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PAPR Reduction in MIMO-OFDM Systems

Ferdosizadeh Naeiny, Mahmoud | 2011

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 41711 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Marvasti, Farrokh
  7. Abstract:
  8. In this thesis, some algorithms for PAPR reduction of OFDM systems are investigated and some of these methods are extended to MIMO-OFDM systems. Two types of multiple antenna OFDM systems are considered; OFDM systems with spatial multiplexing for increasing the data rate and OFDM systems with spatial diversity for improvement of the symbol error rate. For the systems of the first type we have proposed two PAPR reduction algorithms. In the first method, the signals of transmitter antennas are clipped and filtered independently. Then, at the receiver side an iterative algorithm is proposed to compensate for the clipping noise. In the second method, we have extended TR method to spatial multiplexing OFDM systems. In this method, in each transmitter branch some subcarriers are reserved for PAPR reduction. In each iteration, the antenna with maximum PAPR is selected and its reserved tones are updated such that the overall PAPR is reduced. The performance of the proposed method is better than the case where the TR method is applied to the signal of antennas independently. We have also proposed some algorithms for PAPR reduction of spatial diversity OFDM systems with Space-Frequency Block Coding (SFBC). Three variants of ACE method have been proposed for SFBC-OFDM systems. The first two algorithms are based on POCS method and the second one is metric based. All of these algorithms hold the SFBC structure, thus the diversity order remains unchanged. The performance of these methods is very close to the performance of the original methods for the single antenna OFDM systems. In other part of this thesis, we have proposed SLM method for PAPR reduction of SFBC-OFDM systems and a blind detection algorithm has been introduced for the receiver side. In this algorithm the intrinsic redundancy of space frequency codes are used to detect the index of the applied phase sequence. Thus, SLM method can be used without transmission of side information.

  9. Keywords:
  10. Multiple Input Multiple Output (MIMO)System ; Fading Channel ; Orthogonal Frequency Division Multiplexing (OFDM) ; Peak to Average Power Ratio ; Maximum Likelihood Estimation ; Selected Mapping ; Active Constellation Extension (ACE)

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