Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references.

Satellites will play an indispensable role in the deployment of commercial networks to meet an increasing demand for supporting multimedia services at high data rates. Next generation satellite systems, operating at high frequency bands offer large bandwidth and are able to provide broadband services. To interface satellite links with existing terrestrial networks for providing communication access to a variety of users directly, several performance issues need to be addressed. Current thesis presents a technically viable satellite-integrated network model that is efficient in carrying broadband services to users over a wide scattered area. Accurate prediction of attenuation level is necessary for a reliable network model to operate with required service availability. Long term rainfall data has been analysed to characterise attenuation level at a selected region such as Dhaka. It is shown that rainfall is highly seasonal and attenuation level is quite high during monsoon. However, the seasonal behaviour of rainfall can be exploited to improve the link availability. Radar and rain gauge measurements at Sparsholt are also used to find rain cell size distribution, which is an important factor in site diversity implementation to combat severe rain fade. It is found that convective rain cell has extension in the region of 10 km. The network model is designed with dimensioning the effective bandwidth to support a number of users over the satellite link by taking into account the multimedia traffic characteristics. Concatenated coding, a robust coding scheme is implemented to improve the link quality at a level required to deliver broadband services. The ITU-T performance objectives of 7.5×10 for CLR and 1.4×10 for CER over satellite links are met at a required Eb/No of 2.95 dB and 2.88 dB respectively. Different enhancement mechanisms for optimum TCP performance are implemented to combat the large propagation delay associated with a satellite link. It is revealed through the simulation that TCP performance over a satellite link is as efficient as terrestrial links with these enhancement mechanisms Finally, the overall performance of the designed network is evaluated through link budget analysis and simulation. An innovative downlink power control strategy has been implemented to maintain the link during the rainiest months. The interference level due to high power satellite transmission in the designed system is also calculated to protect other existing communication links sharing the same frequency bands. A feasible broadband network designed with characterising propagation as well as networking issues will efficiently deliver broadband communication services to a large population promptly and in a cost-effective manner. Such a network solution will be in the realm of current R & D towards broadband satellite 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.

The use of satellites for mobile communication applications has become a global issue. The use of handheld, vehicle mounted and transportable terminals is a key feature of Satellite Personal Communication Networks (S-PCNs). Due to the higher eirp requirements on the Earths surface and also because of their inherent delay, geostationary (GEO) satellites are not considered suitable for such applications. Instead, constellations of satellites at lower altitudes have been proposed for use in what are termed 2nd generation mobile satellite communication systems. Low intensity regions in the Earths surrounding trapped radiation bands, have resulted in two altitude bands of specific interest, resulting in two constellation types - LEO (Low Earth Orbit) constellations at around 1,000 km and MEO (Medium Earth Orbit) constellations at around 10,000 km. A satellite constellation consists of a number of satellites orbiting at the same altitude and inclination and phased in a specific way. The work reported in this thesis proposes a network control architecture for LEO or MEO based S-PCN systems. Air-interface signalling aspects are then considered for mobility management and call setup signalling. LEO and MEO constellation design aspects and properties are initially considered. Important implications on the control network are drawn based on constellation coverage and connectivity properties. Other system constraints such as terrestrial network interworking considerations as well as user, network operator and regulator requirements are also considered. Finally network and more specifically satellite control signalling is examined before a S-PCN architecture is proposed. The reference architecture results in constellation control being distributed globally with individual satellite control, at any one time, being located at a specific earth station. The use of two earth station types allows network administration to be separated from traffic channel carrying aspects. In order to reduce system setup cost and delay, the reuse of network related standards from the GSM terrestrial mobile communication system is envisaged. An equivalence is made between the S-PCN architecture and the GSMs terrestrial architecture. Network implementation aspects are considered for a 14 satellite MEO constellation. Network implications resulting from the use of LEO and MEO constellations are considered. After an examination of S-PCN traffic demand on a MEO constellation, mobility management signalling is considered. A new approach is proposed based on the use of a positioning system. The performance of this approach is examined from a system signalling viewpoint for both LEO and MEO constellations and a method to minimise the required amount of signalling is described. The air interface signalling procedure for location update, based on a modified GSM network layer protocol, is simulated from a delay point of view for both LEO and MEO constellations. User-originated, user-terminated and user-to-user call setup signalling were also simulated and their delay performance examined. The importance of random access channel delay and of user cooperation with the link were highlighted as aspects which have a significant influence on the average signalling delay. Finally, the effect of common and dedicated control channel system signalling on satellite power consumption, based on busy hour call setup and mobility management signalling estimates, was examined for a MEO constellation. From this, conclusions can be made on the signalling power efficiency of S-PCN systems.

The frequency spectrum allocated to cellular mobile telephone systems is very limited. Efficient channel assignment schemes can significantly increase the utilization of the available frequency channels. Virtually Fixed Channel Assignment (VFCA) is a dynamic channel assignment method. The idea behind it is simple: each cell is allocated a set of nominal channels. A call request generated in a cell is assigned a nominal channel if one is available. Otherwise, a channel from an adjacent cell is borrowed to serve this call as long as frequency interference constraints are satisfied. VFCA is a promising method because (i) it is efficient in channel assignment, and (ii) it is relatively easy to implement compared to other dynamic channel assignment methods. VFCA has been analyzed based primarily on simulation studies in the past twenty years. In this thesis, we focus our study on development of new channel borrowing strategies and analytical models for VFCA. The contribution of this work is summarized as follows. (1) Development of an queuing model for performance analysis of VFCA. This model may also be used to conduct sensitivity analysis on some system parameters when VFCA is used. (2) Proposed a new channel reservation scheme for handoffs. (In a cellular system, when a call using a channel crosses a cell boundary, it needs to be handed off to a new channel in the new cell. This is called a handoff.) An optimization model for this channel reservation scheme is developed. (3) Applied the fluid-flow approach to modeling an integrated mobile cellular system that uses VFCA to estimate the distribution of data queue length in a cell of the system. These results are useful in the design, performance analysis and optimization of VFCA schemes.

The worldwide demand for personal communication system (PCS) devices is motivating the development of compact, high-performance antennas. It is also prompting a better understanding of the effects of the user and the mobile communication environment on the antenna performance. The objective of this dissertation is to add to the current knowledge in both areas. Using the Finite-Difference Time-Domain (FDTD) technique, a monopole antenna and a diversity antenna were modeled for PCS applications. Also, techniques were developed and applied to facilitate the accurate numerical analysis of PCS antennas and to investigate the electromagnetic interaction between PCS antennas and the mobile communication environment. A monopole antenna and a polarization diversity antenna (PDA) were investigated at frequencies near 900 MHz. Antenna performance was evaluated in terms of the far-field radiation patterns, the mean effective gain (MEG), the radiation efficiency and the specific absorption rate (SAR) of energy in the user's body. For the diversity antenna, the statistical independence of the two diversity branches was determined from the correlation coefficient. The antenna modeling incorporated the antenna, a cellular telephone handset, models of the user's head and hand, and a statistical model of the mobile environment. Two mobile environments, an urban outdoor environment and a suburban outdoor environment, were modeled. The results show that (i) changing the antenna configuration from the monopole antenna to the PDA significantly affects the antenna efficiency and SAR in the user’s body; (ii) the type of mobile communication environment chosen (urban or suburban) has a pronounced effect on the correlation coefficient of the PDA and on the MEGs of the PDA and the monopole antenna; (iii) in terms of the MEG, the PDA is more sensitive than the monopole antenna to the presence of the user’s body; and (iv) overall, the PDA performs better than the monopole antenna in terms of antenna efficiency, peak averaged SAR in the head, and MEG. The accurate FDTD modeling of wires is crucial to the FDTD analysis of PCS antennas, particularly as monopole antennas and other linear wire antennas are often used with PCS devices. A study of the FDTD modeling of thin wires is included in this dissertation. The accuracy of the wire models was determined by calculating the input impedance of a dipole antenna over a broad range of dipole radii and comparing with the results of a Method of Moments formulation. Two existing thin wire models were analyzed and found to be inaccurate for some purposes. This finding led to the development of a new model, which includes a special treatment of the field components at the wire ends and a model of the source region. The proposed wire model is more accurate than the two existing wire models for a given spatial resolution. Thus, this new wire model facilitates accurate computations of input impedance and resonant frequency for linear wire antennas. The stability of the wire model was addressed, and a formulation for the maximum stability coefficient to be used with the proposed thin wire model was developed. / Graduate

by Shu-chuen Lee. / "Revised : September 1994." / Thesis (M.Phil.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 61-62). / Acknowledgment --- p.i / Lists of Illustration --- p.ii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- References --- p.4 / Chapter Chapter 2 --- The Meandering Inverted-F Antenna --- p.5 / Chapter 2.1 --- Evolution of the antenna --- p.6 / Chapter 2.2 --- The first prototype --- p.10 / Chapter 2.2.1 --- Geometry of the first prototype --- p.10 / Chapter 2.2.2 --- Resonant frequency --- p.12 / Chapter 2.2.3 --- Bandwidth --- p.16 / Chapter 2.3 --- Antenna with longer meandering line --- p.17 / Chapter 2.4 --- Antenna loaded with dielectric substrate --- p.20 / Chapter 2.4.1 --- Frequency characteristics --- p.21 / Chapter 2.4.2 --- Radiation pattern measurements --- p.22 / Chapter 2.4.3 --- Radiation patterns --- p.26 / Chapter 2.5 --- The 1.9GHz antenna --- p.34 / Chapter 2.6 --- Summary --- p.36 / Chapter 2.7 --- References --- p.37 / Chapter Chapter 3 --- The Meandering Posted Microstrip Antenna --- p.38 / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Theory --- p.40 / Chapter 3.3 --- Meandering Inverted-F antenna implemented on PCB --- p.44 / Chapter 3.3.1 --- Geometry for the antenna --- p.44 / Chapter 3.3.2 --- Microstrip bends --- p.45 / Chapter 3.3.3 --- Frequency characteristics --- p.47 / Chapter 3.3.4 --- Implementation of the microstrip antenna with different line width --- p.49 / Chapter 3.3.5 --- Radiation patterns --- p.51 / Chapter 3.4 --- Physical realization --- p.58 / Chapter 3.5 --- Summary --- p.60 / Chapter 3.6 --- References --- p.61 / Chapter Chapter 4 --- Conclusions --- p.63

Thesis (M.Eng.)(Electronic)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references.

The growth of the mobile communication subscription is the main driver of the operators¡¦ revenues, before the appearance of 3G mobile communication service. As the penetration rate of mobile phones jumped over 100% in Taiwan, it¡¦s obvious that the life cycle of the GSM system has shifted to the mature stage, which all of the operators are under the pressure of low growth rate of voice service and declining ARPU rate due to the fierce price war in the market, and started to introduce 3G service. The 3G mobile communication technology offers users higher speed data communication, mobile commerce solutions, and multimedia services on the current 2G mobile communication basis. This has brought hope to mobile communication industry. In order to enhance the value-added services, operators must evolve its current role, which simply provide equipment and infrastructure service, to become a total solution provider that can integrate the whole industry value chain vertically. Therefore, this study mainly focuses on the 3G industry value chain and the competitive strategies. Moreover, this study will discuss global mobile communication development circumstances and the operation strategies of the worldwide leading players, in order to come up with appropriate managing tactics. Hopefully, the successful experience from successful companies can help Taiwan operators to understand more about the trend of global communication market strategies

In the development of the global telecommunication industry, the telecommunications market in China is very important for development and planning of Multinational Corporations¡¦ (MNCs) global overall arrangement. Thus, the main purpose of this research is to discover the trend of international telecommunications industry, especially mobile communication industry. In addition, discuss the position and importance of China¡¦s telecommunications market within the global market under the framework of international telecommunication market. Moreover, we have to further analyze the policy and planning of the China government. Furthermore, We have to discuss the strategies and cooperated cases of telecom operators and equipment manufacturers in China¡¦s telecommunication market. Besides, Understanding the considerations of China government¡¦s criteria and principle of opening 3G in mainland China¡¦s telecommunication market is also an important issue. Finally, we have to realize what kind of role that foreign telecom firms act in the development of the China¡¦s telecommunications market.