Communications over noncoherent doubly selective channels

 
 
 
 

Communications over noncoherent doubly selective channels

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dc.contributor.advisor Schniter, Philip en_US
dc.contributor.author Pachai Kannu, Arun en_US
dc.date.accessioned 2008-07-07T18:48:07Z
dc.date.available 2008-07-07T18:48:07Z
dc.date.created 2007 en_US
dc.date.issued 2008-07-07T18:48:07Z
dc.identifier.uri http://rave.ohiolink.edu/etdc/view?acc_num=osu1173887288 en_US
dc.identifier.uri http://hdl.handle.net/2374.OX/4722
dc.description Wireless communication systems transferring broadband data in high mobility situations encounter fading channels which are both time and frequency selective. In the noncoherent scenario, the time varying impulse response of the doubly selective channel (DSC) is not available at both the transmitter and the receiver. In this dissertation, we consider the problem of communications over such noncoherent doubly selective channels. Our work has two main themes: to find the fundamental limits on the information rates for reliable communication across noncoherent DSC and to develop simple and efficient encoding/decoding techniques to achieve the promised information rates. Towards this end, we consider block transmissions over DSC and utilize complex-exponential (CE) basis expansion model (BEM) to characterize the channel variation within a block. For noncoherent CE-BEM DSC, we characterize the prelog factor of the constrained ergodic channel capacity in the high SNR regime, when the channel inputs are continuously distributed. Next, we consider the design of pilot aided transmissions (PAT) for CE-BEM DSC, which embeds known pilot signals that the receiver uses to estimate the channel. For a given fixed pilot energy, we derive the necessary and sufficient conditions on the pilot/data pattern to attain minimum mean squared error (MMSE), uncover time-frequency duality of MMSE-PAT structures and obtain novel MMSE-PAT patterns. We obtain bounds on the ergodic achievable rates of MMSE-PAT schemes and perform high signal to noise ratio (SNR) asymptotic analysis which suggests that, a multi-carrier MMSE-PAT achieves higher rates than a single-carrier MMSE-PAT when the channel's delay spread dominates its Doppler spread, and vice versa. We also establish that the pre-log factor of the ergodic rates of all the MMSE-PAT patterns are strictly less than that of the constrained channel capacity, for strictly doubly selective channels. We also design spectrally efficient PAT schemes whose asymptotic achievable rates have the same pre-log factor as that of the constrained channel capacity. Our results provide insights on how the DSC's delay spread and Doppler spread influence the constrained channel capacity and the PAT design. We also extend the MMSE-PAT design to multi-input multi-output (MIMO) CE-BEM DSC. en_US
dc.format application/pdf en_US
dc.rights unrestricted en_US
dc.rights Copyright and permissions information available at the source archive en_US
dc.subject Noncoherent channels en_US
dc.subject doubly selective channels en_US
dc.subject doubly dispersive channels en_US
dc.subject noncoherent communication en_US
dc.subject spectral efficiency en_US
dc.subject channel capacity en_US
dc.subject achievable rates en_US
dc.subject pilot symbols en_US
dc.subject training symbols en_US
dc.subject channel estimation en_US
dc.subject minimum mean squared error en_US
dc.title Communications over noncoherent doubly selective channels en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name PhD en_US
dc.degree.level doctoral en_US
dc.degree.discipline Electrical Engineering en_US
dc.degree.grantor Ohio State University en_US
dc.contributor.publisher Ohio State University / OhioLINK en_US

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