicos, tal como em grandes conferências, festivais e eventos desportivos. Por outro lado, seria uma vantagem importante se os utilizadores pudessem continuar a usar os seus equipamentos e terminais em situações onde o acesso a redes 4G é inexistente, tais como a bordo de um navio, eventos esporádicos em localizações remotas ou em cenários de catástrofe, em que as infraestruturas que permitem as telecomunicações foram danificadas e a cobertura temporária de rede pode ser decisiva em processos de salvamento. Assim sendo, existe uma motivação clara por trás do desenvolvimento de uma infraestrutura celular totalmente reconfigurável e que preencha as características mencionadas anteriormente. Uma possível abordagem consiste numa plataforma de rádio definido por software (SDR), de código aberto, que implementa o standard LTE e corre em processadores de uso geral (GPPs), tornando possível construir uma rede completa investindo somente em hardware - computadores e front-ends de radiofrequência (RF). Após comparação e análise de várias plataformas LTE de código aberto foi selecionado o OpenAirInterface (OAI) da EURECOM, que disponibiliza uma implementação compatível com a Release 8.6 da 3GPP (com parte das funcionalidades da Release 10). O principal objectivo desta dissertação é a implementação de um User Equipment (UE) flexível, usando plataformas SDR de código aberto que corram num computador de placa única (SBC) compacto e de baixa potência, integrado com um front-end de RF - Universal Software Radio Peripheral (USRP). A transmissão de dados em tempo real usando os modos de duplexagem Time Division Duplex (TDD) e Frequency Division Duplex (FDD) é suportada e a reconfiguração de certos parâmetros é permitida, nomeadamente a frequência portadora, a largura de banda e o número de Resource Blocks (RBs) usados. Além disso, é possível partilhar os dados móveis LTE com utilizadores que estejam próximos, semelhante ao que acontece com um hotspot de Wi-Fi. O processo de implementação é descrito, incluindo todos os passos necessários para o seu desenvolvimento, englobando o port do UE de um computador para um SBC. Finalmente, a performance da rede é analisada, discutindo os valores de débitos obtidos.Mobile networks are constantly evolving. 4G is the current generation of broadband cellular network technology and is represented by the Long Term Evolution (LTE) standard, de ned by 3rd Generation Partnership Project (3GPP). There's a high demand for LTE at the moment, with the number of mobile devices requiring an high-speed Internet connection increasing exponentially. This may overcrowd the spectrum on the existing deployments and the signal needs to be reinforced and coverage improved in speci c sites, such as large conferences, festivals and sport events. On the other hand, it would be an important advantage if users could continue to use their equipment and terminals in situations where cellular networks aren't usually available, such as on board of a cruise ship, sporadic events in remote locations, or in catastrophe scenarios in which the telecommunication infrastructure was damaged and the rapid deployment of a temporary network can save lives. In all of these situations, the availability of exible and easily deployable cellular base stations and user terminals operating on standard or custom bands would be very desirable. Thus, there is a clear motivation for the development of a fully recon gurable cellular infrastructure solution that ful lls these requirements. A possible approach is an open-source, low-cost and low maintenance Software-De ned Radio (SDR) software platform that implements the LTE standard and runs on General Purpose Processors (GPPs), making it possible to build an entire network while only spending money on the hardware itself - computers and Radio-Frequency (RF) front-ends. After comparison and analysis of several open-source LTE SDR platforms, the EURECOM's OpenAirInterface (OAI) was chosen, providing a 3GPP standard-compliant implementation of Release 8.6 (with a subset of Release 10 functionalities). The main goal of this dissertation is the implementation of a exible opensource LTE User Equipment (UE) software radio platform on a compact and low-power Single Board Computer (SBC) device, integrated with an RF hardware front-end - Universal Software Radio Peripheral (USRP). It supports real-time Time Division Duplex (TDD) and Frequency Division Duplex (FDD) LTE modes and the recon guration of several parameters, namely the carrier frequency, bandwidth and the number of LTE Resource Blocks (RB) used. It can also share its LTE mobile data with nearby users, similarly to a Wi-Fi hotspot. The implementation is described through its several developing steps, including the porting of the UE from a regular computer to a SBC. The performance of the network is then analysed based on measured results of throughput