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2011-12-16

PhD: On Modulation and Detection Schemes for ...

Doctoral student Muhammad Gufran Khan will defend his doctoral thesis in Telecommunications.

Time: 16 December 2011 at 13:00
Place: Room J1650, BTH, Campus Gräsvik, Karlskrona

Thesis title: On Modulation and Detection Schemes for Low-Complexity Impulse Radio UWB Communications

Research subject: Telecommunications

Principal supervisor and examiner: Professor Ingvar Claesson, BTH

Assistant supervisors:

  • Dr. Jörgen Nordberg, BTH
  • Dr. Benny Sällberg, BTH

Faculty examiner: Dr. Buon Kiong Lau, Lund University

Examining committee:

  • Professor Sven Nordebo, Linnaeus University, Växjö
  • Dr. Ronnie Landqvist, ST-Ericsson, Lund
  • Professor Fu-Chun Cheng, University of Reading, Storbritannien

Deputy member of examining committee: Docent Markus Fiedler, BTH

Please notify Heleen Podsedkowska no later than 9 December if you plan to attend.

Link to thesis

Abstract

Due to wealth of advantages offered by short range ultra wideband (UWB) technology, such as capacity improvement, fading reduction and localization, it has gathered a considerable attention. Distinct UWB qualities also pose many system design challenges like difficulties in using digital processing, complex channel estimation and different propagation characteristics. The main objective of the thesis is to develop and evaluate efficient modulation and detection schemes for impulse radio (IR) UWB with a focus on wireless sensor networks characterized by low cost and low power consumption. The content of the thesis comprises of five parts.

In Part I, a coherent RAKE and non-coherent energy detector (ED) and transmitted reference (TR) receivers are examined and their bit-error-rate (BER) performance is evaluated using channels measured in an industrial environment. In specific, selective RAKE (SRake) and partial RAKE (PRake) for both maximal ratio combining (MRC) and equal gain combining (EGC) are compared. Based on the analysis and simulation results, it is concluded that the SRake with the EGC is to be preferred, whereas the best complexity/performance trade-off is provided by the ED based receivers. Part II presents several signaling and detection schemes; the proposed schemes are recursive TR (R-TR), dual-doublet TR (DDTR), doublet-shift TR (DSTR) and binary pulse position modulation (BPPM)/DSTR. Analysis and simulations verify that the proposed schemes may be preferred over the conventional TR in terms of BER, energy efficiency and/or implementation complexity.

Part III presents a non-coherent kurtosis detector (KD) and a fourth-order detector (FD), which can discriminate between Gaussian noise and non-Gaussian IR-UWB signals by directly stimating the fourth-order moment of the received signal. Empirical evaluations and simulations using channel measurements conducted in a corridor, an office and a laboratory environment verify that performance of the proposed FD receiver is slightly better than the ED in the low SNR region and its performance improves as the SNR increases. Part IV presents a robust weighted ED (WED) in which the weighting coefficients are estimated adaptively based on the received stochastic data. Simulation results confirm that performance of the proposed weight estimation method is close to that of a data-aided (DA) scheme.

Finally, Part V focuses on a multi-user scenario and develops a weighted code-multiplexed TR (WCM-TR) receiver employing the robust adaptive weight estimation scheme. Secondly, a BPPM/CM-TR UWB system is presented to mitigate inter-frame interference (IFI) and multi-user interference (MUI) from other asynchronous users. The BPPM/CM-TR system is 3 dB energy-efficient and improves the BER performance by mitigating MUI/IFI in the high SNR region, while for the low SNR region and a single-user scenario, a dual-mode BPPM/CM-TR system is suggested.

 

Organizer:
School of Engineering

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