Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533184
Title: Low complexity channel estimation for OFDM based satellite systems
Author: Zhu, Mo
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2011
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Abstract:
The demand for high data rate and high user mobility has driven modern wireless communications into a new era, in which advanced technologies are developed to facilitate the fulfilment of such demands, as well as to guarantee the quality of service of transmissions under adverse channel conditions. OFDM has become a popular choice for wideband high data rate communication systems due to its strength in mitigating frequency selective fading as well as inter-symbol interference. However, OFDM operation faces a number of challenges, such as high channel estimation complexity and sensitivity to Doppler shift. In this thesis, we investigate channel estimation techniques for OFDM systems, especially with a view to the optimisation of estimation accuracy at low complexity, so as to maximise the practicability and minimise the cost of user terminals. Firstly, we investigate channel estimation techniques for an OFDM based satellite mobile broadcast system DVB-SH. The main difficulty DVB-SH faces is its large frame size that drastically increases the channel estimation complexity. We have proposed an optimised estimation scheme that has much lower complexity, whilst minimising performance degradation. Secondly, we investigate the impact of severe inter-carrier interference caused by large Doppler shift. Inter-carrier interference damages the orthogonality between subcarriers and leads to performance degradation. In order to optimise the existing interference cancellation techniques, we have proposed an adaptive cancellation scheme that achieves a significant performance improvement over existing technique whilst the computational complexity is maintained at the same level. Finally, we consider channel estimation in the time-domain in the presence of synchronisation errors. We have proposed a low-complexity time-domain scheme that compensates performance degradation due to synchronisation errors. The proposed scheme achieves near-ideal accuracy at low speed while it can be widely applicable to many existing systems.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.533184  DOI: Not available
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