59 research outputs found
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
On the performance and capacity of space-time block coded multicarrier CDMA communication systems
Ph.DDOCTOR OF PHILOSOPH
Comparative Evaluation of UMTS, WLAN, BWA, MBWA, and UWB Systems
UMTS, WLAN, BWA and UWB systems are compared in this paper. The comparative analysis covers system capacity, QoS, and radiowave propagation
Convergence of packet communications over the evolved mobile networks; signal processing and protocol performance
In this thesis, the convergence of packet communications over the evolved mobile networks is studied. The Long Term Evolution (LTE) process is dominating the Third Generation Partnership Project (3GPP) in order to bring technologies to the markets in the spirit of continuous innovation. The global markets of mobile information services are growing towards the Mobile Information Society.
The thesis begins with the principles and theories of the multiple-access transmission schemes, transmitter receiver techniques and signal processing algorithms. Next, packet communications and Internet protocols are referred from the IETF standards with the characteristics of mobile communications in the focus. The mobile network architecture and protocols bind together the evolved packet system of Internet communications to the radio access network technologies. Specifics of the traffic models are shortly visited for their statistical meaning in the radio performance analysis. Radio resource management algorithms and protocols, also procedures, are covered addressing their relevance for the system performance. Throughout these Chapters, the commonalities and differentiators of the WCDMA, WCDMA/HSPA and LTE are covered. The main outcome of the thesis is the performance analysis of the LTE technology beginning from the early discoveries to the analysis of various system features and finally converging to an extensive system analysis campaign. The system performance is analysed with the characteristics of voice over the Internet and best effort traffic of the Internet. These traffic classes represent the majority of the mobile traffic in the converged packet networks, and yet they are simple enough for a fair and generic analysis of technologies. The thesis consists of publications and inventions created by the author that proposed several improvements to the 3G technologies towards the LTE. In the system analysis, the LTE showed by the factor of at least 2.5 to 3 times higher system measures compared to the WCDMA/HSPA reference. The WCDMA/HSPA networks are currently available with over 400 million subscribers and showing increasing growth, in the meanwhile the first LTE roll-outs are scheduled to begin in 2010. Sophisticated 3G LTE mobile devices are expected to appear fluently for all consumer segments in the following years
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
Realizing mobile multimedia systems over emerging fourth-generation wireless technologies
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.Includes bibliographical references (p. [161]-167) and index.by Pei-Jeng Kuo.M.Eng
Efficient Radio Resource Allocation Schemes and Code Optimizations for High Speed Downlink Packet Access Transmission
An important enhancement on the Wideband Code Division Multiple Access
(WCDMA) air interface of the 3G mobile communications, High Speed Downlink
Packet Access (HSDPA) standard has been launched to realize higher spectral
utilization efficiency. It introduces the features of multicode CDMA transmission
and Adaptive Modulation and Coding (AMC) technique, which makes radio resource
allocation feasible and essential. This thesis studies channel-aware resource
allocation schemes, coupled with fast power adjustment and spreading code optimization
techniques, for the HSDPA standard operating over frequency selective
channel.
A two-group resource allocation scheme is developed in order to achieve a
promising balance between performance enhancement and time efficiency. It only
requires calculating two parameters to specify the allocations of discrete bit rates
and transmitted symbol energies in all channels. The thesis develops the calculation
methods of the two parameters for interference-free and interference-present
channels, respectively. For the interference-present channels, the performance of
two-group allocation can be further enhanced by applying a clustering-based channel
removal scheme.
In order to make the two-group approach more time-efficient, reduction in
matrix inversions in optimum energy calculation is then discussed. When the
Minimum Mean Square Error (MMSE) equalizer is applied, optimum energy allocation
can be calculated by iterating a set of eigenvalues and eigenvectors. By
using the MMSE Successive Interference Cancellation (SIC) receiver, the optimum
energies are calculated recursively combined with an optimum channel ordering
scheme for enhancement in both system performance and time efficiency.
This thesis then studies the signature optimization methods with multipath
channel and examines their system performances when combined with different
resource allocation methods. Two multipath-aware signature optimization methods
are developed by applying iterative optimization techniques, for the system
using MMSE equalizer and MMSE precoder respectively. A PAM system using
complex signature sequences is also examined for improving resource utilization
efficiency, where two receiving schemes are proposed to fully take advantage of
PAM features. In addition by applying a short chip sampling window, a Singular
Value Decomposition (SVD) based interference-free signature design method is
presented
Adaptive multicoding and robust linear-quadratic receivers for uncertain CDMA frequency-selective fading channels
Wideband Code Division Multiple Access (WCDMA) communications in the presence of channel uncertainty poses a challenging problem with many practical applications in the wireless communications filed. In this dissertation, robust linear-quadratic (LQ) receivers for time-varying, frequency-selective CDMA channels in the presence of uncertainty regarding instantaneous channel state information are proposed and studied. In order to enhance the performance of the LQ receivers, a novel modulation technique adaptive multicoding is employed. We proposed a simple, intuitively appealing cost function the modified deflection ratio that can be maximized to find signal constellations and associated LQ receivers that are optimal in a certain sense. We discuss the properties of the proposed LQ cost function and derive a related adaptive algorithm for the simultaneous design of signals and receivers based on a simple multicoding technique. The Chernoff bound for the LQ receivers is also derived to compensate for the analytical intractability of the probability of bit error. Finally, in order to achieve higher data rate transmission in favorable channels, we extend our approach from binary signals to M-ary signal constellations in a multi-dimension subspace
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
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