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dc.contributor.advisorThompson, John S
dc.contributor.advisorChung, Pei-Jung
dc.contributor.advisorGrant, Peter M
dc.contributor.advisorLaurenson, David
dc.contributor.authorSong, Shuo
dc.date.accessioned2012-01-18T09:54:44Z
dc.date.available2012-01-18T09:54:44Z
dc.date.issued2011-11-22
dc.identifier.urihttp://hdl.handle.net/1842/5724
dc.description.abstractWireless sensor networks has been one of the major research topics in recent years because of its great potential for a wide range of applications. In some application scenarios, sensor nodes intend to report the sensing data to a far-field destination, which cannot be realized by traditional transmission techniques. Due to the energy limitations and the hardware constraints of sensor nodes, distributed transmit beamforming is considered as an attractive candidate for long-range communications in such scenarios as it can reduce energy requirement of each sensor node and extend the communication range. However, unlike conventional beamforming, which is performed by a centralized antenna array, distributed beamforming is performed by a virtual antenna array composed of randomly located sensor nodes, each of which has an independent oscillator. Sensor nodes have to coordinate with each other and adjust their transmitting signals to collaboratively act as a distributed beamformer. The most crucial problem of realizing distributed beamforming is to achieve carrier phase alignment at the destination. This thesis will investigate distributed beamforming from both theoretical and practical aspects. First, the bit error ratio performance of distributed beamforming with phase errors is analyzed, which is a key metric to measure the system performance in practice. We derive two distinct expressions to approximate the error probability over Rayleigh fading channels corresponding to small numbers of nodes and large numbers of nodes respectively. The accuracy of both expressions is demonstrated by simulation results. The impact of phase errors on the system performance is examined for various numbers of nodes and different levels of transmit power. Second, a novel iterative algorithm is proposed to achieve carrier phase alignment at the destination in static channels, which only requires one-bit feedback from the destination. This algorithm is obtained by combining two novel schemes, both of which can greatly improve the convergence speed of phase alignment. The advantages in the convergence speed are obtained by exploiting the feedback information more efficiently compared to existing solutions. Third, the proposed phase alignment algorithm is modified to track time-varying channels. The modified algorithm has the ability to detect channel amplitude and phase changes that arise over time due to motion of the sensors or the destination. The algorithm can adjust key parameters adaptively according to the changes, which makes it more robust in practical implementation.en
dc.contributor.sponsorChina Scholarship Councilen
dc.contributor.sponsorUniversity of Edinburgh
dc.language.isoenen
dc.publisherThe University of Edinburghen
dc.relation.hasversionShuo Song, John S. Thompson, Pei-Jung Chung, and Peter M. Grant, “BER analysis for distributed beamforming with phase errors,” IEEE Transactions on Vehicular Technology, vol. 59, no. 8, pp. 4169-4174, 2010.en
dc.relation.hasversionShuo Song, and John S. Thompson, “One-bit feedback algorithm with decreasing step size for distributed beamforming,” in Proceeding of UKIWCWS 2010 International Workshop, IIT Delhi, December 2010, pp. 1-5.en
dc.relation.hasversionShuo Song, John S. Thompson, Pei-Jung Chung, and Peter M. Grant, “Improving the one-bit feedback algorithm for distributed beamforming,” in Proceeding of WCNC 2010 International Conference, Sydney, April 2010, pp. 1-6.en
dc.relation.hasversionShuo Song, John S. Thompson, Pei-Jung Chung, and Peter M. Grant, “Probability of error for BPSK modulation in distributed beamforming with phase errors,” in Proceeding of International ITG Workshop on Smart Antennas, Berlin, February 2009, pp. 149-154.en
dc.subjectWireless sensor networksen
dc.subjectdistributed transmit beamformingen
dc.subjectbeamformingen
dc.subjectcarrier phase alignmenten
dc.titlePerformance analysis and algorithm design for distributed transmit beamformingen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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