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Master-Vortrag: Convergence Analysis of BICM-ID Systems with Transformations of Extrinsic Information

Nardine Bebawi
27. April 2015
11:00 Uhr
Hörsaal 4G IKS

Bit Interleaved Coded Modulation with Iterative Decoding (BICM-ID) is characterized by the feedback of reliability information (so-called extrinsic information) from the error protection mechanism to the demodulator. By multiple, iterative exchanges of reliability information between demodulation as well as error protection significant gains can be achieved in case of an appropriate parameterization of the error protection as well as the modulation schemes. Recently, it has been proposed to apply novel Transformations of Extrinsic Information (TEI) in those situations where such an appropriate parameterization is not given by nature. The objective of this master thesis was to analyze BICM-ID with Transformations of Extrinsic Information in detail.

In a first step, a BICM-ID system with TEI was designed which uses 16-QAM modulation. For this purpose, new matrices have been identified which perform the transformation of extrinsic information. Since these matrices operate on so-called L-values representing the reliability information, new “box”-operators have been introduced and studied which became necessary for an efficient implementation of the TEI approach.

The initial simulation results of the Bit Error Rate (BER) performance revealed two specific problems: at first, there was a performance loss of the BICM-ID with TEI approach if compared to the original BICM-ID system without TEI. Secondly, no improvements have been realized for higher numbers of iteration. Solutions to both problems are investigated in deep detail in the second part of the thesis.

On one hand, it has been shown that the performance loss is due to a limitation in the Box-Minus operation. On the other hand, a convergence analysis was performed using EXIT-Charts.

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