Abstract
Development of the Fourth Generation of mobile communication systems, or 4G, has already
begun in various organizations and research institutions worldwide. There is currently
no single conclusive definition for 4G systems, and the process of 4G standardization will
only begin after the World Radiocommunication Conference in 2007. The purpose of this
report is to provide an objective definition of 4G systems based on user requirements, and
to use this definition to determine an appropriate 4G access network architecture.
By examining the current trends in user requirements, and the methodologies proposed by
different researchers, an objective definition of 4G systems was developed. The definition
states that the purpose of 4G systems is to provide users with the capacity to access any
service at any time at a reasonable cost and at the required levels of quality. There are
two developmental methodologies which are currently being considered to achieve this objective:
first the evolution and convergence of existing systems, including cellular, IT and
broadcasting communication systems, and second, the development of a new 4G access
network capable of providing users with access to advanced services. The primary specification
for this new access network is that it must provide a throughput of 1 Mbps for mobile
users and 1 Gbps for users that are stationary. Other requirements include high spectral
efficiency and high capacity and coverage.
The primary focus of this report is the examination of the second of the above methodologies
by evaluating the performance of candidate 4G air-interface architectures so that a
recommendation could be made as to which of the architectures is the preferred choice as the
core component in a new 4G access network. Orthogonal Frequency Division Multiplexing
(OFDM) modulation is a high performance modulation technique capable of achieving high
levels of spectral efficiency and is widely accepted as the technique most capable of meeting
4G access network requirements. There are two primary access network architectures that
make use of OFDM modulation and could form the core components of a 4G air-interface,
the physical component of a 4G access network. To determine which architecture is the
appropriate choice for 4G systems, a series of simulations were run using realistic models
of a wireless environment. The results of those simulations were analyzed, and it was
determined that, due to the absence of multiple access interference found in MC-CDMA,
OFDMA systems better met the defined requirements for a 4G air-interface. The use of
additional techniques such as radio resource management, multi-antennae technologies and
software defined radios are cited as potential methods for improving both OFDMA and
MC-CDMA performance.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/4903 |
| Date | 29 May 2008 |
| Creators | Van den Bergh, Ryan Michael |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 1070633 bytes, application/pdf, application/pdf |
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