Circuits, Systems & Signal Processing

, Volume 28, Issue 3, pp 409–431 | Cite as

Flexible Frequency-Band Reallocation: Complex Versus Real

  • Amir Eghbali
  • Håkan Johansson
  • Per Löwenborg


This paper discusses a new approach for implementing flexible frequency-band reallocation (FFBR) networks for bentpipe satellite payloads which are based on variable oversampled complex-modulated filter banks (FBs). We consider two alternatives to process real signals using real input/output and complex input/output FFBR networks (or simply real and complex FFBR networks, respectively). It is shown that the real case has a lower overall number of processing units, i.e., adders and multipliers, compared to its complex counterpart. In addition, the real system eliminates the need for two Hilbert transformers, further reducing the arithmetic complexity. An analysis of the computational workload shows that the real case has a smaller rate of increase in the arithmetic complexity with respect to the prototype filter order and number of FB channels. This makes the real case suitable for systems with a large number of users. Furthermore, in the complex case, a high efficiency in FBR comes at the expense of high-order Hilbert transformers; thus, trade-offs are necessary. Finally, the performance of the two alternatives based on the error vector magnitude (EVM) for a 16-quadrature amplitude modulation (QAM) signal is presented.


Flexible frequency-band reallocation Multi-input multi-output Discrete Fourier transform Hilbert transformer Arithmetic complexity Error vector magnitude 


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Copyright information

© Birkhäuser Boston 2009

Authors and Affiliations

  • Amir Eghbali
    • 1
  • Håkan Johansson
    • 1
  • Per Löwenborg
    • 1
  1. 1.Division of Electronics Systems, Department of Electrical EngineeringLinköping UniversityLinköpingSweden

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