Linear amplification with multiple nonlinear devices

• Author(s): Astúcia, Vítor Hugo Soares
• Date: 2012
• Persistent ID: http://hdl.handle.net/10362/8229
• Origin: Repositório Institucional da UNL
• Subject(s): Nonlinear amplification; Voronoi; QAM; IB-DFE; Gain/Phase imbalances; SC-FDE
• Document Type: Master thesis
• Language: English
• Advisor(s): Dinis, Rui; Montezuma, Paulo
• Contributor(s): RUN

Description

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e Computadores

In mobile wireless systems, where there are strict power and bandwidth constrains it is desirable to adopt energy efficient constellations combined with powerful equalizer. However, this increased spectral efficiency of multilevel modulations comes at the expense of reduced power efficiency, which is undesirable in systems where power consumption is a constraint. Hence, minimization of the transmitted energy would enable a significant reduction in the total energy consumption of the wireless mobile devices. A simple and practical constellation optimization design would optimize the transmitted energy with a minimum increase in system complexity. The constellation decomposition in terms of a sum of BPSK (Bi-Phase Shift Keying) sub-constellations, relies on an analytical characterization of the mapping rule were the constellation symbols are written as a linear function of the transmitted bits. Moreover, large constellations in general and non-uniform constellations in particular are very sensitive to interference, namely the residual ISI (Inter-Symbol Interference) at the output of a practical equalizer that does not invert completely the channel effects. IB-DFE(Iterative Block DFE) is a promising iterative frequency domain equalization technique for SC-FDE schemes (Single-Carrier with Frequency Domain Equalization) that allows excellent performance. Therefore it is possible to use the decomposition of constellations on BPSK components to define a pragmatic method for designing IB-DFE receivers that can be employed with any constellation. In this thesis we consider SC-DFE schemes based on high orderM-ary energy optimized constellations with IB-DFE receivers. It is proposed a method for designing the receiver that does not require a significant increase in system complexity and can be used for the computation of the receiver parameters for any constellation. This method is then employed to design iterative receivers, implemented in the frequency-domain, which can cope with higher sensitivity to ISI effects of the constellations resulting from the energy optimization process.

Fundação para a Ciência e Tecnologia - MPSat (PTDC/EEA-TEL/099074/2008) project