Maximum Likelihood Decoding of M-ary modulated signals for Multi-Carrier Spread-Sprectrum systems

Authors: A. Dekorsy, S. Fischer, K.-D. Kammeyer
Abstract: For a multi­carrier spread­spectrum (MC­SS) system, the inner spreading can be optimized by applying M­ary orthogonal mod­ulation. In this paper, we investigate the concatenation of max­imum likelihood (ML) Viterbi decoding with M­ary orthogonal demodulation in a MC­SS system. The system operates over a frequency­ selective Rayleigh fading indoor channel in the up­ link. We first evaluate the bit specific log­likelihood ratio for ML Viterbi decoding and present an estimation of the ratio exploiting the MC technique. Furthermore, the trade­off between channel coding, M­ary orthogonal modulation and simple spreading will be considered by Monte­Carlo simulations. The results are al­ways compared with BPSK performance and they emphasize for the concerned indoor transmission scenario that a moderate bit­ error­rate can only be achieved if M­ary orthogonal modulation
is employed.
All simulations are related to the European Hiperlan/2 standard­ization whereas the results are generally valid.
Document type: Conference Paper
Publication: Boston, USA, 8. - 11. September 1998
Conference: IEEE 9th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 98)
Index: 45
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