Date of Award

2014

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Electrical & Electronic Engineering

First Advisor

Dr. Dirk Pesch

Second Advisor

Prof. Michael Kuhn

Abstract

Existing wireless communication systems of emergency services mainly enable ordinary unicast or broadcast voice communications. The increasing demand for data services such as messaging, file transfer, maps, etc requires those long-range communication systems to provide higher data rates while maintaining robustness against link failures. In this thesis, various aspects of a link layer design specifically for narrowband mobile ad-hoc networks (MANETs) that are targeted at emergency services are investigated.

The major aspect of this thesis is the optimisation of a time division multiple access (TDMA) design considering both efficient and reliable multicast resource reservation. An approach to mathematically describe a TDMA design with respect to a set of input parameters is presented. This thesis contributes an approach in order to enable reduction of dead times within slots and TDMA frames for systems considering link adaptation. The basic principle is the transformation of large time slots designed to accommodate of data bursts into blocks of small consecutive time slots. Furthermore, a simplified auxiliary node selection algorithm for multicast resource reservations based on geographical single-hop topology information is presented. The algorithm is able to reduce both the signalling overhead for reservation and the time until the algorithm achieves correct operation (equilibrium) by at least 50 percent compared to the state of the art Narrowband Waveform (NBWF) draft standard reference system.

Since signalling overhead is critical for narrowband MANETs, performance of narrowband systems incorporating link adaptation with respect to delayed feedback and feedback interval is studied. Simulation results confirm the ability of link adaptation in (multi-hop) scenarios to trade throughput for coverage, which provides network designers with an additional degree of freedom.

In order to study MANETs at the system level a framework for Monte Carlo computer simulation has been developed by extending existing open source software. In this context, this thesis contributes a resource efficient approach for modelling spatially correlated shadowing reducing complexity in terms of memory occupation from 0(n2) to 0(n). The proposed approach is based on pregenerated maps representing shadowing fluctuations for geographic locations.

Access Level

info:eu-repo/semantics/openAccess

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