Zur Spektrumseffizienz von Schicht-2 Relais im zellularen Mobilfunk
Authors: Weiss, Erik
Chair of Communication Networks (ComNets), Faculty 6, RWTH Aachen University
Ph. D. Dissertation RWTH Aachen University, ABMT 62, p. 237 , ISBN: 3-86130-942-762, Wissenschaftsverlag Mainz, Year: 2010.
Abstract This thesis investigates a new concept to improve the capacity and coverage of a classic multi-cellular radio network. This concept introduces a new station class named Relay Station (RS). RSs are wirelessly connected to the Access Point (AP), the central point in each cell. Cells equipped with one or more RSs are called Relay Enhanced Cells (RECs). A multi-cellular radio network comprises several cells each established by an AP. In today?s networks Mobile Station (MS) can only connect directly to the AP. The quality of the link between AP and MS depends on its length. If the distance between AP and MS is short, the radio conditions are in most cases good. Under good radio conditions high data rates and high service quality can be offered to the MS. However, at the cell boarder the distance to the AP is long and the signal pathloss is high. Hence, MSs at cell boarder suffer from high intercell interference and high signal attenuation resulting in low signal to noise ratio (SINR). As a consequence, the achievable quality of service and data rate experienced by the customer is low. This is a main drawback of today?s cellular networks: The cell capacity is not distributed evenly accross the cell area. In most cases only customers in close vicinity to the AP experience high capacity whereas customers at the cell boarder suffer from low data rate and low user throughput. For these reasons network operators plan their networks to achive a minimum service at the cell boarder that is still good enough to satisfy the customer. A consequence of this is, that, although the full capacity of a cell might not be required in a certain area, a new cell has to be deployed, since otherwise the service quality at the cell boarder would be too low. Deploying a new cell with the related site costs (rental, maintenance, backhauling, and energy) is the main cost driver for today?s networks. RSs introduced to cellular networks is a spectrally efficient and cost optimum solution. RSs help to distribute the capacity available from the AP evenly in the cell and are therefore on the one hand a measure to optimise the cell capacity. On the other hand RSs may be used to improve the quality of service in the cell and extend the cell coverage supported by one AP. Capacity-improving RSs may be placed within the cell whereas RSs focussing on coverage extension have to be placed close to the cell boarder, or even outside a cell, if the link between AP and RS is supported by antenna gain. Within this thesis, a new analytical evaluation framework is developed that allows to evaluate the upper bound capacity and spectral efficiency of different RS deployment examples. The upper bound capacity is an important parameter, since it provides for the first time a measure for the performance of existing and upcoming wireless access protocols in terms of capacity achieved in a given scenario. By this researchers are enabled to rate a protocol proposed and to understand better which protocol refinements to which extent improve the cell capacity towards the upper bound capacity. The analytical evaluation results give clear evidence of the value of RSs in cellular systems. The results show that RSs improve the cell capacity and increase the spectral efficiency of a system. RECs have to support MSs communicating directly with the AP or multihop via RSs. Thus, RECs have to face more complex protocols for mobility management. This work also evaluates the usability of known routing protocols in RECs. It turns out that some routing protocols perform acceptably well in RECs. The respective results indicate that it is worth developing new or to optimise existing routing protocols for operation in RECs. This will lead to a higher overall system performance.
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Bibtex
@PHDTHESIS{Diss_ErikWeiss_2010,
AUTHOR = {Weiss, E. },
TITLE = {Zur Spektrumseffizienz von Schicht-2 Relais im zellularen Mobilfunk},
YEAR = {2010},
MONTH = {Feb},
PAGES = {237},
PUBLISHER = {Wissenschaftsverlag Mainz},
ADDRESS = {ComNets Research Group, Aachen, Germany},
SCHOOL = {RWTH Aachen University},
SERIES = {ABMT},
EDITION = {1},
AFFILIATION = {Department of Communication Networks (ComNets), Faculty 6, RWTH Aachen University},
ISBN = {3-86130-942-762 }, URL = {https://www.comnets.rwth-aachen.de}
}