Channel Modeling and I/Q Imbalance Analysis in Wireless Networks

  • Bassant Selim

Student thesis: Doctoral Thesis

Abstract

Bassant Selim, Channel Modeling and I/Q Imbalance Analysis in Wireless Net- works, PhD. Thesis, PhD in Engineering, Department of Electrical and Computer Engineering, Khalifa University of Science and Technology, United Arab Emirates, December 2017. Any wireless communication system requires at least a transmitter, a receiver (RX) and a propagation medium called the channel. The channel determines the quality of the wireless link whereas the transceiver allows communication between the individual devices and/or their respective base station. Hence, the characterization of these two components is of paramount importance for the successful planning and deployment of wireless networks. The first part of this thesis presents a unified approach for the modeling of wireless channels by the mixture of Gaussian distribution. The proposed distribution provides an accurate approximation for the envelope and the signal-to-noise ratio distributions of any wireless fading channel. Moreover, several performance metrics including the moment generating function, the raw moments, the amount of fading, the outage probability (OP), the average channel capacity and the probability of energy detection for cognitive radio, are derived. This provides a general framework for the performance analysis of wireless communications over generalized fading conditions. Direct conversion transceivers have attracted considerable attention owing to their suitability for higher levels of integration and their reduced cost and power consumption. However, in practical communication scenarios, these transceivers inevitably suffer from radio frequency front-end related impairments with in-phase/quadrature-phase imbalance (IQI) constituting a major impairment in direct conversion transceivers. In the second part of this thesis, we investigate the effect of IQI on different wireless communication systems. This is achieved by first considering different modulation schemes over single-carrier (SC) and multi-carrier (MC) systems and developing a general framework for the symbol error rate (SER) analysis of coherent phase shift keying, noncoherent differential phase shift keying and noncoherent frequency shift keying under IQI. Moreover, non-orthogonal multiple access (NOMA), a promising candidate for 5G systems, is studied under IQI where analytic expressions for the SINR and the OP of both SC and MC NOMA systems are derived. Capitalizing on these results, it is demonstrated that the effects of IQI differ considerably between the different considered scenarios where some cases of SC transmission appear robust to IQI, whereas MC systems experiencing IQI at the RX usually require compensation in order to achieve a reliable communication link.
Date of AwardDec 2017
Original languageAmerican English
SupervisorSami Muhaidat (Supervisor)

Keywords

  • Fading channels
  • mixture of Gaussian
  • performance analysis
  • I/Q imbalance
  • symbol error rate
  • coherent detection
  • noncoherent detection
  • outage probability
  • non-orthogonal multiple access.

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