Overhead Modellierung und Analyse für IMT Advanced Systeme
Kurzbeschreibung
The candidate should initially review the signaling concepts in LTE, Winner and WiMAX. Apart from this research on system implementations, the candidate uses state-of-the art tools with the WNS simulator.
A signaling scheme for up- and down-link will be implemented and statistically evaluated for different scheduling algorithms.
The third step contains designing more efficient signaling schemes which require less resources. A further degree of freedom to be exploited is the scheduler itself, which can be extended to take the caused signaling information into account. This allows to understand the trade-off between overhead and performance.
Contacts:
Rainer Schoenen, COMNETS, rs@comnets.rwth-aachen.de
James Gross, UMIC MNP, gross@umic.rwth-aachen.de
Inhalt
Next
generation, cellular systems are based on the paradigm to constantly
adapt transmission parameters like power, modulation type, error
coding, spectral resources per user etc. to the current state of the
wireless channel as well as to the current state (and semantics) of
transmission queues. This applies for example to two prominent OFDM
systems currently under standardization: LTE (long-term evolution) as
well as IEEE 802.16e (also referred to as mobile WiMAX). In both
systems OFDMA is applied as multiple access scheme which enables the
division of the sub-carriers into disjoint sets used to convey
packets to different receivers mainly in the down-link. It is well
known that such schemes can increase the system performance
significantly. New techniques like Dynamic Subcarrier Assignment,
Adaptive Modulation&Coding and Adaptive Power Allocation are very
promising. However, these schemes also require a lot of signaling
overhead to be taken into account, i.e. the transmitter has to be
informed (prior to the down-link transmission) about the current
channel states while the receivers have to be informed about their
next set of sub-carriers to receive data on. While system studies
have focused so far on the performance of multi-user OFDMA systems,
they have put only little effort into the overhead characterization.
In this thesis, a detailed consideration is to be performed leading
potentially to new/improved overhead representations.
RHEINISCH – WESTFÄLISCHE
n
detail the candidate should initially review the signaling concepts
in LTE, Winner and WiMAX. This requires literature research as well
as reading through standardization documents. Apart from this
research on system implementations, the candidate is asked to work
through some basic literature as well as the state-of-the art of the
WNS simulation tool used later on for performance evaluation.
As
second step the candidate should implement a signaling scheme for up-
and down-link and statistically evaluate its behavior for different
scheduling algorithms. Focus here is on obtaining statements
regarding the probability of requiring more than a specified amount
of signaling symbols per down-link phase (see Figure above). These
investigations shall be done for LTE primarily.
The
third step contains designing more efficient signaling schemes which
require less resources. For up-link information, lossy coding can be
exploited in order to reduce the overhead. This is not possible for
the down-link. A further degree of freedom to be exploited is the
scheduler itself, which can be extended to take the caused signaling
information into account. This allows to understand the trade-off
between overhead and performance. Optionally further fields of
investigations contain hybrid ARQ and taking error effects (mainly
due to inter-cell interference) into account. Multi-hop extensions
are a further optional problem set to be addressed.
The
thesis is supervised by COMNETS and the UMIC mobile network
performance group. The candidate is expected to have a sound
knowledge of wireless networks and to some extend about physical
layer techniques. As simulation is the main tool for performance
evaluation, the candidate should also bring some programming skills
in C++. We expect motivated thesis candidates which are willing to
learn during their thesis many important engineering skills.
Extensive supervising is granted while the successful candidate is
expected to publish his results in a scientific paper (under guidance
of the supervisors).
Contacts:
Rainer Schoenen, COMNETS, rs@comnets.rwth-aachen.de
James Gross, UMIC MNP, gross@umic.rwth-aachen.de
Letzte Änderung: 22-07-08
