Document Type Master's Dissertation Author Thomas, Robin Rajan email@example.com URN etd-08062012-141451 Document Title Optimisation of adaptive localisation techniques for cognitive radio Degree MEng Department Electrical, Electronic and Computer Engineering Supervisor
Advisor Name Title Prof B T Maharaj Supervisor Keywords
- bandwidth efficiency
- cognitive radio
- maximum-likelihood estimation
- multiband positioning
- least squares estimation
- location awareness
Date 2012-09-06 Availability unrestricted AbstractSpectrum, environment and location awareness are key characteristics of cognitive radio (CR). Knowledge of a userís location as well as the surrounding environment type may enhance various CR tasks, such as spectrum sensing, dynamic channel allocation and interference management. This dissertation deals with the optimisation of adaptive localisation techniques for CR. The first part entails the development and evaluation of an efficient bandwidth determination (BD) model, which is a key component of the cognitive positioning system. This bandwidth efficiency is achieved using the Cramer-Rao lower bound derivations for a single-input-multiple-output (SIMO) antenna scheme. The performances of the single-input-single-output (SISO) and SIMO BD models are compared using three different generalised environmental models, viz. rural, urban and suburban areas. In the case of all three scenarios, the results reveal a marked improvement in the bandwidth efficiency for a SIMO antenna positioning scheme, especially for the 1◊3 urban case, where a 62% root mean square error (RMSE) improvement over the SISO system is observed.
The second part of the dissertation involves the presentation of a multiband time-ofarrival (TOA) positioning technique for CR. The RMSE positional accuracy is evaluated using a fixed and dynamic bandwidth availability model. In the case of the fixed bandwidth availability model, the multiband TOA positioning model is initially evaluated using the two-step maximum-likelihood (TSML) location estimation algorithm for a scenario where line-of-sight represents the dominant signal path. Thereafter, a more realistic dynamic bandwidth availability model has been proposed, which is based on data obtained from an ultra-high frequency spectrum occupancy measurement campaign. The RMSE performance is then verified using the non-linear least squares, linear least squares and TSML location estimation techniques, using five different bandwidths. The proposed multiband positioning model performs well in poor signal-to-noise ratio conditions (-10 dB to 0 dB) when compared to a single band TOA system. These results indicate the advantage of opportunistic TOA location estimation in a CR environment.
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Please cite as follows:
Thomas, RR 2012, Optimisation of adaptive localisation techniques for cognitive radio , MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-08062012-141451/ >
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